Merge "Remove restriction on exported plugins that generate APIs"
diff --git a/android/Android.bp b/android/Android.bp
index 26605a7..279d442 100644
--- a/android/Android.bp
+++ b/android/Android.bp
@@ -6,6 +6,7 @@
         "blueprint-bootstrap",
         "soong",
         "soong-android-soongconfig",
+        "soong-bazel",
         "soong-env",
         "soong-shared",
         "soong-ui-metrics_proto",
@@ -15,6 +16,7 @@
         "apex.go",
         "api_levels.go",
         "arch.go",
+        "arch_list.go",
         "bazel_handler.go",
         "config.go",
         "csuite_config.go",
diff --git a/android/androidmk.go b/android/androidmk.go
index cfd7c91..4adbb22 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -417,7 +417,7 @@
 type androidMkSingleton struct{}
 
 func (c *androidMkSingleton) GenerateBuildActions(ctx SingletonContext) {
-	if !ctx.Config().EmbeddedInMake() {
+	if !ctx.Config().KatiEnabled() {
 		return
 	}
 
diff --git a/android/androidmk_test.go b/android/androidmk_test.go
index 10527b9..bb03378 100644
--- a/android/androidmk_test.go
+++ b/android/androidmk_test.go
@@ -78,7 +78,7 @@
 	`
 
 	config := TestConfig(buildDir, nil, bp, nil)
-	config.inMake = true // Enable androidmk Singleton
+	config.katiEnabled = true // Enable androidmk Singleton
 
 	ctx := NewTestContext(config)
 	ctx.RegisterSingletonType("androidmk", AndroidMkSingleton)
@@ -250,7 +250,7 @@
 
 	for _, testCase := range testCases {
 		config := TestConfig(buildDir, nil, testCase.bp, nil)
-		config.inMake = true // Enable androidmk Singleton
+		config.katiEnabled = true // Enable androidmk Singleton
 
 		ctx := NewTestContext(config)
 		ctx.RegisterSingletonType("androidmk", AndroidMkSingleton)
diff --git a/android/apex.go b/android/apex.go
index 276f7a4..a4ff0f9 100644
--- a/android/apex.go
+++ b/android/apex.go
@@ -25,32 +25,54 @@
 )
 
 var (
+	// This is the sdk version when APEX was first introduced
 	SdkVersion_Android10 = uncheckedFinalApiLevel(29)
 )
 
-// ApexInfo describes the metadata common to all modules in an apexBundle.
+// ApexInfo describes the metadata about one or more apexBundles that an apex variant of a module is
+// part of.  When an apex variant is created, the variant is associated with one apexBundle. But
+// when multiple apex variants are merged for deduping (see mergeApexVariations), this holds the
+// information about the apexBundles that are merged together.
+// Accessible via `ctx.Provider(android.ApexInfoProvider).(android.ApexInfo)`
 type ApexInfo struct {
-	// Name of the apex variation that this module is mutated into, or "" for
-	// a platform variant.  Note that a module can be included in multiple APEXes,
-	// in which case, the module is mutated into one or more variants, each of
-	// which is for one or more APEXes.
+	// Name of the apex variation that this module (i.e. the apex variant of the module) is
+	// mutated into, or "" for a platform (i.e. non-APEX) variant. Note that a module can be
+	// included in multiple APEXes, in which case, the module is mutated into one or more
+	// variants, each of which is for an APEX. The variants then can later be deduped if they
+	// don't need to be compiled differently. This is an optimization done in
+	// mergeApexVariations.
 	ApexVariationName string
 
-	// Serialized ApiLevel. Use via MinSdkVersion() method. Cannot be stored in
-	// its struct form because this is cloned into properties structs, and
-	// ApiLevel has private members.
+	// Serialized ApiLevel that this module has to support at minimum. Should be accessed via
+	// MinSdkVersion() method. Cannot be stored in its struct form because this is cloned into
+	// properties structs, and ApiLevel has private members.
 	MinSdkVersionStr string
 
-	// True if the module comes from an updatable APEX.
-	Updatable    bool
+	// True if this module comes from an updatable apexBundle.
+	Updatable bool
+
+	// The list of SDK modules that the containing apexBundle depends on.
 	RequiredSdks SdkRefs
 
-	InApexes     []string
+	// List of apexBundles that this apex variant of the module is associated with. Initially,
+	// the size of this list is one because one apex variant is associated with one apexBundle.
+	// When multiple apex variants are merged in mergeApexVariations, ApexInfo struct of the
+	// merged variant holds the list of apexBundles that are merged together.
+	InApexes []string
+
+	// Pointers to the ApexContents struct each of which is for apexBundle modules that this
+	// module is part of. The ApexContents gives information about which modules the apexBundle
+	// has and whether a module became part of the apexBundle via a direct dependency or not.
 	ApexContents []*ApexContents
 }
 
 var ApexInfoProvider = blueprint.NewMutatorProvider(ApexInfo{}, "apex")
 
+// mergedName gives the name of the alias variation that will be used when multiple apex variations
+// of a module can be deduped into one variation. For example, if libfoo is included in both apex.a
+// and apex.b, and if the two APEXes have the same min_sdk_version (say 29), then libfoo doesn't
+// have to be built twice, but only once. In that case, the two apex variations apex.a and apex.b
+// are configured to have the same alias variation named apex29.
 func (i ApexInfo) mergedName(ctx PathContext) string {
 	name := "apex" + strconv.Itoa(i.MinSdkVersion(ctx).FinalOrFutureInt())
 	for _, sdk := range i.RequiredSdks {
@@ -59,14 +81,19 @@
 	return name
 }
 
-func (this *ApexInfo) MinSdkVersion(ctx PathContext) ApiLevel {
-	return ApiLevelOrPanic(ctx, this.MinSdkVersionStr)
+// MinSdkVersion gives the api level that this module has to support at minimum. This is from the
+// min_sdk_version property of the containing apexBundle.
+func (i ApexInfo) MinSdkVersion(ctx PathContext) ApiLevel {
+	return ApiLevelOrPanic(ctx, i.MinSdkVersionStr)
 }
 
+// IsForPlatform tells whether this module is for the platform or not. If false is returned, it
+// means that this apex variant of the module is built for an APEX.
 func (i ApexInfo) IsForPlatform() bool {
 	return i.ApexVariationName == ""
 }
 
+// InApex tells whether this apex variant of the module is part of the given apexBundle or not.
 func (i ApexInfo) InApex(apex string) bool {
 	for _, a := range i.InApexes {
 		if a == apex {
@@ -76,102 +103,111 @@
 	return false
 }
 
-// ApexTestForInfo stores the contents of APEXes for which this module is a test and thus has
-// access to APEX internals.
+// ApexTestForInfo stores the contents of APEXes for which this module is a test - although this
+// module is not part of the APEX - and thus has access to APEX internals.
 type ApexTestForInfo struct {
 	ApexContents []*ApexContents
 }
 
 var ApexTestForInfoProvider = blueprint.NewMutatorProvider(ApexTestForInfo{}, "apex_test_for")
 
-// Extracted from ApexModule to make it easier to define custom subsets of the
-// ApexModule interface and improve code navigation within the IDE.
+// DepIsInSameApex defines an interface that should be used to determine whether a given dependency
+// should be considered as part of the same APEX as the current module or not. Note: this was
+// extracted from ApexModule to make it easier to define custom subsets of the ApexModule interface
+// and improve code navigation within the IDE.
 type DepIsInSameApex interface {
-	// DepIsInSameApex tests if the other module 'dep' is installed to the same
-	// APEX as this module
+	// DepIsInSameApex tests if the other module 'dep' is considered as part of the same APEX as
+	// this module. For example, a static lib dependency usually returns true here, while a
+	// shared lib dependency to a stub library returns false.
 	DepIsInSameApex(ctx BaseModuleContext, dep Module) bool
 }
 
-// ApexModule is the interface that a module type is expected to implement if
-// the module has to be built differently depending on whether the module
-// is destined for an apex or not (installed to one of the regular partitions).
+// ApexModule is the interface that a module type is expected to implement if the module has to be
+// built differently depending on whether the module is destined for an APEX or not (i.e., installed
+// to one of the regular partitions).
 //
-// Native shared libraries are one such module type; when it is built for an
-// APEX, it should depend only on stable interfaces such as NDK, stable AIDL,
-// or C APIs from other APEXs.
+// Native shared libraries are one such module type; when it is built for an APEX, it should depend
+// only on stable interfaces such as NDK, stable AIDL, or C APIs from other APEXes.
 //
-// A module implementing this interface will be mutated into multiple
-// variations by apex.apexMutator if it is directly or indirectly included
-// in one or more APEXs. Specifically, if a module is included in apex.foo and
-// apex.bar then three apex variants are created: platform, apex.foo and
-// apex.bar. The platform variant is for the regular partitions
-// (e.g., /system or /vendor, etc.) while the other two are for the APEXs,
-// respectively.
+// A module implementing this interface will be mutated into multiple variations by apex.apexMutator
+// if it is directly or indirectly included in one or more APEXes. Specifically, if a module is
+// included in apex.foo and apex.bar then three apex variants are created: platform, apex.foo and
+// apex.bar. The platform variant is for the regular partitions (e.g., /system or /vendor, etc.)
+// while the other two are for the APEXs, respectively. The latter two variations can be merged (see
+// mergedName) when the two APEXes have the same min_sdk_version requirement.
 type ApexModule interface {
 	Module
 	DepIsInSameApex
 
 	apexModuleBase() *ApexModuleBase
 
-	// Marks that this module should be built for the specified APEX.
-	// Call this before apex.apexMutator is run.
+	// Marks that this module should be built for the specified APEX. Call this BEFORE
+	// apex.apexMutator is run.
 	BuildForApex(apex ApexInfo)
 
-	// Returns true if this module is present in any APEXes
-	// directly or indirectly.
-	// Call this after apex.apexMutator is run.
+	// Returns true if this module is present in any APEX either directly or indirectly. Call
+	// this after apex.apexMutator is run.
 	InAnyApex() bool
 
-	// Returns true if this module is directly in any APEXes.
-	// Call this after apex.apexMutator is run.
+	// Returns true if this module is directly in any APEX. Call this AFTER apex.apexMutator is
+	// run.
 	DirectlyInAnyApex() bool
 
-	// Returns true if any variant of this module is directly in any APEXes.
-	// Call this after apex.apexMutator is run.
+	// Returns true in the primary variant of a module if _any_ variant of the module is
+	// directly in any apex. This includes host, arch, asan, etc. variants. It is unused in any
+	// variant that is not the primary variant. Ideally this wouldn't be used, as it incorrectly
+	// mixes arch variants if only one arch is in an apex, but a few places depend on it, for
+	// example when an ASAN variant is created before the apexMutator. Call this after
+	// apex.apexMutator is run.
 	AnyVariantDirectlyInAnyApex() bool
 
-	// Tests if this module could have APEX variants. APEX variants are
-	// created only for the modules that returns true here. This is useful
-	// for not creating APEX variants for certain types of shared libraries
-	// such as NDK stubs.
+	// Tests if this module could have APEX variants. Even when a module type implements
+	// ApexModule interface, APEX variants are created only for the module instances that return
+	// true here. This is useful for not creating APEX variants for certain types of shared
+	// libraries such as NDK stubs.
 	CanHaveApexVariants() bool
 
-	// Tests if this module can be installed to APEX as a file. For example,
-	// this would return true for shared libs while return false for static
-	// libs.
+	// Tests if this module can be installed to APEX as a file. For example, this would return
+	// true for shared libs while return false for static libs because static libs are not
+	// installable module (but it can still be mutated for APEX)
 	IsInstallableToApex() bool
 
-	// Tests if this module is available for the specified APEX or ":platform"
+	// Tests if this module is available for the specified APEX or ":platform". This is from the
+	// apex_available property of the module.
 	AvailableFor(what string) bool
 
-	// Return true if this module is not available to platform (i.e. apex_available
-	// property doesn't have "//apex_available:platform"), or shouldn't be available
-	// to platform, which is the case when this module depends on other module that
-	// isn't available to platform.
+	// Returns true if this module is not available to platform (i.e. apex_available property
+	// doesn't have "//apex_available:platform"), or shouldn't be available to platform, which
+	// is the case when this module depends on other module that isn't available to platform.
 	NotAvailableForPlatform() bool
 
-	// Mark that this module is not available to platform. Set by the
+	// Marks that this module is not available to platform. Set by the
 	// check-platform-availability mutator in the apex package.
 	SetNotAvailableForPlatform()
 
-	// List of APEXes that this module tests. The module has access to
-	// the private part of the listed APEXes even when it is not included in the
-	// APEXes.
+	// Returns the list of APEXes that this module is a test for. The module has access to the
+	// private part of the listed APEXes even when it is not included in the APEXes. This by
+	// default returns nil. A module type should override the default implementation. For
+	// example, cc_test module type returns the value of test_for here.
 	TestFor() []string
 
-	// Returns nil if this module supports sdkVersion
-	// Otherwise, returns error with reason
+	// Returns nil (success) if this module should support the given sdk version. Returns an
+	// error if not. No default implementation is provided for this method. A module type
+	// implementing this interface should provide an implementation. A module supports an sdk
+	// version when the module's min_sdk_version is equal to or less than the given sdk version.
 	ShouldSupportSdkVersion(ctx BaseModuleContext, sdkVersion ApiLevel) error
 
-	// Returns true if this module needs a unique variation per apex, for example if
-	// use_apex_name_macro is set.
+	// Returns true if this module needs a unique variation per apex, effectively disabling the
+	// deduping. This is turned on when, for example if use_apex_name_macro is set so that each
+	// apex variant should be built with different macro definitions.
 	UniqueApexVariations() bool
 }
 
+// Properties that are common to all module types implementing ApexModule interface.
 type ApexProperties struct {
-	// Availability of this module in APEXes. Only the listed APEXes can contain
-	// this module. If the module has stubs then other APEXes and the platform may
-	// access it through them (subject to visibility).
+	// Availability of this module in APEXes. Only the listed APEXes can contain this module. If
+	// the module has stubs then other APEXes and the platform may access it through them
+	// (subject to visibility).
 	//
 	// "//apex_available:anyapex" is a pseudo APEX name that matches to any APEX.
 	// "//apex_available:platform" refers to non-APEX partitions like "system.img".
@@ -179,29 +215,23 @@
 	// Default is ["//apex_available:platform"].
 	Apex_available []string
 
-	// AnyVariantDirectlyInAnyApex is true in the primary variant of a module if _any_ variant
-	// of the module is directly in any apex.  This includes host, arch, asan, etc. variants.
-	// It is unused in any variant that is not the primary variant.
-	// Ideally this wouldn't be used, as it incorrectly mixes arch variants if only one arch
-	// is in an apex, but a few places depend on it, for example when an ASAN variant is
-	// created before the apexMutator.
-	AnyVariantDirectlyInAnyApex bool `blueprint:"mutated"`
-
-	// DirectlyInAnyApex is true if any APEX variant (including the "" variant used for the
-	// platform) of this module is directly in any APEX.
-	DirectlyInAnyApex bool `blueprint:"mutated"`
-
-	// DirectlyInAnyApex is true if any APEX variant (including the "" variant used for the
-	// platform) of this module is directly or indirectly in any APEX.
+	// See ApexModule.InAnyApex()
 	InAnyApex bool `blueprint:"mutated"`
 
+	// See ApexModule.DirectlyInAnyApex()
+	DirectlyInAnyApex bool `blueprint:"mutated"`
+
+	// See ApexModule.AnyVariantDirectlyInAnyApex()
+	AnyVariantDirectlyInAnyApex bool `blueprint:"mutated"`
+
+	// See ApexModule.NotAvailableForPlatform()
 	NotAvailableForPlatform bool `blueprint:"mutated"`
 
+	// See ApexModule.UniqueApexVariants()
 	UniqueApexVariationsForDeps bool `blueprint:"mutated"`
 }
 
-// Marker interface that identifies dependencies that are excluded from APEX
-// contents.
+// Marker interface that identifies dependencies that are excluded from APEX contents.
 type ExcludeFromApexContentsTag interface {
 	blueprint.DependencyTag
 
@@ -209,85 +239,122 @@
 	ExcludeFromApexContents()
 }
 
-// Marker interface that identifies dependencies that should inherit the DirectlyInAnyApex
-// state from the parent to the child.  For example, stubs libraries are marked as
-// DirectlyInAnyApex if their implementation is in an apex.
+// Marker interface that identifies dependencies that should inherit the DirectlyInAnyApex state
+// from the parent to the child. For example, stubs libraries are marked as DirectlyInAnyApex if
+// their implementation is in an apex.
 type CopyDirectlyInAnyApexTag interface {
 	blueprint.DependencyTag
 
+	// Method that differentiates this interface from others.
 	CopyDirectlyInAnyApex()
 }
 
-// Provides default implementation for the ApexModule interface. APEX-aware
+// ApexModuleBase provides the default implementation for the ApexModule interface. APEX-aware
 // modules are expected to include this struct and call InitApexModule().
 type ApexModuleBase struct {
 	ApexProperties ApexProperties
 
 	canHaveApexVariants bool
 
-	apexVariationsLock sync.Mutex // protects apexVariations during parallel apexDepsMutator
-	apexVariations     []ApexInfo
+	apexInfos     []ApexInfo
+	apexInfosLock sync.Mutex // protects apexInfos during parallel apexDepsMutator
 }
 
+// Initializes ApexModuleBase struct. Not calling this (even when inheriting from ApexModuleBase)
+// prevents the module from being mutated for apexBundle.
+func InitApexModule(m ApexModule) {
+	base := m.apexModuleBase()
+	base.canHaveApexVariants = true
+
+	m.AddProperties(&base.ApexProperties)
+}
+
+// Implements ApexModule
 func (m *ApexModuleBase) apexModuleBase() *ApexModuleBase {
 	return m
 }
 
+// Implements ApexModule
 func (m *ApexModuleBase) ApexAvailable() []string {
 	return m.ApexProperties.Apex_available
 }
 
-func (m *ApexModuleBase) TestFor() []string {
-	// To be implemented by concrete types inheriting ApexModuleBase
-	return nil
-}
-
-func (m *ApexModuleBase) UniqueApexVariations() bool {
-	return false
-}
-
+// Implements ApexModule
 func (m *ApexModuleBase) BuildForApex(apex ApexInfo) {
-	m.apexVariationsLock.Lock()
-	defer m.apexVariationsLock.Unlock()
-	for _, v := range m.apexVariations {
+	m.apexInfosLock.Lock()
+	defer m.apexInfosLock.Unlock()
+	for _, v := range m.apexInfos {
 		if v.ApexVariationName == apex.ApexVariationName {
 			return
 		}
 	}
-	m.apexVariations = append(m.apexVariations, apex)
+	m.apexInfos = append(m.apexInfos, apex)
 }
 
-func (m *ApexModuleBase) DirectlyInAnyApex() bool {
-	return m.ApexProperties.DirectlyInAnyApex
-}
-
-func (m *ApexModuleBase) AnyVariantDirectlyInAnyApex() bool {
-	return m.ApexProperties.AnyVariantDirectlyInAnyApex
-}
-
+// Implements ApexModule
 func (m *ApexModuleBase) InAnyApex() bool {
 	return m.ApexProperties.InAnyApex
 }
 
+// Implements ApexModule
+func (m *ApexModuleBase) DirectlyInAnyApex() bool {
+	return m.ApexProperties.DirectlyInAnyApex
+}
+
+// Implements ApexModule
+func (m *ApexModuleBase) AnyVariantDirectlyInAnyApex() bool {
+	return m.ApexProperties.AnyVariantDirectlyInAnyApex
+}
+
+// Implements ApexModule
 func (m *ApexModuleBase) CanHaveApexVariants() bool {
 	return m.canHaveApexVariants
 }
 
+// Implements ApexModule
 func (m *ApexModuleBase) IsInstallableToApex() bool {
-	// should be overriden if needed
+	// If needed, this will bel overridden by concrete types inheriting
+	// ApexModuleBase
 	return false
 }
 
+// Implements ApexModule
+func (m *ApexModuleBase) TestFor() []string {
+	// If needed, this will be overridden by concrete types inheriting
+	// ApexModuleBase
+	return nil
+}
+
+// Implements ApexModule
+func (m *ApexModuleBase) UniqueApexVariations() bool {
+	// If needed, this will bel overridden by concrete types inheriting
+	// ApexModuleBase
+	return false
+}
+
+// Implements ApexModule
+func (m *ApexModuleBase) DepIsInSameApex(ctx BaseModuleContext, dep Module) bool {
+	// By default, if there is a dependency from A to B, we try to include both in the same
+	// APEX, unless B is explicitly from outside of the APEX (i.e. a stubs lib). Thus, returning
+	// true. This is overridden by some module types like apex.ApexBundle, cc.Module,
+	// java.Module, etc.
+	return true
+}
+
 const (
 	AvailableToPlatform = "//apex_available:platform"
 	AvailableToAnyApex  = "//apex_available:anyapex"
 	AvailableToGkiApex  = "com.android.gki.*"
 )
 
+// CheckAvailableForApex provides the default algorithm for checking the apex availability. When the
+// availability is empty, it defaults to ["//apex_available:platform"] which means "available to the
+// platform but not available to any APEX". When the list is not empty, `what` is matched against
+// the list. If there is any matching element in the list, thus function returns true. The special
+// availability "//apex_available:anyapex" matches with anything except for
+// "//apex_available:platform".
 func CheckAvailableForApex(what string, apex_available []string) bool {
 	if len(apex_available) == 0 {
-		// apex_available defaults to ["//apex_available:platform"],
-		// which means 'available to the platform but no apexes'.
 		return what == AvailableToPlatform
 	}
 	return InList(what, apex_available) ||
@@ -295,25 +362,22 @@
 		(strings.HasPrefix(what, "com.android.gki.") && InList(AvailableToGkiApex, apex_available))
 }
 
+// Implements ApexModule
 func (m *ApexModuleBase) AvailableFor(what string) bool {
 	return CheckAvailableForApex(what, m.ApexProperties.Apex_available)
 }
 
+// Implements ApexModule
 func (m *ApexModuleBase) NotAvailableForPlatform() bool {
 	return m.ApexProperties.NotAvailableForPlatform
 }
 
+// Implements ApexModule
 func (m *ApexModuleBase) SetNotAvailableForPlatform() {
 	m.ApexProperties.NotAvailableForPlatform = true
 }
 
-func (m *ApexModuleBase) DepIsInSameApex(ctx BaseModuleContext, dep Module) bool {
-	// By default, if there is a dependency from A to B, we try to include both in the same APEX,
-	// unless B is explicitly from outside of the APEX (i.e. a stubs lib). Thus, returning true.
-	// This is overridden by some module types like apex.ApexBundle, cc.Module, java.Module, etc.
-	return true
-}
-
+// This function makes sure that the apex_available property is valid
 func (m *ApexModuleBase) checkApexAvailableProperty(mctx BaseModuleContext) {
 	for _, n := range m.ApexProperties.Apex_available {
 		if n == AvailableToPlatform || n == AvailableToAnyApex || n == AvailableToGkiApex {
@@ -331,22 +395,23 @@
 func (a byApexName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 func (a byApexName) Less(i, j int) bool { return a[i].ApexVariationName < a[j].ApexVariationName }
 
-// mergeApexVariations deduplicates APEX variations that would build identically into a common
-// variation.  It returns the reduced list of variations and a list of aliases from the original
+// mergeApexVariations deduplicates apex variations that would build identically into a common
+// variation. It returns the reduced list of variations and a list of aliases from the original
 // variation names to the new variation names.
-func mergeApexVariations(ctx PathContext, apexVariations []ApexInfo) (merged []ApexInfo, aliases [][2]string) {
-	sort.Sort(byApexName(apexVariations))
+func mergeApexVariations(ctx PathContext, apexInfos []ApexInfo) (merged []ApexInfo, aliases [][2]string) {
+	sort.Sort(byApexName(apexInfos))
 	seen := make(map[string]int)
-	for _, apexInfo := range apexVariations {
+	for _, apexInfo := range apexInfos {
 		apexName := apexInfo.ApexVariationName
 		mergedName := apexInfo.mergedName(ctx)
 		if index, exists := seen[mergedName]; exists {
+			// Variants having the same mergedName are deduped
 			merged[index].InApexes = append(merged[index].InApexes, apexName)
 			merged[index].ApexContents = append(merged[index].ApexContents, apexInfo.ApexContents...)
 			merged[index].Updatable = merged[index].Updatable || apexInfo.Updatable
 		} else {
 			seen[mergedName] = len(merged)
-			apexInfo.ApexVariationName = apexInfo.mergedName(ctx)
+			apexInfo.ApexVariationName = mergedName
 			apexInfo.InApexes = CopyOf(apexInfo.InApexes)
 			apexInfo.ApexContents = append([]*ApexContents(nil), apexInfo.ApexContents...)
 			merged = append(merged, apexInfo)
@@ -356,75 +421,78 @@
 	return merged, aliases
 }
 
+// CreateApexVariations mutates a given module into multiple apex variants each of which is for an
+// apexBundle (and/or the platform) where the module is part of.
 func CreateApexVariations(mctx BottomUpMutatorContext, module ApexModule) []Module {
 	base := module.apexModuleBase()
-	if len(base.apexVariations) > 0 {
-		base.checkApexAvailableProperty(mctx)
 
-		var apexVariations []ApexInfo
-		var aliases [][2]string
-		if !mctx.Module().(ApexModule).UniqueApexVariations() && !base.ApexProperties.UniqueApexVariationsForDeps {
-			apexVariations, aliases = mergeApexVariations(mctx, base.apexVariations)
-		} else {
-			apexVariations = base.apexVariations
-		}
-		// base.apexVariations is only needed to propagate the list of apexes from
-		// apexDepsMutator to apexMutator.  It is no longer accurate after
-		// mergeApexVariations, and won't be copied to all but the first created
-		// variant.  Clear it so it doesn't accidentally get used later.
-		base.apexVariations = nil
-
-		sort.Sort(byApexName(apexVariations))
-		variations := []string{}
-		variations = append(variations, "") // Original variation for platform
-		for _, apex := range apexVariations {
-			variations = append(variations, apex.ApexVariationName)
-		}
-
-		defaultVariation := ""
-		mctx.SetDefaultDependencyVariation(&defaultVariation)
-
-		var inApex ApexMembership
-		for _, a := range apexVariations {
-			for _, apexContents := range a.ApexContents {
-				inApex = inApex.merge(apexContents.contents[mctx.ModuleName()])
-			}
-		}
-
-		base.ApexProperties.InAnyApex = true
-		base.ApexProperties.DirectlyInAnyApex = inApex == directlyInApex
-
-		modules := mctx.CreateVariations(variations...)
-		for i, mod := range modules {
-			platformVariation := i == 0
-			if platformVariation && !mctx.Host() && !mod.(ApexModule).AvailableFor(AvailableToPlatform) {
-				// Do not install the module for platform, but still allow it to output
-				// uninstallable AndroidMk entries in certain cases when they have
-				// side effects.
-				mod.MakeUninstallable()
-			}
-			if !platformVariation {
-				mctx.SetVariationProvider(mod, ApexInfoProvider, apexVariations[i-1])
-			}
-		}
-
-		for _, alias := range aliases {
-			mctx.CreateAliasVariation(alias[0], alias[1])
-		}
-
-		return modules
+	// Shortcut
+	if len(base.apexInfos) == 0 {
+		return nil
 	}
-	return nil
+
+	// Do some validity checks.
+	// TODO(jiyong): is this the right place?
+	base.checkApexAvailableProperty(mctx)
+
+	var apexInfos []ApexInfo
+	var aliases [][2]string
+	if !mctx.Module().(ApexModule).UniqueApexVariations() && !base.ApexProperties.UniqueApexVariationsForDeps {
+		apexInfos, aliases = mergeApexVariations(mctx, base.apexInfos)
+	} else {
+		apexInfos = base.apexInfos
+	}
+	// base.apexInfos is only needed to propagate the list of apexes from apexDepsMutator to
+	// apexMutator. It is no longer accurate after mergeApexVariations, and won't be copied to
+	// all but the first created variant. Clear it so it doesn't accidentally get used later.
+	base.apexInfos = nil
+	sort.Sort(byApexName(apexInfos))
+
+	var inApex ApexMembership
+	for _, a := range apexInfos {
+		for _, apexContents := range a.ApexContents {
+			inApex = inApex.merge(apexContents.contents[mctx.ModuleName()])
+		}
+	}
+	base.ApexProperties.InAnyApex = true
+	base.ApexProperties.DirectlyInAnyApex = inApex == directlyInApex
+
+	defaultVariation := ""
+	mctx.SetDefaultDependencyVariation(&defaultVariation)
+
+	variations := []string{defaultVariation}
+	for _, a := range apexInfos {
+		variations = append(variations, a.ApexVariationName)
+	}
+	modules := mctx.CreateVariations(variations...)
+	for i, mod := range modules {
+		platformVariation := i == 0
+		if platformVariation && !mctx.Host() && !mod.(ApexModule).AvailableFor(AvailableToPlatform) {
+			// Do not install the module for platform, but still allow it to output
+			// uninstallable AndroidMk entries in certain cases when they have side
+			// effects.  TODO(jiyong): move this routine to somewhere else
+			mod.MakeUninstallable()
+		}
+		if !platformVariation {
+			mctx.SetVariationProvider(mod, ApexInfoProvider, apexInfos[i-1])
+		}
+	}
+
+	for _, alias := range aliases {
+		mctx.CreateAliasVariation(alias[0], alias[1])
+	}
+
+	return modules
 }
 
-// UpdateUniqueApexVariationsForDeps sets UniqueApexVariationsForDeps if any dependencies
-// that are in the same APEX have unique APEX variations so that the module can link against
-// the right variant.
+// UpdateUniqueApexVariationsForDeps sets UniqueApexVariationsForDeps if any dependencies that are
+// in the same APEX have unique APEX variations so that the module can link against the right
+// variant.
 func UpdateUniqueApexVariationsForDeps(mctx BottomUpMutatorContext, am ApexModule) {
-	// anyInSameApex returns true if the two ApexInfo lists contain any values in an InApexes list
-	// in common.  It is used instead of DepIsInSameApex because it needs to determine if the dep
-	// is in the same APEX due to being directly included, not only if it is included _because_ it
-	// is a dependency.
+	// anyInSameApex returns true if the two ApexInfo lists contain any values in an InApexes
+	// list in common. It is used instead of DepIsInSameApex because it needs to determine if
+	// the dep is in the same APEX due to being directly included, not only if it is included
+	// _because_ it is a dependency.
 	anyInSameApex := func(a, b []ApexInfo) bool {
 		collectApexes := func(infos []ApexInfo) []string {
 			var ret []string
@@ -446,9 +514,10 @@
 		return false
 	}
 
+	// If any of the dependencies requires unique apex variations, so does this module.
 	mctx.VisitDirectDeps(func(dep Module) {
 		if depApexModule, ok := dep.(ApexModule); ok {
-			if anyInSameApex(depApexModule.apexModuleBase().apexVariations, am.apexModuleBase().apexVariations) &&
+			if anyInSameApex(depApexModule.apexModuleBase().apexInfos, am.apexModuleBase().apexInfos) &&
 				(depApexModule.UniqueApexVariations() ||
 					depApexModule.apexModuleBase().ApexProperties.UniqueApexVariationsForDeps) {
 				am.apexModuleBase().ApexProperties.UniqueApexVariationsForDeps = true
@@ -457,10 +526,10 @@
 	})
 }
 
-// UpdateDirectlyInAnyApex uses the final module to store if any variant of this
-// module is directly in any APEX, and then copies the final value to all the modules.
-// It also copies the DirectlyInAnyApex value to any direct dependencies with a
-// CopyDirectlyInAnyApexTag dependency tag.
+// UpdateDirectlyInAnyApex uses the final module to store if any variant of this module is directly
+// in any APEX, and then copies the final value to all the modules. It also copies the
+// DirectlyInAnyApex value to any direct dependencies with a CopyDirectlyInAnyApexTag dependency
+// tag.
 func UpdateDirectlyInAnyApex(mctx BottomUpMutatorContext, am ApexModule) {
 	base := am.apexModuleBase()
 	// Copy DirectlyInAnyApex and InAnyApex from any direct dependencies with a
@@ -475,14 +544,13 @@
 
 	if base.ApexProperties.DirectlyInAnyApex {
 		// Variants of a module are always visited sequentially in order, so it is safe to
-		// write to another variant of this module.
-		// For a BottomUpMutator the PrimaryModule() is visited first and FinalModule() is
-		// visited last.
+		// write to another variant of this module. For a BottomUpMutator the
+		// PrimaryModule() is visited first and FinalModule() is visited last.
 		mctx.FinalModule().(ApexModule).apexModuleBase().ApexProperties.AnyVariantDirectlyInAnyApex = true
 	}
 
-	// If this is the FinalModule (last visited module) copy AnyVariantDirectlyInAnyApex to
-	// all the other variants
+	// If this is the FinalModule (last visited module) copy
+	// AnyVariantDirectlyInAnyApex to all the other variants
 	if am == mctx.FinalModule().(ApexModule) {
 		mctx.VisitAllModuleVariants(func(variant Module) {
 			variant.(ApexModule).apexModuleBase().ApexProperties.AnyVariantDirectlyInAnyApex =
@@ -491,6 +559,7 @@
 	}
 }
 
+// ApexMembership tells how a module became part of an APEX.
 type ApexMembership int
 
 const (
@@ -499,20 +568,21 @@
 	directlyInApex
 )
 
-// Each apexBundle has an apexContents, and modules in that apex have a provider containing the
-// apexContents of each apexBundle they are part of.
+// ApexContents gives an information about member modules of an apexBundle.  Each apexBundle has an
+// apexContents, and modules in that apex have a provider containing the apexContents of each
+// apexBundle they are part of.
 type ApexContents struct {
-	ApexName string
+	// map from a module name to its membership to this apexBUndle
 	contents map[string]ApexMembership
 }
 
-func NewApexContents(name string, contents map[string]ApexMembership) *ApexContents {
+func NewApexContents(contents map[string]ApexMembership) *ApexContents {
 	return &ApexContents{
-		ApexName: name,
 		contents: contents,
 	}
 }
 
+// Updates an existing membership by adding a new direct (or indirect) membership
 func (i ApexMembership) Add(direct bool) ApexMembership {
 	if direct || i == directlyInApex {
 		return directlyInApex
@@ -520,6 +590,10 @@
 	return indirectlyInApex
 }
 
+// Merges two membership into one. Merging is needed because a module can be a part of an apexBundle
+// in many different paths. For example, it could be dependend on by the apexBundle directly, but at
+// the same time, there might be an indirect dependency to the module. In that case, the more
+// specific dependency (the direct one) is chosen.
 func (i ApexMembership) merge(other ApexMembership) ApexMembership {
 	if other == directlyInApex || i == directlyInApex {
 		return directlyInApex
@@ -531,16 +605,19 @@
 	return notInApex
 }
 
-func (ac *ApexContents) DirectlyInApex(name string) bool {
-	return ac.contents[name] == directlyInApex
+// Tests whether a module named moduleName is directly included in the apexBundle where this
+// ApexContents is tagged.
+func (ac *ApexContents) DirectlyInApex(moduleName string) bool {
+	return ac.contents[moduleName] == directlyInApex
 }
 
-func (ac *ApexContents) InApex(name string) bool {
-	return ac.contents[name] != notInApex
+// Tests whether a module named moduleName is included in the apexBundle where this ApexContent is
+// tagged.
+func (ac *ApexContents) InApex(moduleName string) bool {
+	return ac.contents[moduleName] != notInApex
 }
 
-// Tests whether a module named moduleName is directly depended on by all APEXes
-// in an ApexInfo.
+// Tests whether a module named moduleName is directly depended on by all APEXes in an ApexInfo.
 func DirectlyInAllApexes(apexInfo ApexInfo, moduleName string) bool {
 	for _, contents := range apexInfo.ApexContents {
 		if !contents.DirectlyInApex(moduleName) {
@@ -550,12 +627,15 @@
 	return true
 }
 
-func InitApexModule(m ApexModule) {
-	base := m.apexModuleBase()
-	base.canHaveApexVariants = true
-
-	m.AddProperties(&base.ApexProperties)
-}
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//Below are routines for extra safety checks.
+//
+// BuildDepsInfoLists is to flatten the dependency graph for an apexBundle into a text file
+// (actually two in slightly different formats). The files are mostly for debugging, for example to
+// see why a certain module is included in an APEX via which dependency path.
+//
+// CheckMinSdkVersion is to make sure that all modules in an apexBundle satisfy the min_sdk_version
+// requirement of the apexBundle.
 
 // A dependency info for a single ApexModule, either direct or transitive.
 type ApexModuleDepInfo struct {
@@ -705,7 +785,8 @@
 	WalkPayloadDeps(ctx ModuleContext, do PayloadDepsCallback)
 }
 
-// CheckMinSdkVersion checks if every dependency of an updatable module sets min_sdk_version accordingly
+// CheckMinSdkVersion checks if every dependency of an updatable module sets min_sdk_version
+// accordingly
 func CheckMinSdkVersion(m UpdatableModule, ctx ModuleContext, minSdkVersion ApiLevel) {
 	// do not enforce min_sdk_version for host
 	if ctx.Host() {
@@ -725,8 +806,9 @@
 
 	m.WalkPayloadDeps(ctx, func(ctx ModuleContext, from blueprint.Module, to ApexModule, externalDep bool) bool {
 		if externalDep {
-			// external deps are outside the payload boundary, which is "stable" interface.
-			// We don't have to check min_sdk_version for external dependencies.
+			// external deps are outside the payload boundary, which is "stable"
+			// interface. We don't have to check min_sdk_version for external
+			// dependencies.
 			return false
 		}
 		if am, ok := from.(DepIsInSameApex); ok && !am.DepIsInSameApex(ctx, to) {
diff --git a/android/arch.go b/android/arch.go
index afb9c7f..eb651e6 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -27,28 +27,6 @@
 	"github.com/google/blueprint/proptools"
 )
 
-const COMMON_VARIANT = "common"
-
-var (
-	archTypeList []ArchType
-
-	Arm    = newArch("arm", "lib32")
-	Arm64  = newArch("arm64", "lib64")
-	X86    = newArch("x86", "lib32")
-	X86_64 = newArch("x86_64", "lib64")
-
-	Common = ArchType{
-		Name: COMMON_VARIANT,
-	}
-)
-
-var archTypeMap = map[string]ArchType{
-	"arm":    Arm,
-	"arm64":  Arm64,
-	"x86":    X86,
-	"x86_64": X86_64,
-}
-
 /*
 Example blueprints file containing all variant property groups, with comment listing what type
 of variants get properties in that group:
@@ -111,405 +89,26 @@
 }
 */
 
-var archVariants = map[ArchType][]string{
-	Arm: {
-		"armv7-a",
-		"armv7-a-neon",
-		"armv8-a",
-		"armv8-2a",
-		"cortex-a7",
-		"cortex-a8",
-		"cortex-a9",
-		"cortex-a15",
-		"cortex-a53",
-		"cortex-a53-a57",
-		"cortex-a55",
-		"cortex-a72",
-		"cortex-a73",
-		"cortex-a75",
-		"cortex-a76",
-		"krait",
-		"kryo",
-		"kryo385",
-		"exynos-m1",
-		"exynos-m2",
-	},
-	Arm64: {
-		"armv8_a",
-		"armv8_2a",
-		"armv8-2a-dotprod",
-		"cortex-a53",
-		"cortex-a55",
-		"cortex-a72",
-		"cortex-a73",
-		"cortex-a75",
-		"cortex-a76",
-		"kryo",
-		"kryo385",
-		"exynos-m1",
-		"exynos-m2",
-	},
-	X86: {
-		"amberlake",
-		"atom",
-		"broadwell",
-		"haswell",
-		"icelake",
-		"ivybridge",
-		"kabylake",
-		"sandybridge",
-		"silvermont",
-		"skylake",
-		"stoneyridge",
-		"tigerlake",
-		"whiskeylake",
-		"x86_64",
-	},
-	X86_64: {
-		"amberlake",
-		"broadwell",
-		"haswell",
-		"icelake",
-		"ivybridge",
-		"kabylake",
-		"sandybridge",
-		"silvermont",
-		"skylake",
-		"stoneyridge",
-		"tigerlake",
-		"whiskeylake",
-	},
-}
-
-var archFeatures = map[ArchType][]string{
-	Arm: {
-		"neon",
-	},
-	Arm64: {
-		"dotprod",
-	},
-	X86: {
-		"ssse3",
-		"sse4",
-		"sse4_1",
-		"sse4_2",
-		"aes_ni",
-		"avx",
-		"avx2",
-		"avx512",
-		"popcnt",
-		"movbe",
-	},
-	X86_64: {
-		"ssse3",
-		"sse4",
-		"sse4_1",
-		"sse4_2",
-		"aes_ni",
-		"avx",
-		"avx2",
-		"avx512",
-		"popcnt",
-	},
-}
-
-var archFeatureMap = map[ArchType]map[string][]string{
-	Arm: {
-		"armv7-a-neon": {
-			"neon",
-		},
-		"armv8-a": {
-			"neon",
-		},
-		"armv8-2a": {
-			"neon",
-		},
-	},
-	Arm64: {
-		"armv8-2a-dotprod": {
-			"dotprod",
-		},
-	},
-	X86: {
-		"amberlake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"aes_ni",
-			"popcnt",
-		},
-		"atom": {
-			"ssse3",
-			"movbe",
-		},
-		"broadwell": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"aes_ni",
-			"popcnt",
-		},
-		"haswell": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"aes_ni",
-			"avx",
-			"popcnt",
-			"movbe",
-		},
-		"icelake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"avx512",
-			"aes_ni",
-			"popcnt",
-		},
-		"ivybridge": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"aes_ni",
-			"avx",
-			"popcnt",
-		},
-		"kabylake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"aes_ni",
-			"popcnt",
-		},
-		"sandybridge": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"popcnt",
-		},
-		"silvermont": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"aes_ni",
-			"popcnt",
-			"movbe",
-		},
-		"skylake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"avx512",
-			"aes_ni",
-			"popcnt",
-		},
-		"stoneyridge": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"aes_ni",
-			"avx",
-			"avx2",
-			"popcnt",
-			"movbe",
-		},
-		"tigerlake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"avx512",
-			"aes_ni",
-			"popcnt",
-		},
-		"whiskeylake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"avx512",
-			"aes_ni",
-			"popcnt",
-		},
-		"x86_64": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"popcnt",
-		},
-	},
-	X86_64: {
-		"amberlake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"aes_ni",
-			"popcnt",
-		},
-		"broadwell": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"aes_ni",
-			"popcnt",
-		},
-		"haswell": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"aes_ni",
-			"avx",
-			"popcnt",
-		},
-		"icelake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"avx512",
-			"aes_ni",
-			"popcnt",
-		},
-		"ivybridge": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"aes_ni",
-			"avx",
-			"popcnt",
-		},
-		"kabylake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"aes_ni",
-			"popcnt",
-		},
-		"sandybridge": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"popcnt",
-		},
-		"silvermont": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"aes_ni",
-			"popcnt",
-		},
-		"skylake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"avx512",
-			"aes_ni",
-			"popcnt",
-		},
-		"stoneyridge": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"aes_ni",
-			"avx",
-			"avx2",
-			"popcnt",
-		},
-		"tigerlake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"avx512",
-			"aes_ni",
-			"popcnt",
-		},
-		"whiskeylake": {
-			"ssse3",
-			"sse4",
-			"sse4_1",
-			"sse4_2",
-			"avx",
-			"avx2",
-			"avx512",
-			"aes_ni",
-			"popcnt",
-		},
-	},
-}
-
-var defaultArchFeatureMap = map[OsType]map[ArchType][]string{}
-
-func RegisterDefaultArchVariantFeatures(os OsType, arch ArchType, features ...string) {
-	checkCalledFromInit()
-
-	for _, feature := range features {
-		if !InList(feature, archFeatures[arch]) {
-			panic(fmt.Errorf("Invalid feature %q for arch %q variant \"\"", feature, arch))
-		}
-	}
-
-	if defaultArchFeatureMap[os] == nil {
-		defaultArchFeatureMap[os] = make(map[ArchType][]string)
-	}
-	defaultArchFeatureMap[os][arch] = features
-}
-
 // An Arch indicates a single CPU architecture.
 type Arch struct {
-	ArchType     ArchType
-	ArchVariant  string
-	CpuVariant   string
-	Abi          []string
+	// The type of the architecture (arm, arm64, x86, or x86_64).
+	ArchType ArchType
+
+	// The variant of the architecture, for example "armv7-a" or "armv7-a-neon" for arm.
+	ArchVariant string
+
+	// The variant of the CPU, for example "cortex-a53" for arm64.
+	CpuVariant string
+
+	// The list of Android app ABIs supported by the CPU architecture, for example "arm64-v8a".
+	Abi []string
+
+	// The list of arch-specific features supported by the CPU architecture, for example "neon".
 	ArchFeatures []string
 }
 
+// String returns the Arch as a string.  The value is used as the name of the variant created
+// by archMutator.
 func (a Arch) String() string {
 	s := a.ArchType.String()
 	if a.ArchVariant != "" {
@@ -521,12 +120,42 @@
 	return s
 }
 
+// ArchType is used to define the 4 supported architecture types (arm, arm64, x86, x86_64), as
+// well as the "common" architecture used for modules that support multiple architectures, for
+// example Java modules.
 type ArchType struct {
-	Name     string
-	Field    string
+	// Name is the name of the architecture type, "arm", "arm64", "x86", or "x86_64".
+	Name string
+
+	// Field is the name of the field used in properties that refer to the architecture, e.g. "Arm64".
+	Field string
+
+	// Multilib is either "lib32" or "lib64" for 32-bit or 64-bit architectures.
 	Multilib string
 }
 
+// String returns the name of the ArchType.
+func (a ArchType) String() string {
+	return a.Name
+}
+
+const COMMON_VARIANT = "common"
+
+var (
+	archTypeList []ArchType
+
+	Arm    = newArch("arm", "lib32")
+	Arm64  = newArch("arm64", "lib64")
+	X86    = newArch("x86", "lib32")
+	X86_64 = newArch("x86_64", "lib64")
+
+	Common = ArchType{
+		Name: COMMON_VARIANT,
+	}
+)
+
+var archTypeMap = map[string]ArchType{}
+
 func newArch(name, multilib string) ArchType {
 	archType := ArchType{
 		Name:     name,
@@ -534,25 +163,25 @@
 		Multilib: multilib,
 	}
 	archTypeList = append(archTypeList, archType)
+	archTypeMap[name] = archType
 	return archType
 }
 
+// ArchTypeList returns the 4 supported ArchTypes for arm, arm64, x86 and x86_64.
 func ArchTypeList() []ArchType {
 	return append([]ArchType(nil), archTypeList...)
 }
 
-func (a ArchType) String() string {
-	return a.Name
-}
-
-var _ encoding.TextMarshaler = ArchType{}
-
+// MarshalText allows an ArchType to be serialized through any encoder that supports
+// encoding.TextMarshaler.
 func (a ArchType) MarshalText() ([]byte, error) {
 	return []byte(strconv.Quote(a.String())), nil
 }
 
-var _ encoding.TextUnmarshaler = &ArchType{}
+var _ encoding.TextMarshaler = ArchType{}
 
+// UnmarshalText allows an ArchType to be deserialized through any decoder that supports
+// encoding.TextUnmarshaler.
 func (a *ArchType) UnmarshalText(text []byte) error {
 	if u, ok := archTypeMap[string(text)]; ok {
 		*a = u
@@ -562,67 +191,22 @@
 	return fmt.Errorf("unknown ArchType %q", text)
 }
 
-var BuildOs = func() OsType {
-	switch runtime.GOOS {
-	case "linux":
-		return Linux
-	case "darwin":
-		return Darwin
-	default:
-		panic(fmt.Sprintf("unsupported OS: %s", runtime.GOOS))
-	}
-}()
+var _ encoding.TextUnmarshaler = &ArchType{}
 
-var BuildArch = func() ArchType {
-	switch runtime.GOARCH {
-	case "amd64":
-		return X86_64
-	default:
-		panic(fmt.Sprintf("unsupported Arch: %s", runtime.GOARCH))
-	}
-}()
-
-var (
-	OsTypeList      []OsType
-	commonTargetMap = make(map[string]Target)
-
-	NoOsType    OsType
-	Linux       = NewOsType("linux_glibc", Host, false)
-	Darwin      = NewOsType("darwin", Host, false)
-	LinuxBionic = NewOsType("linux_bionic", Host, false)
-	Windows     = NewOsType("windows", Host, true)
-	Android     = NewOsType("android", Device, false)
-	Fuchsia     = NewOsType("fuchsia", Device, false)
-
-	// A pseudo OSType for a common os variant, which is OSType agnostic and which
-	// has dependencies on all the OS variants.
-	CommonOS = NewOsType("common_os", Generic, false)
-
-	osArchTypeMap = map[OsType][]ArchType{
-		Linux:       []ArchType{X86, X86_64},
-		LinuxBionic: []ArchType{Arm64, X86_64},
-		Darwin:      []ArchType{X86_64},
-		Windows:     []ArchType{X86, X86_64},
-		Android:     []ArchType{Arm, Arm64, X86, X86_64},
-		Fuchsia:     []ArchType{Arm64, X86_64},
-	}
-)
-
-type OsType struct {
-	Name, Field string
-	Class       OsClass
-
-	DefaultDisabled bool
-}
-
+// OsClass is an enum that describes whether a variant of a module runs on the host, on the device,
+// or is generic.
 type OsClass int
 
 const (
+	// Generic is used for variants of modules that are not OS-specific.
 	Generic OsClass = iota
+	// Device is used for variants of modules that run on the device.
 	Device
+	// Host is used for variants of modules that run on the host.
 	Host
 )
 
+// String returns the OsClass as a string.
 func (class OsClass) String() string {
 	switch class {
 	case Generic:
@@ -636,22 +220,48 @@
 	}
 }
 
+// OsType describes an OS variant of a module.
+type OsType struct {
+	// Name is the name of the OS.  It is also used as the name of the property in Android.bp
+	// files.
+	Name string
+
+	// Field is the name of the OS converted to an exported field name, i.e. with the first
+	// character capitalized.
+	Field string
+
+	// Class is the OsClass of the OS.
+	Class OsClass
+
+	// DefaultDisabled is set when the module variants for the OS should not be created unless
+	// the module explicitly requests them.  This is used to limit Windows cross compilation to
+	// only modules that need it.
+	DefaultDisabled bool
+}
+
+// String returns the name of the OsType.
 func (os OsType) String() string {
 	return os.Name
 }
 
+// Bionic returns true if the OS uses the Bionic libc runtime, i.e. if the OS is Android or
+// is Linux with Bionic.
 func (os OsType) Bionic() bool {
 	return os == Android || os == LinuxBionic
 }
 
+// Linux returns true if the OS uses the Linux kernel, i.e. if the OS is Android or is Linux
+// with or without the Bionic libc runtime.
 func (os OsType) Linux() bool {
 	return os == Android || os == Linux || os == LinuxBionic
 }
 
-func NewOsType(name string, class OsClass, defDisabled bool) OsType {
+// newOsType constructs an OsType and adds it to the global lists.
+func newOsType(name string, class OsClass, defDisabled bool, archTypes ...ArchType) OsType {
+	checkCalledFromInit()
 	os := OsType{
 		Name:  name,
-		Field: strings.Title(name),
+		Field: proptools.FieldNameForProperty(name),
 		Class: class,
 
 		DefaultDisabled: defDisabled,
@@ -663,10 +273,12 @@
 	} else {
 		commonTargetMap[name] = Target{Os: os, Arch: Arch{ArchType: Common}}
 	}
+	osArchTypeMap[os] = archTypes
 
 	return os
 }
 
+// osByName returns the OsType that has the given name, or NoOsType if none match.
 func osByName(name string) OsType {
 	for _, os := range OsTypeList {
 		if os.Name == name {
@@ -677,18 +289,74 @@
 	return NoOsType
 }
 
-type NativeBridgeSupport bool
+// BuildOs returns the OsType for the OS that the build is running on.
+var BuildOs = func() OsType {
+	switch runtime.GOOS {
+	case "linux":
+		return Linux
+	case "darwin":
+		return Darwin
+	default:
+		panic(fmt.Sprintf("unsupported OS: %s", runtime.GOOS))
+	}
+}()
 
-const (
-	NativeBridgeDisabled NativeBridgeSupport = false
-	NativeBridgeEnabled  NativeBridgeSupport = true
+// BuildArch returns the ArchType for the CPU that the build is running on.
+var BuildArch = func() ArchType {
+	switch runtime.GOARCH {
+	case "amd64":
+		return X86_64
+	default:
+		panic(fmt.Sprintf("unsupported Arch: %s", runtime.GOARCH))
+	}
+}()
+
+var (
+	// OsTypeList contains a list of all the supported OsTypes, including ones not supported
+	// by the current build host or the target device.
+	OsTypeList []OsType
+	// commonTargetMap maps names of OsTypes to the corresponding common Target, i.e. the
+	// Target with the same OsType and the common ArchType.
+	commonTargetMap = make(map[string]Target)
+	// osArchTypeMap maps OsTypes to the list of supported ArchTypes for that OS.
+	osArchTypeMap = map[OsType][]ArchType{}
+
+	// NoOsType is a placeholder for when no OS is needed.
+	NoOsType OsType
+	// Linux is the OS for the Linux kernel plus the glibc runtime.
+	Linux = newOsType("linux_glibc", Host, false, X86, X86_64)
+	// Darwin is the OS for MacOS/Darwin host machines.
+	Darwin = newOsType("darwin", Host, false, X86_64)
+	// LinuxBionic is the OS for the Linux kernel plus the Bionic libc runtime, but without the
+	// rest of Android.
+	LinuxBionic = newOsType("linux_bionic", Host, false, Arm64, X86_64)
+	// Windows the OS for Windows host machines.
+	Windows = newOsType("windows", Host, true, X86, X86_64)
+	// Android is the OS for target devices that run all of Android, including the Linux kernel
+	// and the Bionic libc runtime.
+	Android = newOsType("android", Device, false, Arm, Arm64, X86, X86_64)
+	// Fuchsia is the OS for target devices that run Fuchsia.
+	Fuchsia = newOsType("fuchsia", Device, false, Arm64, X86_64)
+
+	// CommonOS is a pseudo OSType for a common OS variant, which is OsType agnostic and which
+	// has dependencies on all the OS variants.
+	CommonOS = newOsType("common_os", Generic, false)
 )
 
+// Target specifies the OS and architecture that a module is being compiled for.
 type Target struct {
-	Os                       OsType
-	Arch                     Arch
-	NativeBridge             NativeBridgeSupport
+	// Os the OS that the module is being compiled for (e.g. "linux_glibc", "android").
+	Os OsType
+	// Arch is the architecture that the module is being compiled for.
+	Arch Arch
+	// NativeBridge is NativeBridgeEnabled if the architecture is supported using NativeBridge
+	// (i.e. arm on x86) for this device.
+	NativeBridge NativeBridgeSupport
+	// NativeBridgeHostArchName is the name of the real architecture that is used to implement
+	// the NativeBridge architecture.  For example, for arm on x86 this would be "x86".
 	NativeBridgeHostArchName string
+	// NativeBridgeRelativePath is the name of the subdirectory that will contain NativeBridge
+	// libraries and binaries.
 	NativeBridgeRelativePath string
 
 	// HostCross is true when the target cannot run natively on the current build host.
@@ -697,14 +365,25 @@
 	HostCross bool
 }
 
+// NativeBridgeSupport is an enum that specifies if a Target supports NativeBridge.
+type NativeBridgeSupport bool
+
+const (
+	NativeBridgeDisabled NativeBridgeSupport = false
+	NativeBridgeEnabled  NativeBridgeSupport = true
+)
+
+// String returns the OS and arch variations used for the Target.
 func (target Target) String() string {
 	return target.OsVariation() + "_" + target.ArchVariation()
 }
 
+// OsVariation returns the name of the variation used by the osMutator for the Target.
 func (target Target) OsVariation() string {
 	return target.Os.String()
 }
 
+// ArchVariation returns the name of the variation used by the archMutator for the Target.
 func (target Target) ArchVariation() string {
 	var variation string
 	if target.NativeBridge {
@@ -715,6 +394,8 @@
 	return variation
 }
 
+// Variations returns a list of blueprint.Variations for the osMutator and archMutator for the
+// Target.
 func (target Target) Variations() []blueprint.Variation {
 	return []blueprint.Variation{
 		{Mutator: "os", Variation: target.OsVariation()},
@@ -722,10 +403,16 @@
 	}
 }
 
+// osMutator splits an arch-specific module into a variant for each OS that is enabled for the
+// module.  It uses the HostOrDevice value passed to InitAndroidArchModule and the
+// device_supported and host_supported properties to determine which OsTypes are enabled for this
+// module, then searches through the Targets to determine which have enabled Targets for this
+// module.
 func osMutator(bpctx blueprint.BottomUpMutatorContext) {
 	var module Module
 	var ok bool
 	if module, ok = bpctx.Module().(Module); !ok {
+		// The module is not a Soong module, it is a Blueprint module.
 		if bootstrap.IsBootstrapModule(bpctx.Module()) {
 			// Bootstrap Go modules are always the build OS or linux bionic.
 			config := bpctx.Config().(Config)
@@ -749,12 +436,14 @@
 
 	base := module.base()
 
+	// Nothing to do for modules that are not architecture specific (e.g. a genrule).
 	if !base.ArchSpecific() {
 		return
 	}
 
+	// Collect a list of OSTypes supported by this module based on the HostOrDevice value
+	// passed to InitAndroidArchModule and the device_supported and host_supported properties.
 	var moduleOSList []OsType
-
 	for _, os := range OsTypeList {
 		for _, t := range mctx.Config().Targets[os] {
 			if base.supportsTarget(t) {
@@ -764,20 +453,21 @@
 		}
 	}
 
+	// If there are no supported OSes then disable the module.
 	if len(moduleOSList) == 0 {
 		base.Disable()
 		return
 	}
 
+	// Convert the list of supported OsTypes to the variation names.
 	osNames := make([]string, len(moduleOSList))
-
 	for i, os := range moduleOSList {
 		osNames[i] = os.String()
 	}
 
 	createCommonOSVariant := base.commonProperties.CreateCommonOSVariant
 	if createCommonOSVariant {
-		// A CommonOS variant was requested so add it to the list of OS's variants to
+		// A CommonOS variant was requested so add it to the list of OS variants to
 		// create. It needs to be added to the end because it needs to depend on the
 		// the other variants in the list returned by CreateVariations(...) and inter
 		// variant dependencies can only be created from a later variant in that list to
@@ -787,6 +477,8 @@
 		moduleOSList = append(moduleOSList, CommonOS)
 	}
 
+	// Create the variations, annotate each one with which OS it was created for, and
+	// squash the appropriate OS-specific properties into the top level properties.
 	modules := mctx.CreateVariations(osNames...)
 	for i, m := range modules {
 		m.base().commonProperties.CompileOS = moduleOSList[i]
@@ -841,7 +533,7 @@
 }
 
 // archMutator splits a module into a variant for each Target requested by the module.  Target selection
-// for a module is in three levels, OsClass, mulitlib, and then Target.
+// for a module is in three levels, OsClass, multilib, and then Target.
 // OsClass selection is determined by:
 //    - The HostOrDeviceSupported value passed in to InitAndroidArchModule by the module type factory, which selects
 //      whether the module type can compile for host, device or both.
@@ -858,7 +550,11 @@
 //        but may be arm for a 32-bit only build.
 //    "32": compile for only a single 32-bit Target supported by the OsClass.
 //    "64": compile for only a single 64-bit Target supported by the OsClass.
-//    "common": compile a for a single Target that will work on all Targets suported by the OsClass (for example Java).
+//    "common": compile a for a single Target that will work on all Targets supported by the OsClass (for example Java).
+//    "common_first": compile a for a Target that will work on all Targets supported by the OsClass
+//        (same as "common"), plus a second Target for the preferred Target supported by the OsClass
+//        (same as "first").  This is used for java_binary that produces a common .jar and a wrapper
+//        executable script.
 //
 // Once the list of Targets is determined, the module is split into a variant for each Target.
 //
@@ -899,8 +595,8 @@
 
 	osTargets := mctx.Config().Targets[os]
 	image := base.commonProperties.ImageVariation
-	// Filter NativeBridge targets unless they are explicitly supported
-	// Skip creating native bridge variants for vendor modules
+	// Filter NativeBridge targets unless they are explicitly supported.
+	// Skip creating native bridge variants for non-core modules.
 	if os == Android &&
 		!(Bool(base.commonProperties.Native_bridge_supported) && image == CoreVariation) {
 
@@ -919,17 +615,24 @@
 		osTargets = []Target{osTargets[0]}
 	}
 
+	// Some modules want compile_multilib: "first" to mean 32-bit, not 64-bit.
+	// This is used for Windows support and for HOST_PREFER_32_BIT=true support for Art modules.
 	prefer32 := false
 	if base.prefer32 != nil {
 		prefer32 = base.prefer32(mctx, base, os)
 	}
 
+	// Determine the multilib selection for this module.
 	multilib, extraMultilib := decodeMultilib(base, os.Class)
+
+	// Convert the multilib selection into a list of Targets.
 	targets, err := decodeMultilibTargets(multilib, osTargets, prefer32)
 	if err != nil {
 		mctx.ModuleErrorf("%s", err.Error())
 	}
 
+	// If the module is using extraMultilib, decode the extraMultilib selection into
+	// a separate list of Targets.
 	var multiTargets []Target
 	if extraMultilib != "" {
 		multiTargets, err = decodeMultilibTargets(extraMultilib, osTargets, prefer32)
@@ -938,23 +641,27 @@
 		}
 	}
 
+	// Recovery is always the primary architecture, filter out any other architectures.
 	if image == RecoveryVariation {
 		primaryArch := mctx.Config().DevicePrimaryArchType()
 		targets = filterToArch(targets, primaryArch)
 		multiTargets = filterToArch(multiTargets, primaryArch)
 	}
 
+	// If there are no supported targets disable the module.
 	if len(targets) == 0 {
 		base.Disable()
 		return
 	}
 
+	// Convert the targets into a list of arch variation names.
 	targetNames := make([]string, len(targets))
-
 	for i, target := range targets {
 		targetNames[i] = target.ArchVariation()
 	}
 
+	// Create the variations, annotate each one with which Target it was created for, and
+	// squash the appropriate arch-specific properties into the top level properties.
 	modules := mctx.CreateVariations(targetNames...)
 	for i, m := range modules {
 		addTargetProperties(m, targets[i], multiTargets, i == 0)
@@ -968,22 +675,34 @@
 	}
 }
 
+// addTargetProperties annotates a variant with the Target is is being compiled for, the list
+// of additional Targets it is supporting (if any), and whether it is the primary Target for
+// the module.
 func addTargetProperties(m Module, target Target, multiTargets []Target, primaryTarget bool) {
 	m.base().commonProperties.CompileTarget = target
 	m.base().commonProperties.CompileMultiTargets = multiTargets
 	m.base().commonProperties.CompilePrimary = primaryTarget
 }
 
+// decodeMultilib returns the appropriate compile_multilib property for the module, or the default
+// multilib from the factory's call to InitAndroidArchModule if none was set.  For modules that
+// called InitAndroidMultiTargetsArchModule it always returns "common" for multilib, and returns
+// the actual multilib in extraMultilib.
 func decodeMultilib(base *ModuleBase, class OsClass) (multilib, extraMultilib string) {
+	// First check the "android.compile_multilib" or "host.compile_multilib" properties.
 	switch class {
 	case Device:
 		multilib = String(base.commonProperties.Target.Android.Compile_multilib)
 	case Host:
 		multilib = String(base.commonProperties.Target.Host.Compile_multilib)
 	}
+
+	// If those aren't set, try the "compile_multilib" property.
 	if multilib == "" {
 		multilib = String(base.commonProperties.Compile_multilib)
 	}
+
+	// If that wasn't set, use the default multilib set by the factory.
 	if multilib == "" {
 		multilib = base.commonProperties.Default_multilib
 	}
@@ -1000,6 +719,8 @@
 	}
 }
 
+// filterToArch takes a list of Targets and an ArchType, and returns a modified list that contains
+// only Targets that have the specified ArchType.
 func filterToArch(targets []Target, arch ArchType) []Target {
 	for i := 0; i < len(targets); i++ {
 		if targets[i].Arch.ArchType != arch {
@@ -1010,17 +731,27 @@
 	return targets
 }
 
-type archPropTypeDesc struct {
-	arch, multilib, target reflect.Type
-}
-
+// archPropRoot is a struct type used as the top level of the arch-specific properties.  It
+// contains the "arch", "multilib", and "target" property structs.  It is used to split up the
+// property structs to limit how much is allocated when a single arch-specific property group is
+// used.  The types are interface{} because they will hold instances of runtime-created types.
 type archPropRoot struct {
 	Arch, Multilib, Target interface{}
 }
 
+// archPropTypeDesc holds the runtime-created types for the property structs to instantiate to
+// create an archPropRoot property struct.
+type archPropTypeDesc struct {
+	arch, multilib, target reflect.Type
+}
+
 // createArchPropTypeDesc takes a reflect.Type that is either a struct or a pointer to a struct, and
 // returns lists of reflect.Types that contains the arch-variant properties inside structs for each
 // arch, multilib and target property.
+//
+// This is a relatively expensive operation, so the results are cached in the global
+// archPropTypeMap.  It is constructed entirely based on compile-time data, so there is no need
+// to isolate the results between multiple tests running in parallel.
 func createArchPropTypeDesc(props reflect.Type) []archPropTypeDesc {
 	// Each property struct shard will be nested many times under the runtime generated arch struct,
 	// which can hit the limit of 64kB for the name of runtime generated structs.  They are nested
@@ -1029,7 +760,12 @@
 	// could cause problems if a single deeply nested property no longer fits in the name.
 	const maxArchTypeNameSize = 500
 
+	// Convert the type to a new set of types that contains only the arch-specific properties
+	// (those that are tagged with `android:"arch_specific"`), and sharded into multiple types
+	// to keep the runtime-generated names under the limit.
 	propShards, _ := proptools.FilterPropertyStructSharded(props, maxArchTypeNameSize, filterArchStruct)
+
+	// If the type has no arch-specific properties there is nothing to do.
 	if len(propShards) == 0 {
 		return nil
 	}
@@ -1037,6 +773,8 @@
 	var ret []archPropTypeDesc
 	for _, props := range propShards {
 
+		// variantFields takes a list of variant property field names and returns a list the
+		// StructFields with the names and the type of the current shard.
 		variantFields := func(names []string) []reflect.StructField {
 			ret := make([]reflect.StructField, len(names))
 
@@ -1048,9 +786,11 @@
 			return ret
 		}
 
+		// Create a type that contains the properties in this shard repeated for each
+		// architecture, architecture variant, and architecture feature.
 		archFields := make([]reflect.StructField, len(archTypeList))
 		for i, arch := range archTypeList {
-			variants := []string{}
+			var variants []string
 
 			for _, archVariant := range archVariants[arch] {
 				archVariant := variantReplacer.Replace(archVariant)
@@ -1061,8 +801,13 @@
 				variants = append(variants, proptools.FieldNameForProperty(feature))
 			}
 
+			// Create the StructFields for each architecture variant architecture feature
+			// (e.g. "arch.arm.cortex-a53" or "arch.arm.neon").
 			fields := variantFields(variants)
 
+			// Create the StructField for the architecture itself (e.g. "arch.arm").  The special
+			// "BlueprintEmbed" name is used by Blueprint to put the properties in the
+			// parent struct.
 			fields = append([]reflect.StructField{{
 				Name:      "BlueprintEmbed",
 				Type:      props,
@@ -1074,10 +819,15 @@
 				Type: reflect.StructOf(fields),
 			}
 		}
+
+		// Create the type of the "arch" property struct for this shard.
 		archType := reflect.StructOf(archFields)
 
+		// Create the type for the "multilib" property struct for this shard, containing the
+		// "multilib.lib32" and "multilib.lib64" property structs.
 		multilibType := reflect.StructOf(variantFields([]string{"Lib32", "Lib64"}))
 
+		// Start with a list of the special targets
 		targets := []string{
 			"Host",
 			"Android64",
@@ -1090,11 +840,14 @@
 			"Native_bridge",
 		}
 		for _, os := range OsTypeList {
+			// Add all the OSes.
 			targets = append(targets, os.Field)
 
+			// Add the OS/Arch combinations, e.g. "android_arm64".
 			for _, archType := range osArchTypeMap[os] {
 				targets = append(targets, os.Field+"_"+archType.Name)
 
+				// Also add the special "linux_<arch>" and "bionic_<arch>" property structs.
 				if os.Linux() {
 					target := "Linux_" + archType.Name
 					if !InList(target, targets) {
@@ -1110,8 +863,10 @@
 			}
 		}
 
+		// Create the type for the "target" property struct for this shard.
 		targetType := reflect.StructOf(variantFields(targets))
 
+		// Return a descriptor of the 3 runtime-created types.
 		ret = append(ret, archPropTypeDesc{
 			arch:     reflect.PtrTo(archType),
 			multilib: reflect.PtrTo(multilibType),
@@ -1121,6 +876,11 @@
 	return ret
 }
 
+// variantReplacer converts architecture variant or architecture feature names into names that
+// are valid for an Android.bp file.
+var variantReplacer = strings.NewReplacer("-", "_", ".", "_")
+
+// filterArchStruct returns true if the given field is an architecture specific property.
 func filterArchStruct(field reflect.StructField, prefix string) (bool, reflect.StructField) {
 	if proptools.HasTag(field, "android", "arch_variant") {
 		// The arch_variant field isn't necessary past this point
@@ -1147,12 +907,17 @@
 	return false, field
 }
 
+// archPropTypeMap contains a cache of the results of createArchPropTypeDesc for each type.  It is
+// shared across all Contexts, but is constructed based only on compile-time information so there
+// is no risk of contaminating one Context with data from another.
 var archPropTypeMap OncePer
 
-func InitArchModule(m Module) {
+// initArchModule adds the architecture-specific property structs to a Module.
+func initArchModule(m Module) {
 
 	base := m.base()
 
+	// Store the original list of top level property structs
 	base.generalProperties = m.GetProperties()
 
 	for _, properties := range base.generalProperties {
@@ -1169,10 +934,13 @@
 				propertiesValue.Interface()))
 		}
 
+		// Get or create the arch-specific property struct types for this property struct type.
 		archPropTypes := archPropTypeMap.Once(NewCustomOnceKey(t), func() interface{} {
 			return createArchPropTypeDesc(t)
 		}).([]archPropTypeDesc)
 
+		// Instantiate one of each arch-specific property struct type and add it to the
+		// properties for the Module.
 		var archProperties []interface{}
 		for _, t := range archPropTypes {
 			archProperties = append(archProperties, &archPropRoot{
@@ -1185,14 +953,18 @@
 		m.AddProperties(archProperties...)
 	}
 
+	// Update the list of properties that can be set by a defaults module or a call to
+	// AppendMatchingProperties or PrependMatchingProperties.
 	base.customizableProperties = m.GetProperties()
 }
 
-var variantReplacer = strings.NewReplacer("-", "_", ".", "_")
-
+// appendProperties squashes properties from the given field of the given src property struct
+// into the dst property struct.  Returns the reflect.Value of the field in the src property
+// struct to be used for further appendProperties calls on fields of that property struct.
 func (m *ModuleBase) appendProperties(ctx BottomUpMutatorContext,
 	dst interface{}, src reflect.Value, field, srcPrefix string) reflect.Value {
 
+	// Step into non-nil pointers to structs in the src value.
 	if src.Kind() == reflect.Ptr {
 		if src.IsNil() {
 			return src
@@ -1200,18 +972,25 @@
 		src = src.Elem()
 	}
 
+	// Find the requested field in the src struct.
 	src = src.FieldByName(field)
 	if !src.IsValid() {
 		ctx.ModuleErrorf("field %q does not exist", srcPrefix)
 		return src
 	}
 
+	// Save the value of the field in the src struct to return.
 	ret := src
 
+	// If the value of the field is a struct (as opposed to a pointer to a struct) then step
+	// into the BlueprintEmbed field.
 	if src.Kind() == reflect.Struct {
 		src = src.FieldByName("BlueprintEmbed")
 	}
 
+	// order checks the `android:"variant_prepend"` tag to handle properties where the
+	// arch-specific value needs to come before the generic value, for example for lists of
+	// include directories.
 	order := func(property string,
 		dstField, srcField reflect.StructField,
 		dstValue, srcValue interface{}) (proptools.Order, error) {
@@ -1222,6 +1001,7 @@
 		}
 	}
 
+	// Squash the located property struct into the destination property struct.
 	err := proptools.ExtendMatchingProperties([]interface{}{dst}, src.Interface(), nil, order)
 	if err != nil {
 		if propertyErr, ok := err.(*proptools.ExtendPropertyError); ok {
@@ -1234,7 +1014,8 @@
 	return ret
 }
 
-// Rewrite the module's properties structs to contain os-specific values.
+// Squash the appropriate OS-specific property structs into the matching top level property structs
+// based on the CompileOS value that was annotated on the variant.
 func (m *ModuleBase) setOSProperties(ctx BottomUpMutatorContext) {
 	os := m.commonProperties.CompileOS
 
@@ -1328,7 +1109,8 @@
 	}
 }
 
-// Rewrite the module's properties structs to contain arch-specific values.
+// Squash the appropriate arch-specific property structs into the matching top level property
+// structs based on the CompileTarget value that was annotated on the variant.
 func (m *ModuleBase) setArchProperties(ctx BottomUpMutatorContext) {
 	arch := m.Arch()
 	os := m.Os()
@@ -1480,22 +1262,7 @@
 	}
 }
 
-func forEachInterface(v reflect.Value, f func(reflect.Value)) {
-	switch v.Kind() {
-	case reflect.Interface:
-		f(v)
-	case reflect.Struct:
-		for i := 0; i < v.NumField(); i++ {
-			forEachInterface(v.Field(i), f)
-		}
-	case reflect.Ptr:
-		forEachInterface(v.Elem(), f)
-	default:
-		panic(fmt.Errorf("Unsupported kind %s", v.Kind()))
-	}
-}
-
-// Convert the arch product variables into a list of targets for each os class structs
+// Convert the arch product variables into a list of targets for each OsType.
 func decodeTargetProductVariables(config *config) (map[OsType][]Target, error) {
 	variables := config.productVariables
 
@@ -1567,19 +1334,26 @@
 		return nil, fmt.Errorf("No host primary architecture set")
 	}
 
+	// The primary host target, which must always exist.
 	addTarget(BuildOs, *variables.HostArch, nil, nil, nil, NativeBridgeDisabled, nil, nil)
 
+	// An optional secondary host target.
 	if variables.HostSecondaryArch != nil && *variables.HostSecondaryArch != "" {
 		addTarget(BuildOs, *variables.HostSecondaryArch, nil, nil, nil, NativeBridgeDisabled, nil, nil)
 	}
 
+	// An optional host target that uses the Bionic glibc runtime.
 	if Bool(config.Host_bionic) {
 		addTarget(LinuxBionic, "x86_64", nil, nil, nil, NativeBridgeDisabled, nil, nil)
 	}
+
+	// An optional cross-compiled host target that uses the Bionic glibc runtime on an arm64
+	// architecture.
 	if Bool(config.Host_bionic_arm64) {
 		addTarget(LinuxBionic, "arm64", nil, nil, nil, NativeBridgeDisabled, nil, nil)
 	}
 
+	// Optional cross-compiled host targets, generally Windows.
 	if String(variables.CrossHost) != "" {
 		crossHostOs := osByName(*variables.CrossHost)
 		if crossHostOs == NoOsType {
@@ -1590,28 +1364,34 @@
 			return nil, fmt.Errorf("No cross-host primary architecture set")
 		}
 
+		// The primary cross-compiled host target.
 		addTarget(crossHostOs, *variables.CrossHostArch, nil, nil, nil, NativeBridgeDisabled, nil, nil)
 
+		// An optional secondary cross-compiled host target.
 		if variables.CrossHostSecondaryArch != nil && *variables.CrossHostSecondaryArch != "" {
 			addTarget(crossHostOs, *variables.CrossHostSecondaryArch, nil, nil, nil, NativeBridgeDisabled, nil, nil)
 		}
 	}
 
+	// Optional device targets
 	if variables.DeviceArch != nil && *variables.DeviceArch != "" {
 		var target = Android
 		if Bool(variables.Fuchsia) {
 			target = Fuchsia
 		}
 
+		// The primary device target.
 		addTarget(target, *variables.DeviceArch, variables.DeviceArchVariant,
 			variables.DeviceCpuVariant, variables.DeviceAbi, NativeBridgeDisabled, nil, nil)
 
+		// An optional secondary device target.
 		if variables.DeviceSecondaryArch != nil && *variables.DeviceSecondaryArch != "" {
 			addTarget(Android, *variables.DeviceSecondaryArch,
 				variables.DeviceSecondaryArchVariant, variables.DeviceSecondaryCpuVariant,
 				variables.DeviceSecondaryAbi, NativeBridgeDisabled, nil, nil)
 		}
 
+		// An optional NativeBridge device target.
 		if variables.NativeBridgeArch != nil && *variables.NativeBridgeArch != "" {
 			addTarget(Android, *variables.NativeBridgeArch,
 				variables.NativeBridgeArchVariant, variables.NativeBridgeCpuVariant,
@@ -1619,6 +1399,7 @@
 				variables.NativeBridgeRelativePath)
 		}
 
+		// An optional secondary NativeBridge device target.
 		if variables.DeviceSecondaryArch != nil && *variables.DeviceSecondaryArch != "" &&
 			variables.NativeBridgeSecondaryArch != nil && *variables.NativeBridgeSecondaryArch != "" {
 			addTarget(Android, *variables.NativeBridgeSecondaryArch,
@@ -1653,6 +1434,7 @@
 	return false
 }
 
+// archConfig describes a built-in configuration.
 type archConfig struct {
 	arch        string
 	archVariant string
@@ -1660,6 +1442,7 @@
 	abi         []string
 }
 
+// getMegaDeviceConfig returns a list of archConfigs for every architecture simultaneously.
 func getMegaDeviceConfig() []archConfig {
 	return []archConfig{
 		{"arm", "armv7-a", "generic", []string{"armeabi-v7a"}},
@@ -1706,6 +1489,7 @@
 	}
 }
 
+// getNdkAbisConfig returns a list of archConfigs for the ABIs supported by the NDK.
 func getNdkAbisConfig() []archConfig {
 	return []archConfig{
 		{"arm", "armv7-a", "", []string{"armeabi-v7a"}},
@@ -1715,6 +1499,7 @@
 	}
 }
 
+// getAmlAbisConfig returns a list of archConfigs for the ABIs supported by mainline modules.
 func getAmlAbisConfig() []archConfig {
 	return []archConfig{
 		{"arm", "armv7-a-neon", "", []string{"armeabi-v7a"}},
@@ -1724,6 +1509,7 @@
 	}
 }
 
+// decodeArchSettings converts a list of archConfigs into a list of Targets for the given OsType.
 func decodeArchSettings(os OsType, archConfigs []archConfig) ([]Target, error) {
 	var ret []Target
 
@@ -1743,15 +1529,9 @@
 	return ret, nil
 }
 
-// Convert a set of strings from product variables into a single Arch struct
+// decodeArch converts a set of strings from product variables into an Arch struct.
 func decodeArch(os OsType, arch string, archVariant, cpuVariant *string, abi []string) (Arch, error) {
-	stringPtr := func(p *string) string {
-		if p != nil {
-			return *p
-		}
-		return ""
-	}
-
+	// Verify the arch is valid
 	archType, ok := archTypeMap[arch]
 	if !ok {
 		return Arch{}, fmt.Errorf("unknown arch %q", arch)
@@ -1759,19 +1539,22 @@
 
 	a := Arch{
 		ArchType:    archType,
-		ArchVariant: stringPtr(archVariant),
-		CpuVariant:  stringPtr(cpuVariant),
+		ArchVariant: String(archVariant),
+		CpuVariant:  String(cpuVariant),
 		Abi:         abi,
 	}
 
+	// Convert generic arch variants into the empty string.
 	if a.ArchVariant == a.ArchType.Name || a.ArchVariant == "generic" {
 		a.ArchVariant = ""
 	}
 
+	// Convert generic CPU variants into the empty string.
 	if a.CpuVariant == a.ArchType.Name || a.CpuVariant == "generic" {
 		a.CpuVariant = ""
 	}
 
+	// Filter empty ABIs out of the list.
 	for i := 0; i < len(a.Abi); i++ {
 		if a.Abi[i] == "" {
 			a.Abi = append(a.Abi[:i], a.Abi[i+1:]...)
@@ -1780,10 +1563,12 @@
 	}
 
 	if a.ArchVariant == "" {
+		// Set ArchFeatures from the default arch features.
 		if featureMap, ok := defaultArchFeatureMap[os]; ok {
 			a.ArchFeatures = featureMap[archType]
 		}
 	} else {
+		// Set ArchFeatures from the arch type.
 		if featureMap, ok := archFeatureMap[archType]; ok {
 			a.ArchFeatures = featureMap[a.ArchVariant]
 		}
@@ -1792,6 +1577,8 @@
 	return a, nil
 }
 
+// filterMultilibTargets takes a list of Targets and a multilib value and returns a new list of
+// Targets containing only those that have the given multilib value.
 func filterMultilibTargets(targets []Target, multilib string) []Target {
 	var ret []Target
 	for _, t := range targets {
@@ -1802,8 +1589,8 @@
 	return ret
 }
 
-// Return the set of Os specific common architecture targets for each Os in a list of
-// targets.
+// getCommonTargets returns the set of Os specific common architecture targets for each Os in a list
+// of targets.
 func getCommonTargets(targets []Target) []Target {
 	var ret []Target
 	set := make(map[string]bool)
@@ -1818,6 +1605,9 @@
 	return ret
 }
 
+// firstTarget takes a list of Targets and a list of multilib values and returns a list of Targets
+// that contains zero or one Target for each OsType, selecting the one that matches the earliest
+// filter.
 func firstTarget(targets []Target, filters ...string) []Target {
 	// find the first target from each OS
 	var ret []Target
@@ -1837,9 +1627,10 @@
 	return ret
 }
 
-// Use the module multilib setting to select one or more targets from a target list
+// decodeMultilibTargets uses the module's multilib setting to select one or more targets from a
+// list of Targets.
 func decodeMultilibTargets(multilib string, targets []Target, prefer32 bool) ([]Target, error) {
-	buildTargets := []Target{}
+	var buildTargets []Target
 
 	switch multilib {
 	case "common":
diff --git a/android/arch_list.go b/android/arch_list.go
new file mode 100644
index 0000000..0c33b9d
--- /dev/null
+++ b/android/arch_list.go
@@ -0,0 +1,410 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package android
+
+import "fmt"
+
+var archVariants = map[ArchType][]string{
+	Arm: {
+		"armv7-a",
+		"armv7-a-neon",
+		"armv8-a",
+		"armv8-2a",
+		"cortex-a7",
+		"cortex-a8",
+		"cortex-a9",
+		"cortex-a15",
+		"cortex-a53",
+		"cortex-a53-a57",
+		"cortex-a55",
+		"cortex-a72",
+		"cortex-a73",
+		"cortex-a75",
+		"cortex-a76",
+		"krait",
+		"kryo",
+		"kryo385",
+		"exynos-m1",
+		"exynos-m2",
+	},
+	Arm64: {
+		"armv8_a",
+		"armv8_2a",
+		"armv8-2a-dotprod",
+		"cortex-a53",
+		"cortex-a55",
+		"cortex-a72",
+		"cortex-a73",
+		"cortex-a75",
+		"cortex-a76",
+		"kryo",
+		"kryo385",
+		"exynos-m1",
+		"exynos-m2",
+	},
+	X86: {
+		"amberlake",
+		"atom",
+		"broadwell",
+		"haswell",
+		"icelake",
+		"ivybridge",
+		"kabylake",
+		"sandybridge",
+		"silvermont",
+		"skylake",
+		"stoneyridge",
+		"tigerlake",
+		"whiskeylake",
+		"x86_64",
+	},
+	X86_64: {
+		"amberlake",
+		"broadwell",
+		"haswell",
+		"icelake",
+		"ivybridge",
+		"kabylake",
+		"sandybridge",
+		"silvermont",
+		"skylake",
+		"stoneyridge",
+		"tigerlake",
+		"whiskeylake",
+	},
+}
+
+var archFeatures = map[ArchType][]string{
+	Arm: {
+		"neon",
+	},
+	Arm64: {
+		"dotprod",
+	},
+	X86: {
+		"ssse3",
+		"sse4",
+		"sse4_1",
+		"sse4_2",
+		"aes_ni",
+		"avx",
+		"avx2",
+		"avx512",
+		"popcnt",
+		"movbe",
+	},
+	X86_64: {
+		"ssse3",
+		"sse4",
+		"sse4_1",
+		"sse4_2",
+		"aes_ni",
+		"avx",
+		"avx2",
+		"avx512",
+		"popcnt",
+	},
+}
+
+var archFeatureMap = map[ArchType]map[string][]string{
+	Arm: {
+		"armv7-a-neon": {
+			"neon",
+		},
+		"armv8-a": {
+			"neon",
+		},
+		"armv8-2a": {
+			"neon",
+		},
+	},
+	Arm64: {
+		"armv8-2a-dotprod": {
+			"dotprod",
+		},
+	},
+	X86: {
+		"amberlake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"aes_ni",
+			"popcnt",
+		},
+		"atom": {
+			"ssse3",
+			"movbe",
+		},
+		"broadwell": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"aes_ni",
+			"popcnt",
+		},
+		"haswell": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"aes_ni",
+			"avx",
+			"popcnt",
+			"movbe",
+		},
+		"icelake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"avx512",
+			"aes_ni",
+			"popcnt",
+		},
+		"ivybridge": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"aes_ni",
+			"avx",
+			"popcnt",
+		},
+		"kabylake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"aes_ni",
+			"popcnt",
+		},
+		"sandybridge": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"popcnt",
+		},
+		"silvermont": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"aes_ni",
+			"popcnt",
+			"movbe",
+		},
+		"skylake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"avx512",
+			"aes_ni",
+			"popcnt",
+		},
+		"stoneyridge": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"aes_ni",
+			"avx",
+			"avx2",
+			"popcnt",
+			"movbe",
+		},
+		"tigerlake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"avx512",
+			"aes_ni",
+			"popcnt",
+		},
+		"whiskeylake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"avx512",
+			"aes_ni",
+			"popcnt",
+		},
+		"x86_64": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"popcnt",
+		},
+	},
+	X86_64: {
+		"amberlake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"aes_ni",
+			"popcnt",
+		},
+		"broadwell": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"aes_ni",
+			"popcnt",
+		},
+		"haswell": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"aes_ni",
+			"avx",
+			"popcnt",
+		},
+		"icelake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"avx512",
+			"aes_ni",
+			"popcnt",
+		},
+		"ivybridge": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"aes_ni",
+			"avx",
+			"popcnt",
+		},
+		"kabylake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"aes_ni",
+			"popcnt",
+		},
+		"sandybridge": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"popcnt",
+		},
+		"silvermont": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"aes_ni",
+			"popcnt",
+		},
+		"skylake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"avx512",
+			"aes_ni",
+			"popcnt",
+		},
+		"stoneyridge": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"aes_ni",
+			"avx",
+			"avx2",
+			"popcnt",
+		},
+		"tigerlake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"avx512",
+			"aes_ni",
+			"popcnt",
+		},
+		"whiskeylake": {
+			"ssse3",
+			"sse4",
+			"sse4_1",
+			"sse4_2",
+			"avx",
+			"avx2",
+			"avx512",
+			"aes_ni",
+			"popcnt",
+		},
+	},
+}
+
+var defaultArchFeatureMap = map[OsType]map[ArchType][]string{}
+
+// RegisterDefaultArchVariantFeatures is called by files that define Toolchains to specify the
+// arch features that are available for the default arch variant.  It must be called from an
+// init() function.
+func RegisterDefaultArchVariantFeatures(os OsType, arch ArchType, features ...string) {
+	checkCalledFromInit()
+
+	for _, feature := range features {
+		if !InList(feature, archFeatures[arch]) {
+			panic(fmt.Errorf("Invalid feature %q for arch %q variant \"\"", feature, arch))
+		}
+	}
+
+	if defaultArchFeatureMap[os] == nil {
+		defaultArchFeatureMap[os] = make(map[ArchType][]string)
+	}
+	defaultArchFeatureMap[os][arch] = features
+}
diff --git a/android/config.go b/android/config.go
index d833c5c..10e7b24 100644
--- a/android/config.go
+++ b/android/config.go
@@ -112,7 +112,9 @@
 	envDeps   map[string]string
 	envFrozen bool
 
-	inMake bool
+	// Changes behavior based on whether Kati runs after soong_build, or if soong_build
+	// runs standalone.
+	katiEnabled bool
 
 	captureBuild      bool // true for tests, saves build parameters for each module
 	ignoreEnvironment bool // true for tests, returns empty from all Getenv calls
@@ -263,10 +265,6 @@
 
 	config.mockFileSystem(bp, fs)
 
-	if err := config.fromEnv(); err != nil {
-		panic(err)
-	}
-
 	return Config{config}
 }
 
@@ -390,9 +388,9 @@
 		return Config{}, err
 	}
 
-	inMakeFile := filepath.Join(buildDir, ".soong.in_make")
-	if _, err := os.Stat(absolutePath(inMakeFile)); err == nil {
-		config.inMake = true
+	KatiEnabledMarkerFile := filepath.Join(buildDir, ".soong.kati_enabled")
+	if _, err := os.Stat(absolutePath(KatiEnabledMarkerFile)); err == nil {
+		config.katiEnabled = true
 	}
 
 	targets, err := decodeTargetProductVariables(config)
@@ -436,10 +434,6 @@
 		config.AndroidFirstDeviceTarget = firstTarget(config.Targets[Android], "lib64", "lib32")[0]
 	}
 
-	if err := config.fromEnv(); err != nil {
-		return Config{}, err
-	}
-
 	if Bool(config.productVariables.GcovCoverage) && Bool(config.productVariables.ClangCoverage) {
 		return Config{}, fmt.Errorf("GcovCoverage and ClangCoverage cannot both be set")
 	}
@@ -487,17 +481,6 @@
 	c.mockBpList = blueprint.MockModuleListFile
 }
 
-func (c *config) fromEnv() error {
-	switch c.Getenv("EXPERIMENTAL_JAVA_LANGUAGE_LEVEL_9") {
-	case "", "true":
-		// Do nothing
-	default:
-		return fmt.Errorf("The environment variable EXPERIMENTAL_JAVA_LANGUAGE_LEVEL_9 is no longer supported. Java language level 9 is now the global default.")
-	}
-
-	return nil
-}
-
 func (c *config) StopBefore() bootstrap.StopBefore {
 	return c.stopBefore
 }
@@ -619,8 +602,8 @@
 	return c.envDeps
 }
 
-func (c *config) EmbeddedInMake() bool {
-	return c.inMake
+func (c *config) KatiEnabled() bool {
+	return c.katiEnabled
 }
 
 func (c *config) BuildId() string {
diff --git a/android/defaults.go b/android/defaults.go
index eb013d7..44753ce 100644
--- a/android/defaults.go
+++ b/android/defaults.go
@@ -183,7 +183,7 @@
 
 	initAndroidModuleBase(module)
 	initProductVariableModule(module)
-	InitArchModule(module)
+	initArchModule(module)
 	InitDefaultableModule(module)
 
 	// Add properties that will not have defaults applied to them.
diff --git a/android/filegroup.go b/android/filegroup.go
index 68311e3..9425616 100644
--- a/android/filegroup.go
+++ b/android/filegroup.go
@@ -15,6 +15,7 @@
 package android
 
 import (
+	"android/soong/bazel"
 	"strings"
 )
 
@@ -37,6 +38,9 @@
 	// Create a make variable with the specified name that contains the list of files in the
 	// filegroup, relative to the root of the source tree.
 	Export_to_make_var *string
+
+	// Properties for Bazel migration purposes.
+	bazel.Properties
 }
 
 type fileGroup struct {
diff --git a/android/makevars.go b/android/makevars.go
index f784395..5101436 100644
--- a/android/makevars.go
+++ b/android/makevars.go
@@ -213,7 +213,7 @@
 }
 
 func (s *makeVarsSingleton) GenerateBuildActions(ctx SingletonContext) {
-	if !ctx.Config().EmbeddedInMake() {
+	if !ctx.Config().KatiEnabled() {
 		return
 	}
 
diff --git a/android/module.go b/android/module.go
index eeb4fae..7a05096 100644
--- a/android/module.go
+++ b/android/module.go
@@ -717,7 +717,9 @@
 	DebugMutators   []string `blueprint:"mutated"`
 	DebugVariations []string `blueprint:"mutated"`
 
-	// set by ImageMutator
+	// ImageVariation is set by ImageMutator to specify which image this variation is for,
+	// for example "" for core or "recovery" for recovery.  It will often be set to one of the
+	// constants in image.go, but can also be set to a custom value by individual module types.
 	ImageVariation string `blueprint:"mutated"`
 }
 
@@ -825,6 +827,8 @@
 	m.base().module = m
 }
 
+// InitAndroidModule initializes the Module as an Android module that is not architecture-specific.
+// It adds the common properties, for example "name" and "enabled".
 func InitAndroidModule(m Module) {
 	initAndroidModuleBase(m)
 	base := m.base()
@@ -844,6 +848,12 @@
 	setPrimaryVisibilityProperty(m, "visibility", &base.commonProperties.Visibility)
 }
 
+// InitAndroidArchModule initializes the Module as an Android module that is architecture-specific.
+// It adds the common properties, for example "name" and "enabled", as well as runtime generated
+// property structs for architecture-specific versions of generic properties tagged with
+// `android:"arch_variant"`.
+//
+//  InitAndroidModule should not be called if InitAndroidArchModule was called.
 func InitAndroidArchModule(m Module, hod HostOrDeviceSupported, defaultMultilib Multilib) {
 	InitAndroidModule(m)
 
@@ -857,16 +867,33 @@
 		m.AddProperties(&base.hostAndDeviceProperties)
 	}
 
-	InitArchModule(m)
+	initArchModule(m)
 }
 
+// InitAndroidMultiTargetsArchModule initializes the Module as an Android module that is
+// architecture-specific, but will only have a single variant per OS that handles all the
+// architectures simultaneously.  The list of Targets that it must handle will be available from
+// ModuleContext.MultiTargets. It adds the common properties, for example "name" and "enabled", as
+// well as runtime generated property structs for architecture-specific versions of generic
+// properties tagged with `android:"arch_variant"`.
+//
+// InitAndroidModule or InitAndroidArchModule should not be called if
+// InitAndroidMultiTargetsArchModule was called.
 func InitAndroidMultiTargetsArchModule(m Module, hod HostOrDeviceSupported, defaultMultilib Multilib) {
 	InitAndroidArchModule(m, hod, defaultMultilib)
 	m.base().commonProperties.UseTargetVariants = false
 }
 
-// As InitAndroidMultiTargetsArchModule except it creates an additional CommonOS variant that
-// has dependencies on all the OsType specific variants.
+// InitCommonOSAndroidMultiTargetsArchModule initializes the Module as an Android module that is
+// architecture-specific, but will only have a single variant per OS that handles all the
+// architectures simultaneously, and will also have an additional CommonOS variant that has
+// dependencies on all the OS-specific variants.  The list of Targets that it must handle will be
+// available from ModuleContext.MultiTargets.  It adds the common properties, for example "name" and
+// "enabled", as well as runtime generated property structs for architecture-specific versions of
+// generic properties tagged with `android:"arch_variant"`.
+//
+// InitAndroidModule, InitAndroidArchModule or InitAndroidMultiTargetsArchModule should not be
+// called if InitCommonOSAndroidMultiTargetsArchModule was called.
 func InitCommonOSAndroidMultiTargetsArchModule(m Module, hod HostOrDeviceSupported, defaultMultilib Multilib) {
 	InitAndroidArchModule(m, hod, defaultMultilib)
 	m.base().commonProperties.UseTargetVariants = false
@@ -1413,7 +1440,7 @@
 
 	if len(deps) > 0 {
 		suffix := ""
-		if ctx.Config().EmbeddedInMake() {
+		if ctx.Config().KatiEnabled() {
 			suffix = "-soong"
 		}
 
@@ -2293,7 +2320,7 @@
 	}
 
 	if m.Device() {
-		if m.Config().EmbeddedInMake() && !m.InstallBypassMake() {
+		if m.Config().KatiEnabled() && !m.InstallBypassMake() {
 			return true
 		}
 
@@ -2346,7 +2373,7 @@
 			Input:       srcPath,
 			Implicits:   implicitDeps,
 			OrderOnly:   orderOnlyDeps,
-			Default:     !m.Config().EmbeddedInMake(),
+			Default:     !m.Config().KatiEnabled(),
 		})
 
 		m.installFiles = append(m.installFiles, fullInstallPath)
@@ -2378,7 +2405,7 @@
 			Description: "install symlink " + fullInstallPath.Base(),
 			Output:      fullInstallPath,
 			Input:       srcPath,
-			Default:     !m.Config().EmbeddedInMake(),
+			Default:     !m.Config().KatiEnabled(),
 			Args: map[string]string{
 				"fromPath": relPath,
 			},
@@ -2409,7 +2436,7 @@
 			Rule:        Symlink,
 			Description: "install symlink " + fullInstallPath.Base() + " -> " + absPath,
 			Output:      fullInstallPath,
-			Default:     !m.Config().EmbeddedInMake(),
+			Default:     !m.Config().KatiEnabled(),
 			Args: map[string]string{
 				"fromPath": absPath,
 			},
@@ -2551,6 +2578,15 @@
 			return nil, fmt.Errorf("failed to get output files from module %q", pathContextName(ctx, module))
 		}
 		return paths, nil
+	} else if sourceFileProducer, ok := module.(SourceFileProducer); ok {
+		if tag != "" {
+			return nil, fmt.Errorf("module %q is a SourceFileProducer, not an OutputFileProducer, and so does not support tag %q", pathContextName(ctx, module), tag)
+		}
+		paths := sourceFileProducer.Srcs()
+		if len(paths) == 0 {
+			return nil, fmt.Errorf("failed to get output files from module %q", pathContextName(ctx, module))
+		}
+		return paths, nil
 	} else {
 		return nil, fmt.Errorf("module %q is not an OutputFileProducer", pathContextName(ctx, module))
 	}
@@ -2638,7 +2674,7 @@
 	})
 
 	suffix := ""
-	if ctx.Config().EmbeddedInMake() {
+	if ctx.Config().KatiEnabled() {
 		suffix = "-soong"
 	}
 
@@ -2646,7 +2682,7 @@
 	ctx.Phony("checkbuild"+suffix, checkbuildDeps...)
 
 	// Make will generate the MODULES-IN-* targets
-	if ctx.Config().EmbeddedInMake() {
+	if ctx.Config().KatiEnabled() {
 		return
 	}
 
diff --git a/android/path_properties.go b/android/path_properties.go
index 6b1cdb3..4bb706a 100644
--- a/android/path_properties.go
+++ b/android/path_properties.go
@@ -21,27 +21,31 @@
 	"github.com/google/blueprint/proptools"
 )
 
+// This file implements support for automatically adding dependencies on any module referenced
+// with the ":module" module reference syntax in a property that is annotated with `android:"path"`.
+// The dependency is used by android.PathForModuleSrc to convert the module reference into the path
+// to the output file of the referenced module.
+
 func registerPathDepsMutator(ctx RegisterMutatorsContext) {
 	ctx.BottomUp("pathdeps", pathDepsMutator).Parallel()
 }
 
-// The pathDepsMutator automatically adds dependencies on any module that is listed with ":module" syntax in a
-// property that is tagged with android:"path".
+// The pathDepsMutator automatically adds dependencies on any module that is listed with the
+// ":module" module reference syntax in a property that is tagged with `android:"path"`.
 func pathDepsMutator(ctx BottomUpMutatorContext) {
-	m := ctx.Module().(Module)
-	if m == nil {
-		return
-	}
+	props := ctx.Module().base().generalProperties
 
-	props := m.base().generalProperties
-
+	// Iterate through each property struct of the module extracting the contents of all properties
+	// tagged with `android:"path"`.
 	var pathProperties []string
 	for _, ps := range props {
-		pathProperties = append(pathProperties, pathPropertiesForPropertyStruct(ctx, ps)...)
+		pathProperties = append(pathProperties, pathPropertiesForPropertyStruct(ps)...)
 	}
 
+	// Remove duplicates to avoid multiple dependencies.
 	pathProperties = FirstUniqueStrings(pathProperties)
 
+	// Add dependencies to anything that is a module reference.
 	for _, s := range pathProperties {
 		if m, t := SrcIsModuleWithTag(s); m != "" {
 			ctx.AddDependency(ctx.Module(), sourceOrOutputDepTag(t), m)
@@ -49,34 +53,45 @@
 	}
 }
 
-// pathPropertiesForPropertyStruct uses the indexes of properties that are tagged with android:"path" to extract
-// all their values from a property struct, returning them as a single slice of strings..
-func pathPropertiesForPropertyStruct(ctx BottomUpMutatorContext, ps interface{}) []string {
+// pathPropertiesForPropertyStruct uses the indexes of properties that are tagged with
+// android:"path" to extract all their values from a property struct, returning them as a single
+// slice of strings.
+func pathPropertiesForPropertyStruct(ps interface{}) []string {
 	v := reflect.ValueOf(ps)
 	if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct {
 		panic(fmt.Errorf("type %s is not a pointer to a struct", v.Type()))
 	}
+
+	// If the property struct is a nil pointer it can't have any paths set in it.
 	if v.IsNil() {
 		return nil
 	}
+
+	// v is now the reflect.Value for the concrete property struct.
 	v = v.Elem()
 
+	// Get or create the list of indexes of properties that are tagged with `android:"path"`.
 	pathPropertyIndexes := pathPropertyIndexesForPropertyStruct(ps)
 
 	var ret []string
 
 	for _, i := range pathPropertyIndexes {
+		// Turn an index into a field.
 		sv := fieldByIndex(v, i)
 		if !sv.IsValid() {
+			// Skip properties inside a nil pointer.
 			continue
 		}
 
+		// If the field is a non-nil pointer step into it.
 		if sv.Kind() == reflect.Ptr {
 			if sv.IsNil() {
 				continue
 			}
 			sv = sv.Elem()
 		}
+
+		// Collect paths from all strings and slices of strings.
 		switch sv.Kind() {
 		case reflect.String:
 			ret = append(ret, sv.String())
@@ -91,8 +106,8 @@
 	return ret
 }
 
-// fieldByIndex is like reflect.Value.FieldByIndex, but returns an invalid reflect.Value when traversing a nil pointer
-// to a struct.
+// fieldByIndex is like reflect.Value.FieldByIndex, but returns an invalid reflect.Value when
+// traversing a nil pointer to a struct.
 func fieldByIndex(v reflect.Value, index []int) reflect.Value {
 	if len(index) == 1 {
 		return v.Field(index[0])
@@ -111,9 +126,9 @@
 
 var pathPropertyIndexesCache OncePer
 
-// pathPropertyIndexesForPropertyStruct returns a list of all of the indexes of properties in property struct type that
-// are tagged with android:"path".  Each index is a []int suitable for passing to reflect.Value.FieldByIndex.  The value
-// is cached in a global cache by type.
+// pathPropertyIndexesForPropertyStruct returns a list of all of the indexes of properties in
+// property struct type that are tagged with `android:"path"`.  Each index is a []int suitable for
+// passing to reflect.Value.FieldByIndex.  The value is cached in a global cache by type.
 func pathPropertyIndexesForPropertyStruct(ps interface{}) [][]int {
 	key := NewCustomOnceKey(reflect.TypeOf(ps))
 	return pathPropertyIndexesCache.Once(key, func() interface{} {
diff --git a/android/paths.go b/android/paths.go
index b13979d..a62c9e3 100644
--- a/android/paths.go
+++ b/android/paths.go
@@ -1312,7 +1312,7 @@
 
 	ret := pathForInstall(ctx, os, arch, partition, ctx.Debug(), pathComponents...)
 
-	if ctx.InstallBypassMake() && ctx.Config().EmbeddedInMake() {
+	if ctx.InstallBypassMake() && ctx.Config().KatiEnabled() {
 		ret = ret.ToMakePath()
 	}
 
diff --git a/android/phony.go b/android/phony.go
index f8e5a44..0adbb55 100644
--- a/android/phony.go
+++ b/android/phony.go
@@ -53,7 +53,7 @@
 		p.phonyMap[phony] = SortedUniquePaths(p.phonyMap[phony])
 	}
 
-	if !ctx.Config().EmbeddedInMake() {
+	if !ctx.Config().KatiEnabled() {
 		for _, phony := range p.phonyList {
 			ctx.Build(pctx, BuildParams{
 				Rule:      blueprint.Phony,
diff --git a/android/testing.go b/android/testing.go
index 1e2ae13..6539063 100644
--- a/android/testing.go
+++ b/android/testing.go
@@ -424,8 +424,8 @@
 
 }
 
-func SetInMakeForTests(config Config) {
-	config.inMake = true
+func SetKatiEnabledForTests(config Config) {
+	config.katiEnabled = true
 }
 
 func AndroidMkEntriesForTest(t *testing.T, config Config, bpPath string, mod blueprint.Module) []AndroidMkEntries {
diff --git a/androidmk/androidmk/androidmk.go b/androidmk/androidmk/androidmk.go
index 03cf74d..f4e5fa0 100644
--- a/androidmk/androidmk/androidmk.go
+++ b/androidmk/androidmk/androidmk.go
@@ -137,7 +137,14 @@
 
 		switch x := node.(type) {
 		case *mkparser.Comment:
-			file.insertComment("//" + x.Comment)
+			// Split the comment on escaped newlines and then
+			// add each chunk separately.
+			chunks := strings.Split(x.Comment, "\\\n")
+			file.insertComment("//" + chunks[0])
+			for i := 1; i < len(chunks); i++ {
+				file.bpPos.Line++
+				file.insertComment("//" + chunks[i])
+			}
 		case *mkparser.Assignment:
 			handleAssignment(file, x, assignmentCond)
 		case *mkparser.Directive:
diff --git a/androidmk/androidmk/androidmk_test.go b/androidmk/androidmk/androidmk_test.go
index 16cb138..f32ff2a 100644
--- a/androidmk/androidmk/androidmk_test.go
+++ b/androidmk/androidmk/androidmk_test.go
@@ -1260,10 +1260,10 @@
 		desc: "comment with ESC",
 		in: `
 # Comment line 1 \
-# Comment line 2
+ Comment line 2
 `,
 		expected: `
-// Comment line 1 \
+// Comment line 1
 // Comment line 2
 `,
 	},
diff --git a/androidmk/parser/parser.go b/androidmk/parser/parser.go
index e61241b..c14910a 100644
--- a/androidmk/parser/parser.go
+++ b/androidmk/parser/parser.go
@@ -497,12 +497,6 @@
 		switch p.tok {
 		case '\\':
 			p.parseEscape()
-			if p.tok == '\n' {
-				// Special case: '\' does not "escape" newline in comment (b/127521510)
-				comment += "\\"
-				p.accept(p.tok)
-				break loop
-			}
 			comment += "\\" + p.scanner.TokenText()
 			p.accept(p.tok)
 		case '\n':
diff --git a/apex/androidmk.go b/apex/androidmk.go
index 993260c..fe89b73 100644
--- a/apex/androidmk.go
+++ b/apex/androidmk.go
@@ -36,6 +36,33 @@
 	return a.androidMkForType()
 }
 
+// nameInMake converts apexFileClass into the corresponding class name in Make.
+func (class apexFileClass) nameInMake() string {
+	switch class {
+	case etc:
+		return "ETC"
+	case nativeSharedLib:
+		return "SHARED_LIBRARIES"
+	case nativeExecutable, shBinary, pyBinary, goBinary:
+		return "EXECUTABLES"
+	case javaSharedLib:
+		return "JAVA_LIBRARIES"
+	case nativeTest:
+		return "NATIVE_TESTS"
+	case app, appSet:
+		// b/142537672 Why isn't this APP? We want to have full control over
+		// the paths and file names of the apk file under the flattend APEX.
+		// If this is set to APP, then the paths and file names are modified
+		// by the Make build system. For example, it is installed to
+		// /system/apex/<apexname>/app/<Appname>/<apexname>.<Appname>/ instead of
+		// /system/apex/<apexname>/app/<Appname> because the build system automatically
+		// appends module name (which is <apexname>.<Appname> to the path.
+		return "ETC"
+	default:
+		panic(fmt.Errorf("unknown class %d", class))
+	}
+}
+
 func (a *apexBundle) androidMkForFiles(w io.Writer, apexBundleName, apexName, moduleDir string,
 	apexAndroidMkData android.AndroidMkData) []string {
 
@@ -68,10 +95,10 @@
 
 	var postInstallCommands []string
 	for _, fi := range a.filesInfo {
-		if a.linkToSystemLib && fi.transitiveDep && fi.AvailableToPlatform() {
+		if a.linkToSystemLib && fi.transitiveDep && fi.availableToPlatform() {
 			// TODO(jiyong): pathOnDevice should come from fi.module, not being calculated here
-			linkTarget := filepath.Join("/system", fi.Path())
-			linkPath := filepath.Join(a.installDir.ToMakePath().String(), apexBundleName, fi.Path())
+			linkTarget := filepath.Join("/system", fi.path())
+			linkPath := filepath.Join(a.installDir.ToMakePath().String(), apexBundleName, fi.path())
 			mkdirCmd := "mkdir -p " + filepath.Dir(linkPath)
 			linkCmd := "ln -sfn " + linkTarget + " " + linkPath
 			postInstallCommands = append(postInstallCommands, mkdirCmd, linkCmd)
@@ -85,7 +112,7 @@
 			continue
 		}
 
-		linkToSystemLib := a.linkToSystemLib && fi.transitiveDep && fi.AvailableToPlatform()
+		linkToSystemLib := a.linkToSystemLib && fi.transitiveDep && fi.availableToPlatform()
 
 		var moduleName string
 		if linkToSystemLib {
@@ -151,7 +178,7 @@
 			fmt.Fprintln(w, "LOCAL_NO_NOTICE_FILE := true")
 		}
 		fmt.Fprintln(w, "LOCAL_PREBUILT_MODULE_FILE :=", fi.builtFile.String())
-		fmt.Fprintln(w, "LOCAL_MODULE_CLASS :=", fi.class.NameInMake())
+		fmt.Fprintln(w, "LOCAL_MODULE_CLASS :=", fi.class.nameInMake())
 		if fi.module != nil {
 			archStr := fi.module.Target().Arch.ArchType.String()
 			host := false
@@ -189,7 +216,7 @@
 			// soong_java_prebuilt.mk sets LOCAL_MODULE_SUFFIX := .jar  Therefore
 			// we need to remove the suffix from LOCAL_MODULE_STEM, otherwise
 			// we will have foo.jar.jar
-			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", strings.TrimSuffix(fi.Stem(), ".jar"))
+			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", strings.TrimSuffix(fi.stem(), ".jar"))
 			if javaModule, ok := fi.module.(java.ApexDependency); ok {
 				fmt.Fprintln(w, "LOCAL_SOONG_CLASSES_JAR :=", javaModule.ImplementationAndResourcesJars()[0].String())
 				fmt.Fprintln(w, "LOCAL_SOONG_HEADER_JAR :=", javaModule.HeaderJars()[0].String())
@@ -205,7 +232,7 @@
 			// soong_app_prebuilt.mk sets LOCAL_MODULE_SUFFIX := .apk  Therefore
 			// we need to remove the suffix from LOCAL_MODULE_STEM, otherwise
 			// we will have foo.apk.apk
-			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", strings.TrimSuffix(fi.Stem(), ".apk"))
+			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", strings.TrimSuffix(fi.stem(), ".apk"))
 			if app, ok := fi.module.(*java.AndroidApp); ok {
 				if jniCoverageOutputs := app.JniCoverageOutputs(); len(jniCoverageOutputs) > 0 {
 					fmt.Fprintln(w, "LOCAL_PREBUILT_COVERAGE_ARCHIVE :=", strings.Join(jniCoverageOutputs.Strings(), " "))
@@ -224,7 +251,7 @@
 			fmt.Fprintln(w, "LOCAL_APKCERTS_FILE :=", as.APKCertsFile().String())
 			fmt.Fprintln(w, "include $(BUILD_SYSTEM)/soong_android_app_set.mk")
 		case nativeSharedLib, nativeExecutable, nativeTest:
-			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", fi.Stem())
+			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", fi.stem())
 			if ccMod, ok := fi.module.(*cc.Module); ok {
 				if ccMod.UnstrippedOutputFile() != nil {
 					fmt.Fprintln(w, "LOCAL_SOONG_UNSTRIPPED_BINARY :=", ccMod.UnstrippedOutputFile().String())
@@ -236,7 +263,7 @@
 			}
 			fmt.Fprintln(w, "include $(BUILD_SYSTEM)/soong_cc_prebuilt.mk")
 		default:
-			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", fi.Stem())
+			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", fi.stem())
 			if fi.builtFile == a.manifestPbOut && apexType == flattenedApex {
 				if a.primaryApexType {
 					// To install companion files (init_rc, vintf_fragments)
diff --git a/apex/apex.go b/apex/apex.go
index 91770f4..a645b06 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// package apex implements build rules for creating the APEX files which are container for
+// lower-level system components. See https://source.android.com/devices/tech/ota/apex
 package apex
 
 import (
@@ -33,11 +35,937 @@
 	"android/soong/sh"
 )
 
+func init() {
+	android.RegisterModuleType("apex", BundleFactory)
+	android.RegisterModuleType("apex_test", testApexBundleFactory)
+	android.RegisterModuleType("apex_vndk", vndkApexBundleFactory)
+	android.RegisterModuleType("apex_defaults", defaultsFactory)
+	android.RegisterModuleType("prebuilt_apex", PrebuiltFactory)
+	android.RegisterModuleType("override_apex", overrideApexFactory)
+	android.RegisterModuleType("apex_set", apexSetFactory)
+
+	android.PreDepsMutators(RegisterPreDepsMutators)
+	android.PostDepsMutators(RegisterPostDepsMutators)
+}
+
+func RegisterPreDepsMutators(ctx android.RegisterMutatorsContext) {
+	ctx.TopDown("apex_vndk", apexVndkMutator).Parallel()
+	ctx.BottomUp("apex_vndk_deps", apexVndkDepsMutator).Parallel()
+}
+
+func RegisterPostDepsMutators(ctx android.RegisterMutatorsContext) {
+	ctx.TopDown("apex_deps", apexDepsMutator).Parallel()
+	ctx.BottomUp("apex_unique", apexUniqueVariationsMutator).Parallel()
+	ctx.BottomUp("apex_test_for_deps", apexTestForDepsMutator).Parallel()
+	ctx.BottomUp("apex_test_for", apexTestForMutator).Parallel()
+	ctx.BottomUp("apex", apexMutator).Parallel()
+	ctx.BottomUp("apex_directly_in_any", apexDirectlyInAnyMutator).Parallel()
+	ctx.BottomUp("apex_flattened", apexFlattenedMutator).Parallel()
+	ctx.BottomUp("mark_platform_availability", markPlatformAvailability).Parallel()
+}
+
+type apexBundleProperties struct {
+	// Json manifest file describing meta info of this APEX bundle. Refer to
+	// system/apex/proto/apex_manifest.proto for the schema. Default: "apex_manifest.json"
+	Manifest *string `android:"path"`
+
+	// AndroidManifest.xml file used for the zip container of this APEX bundle. If unspecified,
+	// a default one is automatically generated.
+	AndroidManifest *string `android:"path"`
+
+	// Canonical name of this APEX bundle. Used to determine the path to the activated APEX on
+	// device (/apex/<apex_name>). If unspecified, follows the name property.
+	Apex_name *string
+
+	// Determines the file contexts file for setting the security contexts to files in this APEX
+	// bundle. For platform APEXes, this should points to a file under /system/sepolicy Default:
+	// /system/sepolicy/apex/<module_name>_file_contexts.
+	File_contexts *string `android:"path"`
+
+	ApexNativeDependencies
+
+	Multilib apexMultilibProperties
+
+	// List of java libraries that are embedded inside this APEX bundle.
+	Java_libs []string
+
+	// List of prebuilt files that are embedded inside this APEX bundle.
+	Prebuilts []string
+
+	// List of BPF programs inside this APEX bundle.
+	Bpfs []string
+
+	// Name of the apex_key module that provides the private key to sign this APEX bundle.
+	Key *string
+
+	// Specifies the certificate and the private key to sign the zip container of this APEX. If
+	// this is "foo", foo.x509.pem and foo.pk8 under PRODUCT_DEFAULT_DEV_CERTIFICATE are used
+	// as the certificate and the private key, respectively. If this is ":module", then the
+	// certificate and the private key are provided from the android_app_certificate module
+	// named "module".
+	Certificate *string
+
+	// The minimum SDK version that this APEX must support at minimum. This is usually set to
+	// the SDK version that the APEX was first introduced.
+	Min_sdk_version *string
+
+	// Whether this APEX is considered updatable or not. When set to true, this will enforce
+	// additional rules for making sure that the APEX is truly updatable. To be updatable,
+	// min_sdk_version should be set as well. This will also disable the size optimizations like
+	// symlinking to the system libs. Default is false.
+	Updatable *bool
+
+	// Whether this APEX is installable to one of the partitions like system, vendor, etc.
+	// Default: true.
+	Installable *bool
+
+	// For native libraries and binaries, use the vendor variant instead of the core (platform)
+	// variant. Default is false. DO NOT use this for APEXes that are installed to the system or
+	// system_ext partition.
+	Use_vendor *bool
+
+	// If set true, VNDK libs are considered as stable libs and are not included in this APEX.
+	// Should be only used in non-system apexes (e.g. vendor: true). Default is false.
+	Use_vndk_as_stable *bool
+
+	// List of SDKs that are used to build this APEX. A reference to an SDK should be either
+	// `name#version` or `name` which is an alias for `name#current`. If left empty,
+	// `platform#current` is implied. This value affects all modules included in this APEX. In
+	// other words, they are also built with the SDKs specified here.
+	Uses_sdks []string
+
+	// The type of APEX to build. Controls what the APEX payload is. Either 'image', 'zip' or
+	// 'both'. When set to image, contents are stored in a filesystem image inside a zip
+	// container. When set to zip, contents are stored in a zip container directly. This type is
+	// mostly for host-side debugging. When set to both, the two types are both built. Default
+	// is 'image'.
+	Payload_type *string
+
+	// The type of filesystem to use when the payload_type is 'image'. Either 'ext4' or 'f2fs'.
+	// Default 'ext4'.
+	Payload_fs_type *string
+
+	// For telling the APEX to ignore special handling for system libraries such as bionic.
+	// Default is false.
+	Ignore_system_library_special_case *bool
+
+	// Whenever apex_payload.img of the APEX should include dm-verity hashtree. Should be only
+	// used in tests.
+	Test_only_no_hashtree *bool
+
+	// Whenever apex_payload.img of the APEX should not be dm-verity signed. Should be only
+	// used in tests.
+	Test_only_unsigned_payload *bool
+
+	IsCoverageVariant bool `blueprint:"mutated"`
+
+	// List of sanitizer names that this APEX is enabled for
+	SanitizerNames []string `blueprint:"mutated"`
+
+	PreventInstall bool `blueprint:"mutated"`
+
+	HideFromMake bool `blueprint:"mutated"`
+
+	// Internal package method for this APEX. When payload_type is image, this can be either
+	// imageApex or flattenedApex depending on Config.FlattenApex(). When payload_type is zip,
+	// this becomes zipApex.
+	ApexType apexPackaging `blueprint:"mutated"`
+}
+
+type ApexNativeDependencies struct {
+	// List of native libraries that are embedded inside this APEX.
+	Native_shared_libs []string
+
+	// List of JNI libraries that are embedded inside this APEX.
+	Jni_libs []string
+
+	// List of native executables that are embedded inside this APEX.
+	Binaries []string
+
+	// List of native tests that are embedded inside this APEX.
+	Tests []string
+}
+
+type apexMultilibProperties struct {
+	// Native dependencies whose compile_multilib is "first"
+	First ApexNativeDependencies
+
+	// Native dependencies whose compile_multilib is "both"
+	Both ApexNativeDependencies
+
+	// Native dependencies whose compile_multilib is "prefer32"
+	Prefer32 ApexNativeDependencies
+
+	// Native dependencies whose compile_multilib is "32"
+	Lib32 ApexNativeDependencies
+
+	// Native dependencies whose compile_multilib is "64"
+	Lib64 ApexNativeDependencies
+}
+
+type apexTargetBundleProperties struct {
+	Target struct {
+		// Multilib properties only for android.
+		Android struct {
+			Multilib apexMultilibProperties
+		}
+
+		// Multilib properties only for host.
+		Host struct {
+			Multilib apexMultilibProperties
+		}
+
+		// Multilib properties only for host linux_bionic.
+		Linux_bionic struct {
+			Multilib apexMultilibProperties
+		}
+
+		// Multilib properties only for host linux_glibc.
+		Linux_glibc struct {
+			Multilib apexMultilibProperties
+		}
+	}
+}
+
+// These properties can be used in override_apex to override the corresponding properties in the
+// base apex.
+type overridableProperties struct {
+	// List of APKs that are embedded inside this APEX.
+	Apps []string
+
+	// List of runtime resource overlays (RROs) that are embedded inside this APEX.
+	Rros []string
+
+	// Names of modules to be overridden. Listed modules can only be other binaries (in Make or
+	// Soong). This does not completely prevent installation of the overridden binaries, but if
+	// both binaries would be installed by default (in PRODUCT_PACKAGES) the other binary will
+	// be removed from PRODUCT_PACKAGES.
+	Overrides []string
+
+	// Logging parent value.
+	Logging_parent string
+
+	// Apex Container package name. Override value for attribute package:name in
+	// AndroidManifest.xml
+	Package_name string
+
+	// A txt file containing list of files that are allowed to be included in this APEX.
+	Allowed_files *string `android:"path"`
+}
+
+type apexBundle struct {
+	// Inherited structs
+	android.ModuleBase
+	android.DefaultableModuleBase
+	android.OverridableModuleBase
+	android.SdkBase
+
+	// Properties
+	properties            apexBundleProperties
+	targetProperties      apexTargetBundleProperties
+	overridableProperties overridableProperties
+	vndkProperties        apexVndkProperties // only for apex_vndk modules
+
+	///////////////////////////////////////////////////////////////////////////////////////////
+	// Inputs
+
+	// Keys for apex_paylaod.img
+	public_key_file  android.Path
+	private_key_file android.Path
+
+	// Cert/priv-key for the zip container
+	container_certificate_file android.Path
+	container_private_key_file android.Path
+
+	// Flags for special variants of APEX
+	testApex bool
+	vndkApex bool
+	artApex  bool
+
+	// Tells whether this variant of the APEX bundle is the primary one or not. Only the primary
+	// one gets installed to the device.
+	primaryApexType bool
+
+	// Suffix of module name in Android.mk ".flattened", ".apex", ".zipapex", or ""
+	suffix string
+
+	// File system type of apex_payload.img
+	payloadFsType fsType
+
+	// Whether to create symlink to the system file instead of having a file inside the apex or
+	// not
+	linkToSystemLib bool
+
+	// List of files to be included in this APEX. This is filled in the first part of
+	// GenerateAndroidBuildActions.
+	filesInfo []apexFile
+
+	// List of other module names that should be installed when this APEX gets installed.
+	requiredDeps []string
+
+	///////////////////////////////////////////////////////////////////////////////////////////
+	// Outputs (final and intermediates)
+
+	// Processed apex manifest in JSONson format (for Q)
+	manifestJsonOut android.WritablePath
+
+	// Processed apex manifest in PB format (for R+)
+	manifestPbOut android.WritablePath
+
+	// Processed file_contexts files
+	fileContexts android.WritablePath
+
+	// Struct holding the merged notice file paths in different formats
+	mergedNotices android.NoticeOutputs
+
+	// The built APEX file. This is the main product.
+	outputFile android.WritablePath
+
+	// The built APEX file in app bundle format. This file is not directly installed to the
+	// device. For an APEX, multiple app bundles are created each of which is for a specific ABI
+	// like arm, arm64, x86, etc. Then they are processed again (outside of the Android build
+	// system) to be merged into a single app bundle file that Play accepts. See
+	// vendor/google/build/build_unbundled_mainline_module.sh for more detail.
+	bundleModuleFile android.WritablePath
+
+	// Target path to install this APEX. Usually out/target/product/<device>/<partition>/apex.
+	installDir android.InstallPath
+
+	// List of commands to create symlinks for backward compatibility. These commands will be
+	// attached as LOCAL_POST_INSTALL_CMD to apex package itself (for unflattened build) or
+	// apex_manifest (for flattened build) so that compat symlinks are always installed
+	// regardless of TARGET_FLATTEN_APEX setting.
+	compatSymlinks []string
+
+	// Text file having the list of individual files that are included in this APEX. Used for
+	// debugging purpose.
+	installedFilesFile android.WritablePath
+
+	// List of module names that this APEX is including (to be shown via *-deps-info target).
+	// Used for debugging purpose.
+	android.ApexBundleDepsInfo
+
+	// Optional list of lint report zip files for apexes that contain java or app modules
+	lintReports android.Paths
+
+	prebuiltFileToDelete string
+
+	distFiles android.TaggedDistFiles
+}
+
+// apexFileClass represents a type of file that can be included in APEX.
+type apexFileClass int
+
 const (
+	app apexFileClass = iota
+	appSet
+	etc
+	goBinary
+	javaSharedLib
+	nativeExecutable
+	nativeSharedLib
+	nativeTest
+	pyBinary
+	shBinary
+)
+
+// apexFile represents a file in an APEX bundle. This is created during the first half of
+// GenerateAndroidBuildActions by traversing the dependencies of the APEX. Then in the second half
+// of the function, this is used to create commands that copies the files into a staging directory,
+// where they are packaged into the APEX file. This struct is also used for creating Make modules
+// for each of the files in case when the APEX is flattened.
+type apexFile struct {
+	// buildFile is put in the installDir inside the APEX.
+	builtFile   android.Path
+	noticeFiles android.Paths
+	installDir  string
+	customStem  string
+	symlinks    []string // additional symlinks
+
+	// Info for Android.mk Module name of `module` in AndroidMk. Note the generated AndroidMk
+	// module for apexFile is named something like <AndroidMk module name>.<apex name>[<apex
+	// suffix>]
+	androidMkModuleName       string             // becomes LOCAL_MODULE
+	class                     apexFileClass      // becomes LOCAL_MODULE_CLASS
+	moduleDir                 string             // becomes LOCAL_PATH
+	requiredModuleNames       []string           // becomes LOCAL_REQUIRED_MODULES
+	targetRequiredModuleNames []string           // becomes LOCAL_TARGET_REQUIRED_MODULES
+	hostRequiredModuleNames   []string           // becomes LOCAL_HOST_REQUIRED_MODULES
+	dataPaths                 []android.DataPath // becomes LOCAL_TEST_DATA
+
+	jacocoReportClassesFile android.Path     // only for javalibs and apps
+	lintDepSets             java.LintDepSets // only for javalibs and apps
+	certificate             java.Certificate // only for apps
+	overriddenPackageName   string           // only for apps
+
+	transitiveDep bool
+	isJniLib      bool
+
+	// TODO(jiyong): remove this
+	module android.Module
+}
+
+// TODO(jiyong): shorten the arglist using an option struct
+func newApexFile(ctx android.BaseModuleContext, builtFile android.Path, androidMkModuleName string, installDir string, class apexFileClass, module android.Module) apexFile {
+	ret := apexFile{
+		builtFile:           builtFile,
+		installDir:          installDir,
+		androidMkModuleName: androidMkModuleName,
+		class:               class,
+		module:              module,
+	}
+	if module != nil {
+		ret.noticeFiles = module.NoticeFiles()
+		ret.moduleDir = ctx.OtherModuleDir(module)
+		ret.requiredModuleNames = module.RequiredModuleNames()
+		ret.targetRequiredModuleNames = module.TargetRequiredModuleNames()
+		ret.hostRequiredModuleNames = module.HostRequiredModuleNames()
+	}
+	return ret
+}
+
+func (af *apexFile) ok() bool {
+	return af.builtFile != nil && af.builtFile.String() != ""
+}
+
+// apexRelativePath returns the relative path of the given path from the install directory of this
+// apexFile.
+// TODO(jiyong): rename this
+func (af *apexFile) apexRelativePath(path string) string {
+	return filepath.Join(af.installDir, path)
+}
+
+// path returns path of this apex file relative to the APEX root
+func (af *apexFile) path() string {
+	return af.apexRelativePath(af.stem())
+}
+
+// stem returns the base filename of this apex file
+func (af *apexFile) stem() string {
+	if af.customStem != "" {
+		return af.customStem
+	}
+	return af.builtFile.Base()
+}
+
+// symlinkPaths returns paths of the symlinks (if any) relative to the APEX root
+func (af *apexFile) symlinkPaths() []string {
+	var ret []string
+	for _, symlink := range af.symlinks {
+		ret = append(ret, af.apexRelativePath(symlink))
+	}
+	return ret
+}
+
+// availableToPlatform tests whether this apexFile is from a module that can be installed to the
+// platform.
+func (af *apexFile) availableToPlatform() bool {
+	if af.module == nil {
+		return false
+	}
+	if am, ok := af.module.(android.ApexModule); ok {
+		return am.AvailableFor(android.AvailableToPlatform)
+	}
+	return false
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Mutators
+//
+// Brief description about mutators for APEX. The following three mutators are the most important
+// ones.
+//
+// 1) DepsMutator: from the properties like native_shared_libs, java_libs, etc., modules are added
+// to the (direct) dependencies of this APEX bundle.
+//
+// 2) apexDepsMutator: this is a post-deps mutator, so runs after DepsMutator. Its goal is to
+// collect modules that are direct and transitive dependencies of each APEX bundle. The collected
+// modules are marked as being included in the APEX via BuildForApex().
+//
+// 3) apexMutator: this is a post-deps mutator that runs after apexDepsMutator. For each module that
+// are marked by the apexDepsMutator, apex variations are created using CreateApexVariations().
+
+type dependencyTag struct {
+	blueprint.BaseDependencyTag
+	name string
+
+	// Determines if the dependent will be part of the APEX payload. Can be false for the
+	// dependencies to the signing key module, etc.
+	payload bool
+}
+
+var (
+	androidAppTag  = dependencyTag{name: "androidApp", payload: true}
+	bpfTag         = dependencyTag{name: "bpf", payload: true}
+	certificateTag = dependencyTag{name: "certificate"}
+	executableTag  = dependencyTag{name: "executable", payload: true}
+	javaLibTag     = dependencyTag{name: "javaLib", payload: true}
+	jniLibTag      = dependencyTag{name: "jniLib", payload: true}
+	keyTag         = dependencyTag{name: "key"}
+	prebuiltTag    = dependencyTag{name: "prebuilt", payload: true}
+	rroTag         = dependencyTag{name: "rro", payload: true}
+	sharedLibTag   = dependencyTag{name: "sharedLib", payload: true}
+	testForTag     = dependencyTag{name: "test for"}
+	testTag        = dependencyTag{name: "test", payload: true}
+)
+
+// TODO(jiyong): shorten this function signature
+func addDependenciesForNativeModules(ctx android.BottomUpMutatorContext, nativeModules ApexNativeDependencies, target android.Target, imageVariation string) {
+	binVariations := target.Variations()
+	libVariations := append(target.Variations(), blueprint.Variation{Mutator: "link", Variation: "shared"})
+
+	if ctx.Device() {
+		binVariations = append(binVariations, blueprint.Variation{Mutator: "image", Variation: imageVariation})
+		libVariations = append(libVariations,
+			blueprint.Variation{Mutator: "image", Variation: imageVariation},
+			blueprint.Variation{Mutator: "version", Variation: ""}, // "" is the non-stub variant
+		)
+	}
+
+	// Use *FarVariation* to be able to depend on modules having conflicting variations with
+	// this module. This is required since arch variant of an APEX bundle is 'common' but it is
+	// 'arm' or 'arm64' for native shared libs.
+	ctx.AddFarVariationDependencies(binVariations, executableTag, nativeModules.Binaries...)
+	ctx.AddFarVariationDependencies(binVariations, testTag, nativeModules.Tests...)
+	ctx.AddFarVariationDependencies(libVariations, jniLibTag, nativeModules.Jni_libs...)
+	ctx.AddFarVariationDependencies(libVariations, sharedLibTag, nativeModules.Native_shared_libs...)
+}
+
+func (a *apexBundle) combineProperties(ctx android.BottomUpMutatorContext) {
+	if ctx.Device() {
+		proptools.AppendProperties(&a.properties.Multilib, &a.targetProperties.Target.Android.Multilib, nil)
+	} else {
+		proptools.AppendProperties(&a.properties.Multilib, &a.targetProperties.Target.Host.Multilib, nil)
+		if ctx.Os().Bionic() {
+			proptools.AppendProperties(&a.properties.Multilib, &a.targetProperties.Target.Linux_bionic.Multilib, nil)
+		} else {
+			proptools.AppendProperties(&a.properties.Multilib, &a.targetProperties.Target.Linux_glibc.Multilib, nil)
+		}
+	}
+}
+
+// getImageVariation returns the image variant name for this apexBundle. In most cases, it's simply
+// android.CoreVariation, but gets complicated for the vendor APEXes and the VNDK APEX.
+func (a *apexBundle) getImageVariation(ctx android.BottomUpMutatorContext) string {
+	deviceConfig := ctx.DeviceConfig()
+	if a.vndkApex {
+		return cc.VendorVariationPrefix + a.vndkVersion(deviceConfig)
+	}
+
+	var prefix string
+	var vndkVersion string
+	if deviceConfig.VndkVersion() != "" {
+		if proptools.Bool(a.properties.Use_vendor) {
+			prefix = cc.VendorVariationPrefix
+			vndkVersion = deviceConfig.PlatformVndkVersion()
+		} else if a.SocSpecific() || a.DeviceSpecific() {
+			prefix = cc.VendorVariationPrefix
+			vndkVersion = deviceConfig.VndkVersion()
+		} else if a.ProductSpecific() {
+			prefix = cc.ProductVariationPrefix
+			vndkVersion = deviceConfig.ProductVndkVersion()
+		}
+	}
+	if vndkVersion == "current" {
+		vndkVersion = deviceConfig.PlatformVndkVersion()
+	}
+	if vndkVersion != "" {
+		return prefix + vndkVersion
+	}
+
+	return android.CoreVariation // The usual case
+}
+
+func (a *apexBundle) DepsMutator(ctx android.BottomUpMutatorContext) {
+	// TODO(jiyong): move this kind of checks to GenerateAndroidBuildActions?
+	checkUseVendorProperty(ctx, a)
+
+	// apexBundle is a multi-arch targets module. Arch variant of apexBundle is set to 'common'.
+	// arch-specific targets are enabled by the compile_multilib setting of the apex bundle. For
+	// each target os/architectures, appropriate dependencies are selected by their
+	// target.<os>.multilib.<type> groups and are added as (direct) dependencies.
+	targets := ctx.MultiTargets()
+	config := ctx.DeviceConfig()
+	imageVariation := a.getImageVariation(ctx)
+
+	a.combineProperties(ctx)
+
+	has32BitTarget := false
+	for _, target := range targets {
+		if target.Arch.ArchType.Multilib == "lib32" {
+			has32BitTarget = true
+		}
+	}
+	for i, target := range targets {
+		// Don't include artifacts for the host cross targets because there is no way for us
+		// to run those artifacts natively on host
+		if target.HostCross {
+			continue
+		}
+
+		var depsList []ApexNativeDependencies
+
+		// Add native modules targeting both ABIs. When multilib.* is omitted for
+		// native_shared_libs/jni_libs/tests, it implies multilib.both
+		depsList = append(depsList, a.properties.Multilib.Both)
+		depsList = append(depsList, ApexNativeDependencies{
+			Native_shared_libs: a.properties.Native_shared_libs,
+			Tests:              a.properties.Tests,
+			Jni_libs:           a.properties.Jni_libs,
+			Binaries:           nil,
+		})
+
+		// Add native modules targeting the first ABI When multilib.* is omitted for
+		// binaries, it implies multilib.first
+		isPrimaryAbi := i == 0
+		if isPrimaryAbi {
+			depsList = append(depsList, a.properties.Multilib.First)
+			depsList = append(depsList, ApexNativeDependencies{
+				Native_shared_libs: nil,
+				Tests:              nil,
+				Jni_libs:           nil,
+				Binaries:           a.properties.Binaries,
+			})
+		}
+
+		// Add native modules targeting either 32-bit or 64-bit ABI
+		switch target.Arch.ArchType.Multilib {
+		case "lib32":
+			depsList = append(depsList, a.properties.Multilib.Lib32)
+			depsList = append(depsList, a.properties.Multilib.Prefer32)
+		case "lib64":
+			depsList = append(depsList, a.properties.Multilib.Lib64)
+			if !has32BitTarget {
+				depsList = append(depsList, a.properties.Multilib.Prefer32)
+			}
+		}
+
+		for _, d := range depsList {
+			addDependenciesForNativeModules(ctx, d, target, imageVariation)
+		}
+	}
+
+	// For prebuilt_etc, use the first variant (64 on 64/32bit device, 32 on 32bit device)
+	// regardless of the TARGET_PREFER_* setting. See b/144532908
+	archForPrebuiltEtc := config.Arches()[0]
+	for _, arch := range config.Arches() {
+		// Prefer 64-bit arch if there is any
+		if arch.ArchType.Multilib == "lib64" {
+			archForPrebuiltEtc = arch
+			break
+		}
+	}
+	ctx.AddFarVariationDependencies([]blueprint.Variation{
+		{Mutator: "os", Variation: ctx.Os().String()},
+		{Mutator: "arch", Variation: archForPrebuiltEtc.String()},
+	}, prebuiltTag, a.properties.Prebuilts...)
+
+	// Common-arch dependencies come next
+	commonVariation := ctx.Config().AndroidCommonTarget.Variations()
+	ctx.AddFarVariationDependencies(commonVariation, javaLibTag, a.properties.Java_libs...)
+	ctx.AddFarVariationDependencies(commonVariation, bpfTag, a.properties.Bpfs...)
+
+	// With EMMA_INSTRUMENT_FRAMEWORK=true the ART boot image includes jacoco library.
+	if a.artApex && ctx.Config().IsEnvTrue("EMMA_INSTRUMENT_FRAMEWORK") {
+		ctx.AddFarVariationDependencies(commonVariation, javaLibTag, "jacocoagent")
+	}
+
+	// Dependencies for signing
+	if String(a.properties.Key) == "" {
+		ctx.PropertyErrorf("key", "missing")
+		return
+	}
+	ctx.AddDependency(ctx.Module(), keyTag, String(a.properties.Key))
+
+	cert := android.SrcIsModule(a.getCertString(ctx))
+	if cert != "" {
+		ctx.AddDependency(ctx.Module(), certificateTag, cert)
+		// empty cert is not an error. Cert and private keys will be directly found under
+		// PRODUCT_DEFAULT_DEV_CERTIFICATE
+	}
+
+	// Marks that this APEX (in fact all the modules in it) has to be built with the given SDKs.
+	// This field currently isn't used.
+	// TODO(jiyong): consider dropping this feature
+	// TODO(jiyong): ensure that all apexes are with non-empty uses_sdks
+	if len(a.properties.Uses_sdks) > 0 {
+		sdkRefs := []android.SdkRef{}
+		for _, str := range a.properties.Uses_sdks {
+			parsed := android.ParseSdkRef(ctx, str, "uses_sdks")
+			sdkRefs = append(sdkRefs, parsed)
+		}
+		a.BuildWithSdks(sdkRefs)
+	}
+}
+
+// DepsMutator for the overridden properties.
+func (a *apexBundle) OverridablePropertiesDepsMutator(ctx android.BottomUpMutatorContext) {
+	if a.overridableProperties.Allowed_files != nil {
+		android.ExtractSourceDeps(ctx, a.overridableProperties.Allowed_files)
+	}
+
+	commonVariation := ctx.Config().AndroidCommonTarget.Variations()
+	ctx.AddFarVariationDependencies(commonVariation, androidAppTag, a.overridableProperties.Apps...)
+	ctx.AddFarVariationDependencies(commonVariation, rroTag, a.overridableProperties.Rros...)
+}
+
+type ApexBundleInfo struct {
+	Contents *android.ApexContents
+}
+
+var ApexBundleInfoProvider = blueprint.NewMutatorProvider(ApexBundleInfo{}, "apex_deps")
+
+// apexDepsMutator is responsible for collecting modules that need to have apex variants. They are
+// identified by doing a graph walk starting from an apexBundle. Basically, all the (direct and
+// indirect) dependencies are collected. But a few types of modules that shouldn't be included in
+// the apexBundle (e.g. stub libraries) are not collected. Note that a single module can be depended
+// on by multiple apexBundles. In that case, the module is collected for all of the apexBundles.
+func apexDepsMutator(mctx android.TopDownMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
+
+	a, ok := mctx.Module().(*apexBundle)
+	if !ok {
+		return
+	}
+
+	// The VNDK APEX is special. For the APEX, the membership is described in a very different
+	// way. There is no dependency from the VNDK APEX to the VNDK libraries. Instead, VNDK
+	// libraries are self-identified by their vndk.enabled properties. There is no need to run
+	// this mutator for the APEX as nothing will be collected. So, let's return fast.
+	if a.vndkApex {
+		return
+	}
+
+	// Special casing for APEXes on non-system (e.g., vendor, odm, etc.) partitions. They are
+	// provided with a property named use_vndk_as_stable, which when set to true doesn't collect
+	// VNDK libraries as transitive dependencies. This option is useful for reducing the size of
+	// the non-system APEXes because the VNDK libraries won't be included (and duped) in the
+	// APEX, but shared across APEXes via the VNDK APEX.
+	useVndk := a.SocSpecific() || a.DeviceSpecific() || (a.ProductSpecific() && mctx.Config().EnforceProductPartitionInterface())
+	excludeVndkLibs := useVndk && proptools.Bool(a.properties.Use_vndk_as_stable)
+	if !useVndk && proptools.Bool(a.properties.Use_vndk_as_stable) {
+		mctx.PropertyErrorf("use_vndk_as_stable", "not supported for system/system_ext APEXes")
+		return
+	}
+
+	continueApexDepsWalk := func(child, parent android.Module) bool {
+		am, ok := child.(android.ApexModule)
+		if !ok || !am.CanHaveApexVariants() {
+			return false
+		}
+		if !parent.(android.DepIsInSameApex).DepIsInSameApex(mctx, child) {
+			return false
+		}
+		if excludeVndkLibs {
+			if c, ok := child.(*cc.Module); ok && c.IsVndk() {
+				return false
+			}
+		}
+		// By default, all the transitive dependencies are collected, unless filtered out
+		// above.
+		return true
+	}
+
+	// Records whether a certain module is included in this apexBundle via direct dependency or
+	// inndirect dependency.
+	contents := make(map[string]android.ApexMembership)
+	mctx.WalkDeps(func(child, parent android.Module) bool {
+		if !continueApexDepsWalk(child, parent) {
+			return false
+		}
+		// If the parent is apexBundle, this child is directly depended.
+		_, directDep := parent.(*apexBundle)
+		depName := mctx.OtherModuleName(child)
+		contents[depName] = contents[depName].Add(directDep)
+		return true
+	})
+
+	// The membership information is saved for later access
+	apexContents := android.NewApexContents(contents)
+	mctx.SetProvider(ApexBundleInfoProvider, ApexBundleInfo{
+		Contents: apexContents,
+	})
+
+	// This is the main part of this mutator. Mark the collected dependencies that they need to
+	// be built for this apexBundle.
+	apexInfo := android.ApexInfo{
+		ApexVariationName: mctx.ModuleName(),
+		MinSdkVersionStr:  a.minSdkVersion(mctx).String(),
+		RequiredSdks:      a.RequiredSdks(),
+		Updatable:         a.Updatable(),
+		InApexes:          []string{mctx.ModuleName()},
+		ApexContents:      []*android.ApexContents{apexContents},
+	}
+	mctx.WalkDeps(func(child, parent android.Module) bool {
+		if !continueApexDepsWalk(child, parent) {
+			return false
+		}
+		child.(android.ApexModule).BuildForApex(apexInfo) // leave a mark!
+		return true
+	})
+}
+
+// apexUniqueVariationsMutator checks if any dependencies use unique apex variations. If so, use
+// unique apex variations for this module. See android/apex.go for more about unique apex variant.
+// TODO(jiyong): move this to android/apex.go?
+func apexUniqueVariationsMutator(mctx android.BottomUpMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
+	if am, ok := mctx.Module().(android.ApexModule); ok {
+		android.UpdateUniqueApexVariationsForDeps(mctx, am)
+	}
+}
+
+// apexTestForDepsMutator checks if this module is a test for an apex. If so, add a dependency on
+// the apex in order to retrieve its contents later.
+// TODO(jiyong): move this to android/apex.go?
+func apexTestForDepsMutator(mctx android.BottomUpMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
+	if am, ok := mctx.Module().(android.ApexModule); ok {
+		if testFor := am.TestFor(); len(testFor) > 0 {
+			mctx.AddFarVariationDependencies([]blueprint.Variation{
+				{Mutator: "os", Variation: am.Target().OsVariation()},
+				{"arch", "common"},
+			}, testForTag, testFor...)
+		}
+	}
+}
+
+// TODO(jiyong): move this to android/apex.go?
+func apexTestForMutator(mctx android.BottomUpMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
+	if _, ok := mctx.Module().(android.ApexModule); ok {
+		var contents []*android.ApexContents
+		for _, testFor := range mctx.GetDirectDepsWithTag(testForTag) {
+			abInfo := mctx.OtherModuleProvider(testFor, ApexBundleInfoProvider).(ApexBundleInfo)
+			contents = append(contents, abInfo.Contents)
+		}
+		mctx.SetProvider(android.ApexTestForInfoProvider, android.ApexTestForInfo{
+			ApexContents: contents,
+		})
+	}
+}
+
+// markPlatformAvailability marks whether or not a module can be available to platform. A module
+// cannot be available to platform if 1) it is explicitly marked as not available (i.e.
+// "//apex_available:platform" is absent) or 2) it depends on another module that isn't (or can't
+// be) available to platform
+// TODO(jiyong): move this to android/apex.go?
+func markPlatformAvailability(mctx android.BottomUpMutatorContext) {
+	// Host and recovery are not considered as platform
+	if mctx.Host() || mctx.Module().InstallInRecovery() {
+		return
+	}
+
+	am, ok := mctx.Module().(android.ApexModule)
+	if !ok {
+		return
+	}
+
+	availableToPlatform := am.AvailableFor(android.AvailableToPlatform)
+
+	// If any of the dep is not available to platform, this module is also considered as being
+	// not available to platform even if it has "//apex_available:platform"
+	mctx.VisitDirectDeps(func(child android.Module) {
+		if !am.DepIsInSameApex(mctx, child) {
+			// if the dependency crosses apex boundary, don't consider it
+			return
+		}
+		if dep, ok := child.(android.ApexModule); ok && dep.NotAvailableForPlatform() {
+			availableToPlatform = false
+			// TODO(b/154889534) trigger an error when 'am' has
+			// "//apex_available:platform"
+		}
+	})
+
+	// Exception 1: stub libraries and native bridge libraries are always available to platform
+	if cc, ok := mctx.Module().(*cc.Module); ok &&
+		(cc.IsStubs() || cc.Target().NativeBridge == android.NativeBridgeEnabled) {
+		availableToPlatform = true
+	}
+
+	// Exception 2: bootstrap bionic libraries are also always available to platform
+	if cc.InstallToBootstrap(mctx.ModuleName(), mctx.Config()) {
+		availableToPlatform = true
+	}
+
+	if !availableToPlatform {
+		am.SetNotAvailableForPlatform()
+	}
+}
+
+// apexMutator visits each module and creates apex variations if the module was marked in the
+// previous run of apexDepsMutator.
+func apexMutator(mctx android.BottomUpMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
+
+	// This is the usual path.
+	if am, ok := mctx.Module().(android.ApexModule); ok && am.CanHaveApexVariants() {
+		android.CreateApexVariations(mctx, am)
+		return
+	}
+
+	// apexBundle itself is mutated so that it and its dependencies have the same apex variant.
+	// TODO(jiyong): document the reason why the VNDK APEX is an exception here.
+	if a, ok := mctx.Module().(*apexBundle); ok && !a.vndkApex {
+		apexBundleName := mctx.ModuleName()
+		mctx.CreateVariations(apexBundleName)
+	} else if o, ok := mctx.Module().(*OverrideApex); ok {
+		apexBundleName := o.GetOverriddenModuleName()
+		if apexBundleName == "" {
+			mctx.ModuleErrorf("base property is not set")
+			return
+		}
+		mctx.CreateVariations(apexBundleName)
+	}
+}
+
+// See android.UpdateDirectlyInAnyApex
+// TODO(jiyong): move this to android/apex.go?
+func apexDirectlyInAnyMutator(mctx android.BottomUpMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
+	if am, ok := mctx.Module().(android.ApexModule); ok {
+		android.UpdateDirectlyInAnyApex(mctx, am)
+	}
+}
+
+// apexPackaging represents a specific packaging method for an APEX.
+type apexPackaging int
+
+const (
+	// imageApex is a packaging method where contents are included in a filesystem image which
+	// is then included in a zip container. This is the most typical way of packaging.
+	imageApex apexPackaging = iota
+
+	// zipApex is a packaging method where contents are directly included in the zip container.
+	// This is used for host-side testing - because the contents are easily accessible by
+	// unzipping the container.
+	zipApex
+
+	// flattendApex is a packaging method where contents are not included in the APEX file, but
+	// installed to /apex/<apexname> directory on the device. This packaging method is used for
+	// old devices where the filesystem-based APEX file can't be supported.
+	flattenedApex
+)
+
+const (
+	// File extensions of an APEX for different packaging methods
 	imageApexSuffix = ".apex"
 	zipApexSuffix   = ".zipapex"
 	flattenedSuffix = ".flattened"
 
+	// variant names each of which is for a packaging method
 	imageApexType     = "image"
 	zipApexType       = "zip"
 	flattenedApexType = "flattened"
@@ -46,33 +974,1111 @@
 	f2fsFsType = "f2fs"
 )
 
-type dependencyTag struct {
-	blueprint.BaseDependencyTag
-	name string
+// The suffix for the output "file", not the module
+func (a apexPackaging) suffix() string {
+	switch a {
+	case imageApex:
+		return imageApexSuffix
+	case zipApex:
+		return zipApexSuffix
+	default:
+		panic(fmt.Errorf("unknown APEX type %d", a))
+	}
+}
 
-	// determines if the dependent will be part of the APEX payload
-	payload bool
+func (a apexPackaging) name() string {
+	switch a {
+	case imageApex:
+		return imageApexType
+	case zipApex:
+		return zipApexType
+	default:
+		panic(fmt.Errorf("unknown APEX type %d", a))
+	}
+}
+
+// apexFlattenedMutator creates one or more variations each of which is for a packaging method.
+// TODO(jiyong): give a better name to this mutator
+func apexFlattenedMutator(mctx android.BottomUpMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
+	if ab, ok := mctx.Module().(*apexBundle); ok {
+		var variants []string
+		switch proptools.StringDefault(ab.properties.Payload_type, "image") {
+		case "image":
+			// This is the normal case. Note that both image and flattend APEXes are
+			// created. The image type is installed to the system partition, while the
+			// flattened APEX is (optionally) installed to the system_ext partition.
+			// This is mostly for GSI which has to support wide range of devices. If GSI
+			// is installed on a newer (APEX-capable) device, the image APEX in the
+			// system will be used. However, if the same GSI is installed on an old
+			// device which can't support image APEX, the flattened APEX in the
+			// system_ext partion (which still is part of GSI) is used instead.
+			variants = append(variants, imageApexType, flattenedApexType)
+		case "zip":
+			variants = append(variants, zipApexType)
+		case "both":
+			variants = append(variants, imageApexType, zipApexType, flattenedApexType)
+		default:
+			mctx.PropertyErrorf("payload_type", "%q is not one of \"image\", \"zip\", or \"both\".", *ab.properties.Payload_type)
+			return
+		}
+
+		modules := mctx.CreateLocalVariations(variants...)
+
+		for i, v := range variants {
+			switch v {
+			case imageApexType:
+				modules[i].(*apexBundle).properties.ApexType = imageApex
+			case zipApexType:
+				modules[i].(*apexBundle).properties.ApexType = zipApex
+			case flattenedApexType:
+				modules[i].(*apexBundle).properties.ApexType = flattenedApex
+				// See the comment above for why system_ext.
+				if !mctx.Config().FlattenApex() && ab.Platform() {
+					modules[i].(*apexBundle).MakeAsSystemExt()
+				}
+			}
+		}
+	} else if _, ok := mctx.Module().(*OverrideApex); ok {
+		// payload_type is forcibly overridden to "image"
+		// TODO(jiyong): is this the right decision?
+		mctx.CreateVariations(imageApexType, flattenedApexType)
+	}
+}
+
+// checkUseVendorProperty checks if the use of `use_vendor` property is allowed for the given APEX.
+// When use_vendor is used, native modules are built with __ANDROID_VNDK__ and __ANDROID_APEX__,
+// which may cause compatibility issues. (e.g. libbinder) Even though libbinder restricts its
+// availability via 'apex_available' property and relies on yet another macro
+// __ANDROID_APEX_<NAME>__, we restrict usage of "use_vendor:" from other APEX modules to avoid
+// similar problems.
+func checkUseVendorProperty(ctx android.BottomUpMutatorContext, a *apexBundle) {
+	if proptools.Bool(a.properties.Use_vendor) && !android.InList(a.Name(), useVendorAllowList(ctx.Config())) {
+		ctx.PropertyErrorf("use_vendor", "not allowed to set use_vendor: true")
+	}
 }
 
 var (
-	sharedLibTag   = dependencyTag{name: "sharedLib", payload: true}
-	jniLibTag      = dependencyTag{name: "jniLib", payload: true}
-	executableTag  = dependencyTag{name: "executable", payload: true}
-	javaLibTag     = dependencyTag{name: "javaLib", payload: true}
-	prebuiltTag    = dependencyTag{name: "prebuilt", payload: true}
-	testTag        = dependencyTag{name: "test", payload: true}
-	keyTag         = dependencyTag{name: "key"}
-	certificateTag = dependencyTag{name: "certificate"}
-	androidAppTag  = dependencyTag{name: "androidApp", payload: true}
-	rroTag         = dependencyTag{name: "rro", payload: true}
-	bpfTag         = dependencyTag{name: "bpf", payload: true}
-	testForTag     = dependencyTag{name: "test for"}
+	useVendorAllowListKey = android.NewOnceKey("useVendorAllowList")
+)
 
-	apexAvailBaseline = makeApexAvailableBaseline()
+func useVendorAllowList(config android.Config) []string {
+	return config.Once(useVendorAllowListKey, func() interface{} {
+		return []string{
+			// swcodec uses "vendor" variants for smaller size
+			"com.android.media.swcodec",
+			"test_com.android.media.swcodec",
+		}
+	}).([]string)
+}
 
+// setUseVendorAllowListForTest overrides useVendorAllowList and must be called before the first
+// call to useVendorAllowList()
+func setUseVendorAllowListForTest(config android.Config, allowList []string) {
+	config.Once(useVendorAllowListKey, func() interface{} {
+		return allowList
+	})
+}
+
+var _ android.DepIsInSameApex = (*apexBundle)(nil)
+
+// Implements android.DepInInSameApex
+func (a *apexBundle) DepIsInSameApex(ctx android.BaseModuleContext, dep android.Module) bool {
+	// direct deps of an APEX bundle are all part of the APEX bundle
+	// TODO(jiyong): shouldn't we look into the payload field of the dependencyTag?
+	return true
+}
+
+var _ android.OutputFileProducer = (*apexBundle)(nil)
+
+// Implements android.OutputFileProducer
+func (a *apexBundle) OutputFiles(tag string) (android.Paths, error) {
+	switch tag {
+	case "":
+		return android.Paths{a.outputFile}, nil
+	default:
+		return nil, fmt.Errorf("unsupported module reference tag %q", tag)
+	}
+}
+
+var _ cc.Coverage = (*apexBundle)(nil)
+
+// Implements cc.Coverage
+func (a *apexBundle) IsNativeCoverageNeeded(ctx android.BaseModuleContext) bool {
+	return ctx.Device() && ctx.DeviceConfig().NativeCoverageEnabled()
+}
+
+// Implements cc.Coverage
+func (a *apexBundle) PreventInstall() {
+	a.properties.PreventInstall = true
+}
+
+// Implements cc.Coverage
+func (a *apexBundle) HideFromMake() {
+	a.properties.HideFromMake = true
+}
+
+// Implements cc.Coverage
+func (a *apexBundle) MarkAsCoverageVariant(coverage bool) {
+	a.properties.IsCoverageVariant = coverage
+}
+
+// Implements cc.Coverage
+func (a *apexBundle) EnableCoverageIfNeeded() {}
+
+var _ android.ApexBundleDepsInfoIntf = (*apexBundle)(nil)
+
+// Implements android.ApexBudleDepsInfoIntf
+func (a *apexBundle) Updatable() bool {
+	return proptools.Bool(a.properties.Updatable)
+}
+
+// getCertString returns the name of the cert that should be used to sign this APEX. This is
+// basically from the "certificate" property, but could be overridden by the device config.
+func (a *apexBundle) getCertString(ctx android.BaseModuleContext) string {
+	moduleName := ctx.ModuleName()
+	// VNDK APEXes share the same certificate. To avoid adding a new VNDK version to the
+	// OVERRIDE_* list, we check with the pseudo module name to see if its certificate is
+	// overridden.
+	if a.vndkApex {
+		moduleName = vndkApexName
+	}
+	certificate, overridden := ctx.DeviceConfig().OverrideCertificateFor(moduleName)
+	if overridden {
+		return ":" + certificate
+	}
+	return String(a.properties.Certificate)
+}
+
+// See the installable property
+func (a *apexBundle) installable() bool {
+	return !a.properties.PreventInstall && (a.properties.Installable == nil || proptools.Bool(a.properties.Installable))
+}
+
+// See the test_only_no_hashtree property
+func (a *apexBundle) testOnlyShouldSkipHashtreeGeneration() bool {
+	return proptools.Bool(a.properties.Test_only_no_hashtree)
+}
+
+// See the test_only_unsigned_payload property
+func (a *apexBundle) testOnlyShouldSkipPayloadSign() bool {
+	return proptools.Bool(a.properties.Test_only_unsigned_payload)
+}
+
+// These functions are interfacing with cc/sanitizer.go. The entire APEX (along with all of its
+// members) can be sanitized, either forcibly, or by the global configuration. For some of the
+// sanitizers, extra dependencies can be forcibly added as well.
+
+func (a *apexBundle) EnableSanitizer(sanitizerName string) {
+	if !android.InList(sanitizerName, a.properties.SanitizerNames) {
+		a.properties.SanitizerNames = append(a.properties.SanitizerNames, sanitizerName)
+	}
+}
+
+func (a *apexBundle) IsSanitizerEnabled(ctx android.BaseModuleContext, sanitizerName string) bool {
+	if android.InList(sanitizerName, a.properties.SanitizerNames) {
+		return true
+	}
+
+	// Then follow the global setting
+	globalSanitizerNames := []string{}
+	if a.Host() {
+		globalSanitizerNames = ctx.Config().SanitizeHost()
+	} else {
+		arches := ctx.Config().SanitizeDeviceArch()
+		if len(arches) == 0 || android.InList(a.Arch().ArchType.Name, arches) {
+			globalSanitizerNames = ctx.Config().SanitizeDevice()
+		}
+	}
+	return android.InList(sanitizerName, globalSanitizerNames)
+}
+
+func (a *apexBundle) AddSanitizerDependencies(ctx android.BottomUpMutatorContext, sanitizerName string) {
+	// TODO(jiyong): move this info (the sanitizer name, the lib name, etc.) to cc/sanitize.go
+	// Keep only the mechanism here.
+	if ctx.Device() && sanitizerName == "hwaddress" && strings.HasPrefix(a.Name(), "com.android.runtime") {
+		imageVariation := a.getImageVariation(ctx)
+		for _, target := range ctx.MultiTargets() {
+			if target.Arch.ArchType.Multilib == "lib64" {
+				addDependenciesForNativeModules(ctx, ApexNativeDependencies{
+					Native_shared_libs: []string{"libclang_rt.hwasan-aarch64-android"},
+					Tests:              nil,
+					Jni_libs:           nil,
+					Binaries:           nil,
+				}, target, imageVariation)
+				break
+			}
+		}
+	}
+}
+
+// apexFileFor<Type> functions below create an apexFile struct for a given Soong module. The
+// returned apexFile saves information about the Soong module that will be used for creating the
+// build rules.
+func apexFileForNativeLibrary(ctx android.BaseModuleContext, ccMod *cc.Module, handleSpecialLibs bool) apexFile {
+	// Decide the APEX-local directory by the multilib of the library In the future, we may
+	// query this to the module.
+	// TODO(jiyong): use the new PackagingSpec
+	var dirInApex string
+	switch ccMod.Arch().ArchType.Multilib {
+	case "lib32":
+		dirInApex = "lib"
+	case "lib64":
+		dirInApex = "lib64"
+	}
+	if ccMod.Target().NativeBridge == android.NativeBridgeEnabled {
+		dirInApex = filepath.Join(dirInApex, ccMod.Target().NativeBridgeRelativePath)
+	}
+	dirInApex = filepath.Join(dirInApex, ccMod.RelativeInstallPath())
+	if handleSpecialLibs && cc.InstallToBootstrap(ccMod.BaseModuleName(), ctx.Config()) {
+		// Special case for Bionic libs and other libs installed with them. This is to
+		// prevent those libs from being included in the search path
+		// /apex/com.android.runtime/${LIB}. This exclusion is required because those libs
+		// in the Runtime APEX are available via the legacy paths in /system/lib/. By the
+		// init process, the libs in the APEX are bind-mounted to the legacy paths and thus
+		// will be loaded into the default linker namespace (aka "platform" namespace). If
+		// the libs are directly in /apex/com.android.runtime/${LIB} then the same libs will
+		// be loaded again into the runtime linker namespace, which will result in double
+		// loading of them, which isn't supported.
+		dirInApex = filepath.Join(dirInApex, "bionic")
+	}
+
+	fileToCopy := ccMod.OutputFile().Path()
+	androidMkModuleName := ccMod.BaseModuleName() + ccMod.Properties.SubName
+	return newApexFile(ctx, fileToCopy, androidMkModuleName, dirInApex, nativeSharedLib, ccMod)
+}
+
+func apexFileForExecutable(ctx android.BaseModuleContext, cc *cc.Module) apexFile {
+	dirInApex := "bin"
+	if cc.Target().NativeBridge == android.NativeBridgeEnabled {
+		dirInApex = filepath.Join(dirInApex, cc.Target().NativeBridgeRelativePath)
+	}
+	dirInApex = filepath.Join(dirInApex, cc.RelativeInstallPath())
+	fileToCopy := cc.OutputFile().Path()
+	androidMkModuleName := cc.BaseModuleName() + cc.Properties.SubName
+	af := newApexFile(ctx, fileToCopy, androidMkModuleName, dirInApex, nativeExecutable, cc)
+	af.symlinks = cc.Symlinks()
+	af.dataPaths = cc.DataPaths()
+	return af
+}
+
+func apexFileForPyBinary(ctx android.BaseModuleContext, py *python.Module) apexFile {
+	dirInApex := "bin"
+	fileToCopy := py.HostToolPath().Path()
+	return newApexFile(ctx, fileToCopy, py.BaseModuleName(), dirInApex, pyBinary, py)
+}
+
+func apexFileForGoBinary(ctx android.BaseModuleContext, depName string, gb bootstrap.GoBinaryTool) apexFile {
+	dirInApex := "bin"
+	s, err := filepath.Rel(android.PathForOutput(ctx).String(), gb.InstallPath())
+	if err != nil {
+		ctx.ModuleErrorf("Unable to use compiled binary at %s", gb.InstallPath())
+		return apexFile{}
+	}
+	fileToCopy := android.PathForOutput(ctx, s)
+	// NB: Since go binaries are static we don't need the module for anything here, which is
+	// good since the go tool is a blueprint.Module not an android.Module like we would
+	// normally use.
+	return newApexFile(ctx, fileToCopy, depName, dirInApex, goBinary, nil)
+}
+
+func apexFileForShBinary(ctx android.BaseModuleContext, sh *sh.ShBinary) apexFile {
+	dirInApex := filepath.Join("bin", sh.SubDir())
+	fileToCopy := sh.OutputFile()
+	af := newApexFile(ctx, fileToCopy, sh.BaseModuleName(), dirInApex, shBinary, sh)
+	af.symlinks = sh.Symlinks()
+	return af
+}
+
+func apexFileForPrebuiltEtc(ctx android.BaseModuleContext, prebuilt prebuilt_etc.PrebuiltEtcModule, depName string) apexFile {
+	dirInApex := filepath.Join(prebuilt.BaseDir(), prebuilt.SubDir())
+	fileToCopy := prebuilt.OutputFile()
+	return newApexFile(ctx, fileToCopy, depName, dirInApex, etc, prebuilt)
+}
+
+func apexFileForCompatConfig(ctx android.BaseModuleContext, config java.PlatformCompatConfigIntf, depName string) apexFile {
+	dirInApex := filepath.Join("etc", config.SubDir())
+	fileToCopy := config.CompatConfig()
+	return newApexFile(ctx, fileToCopy, depName, dirInApex, etc, config)
+}
+
+// javaModule is an interface to handle all Java modules (java_library, dex_import, etc) in the same
+// way.
+type javaModule interface {
+	android.Module
+	BaseModuleName() string
+	DexJarBuildPath() android.Path
+	JacocoReportClassesFile() android.Path
+	LintDepSets() java.LintDepSets
+	Stem() string
+}
+
+var _ javaModule = (*java.Library)(nil)
+var _ javaModule = (*java.SdkLibrary)(nil)
+var _ javaModule = (*java.DexImport)(nil)
+var _ javaModule = (*java.SdkLibraryImport)(nil)
+
+func apexFileForJavaModule(ctx android.BaseModuleContext, module javaModule) apexFile {
+	dirInApex := "javalib"
+	fileToCopy := module.DexJarBuildPath()
+	af := newApexFile(ctx, fileToCopy, module.BaseModuleName(), dirInApex, javaSharedLib, module)
+	af.jacocoReportClassesFile = module.JacocoReportClassesFile()
+	af.lintDepSets = module.LintDepSets()
+	af.customStem = module.Stem() + ".jar"
+	return af
+}
+
+// androidApp is an interface to handle all app modules (android_app, android_app_import, etc.) in
+// the same way.
+type androidApp interface {
+	android.Module
+	Privileged() bool
+	InstallApkName() string
+	OutputFile() android.Path
+	JacocoReportClassesFile() android.Path
+	Certificate() java.Certificate
+	BaseModuleName() string
+}
+
+var _ androidApp = (*java.AndroidApp)(nil)
+var _ androidApp = (*java.AndroidAppImport)(nil)
+
+func apexFileForAndroidApp(ctx android.BaseModuleContext, aapp androidApp) apexFile {
+	appDir := "app"
+	if aapp.Privileged() {
+		appDir = "priv-app"
+	}
+	dirInApex := filepath.Join(appDir, aapp.InstallApkName())
+	fileToCopy := aapp.OutputFile()
+	af := newApexFile(ctx, fileToCopy, aapp.BaseModuleName(), dirInApex, app, aapp)
+	af.jacocoReportClassesFile = aapp.JacocoReportClassesFile()
+	af.certificate = aapp.Certificate()
+
+	if app, ok := aapp.(interface {
+		OverriddenManifestPackageName() string
+	}); ok {
+		af.overriddenPackageName = app.OverriddenManifestPackageName()
+	}
+	return af
+}
+
+func apexFileForRuntimeResourceOverlay(ctx android.BaseModuleContext, rro java.RuntimeResourceOverlayModule) apexFile {
+	rroDir := "overlay"
+	dirInApex := filepath.Join(rroDir, rro.Theme())
+	fileToCopy := rro.OutputFile()
+	af := newApexFile(ctx, fileToCopy, rro.Name(), dirInApex, app, rro)
+	af.certificate = rro.Certificate()
+
+	if a, ok := rro.(interface {
+		OverriddenManifestPackageName() string
+	}); ok {
+		af.overriddenPackageName = a.OverriddenManifestPackageName()
+	}
+	return af
+}
+
+func apexFileForBpfProgram(ctx android.BaseModuleContext, builtFile android.Path, bpfProgram bpf.BpfModule) apexFile {
+	dirInApex := filepath.Join("etc", "bpf")
+	return newApexFile(ctx, builtFile, builtFile.Base(), dirInApex, etc, bpfProgram)
+}
+
+// WalyPayloadDeps visits dependencies that contributes to the payload of this APEX. For each of the
+// visited module, the `do` callback is executed. Returning true in the callback continues the visit
+// to the child modules. Returning false makes the visit to continue in the sibling or the parent
+// modules. This is used in check* functions below.
+func (a *apexBundle) WalkPayloadDeps(ctx android.ModuleContext, do android.PayloadDepsCallback) {
+	ctx.WalkDeps(func(child, parent android.Module) bool {
+		am, ok := child.(android.ApexModule)
+		if !ok || !am.CanHaveApexVariants() {
+			return false
+		}
+
+		// Filter-out unwanted depedendencies
+		depTag := ctx.OtherModuleDependencyTag(child)
+		if _, ok := depTag.(android.ExcludeFromApexContentsTag); ok {
+			return false
+		}
+		if dt, ok := depTag.(dependencyTag); ok && !dt.payload {
+			return false
+		}
+
+		ai := ctx.OtherModuleProvider(child, android.ApexInfoProvider).(android.ApexInfo)
+		externalDep := !android.InList(ctx.ModuleName(), ai.InApexes)
+
+		// Visit actually
+		return do(ctx, parent, am, externalDep)
+	})
+}
+
+// filesystem type of the apex_payload.img inside the APEX. Currently, ext4 and f2fs are supported.
+type fsType int
+
+const (
+	ext4 fsType = iota
+	f2fs
+)
+
+func (f fsType) string() string {
+	switch f {
+	case ext4:
+		return ext4FsType
+	case f2fs:
+		return f2fsFsType
+	default:
+		panic(fmt.Errorf("unknown APEX payload type %d", f))
+	}
+}
+
+// Creates build rules for an APEX. It consists of the following major steps:
+//
+// 1) do some validity checks such as apex_available, min_sdk_version, etc.
+// 2) traverse the dependency tree to collect apexFile structs from them.
+// 3) some fields in apexBundle struct are configured
+// 4) generate the build rules to create the APEX. This is mostly done in builder.go.
+func (a *apexBundle) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	////////////////////////////////////////////////////////////////////////////////////////////
+	// 1) do some validity checks such as apex_available, min_sdk_version, etc.
+	a.checkApexAvailability(ctx)
+	a.checkUpdatable(ctx)
+	a.checkMinSdkVersion(ctx)
+	a.checkStaticLinkingToStubLibraries(ctx)
+	if len(a.properties.Tests) > 0 && !a.testApex {
+		ctx.PropertyErrorf("tests", "property allowed only in apex_test module type")
+		return
+	}
+
+	////////////////////////////////////////////////////////////////////////////////////////////
+	// 2) traverse the dependency tree to collect apexFile structs from them.
+
+	// all the files that will be included in this APEX
+	var filesInfo []apexFile
+
+	// native lib dependencies
+	var provideNativeLibs []string
+	var requireNativeLibs []string
+
+	handleSpecialLibs := !android.Bool(a.properties.Ignore_system_library_special_case)
+
+	// TODO(jiyong): do this using WalkPayloadDeps
+	// TODO(jiyong): make this clean!!!
+	ctx.WalkDepsBlueprint(func(child, parent blueprint.Module) bool {
+		depTag := ctx.OtherModuleDependencyTag(child)
+		if _, ok := depTag.(android.ExcludeFromApexContentsTag); ok {
+			return false
+		}
+		depName := ctx.OtherModuleName(child)
+		if _, isDirectDep := parent.(*apexBundle); isDirectDep {
+			switch depTag {
+			case sharedLibTag, jniLibTag:
+				isJniLib := depTag == jniLibTag
+				if c, ok := child.(*cc.Module); ok {
+					fi := apexFileForNativeLibrary(ctx, c, handleSpecialLibs)
+					fi.isJniLib = isJniLib
+					filesInfo = append(filesInfo, fi)
+					// Collect the list of stub-providing libs except:
+					// - VNDK libs are only for vendors
+					// - bootstrap bionic libs are treated as provided by system
+					if c.HasStubsVariants() && !a.vndkApex && !cc.InstallToBootstrap(c.BaseModuleName(), ctx.Config()) {
+						provideNativeLibs = append(provideNativeLibs, fi.stem())
+					}
+					return true // track transitive dependencies
+				} else {
+					propertyName := "native_shared_libs"
+					if isJniLib {
+						propertyName = "jni_libs"
+					}
+					ctx.PropertyErrorf(propertyName, "%q is not a cc_library or cc_library_shared module", depName)
+				}
+			case executableTag:
+				if cc, ok := child.(*cc.Module); ok {
+					filesInfo = append(filesInfo, apexFileForExecutable(ctx, cc))
+					return true // track transitive dependencies
+				} else if sh, ok := child.(*sh.ShBinary); ok {
+					filesInfo = append(filesInfo, apexFileForShBinary(ctx, sh))
+				} else if py, ok := child.(*python.Module); ok && py.HostToolPath().Valid() {
+					filesInfo = append(filesInfo, apexFileForPyBinary(ctx, py))
+				} else if gb, ok := child.(bootstrap.GoBinaryTool); ok && a.Host() {
+					filesInfo = append(filesInfo, apexFileForGoBinary(ctx, depName, gb))
+				} else {
+					ctx.PropertyErrorf("binaries", "%q is neither cc_binary, (embedded) py_binary, (host) blueprint_go_binary, (host) bootstrap_go_binary, nor sh_binary", depName)
+				}
+			case javaLibTag:
+				switch child.(type) {
+				case *java.Library, *java.SdkLibrary, *java.DexImport, *java.SdkLibraryImport:
+					af := apexFileForJavaModule(ctx, child.(javaModule))
+					if !af.ok() {
+						ctx.PropertyErrorf("java_libs", "%q is not configured to be compiled into dex", depName)
+						return false
+					}
+					filesInfo = append(filesInfo, af)
+					return true // track transitive dependencies
+				default:
+					ctx.PropertyErrorf("java_libs", "%q of type %q is not supported", depName, ctx.OtherModuleType(child))
+				}
+			case androidAppTag:
+				if ap, ok := child.(*java.AndroidApp); ok {
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
+					return true // track transitive dependencies
+				} else if ap, ok := child.(*java.AndroidAppImport); ok {
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
+				} else if ap, ok := child.(*java.AndroidTestHelperApp); ok {
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
+				} else if ap, ok := child.(*java.AndroidAppSet); ok {
+					appDir := "app"
+					if ap.Privileged() {
+						appDir = "priv-app"
+					}
+					af := newApexFile(ctx, ap.OutputFile(), ap.BaseModuleName(),
+						filepath.Join(appDir, ap.BaseModuleName()), appSet, ap)
+					af.certificate = java.PresignedCertificate
+					filesInfo = append(filesInfo, af)
+				} else {
+					ctx.PropertyErrorf("apps", "%q is not an android_app module", depName)
+				}
+			case rroTag:
+				if rro, ok := child.(java.RuntimeResourceOverlayModule); ok {
+					filesInfo = append(filesInfo, apexFileForRuntimeResourceOverlay(ctx, rro))
+				} else {
+					ctx.PropertyErrorf("rros", "%q is not an runtime_resource_overlay module", depName)
+				}
+			case bpfTag:
+				if bpfProgram, ok := child.(bpf.BpfModule); ok {
+					filesToCopy, _ := bpfProgram.OutputFiles("")
+					for _, bpfFile := range filesToCopy {
+						filesInfo = append(filesInfo, apexFileForBpfProgram(ctx, bpfFile, bpfProgram))
+					}
+				} else {
+					ctx.PropertyErrorf("bpfs", "%q is not a bpf module", depName)
+				}
+			case prebuiltTag:
+				if prebuilt, ok := child.(prebuilt_etc.PrebuiltEtcModule); ok {
+					filesInfo = append(filesInfo, apexFileForPrebuiltEtc(ctx, prebuilt, depName))
+				} else if prebuilt, ok := child.(java.PlatformCompatConfigIntf); ok {
+					filesInfo = append(filesInfo, apexFileForCompatConfig(ctx, prebuilt, depName))
+				} else {
+					ctx.PropertyErrorf("prebuilts", "%q is not a prebuilt_etc and not a platform_compat_config module", depName)
+				}
+			case testTag:
+				if ccTest, ok := child.(*cc.Module); ok {
+					if ccTest.IsTestPerSrcAllTestsVariation() {
+						// Multiple-output test module (where `test_per_src: true`).
+						//
+						// `ccTest` is the "" ("all tests") variation of a `test_per_src` module.
+						// We do not add this variation to `filesInfo`, as it has no output;
+						// however, we do add the other variations of this module as indirect
+						// dependencies (see below).
+					} else {
+						// Single-output test module (where `test_per_src: false`).
+						af := apexFileForExecutable(ctx, ccTest)
+						af.class = nativeTest
+						filesInfo = append(filesInfo, af)
+					}
+					return true // track transitive dependencies
+				} else {
+					ctx.PropertyErrorf("tests", "%q is not a cc module", depName)
+				}
+			case keyTag:
+				if key, ok := child.(*apexKey); ok {
+					a.private_key_file = key.private_key_file
+					a.public_key_file = key.public_key_file
+				} else {
+					ctx.PropertyErrorf("key", "%q is not an apex_key module", depName)
+				}
+				return false
+			case certificateTag:
+				if dep, ok := child.(*java.AndroidAppCertificate); ok {
+					a.container_certificate_file = dep.Certificate.Pem
+					a.container_private_key_file = dep.Certificate.Key
+				} else {
+					ctx.ModuleErrorf("certificate dependency %q must be an android_app_certificate module", depName)
+				}
+			case android.PrebuiltDepTag:
+				// If the prebuilt is force disabled, remember to delete the prebuilt file
+				// that might have been installed in the previous builds
+				if prebuilt, ok := child.(prebuilt); ok && prebuilt.isForceDisabled() {
+					a.prebuiltFileToDelete = prebuilt.InstallFilename()
+				}
+			}
+		} else if !a.vndkApex {
+			// indirect dependencies
+			if am, ok := child.(android.ApexModule); ok {
+				// We cannot use a switch statement on `depTag` here as the checked
+				// tags used below are private (e.g. `cc.sharedDepTag`).
+				if cc.IsSharedDepTag(depTag) || cc.IsRuntimeDepTag(depTag) {
+					if cc, ok := child.(*cc.Module); ok {
+						if cc.UseVndk() && proptools.Bool(a.properties.Use_vndk_as_stable) && cc.IsVndk() {
+							requireNativeLibs = append(requireNativeLibs, ":vndk")
+							return false
+						}
+						af := apexFileForNativeLibrary(ctx, cc, handleSpecialLibs)
+						af.transitiveDep = true
+						abInfo := ctx.Provider(ApexBundleInfoProvider).(ApexBundleInfo)
+						if !a.Host() && !abInfo.Contents.DirectlyInApex(depName) && (cc.IsStubs() || cc.HasStubsVariants()) {
+							// If the dependency is a stubs lib, don't include it in this APEX,
+							// but make sure that the lib is installed on the device.
+							// In case no APEX is having the lib, the lib is installed to the system
+							// partition.
+							//
+							// Always include if we are a host-apex however since those won't have any
+							// system libraries.
+							if !am.DirectlyInAnyApex() {
+								// we need a module name for Make
+								name := cc.ImplementationModuleName(ctx)
+
+								if !proptools.Bool(a.properties.Use_vendor) {
+									// we don't use subName(.vendor) for a "use_vendor: true" apex
+									// which is supposed to be installed in /system
+									name += cc.Properties.SubName
+								}
+								if !android.InList(name, a.requiredDeps) {
+									a.requiredDeps = append(a.requiredDeps, name)
+								}
+							}
+							requireNativeLibs = append(requireNativeLibs, af.stem())
+							// Don't track further
+							return false
+						}
+						filesInfo = append(filesInfo, af)
+						return true // track transitive dependencies
+					}
+				} else if cc.IsTestPerSrcDepTag(depTag) {
+					if cc, ok := child.(*cc.Module); ok {
+						af := apexFileForExecutable(ctx, cc)
+						// Handle modules created as `test_per_src` variations of a single test module:
+						// use the name of the generated test binary (`fileToCopy`) instead of the name
+						// of the original test module (`depName`, shared by all `test_per_src`
+						// variations of that module).
+						af.androidMkModuleName = filepath.Base(af.builtFile.String())
+						// these are not considered transitive dep
+						af.transitiveDep = false
+						filesInfo = append(filesInfo, af)
+						return true // track transitive dependencies
+					}
+				} else if java.IsJniDepTag(depTag) {
+					// Because APK-in-APEX embeds jni_libs transitively, we don't need to track transitive deps
+					return false
+				} else if java.IsXmlPermissionsFileDepTag(depTag) {
+					if prebuilt, ok := child.(prebuilt_etc.PrebuiltEtcModule); ok {
+						filesInfo = append(filesInfo, apexFileForPrebuiltEtc(ctx, prebuilt, depName))
+					}
+				} else if _, ok := depTag.(android.CopyDirectlyInAnyApexTag); ok {
+					// nothing
+				} else if am.CanHaveApexVariants() && am.IsInstallableToApex() {
+					ctx.ModuleErrorf("unexpected tag %s for indirect dependency %q", android.PrettyPrintTag(depTag), depName)
+				}
+			}
+		}
+		return false
+	})
+	if a.private_key_file == nil {
+		ctx.PropertyErrorf("key", "private_key for %q could not be found", String(a.properties.Key))
+		return
+	}
+
+	// Specific to the ART apex: dexpreopt artifacts for libcore Java libraries. Build rules are
+	// generated by the dexpreopt singleton, and here we access build artifacts via the global
+	// boot image config.
+	if a.artApex {
+		for arch, files := range java.DexpreoptedArtApexJars(ctx) {
+			dirInApex := filepath.Join("javalib", arch.String())
+			for _, f := range files {
+				localModule := "javalib_" + arch.String() + "_" + filepath.Base(f.String())
+				af := newApexFile(ctx, f, localModule, dirInApex, etc, nil)
+				filesInfo = append(filesInfo, af)
+			}
+		}
+	}
+
+	// Remove duplicates in filesInfo
+	removeDup := func(filesInfo []apexFile) []apexFile {
+		encountered := make(map[string]apexFile)
+		for _, f := range filesInfo {
+			dest := filepath.Join(f.installDir, f.builtFile.Base())
+			if e, ok := encountered[dest]; !ok {
+				encountered[dest] = f
+			} else {
+				// If a module is directly included and also transitively depended on
+				// consider it as directly included.
+				e.transitiveDep = e.transitiveDep && f.transitiveDep
+				encountered[dest] = e
+			}
+		}
+		var result []apexFile
+		for _, v := range encountered {
+			result = append(result, v)
+		}
+		return result
+	}
+	filesInfo = removeDup(filesInfo)
+
+	// Sort to have consistent build rules
+	sort.Slice(filesInfo, func(i, j int) bool {
+		return filesInfo[i].builtFile.String() < filesInfo[j].builtFile.String()
+	})
+
+	////////////////////////////////////////////////////////////////////////////////////////////
+	// 3) some fields in apexBundle struct are configured
+	a.installDir = android.PathForModuleInstall(ctx, "apex")
+	a.filesInfo = filesInfo
+
+	// Set suffix and primaryApexType depending on the ApexType
+	buildFlattenedAsDefault := ctx.Config().FlattenApex() && !ctx.Config().UnbundledBuildApps()
+	switch a.properties.ApexType {
+	case imageApex:
+		if buildFlattenedAsDefault {
+			a.suffix = imageApexSuffix
+		} else {
+			a.suffix = ""
+			a.primaryApexType = true
+
+			if ctx.Config().InstallExtraFlattenedApexes() {
+				a.requiredDeps = append(a.requiredDeps, a.Name()+flattenedSuffix)
+			}
+		}
+	case zipApex:
+		if proptools.String(a.properties.Payload_type) == "zip" {
+			a.suffix = ""
+			a.primaryApexType = true
+		} else {
+			a.suffix = zipApexSuffix
+		}
+	case flattenedApex:
+		if buildFlattenedAsDefault {
+			a.suffix = ""
+			a.primaryApexType = true
+		} else {
+			a.suffix = flattenedSuffix
+		}
+	}
+
+	switch proptools.StringDefault(a.properties.Payload_fs_type, ext4FsType) {
+	case ext4FsType:
+		a.payloadFsType = ext4
+	case f2fsFsType:
+		a.payloadFsType = f2fs
+	default:
+		ctx.PropertyErrorf("payload_fs_type", "%q is not a valid filesystem for apex [ext4, f2fs]", *a.properties.Payload_fs_type)
+	}
+
+	// Optimization. If we are building bundled APEX, for the files that are gathered due to the
+	// transitive dependencies, don't place them inside the APEX, but place a symlink pointing
+	// the same library in the system partition, thus effectively sharing the same libraries
+	// across the APEX boundary. For unbundled APEX, all the gathered files are actually placed
+	// in the APEX.
+	a.linkToSystemLib = !ctx.Config().UnbundledBuild() && a.installable() && !proptools.Bool(a.properties.Use_vendor)
+
+	// APEXes targeting other than system/system_ext partitions use vendor/product variants.
+	// So we can't link them to /system/lib libs which are core variants.
+	if a.SocSpecific() || a.DeviceSpecific() || (a.ProductSpecific() && ctx.Config().EnforceProductPartitionInterface()) {
+		a.linkToSystemLib = false
+	}
+
+	// We don't need the optimization for updatable APEXes, as it might give false signal
+	// to the system health when the APEXes are still bundled (b/149805758)
+	if a.Updatable() && a.properties.ApexType == imageApex {
+		a.linkToSystemLib = false
+	}
+
+	// We also don't want the optimization for host APEXes, because it doesn't make sense.
+	if ctx.Host() {
+		a.linkToSystemLib = false
+	}
+
+	a.setCertificateAndPrivateKey(ctx)
+
+	a.compatSymlinks = makeCompatSymlinks(a.BaseModuleName(), ctx)
+
+	////////////////////////////////////////////////////////////////////////////////////////////
+	// 4) generate the build rules to create the APEX. This is done in builder.go.
+	a.buildManifest(ctx, provideNativeLibs, requireNativeLibs)
+	a.buildFileContexts(ctx)
+	if a.properties.ApexType == flattenedApex {
+		a.buildFlattenedApex(ctx)
+	} else {
+		a.buildUnflattenedApex(ctx)
+	}
+	a.buildApexDependencyInfo(ctx)
+	a.buildLintReports(ctx)
+	a.distFiles = a.GenerateTaggedDistFiles(ctx)
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// Factory functions
+//
+
+func newApexBundle() *apexBundle {
+	module := &apexBundle{}
+
+	module.AddProperties(&module.properties)
+	module.AddProperties(&module.targetProperties)
+	module.AddProperties(&module.overridableProperties)
+
+	android.InitAndroidMultiTargetsArchModule(module, android.HostAndDeviceSupported, android.MultilibCommon)
+	android.InitDefaultableModule(module)
+	android.InitSdkAwareModule(module)
+	android.InitOverridableModule(module, &module.overridableProperties.Overrides)
+	return module
+}
+
+func ApexBundleFactory(testApex bool, artApex bool) android.Module {
+	bundle := newApexBundle()
+	bundle.testApex = testApex
+	bundle.artApex = artApex
+	return bundle
+}
+
+// apex_test is an APEX for testing. The difference from the ordinary apex module type is that
+// certain compatibility checks such as apex_available are not done for apex_test.
+func testApexBundleFactory() android.Module {
+	bundle := newApexBundle()
+	bundle.testApex = true
+	return bundle
+}
+
+// apex packages other modules into an APEX file which is a packaging format for system-level
+// components like binaries, shared libraries, etc.
+func BundleFactory() android.Module {
+	return newApexBundle()
+}
+
+type Defaults struct {
+	android.ModuleBase
+	android.DefaultsModuleBase
+}
+
+// apex_defaults provides defaultable properties to other apex modules.
+func defaultsFactory() android.Module {
+	return DefaultsFactory()
+}
+
+func DefaultsFactory(props ...interface{}) android.Module {
+	module := &Defaults{}
+
+	module.AddProperties(props...)
+	module.AddProperties(
+		&apexBundleProperties{},
+		&apexTargetBundleProperties{},
+		&overridableProperties{},
+	)
+
+	android.InitDefaultsModule(module)
+	return module
+}
+
+type OverrideApex struct {
+	android.ModuleBase
+	android.OverrideModuleBase
+}
+
+func (o *OverrideApex) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// All the overrides happen in the base module.
+}
+
+// override_apex is used to create an apex module based on another apex module by overriding some of
+// its properties.
+func overrideApexFactory() android.Module {
+	m := &OverrideApex{}
+
+	m.AddProperties(&overridableProperties{})
+
+	android.InitAndroidMultiTargetsArchModule(m, android.DeviceSupported, android.MultilibCommon)
+	android.InitOverrideModule(m)
+	return m
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// Vality check routines
+//
+// These are called in at the very beginning of GenerateAndroidBuildActions to flag an error when
+// certain conditions are not met.
+//
+// TODO(jiyong): move these checks to a separate go file.
+
+// Entures that min_sdk_version of the included modules are equal or less than the min_sdk_version
+// of this apexBundle.
+func (a *apexBundle) checkMinSdkVersion(ctx android.ModuleContext) {
+	if a.testApex || a.vndkApex {
+		return
+	}
+	// Meaningless to check min_sdk_version when building use_vendor modules against non-Trebleized targets
+	if proptools.Bool(a.properties.Use_vendor) && ctx.DeviceConfig().VndkVersion() == "" {
+		return
+	}
+	// apexBundle::minSdkVersion reports its own errors.
+	minSdkVersion := a.minSdkVersion(ctx)
+	android.CheckMinSdkVersion(a, ctx, minSdkVersion)
+}
+
+func (a *apexBundle) minSdkVersion(ctx android.BaseModuleContext) android.ApiLevel {
+	ver := proptools.String(a.properties.Min_sdk_version)
+	if ver == "" {
+		return android.FutureApiLevel
+	}
+	apiLevel, err := android.ApiLevelFromUser(ctx, ver)
+	if err != nil {
+		ctx.PropertyErrorf("min_sdk_version", "%s", err.Error())
+		return android.NoneApiLevel
+	}
+	if apiLevel.IsPreview() {
+		// All codenames should build against "current".
+		return android.FutureApiLevel
+	}
+	return apiLevel
+}
+
+// Ensures that a lib providing stub isn't statically linked
+func (a *apexBundle) checkStaticLinkingToStubLibraries(ctx android.ModuleContext) {
+	// Practically, we only care about regular APEXes on the device.
+	if ctx.Host() || a.testApex || a.vndkApex {
+		return
+	}
+
+	abInfo := ctx.Provider(ApexBundleInfoProvider).(ApexBundleInfo)
+
+	a.WalkPayloadDeps(ctx, func(ctx android.ModuleContext, from blueprint.Module, to android.ApexModule, externalDep bool) bool {
+		if ccm, ok := to.(*cc.Module); ok {
+			apexName := ctx.ModuleName()
+			fromName := ctx.OtherModuleName(from)
+			toName := ctx.OtherModuleName(to)
+
+			// If `to` is not actually in the same APEX as `from` then it does not need
+			// apex_available and neither do any of its dependencies.
+			if am, ok := from.(android.DepIsInSameApex); ok && !am.DepIsInSameApex(ctx, to) {
+				// As soon as the dependency graph crosses the APEX boundary, don't go further.
+				return false
+			}
+
+			// The dynamic linker and crash_dump tool in the runtime APEX is the only
+			// exception to this rule. It can't make the static dependencies dynamic
+			// because it can't do the dynamic linking for itself.
+			if apexName == "com.android.runtime" && (fromName == "linker" || fromName == "crash_dump") {
+				return false
+			}
+
+			isStubLibraryFromOtherApex := ccm.HasStubsVariants() && !abInfo.Contents.DirectlyInApex(toName)
+			if isStubLibraryFromOtherApex && !externalDep {
+				ctx.ModuleErrorf("%q required by %q is a native library providing stub. "+
+					"It shouldn't be included in this APEX via static linking. Dependency path: %s", to.String(), fromName, ctx.GetPathString(false))
+			}
+
+		}
+		return true
+	})
+}
+
+// Enforce that Java deps of the apex are using stable SDKs to compile
+func (a *apexBundle) checkUpdatable(ctx android.ModuleContext) {
+	if a.Updatable() {
+		if String(a.properties.Min_sdk_version) == "" {
+			ctx.PropertyErrorf("updatable", "updatable APEXes should set min_sdk_version as well")
+		}
+		a.checkJavaStableSdkVersion(ctx)
+	}
+}
+
+func (a *apexBundle) checkJavaStableSdkVersion(ctx android.ModuleContext) {
+	// Visit direct deps only. As long as we guarantee top-level deps are using stable SDKs,
+	// java's checkLinkType guarantees correct usage for transitive deps
+	ctx.VisitDirectDepsBlueprint(func(module blueprint.Module) {
+		tag := ctx.OtherModuleDependencyTag(module)
+		switch tag {
+		case javaLibTag, androidAppTag:
+			if m, ok := module.(interface{ CheckStableSdkVersion() error }); ok {
+				if err := m.CheckStableSdkVersion(); err != nil {
+					ctx.ModuleErrorf("cannot depend on \"%v\": %v", ctx.OtherModuleName(module), err)
+				}
+			}
+		}
+	})
+}
+
+// Ensures that the all the dependencies are marked as available for this APEX
+func (a *apexBundle) checkApexAvailability(ctx android.ModuleContext) {
+	// Let's be practical. Availability for test, host, and the VNDK apex isn't important
+	if ctx.Host() || a.testApex || a.vndkApex {
+		return
+	}
+
+	// Because APEXes targeting other than system/system_ext partitions can't set
+	// apex_available, we skip checks for these APEXes
+	if a.SocSpecific() || a.DeviceSpecific() || (a.ProductSpecific() && ctx.Config().EnforceProductPartitionInterface()) {
+		return
+	}
+
+	// Coverage build adds additional dependencies for the coverage-only runtime libraries.
+	// Requiring them and their transitive depencies with apex_available is not right
+	// because they just add noise.
+	if ctx.Config().IsEnvTrue("EMMA_INSTRUMENT") || a.IsNativeCoverageNeeded(ctx) {
+		return
+	}
+
+	a.WalkPayloadDeps(ctx, func(ctx android.ModuleContext, from blueprint.Module, to android.ApexModule, externalDep bool) bool {
+		// As soon as the dependency graph crosses the APEX boundary, don't go further.
+		if externalDep {
+			return false
+		}
+
+		apexName := ctx.ModuleName()
+		fromName := ctx.OtherModuleName(from)
+		toName := ctx.OtherModuleName(to)
+
+		// If `to` is not actually in the same APEX as `from` then it does not need
+		// apex_available and neither do any of its dependencies.
+		if am, ok := from.(android.DepIsInSameApex); ok && !am.DepIsInSameApex(ctx, to) {
+			// As soon as the dependency graph crosses the APEX boundary, don't go
+			// further.
+			return false
+		}
+
+		if to.AvailableFor(apexName) || baselineApexAvailable(apexName, toName) {
+			return true
+		}
+		ctx.ModuleErrorf("%q requires %q that doesn't list the APEX under 'apex_available'. Dependency path:%s",
+			fromName, toName, ctx.GetPathString(true))
+		// Visit this module's dependencies to check and report any issues with their availability.
+		return true
+	})
+}
+
+var (
+	apexAvailBaseline        = makeApexAvailableBaseline()
 	inverseApexAvailBaseline = invertApexBaseline(apexAvailBaseline)
 )
 
+func baselineApexAvailable(apex, moduleName string) bool {
+	key := apex
+	moduleName = normalizeModuleName(moduleName)
+
+	if val, ok := apexAvailBaseline[key]; ok && android.InList(moduleName, val) {
+		return true
+	}
+
+	key = android.AvailableToAnyApex
+	if val, ok := apexAvailBaseline[key]; ok && android.InList(moduleName, val) {
+		return true
+	}
+
+	return false
+}
+
+func normalizeModuleName(moduleName string) string {
+	// Prebuilt modules (e.g. java_import, etc.) have "prebuilt_" prefix added by the build
+	// system. Trim the prefix for the check since they are confusing
+	moduleName = strings.TrimPrefix(moduleName, "prebuilt_")
+	if strings.HasPrefix(moduleName, "libclang_rt.") {
+		// This module has many arch variants that depend on the product being built.
+		// We don't want to list them all
+		moduleName = "libclang_rt"
+	}
+	if strings.HasPrefix(moduleName, "androidx.") {
+		// TODO(b/156996905) Set apex_available/min_sdk_version for androidx support libraries
+		moduleName = "androidx"
+	}
+	return moduleName
+}
+
 // Transform the map of apex -> modules to module -> apexes.
 func invertApexBaseline(m map[string][]string) map[string][]string {
 	r := make(map[string][]string)
@@ -89,9 +2095,8 @@
 	return inverseApexAvailBaseline[normalizeModuleName(moduleName)]
 }
 
-// This is a map from apex to modules, which overrides the
-// apex_available setting for that particular module to make
-// it available for the apex regardless of its setting.
+// This is a map from apex to modules, which overrides the apex_available setting for that
+// particular module to make it available for the apex regardless of its setting.
 // TODO(b/147364041): remove this
 func makeApexAvailableBaseline() map[string][]string {
 	// The "Module separator"s below are employed to minimize merge conflicts.
@@ -670,6 +2675,26 @@
 	return m
 }
 
+func init() {
+	android.AddNeverAllowRules(createApexPermittedPackagesRules(qModulesPackages())...)
+	android.AddNeverAllowRules(createApexPermittedPackagesRules(rModulesPackages())...)
+}
+
+func createApexPermittedPackagesRules(modules_packages map[string][]string) []android.Rule {
+	rules := make([]android.Rule, 0, len(modules_packages))
+	for module_name, module_packages := range modules_packages {
+		permitted_packages_rule := android.NeverAllow().
+			BootclasspathJar().
+			With("apex_available", module_name).
+			WithMatcher("permitted_packages", android.NotInList(module_packages)).
+			Because("jars that are part of the " + module_name +
+				" module may only allow these packages: " + strings.Join(module_packages, ",") +
+				". Please jarjar or move code around.")
+		rules = append(rules, permitted_packages_rule)
+	}
+	return rules
+}
+
 // DO NOT EDIT! These are the package prefixes that are exempted from being AOT'ed by ART.
 // Adding code to the bootclasspath in new packages will cause issues on module update.
 func qModulesPackages() map[string][]string {
@@ -718,1900 +2743,3 @@
 		},
 	}
 }
-
-func init() {
-	android.RegisterModuleType("apex", BundleFactory)
-	android.RegisterModuleType("apex_test", testApexBundleFactory)
-	android.RegisterModuleType("apex_vndk", vndkApexBundleFactory)
-	android.RegisterModuleType("apex_defaults", defaultsFactory)
-	android.RegisterModuleType("prebuilt_apex", PrebuiltFactory)
-	android.RegisterModuleType("override_apex", overrideApexFactory)
-	android.RegisterModuleType("apex_set", apexSetFactory)
-
-	android.PreDepsMutators(RegisterPreDepsMutators)
-	android.PostDepsMutators(RegisterPostDepsMutators)
-
-	android.AddNeverAllowRules(createApexPermittedPackagesRules(qModulesPackages())...)
-	android.AddNeverAllowRules(createApexPermittedPackagesRules(rModulesPackages())...)
-}
-
-func createApexPermittedPackagesRules(modules_packages map[string][]string) []android.Rule {
-	rules := make([]android.Rule, 0, len(modules_packages))
-	for module_name, module_packages := range modules_packages {
-		permitted_packages_rule := android.NeverAllow().
-			BootclasspathJar().
-			With("apex_available", module_name).
-			WithMatcher("permitted_packages", android.NotInList(module_packages)).
-			Because("jars that are part of the " + module_name +
-				" module may only allow these packages: " + strings.Join(module_packages, ",") +
-				". Please jarjar or move code around.")
-		rules = append(rules, permitted_packages_rule)
-	}
-	return rules
-}
-
-func RegisterPreDepsMutators(ctx android.RegisterMutatorsContext) {
-	ctx.TopDown("apex_vndk", apexVndkMutator).Parallel()
-	ctx.BottomUp("apex_vndk_deps", apexVndkDepsMutator).Parallel()
-}
-
-func RegisterPostDepsMutators(ctx android.RegisterMutatorsContext) {
-	ctx.TopDown("apex_deps", apexDepsMutator).Parallel()
-	ctx.BottomUp("apex_unique", apexUniqueVariationsMutator).Parallel()
-	ctx.BottomUp("apex_test_for_deps", apexTestForDepsMutator).Parallel()
-	ctx.BottomUp("apex_test_for", apexTestForMutator).Parallel()
-	ctx.BottomUp("apex", apexMutator).Parallel()
-	ctx.BottomUp("apex_directly_in_any", apexDirectlyInAnyMutator).Parallel()
-	ctx.BottomUp("apex_flattened", apexFlattenedMutator).Parallel()
-	ctx.BottomUp("mark_platform_availability", markPlatformAvailability).Parallel()
-}
-
-// Mark the direct and transitive dependencies of apex bundles so that they
-// can be built for the apex bundles.
-func apexDepsMutator(mctx android.TopDownMutatorContext) {
-	if !mctx.Module().Enabled() {
-		return
-	}
-	a, ok := mctx.Module().(*apexBundle)
-	if !ok || a.vndkApex {
-		return
-	}
-
-	useVndk := a.SocSpecific() || a.DeviceSpecific() || (a.ProductSpecific() && mctx.Config().EnforceProductPartitionInterface())
-	excludeVndkLibs := useVndk && proptools.Bool(a.properties.Use_vndk_as_stable)
-	if !useVndk && proptools.Bool(a.properties.Use_vndk_as_stable) {
-		mctx.PropertyErrorf("use_vndk_as_stable", "not supported for system/system_ext APEXes")
-		return
-	}
-
-	contents := make(map[string]android.ApexMembership)
-
-	continueApexDepsWalk := func(child, parent android.Module) bool {
-		am, ok := child.(android.ApexModule)
-		if !ok || !am.CanHaveApexVariants() {
-			return false
-		}
-		if !parent.(android.DepIsInSameApex).DepIsInSameApex(mctx, child) {
-			return false
-		}
-		if excludeVndkLibs {
-			if c, ok := child.(*cc.Module); ok && c.IsVndk() {
-				return false
-			}
-		}
-		return true
-	}
-
-	mctx.WalkDeps(func(child, parent android.Module) bool {
-		if !continueApexDepsWalk(child, parent) {
-			return false
-		}
-
-		depName := mctx.OtherModuleName(child)
-		// If the parent is apexBundle, this child is directly depended.
-		_, directDep := parent.(*apexBundle)
-		contents[depName] = contents[depName].Add(directDep)
-		return true
-	})
-
-	apexContents := android.NewApexContents(mctx.ModuleName(), contents)
-	mctx.SetProvider(ApexBundleInfoProvider, ApexBundleInfo{
-		Contents: apexContents,
-	})
-
-	apexInfo := android.ApexInfo{
-		ApexVariationName: mctx.ModuleName(),
-		MinSdkVersionStr:  a.minSdkVersion(mctx).String(),
-		RequiredSdks:      a.RequiredSdks(),
-		Updatable:         a.Updatable(),
-		InApexes:          []string{mctx.ModuleName()},
-		ApexContents:      []*android.ApexContents{apexContents},
-	}
-
-	mctx.WalkDeps(func(child, parent android.Module) bool {
-		if !continueApexDepsWalk(child, parent) {
-			return false
-		}
-
-		child.(android.ApexModule).BuildForApex(apexInfo)
-		return true
-	})
-}
-
-func apexUniqueVariationsMutator(mctx android.BottomUpMutatorContext) {
-	if !mctx.Module().Enabled() {
-		return
-	}
-	if am, ok := mctx.Module().(android.ApexModule); ok {
-		// Check if any dependencies use unique apex variations.  If so, use unique apex variations
-		// for this module.
-		android.UpdateUniqueApexVariationsForDeps(mctx, am)
-	}
-}
-
-func apexTestForDepsMutator(mctx android.BottomUpMutatorContext) {
-	if !mctx.Module().Enabled() {
-		return
-	}
-	// Check if this module is a test for an apex.  If so, add a dependency on the apex
-	// in order to retrieve its contents later.
-	if am, ok := mctx.Module().(android.ApexModule); ok {
-		if testFor := am.TestFor(); len(testFor) > 0 {
-			mctx.AddFarVariationDependencies([]blueprint.Variation{
-				{Mutator: "os", Variation: am.Target().OsVariation()},
-				{"arch", "common"},
-			}, testForTag, testFor...)
-		}
-	}
-}
-
-func apexTestForMutator(mctx android.BottomUpMutatorContext) {
-	if !mctx.Module().Enabled() {
-		return
-	}
-
-	if _, ok := mctx.Module().(android.ApexModule); ok {
-		var contents []*android.ApexContents
-		for _, testFor := range mctx.GetDirectDepsWithTag(testForTag) {
-			abInfo := mctx.OtherModuleProvider(testFor, ApexBundleInfoProvider).(ApexBundleInfo)
-			contents = append(contents, abInfo.Contents)
-		}
-		mctx.SetProvider(android.ApexTestForInfoProvider, android.ApexTestForInfo{
-			ApexContents: contents,
-		})
-	}
-}
-
-// mark if a module cannot be available to platform. A module cannot be available
-// to platform if 1) it is explicitly marked as not available (i.e. "//apex_available:platform"
-// is absent) or 2) it depends on another module that isn't (or can't be) available to platform
-func markPlatformAvailability(mctx android.BottomUpMutatorContext) {
-	// Host and recovery are not considered as platform
-	if mctx.Host() || mctx.Module().InstallInRecovery() {
-		return
-	}
-
-	if am, ok := mctx.Module().(android.ApexModule); ok {
-		availableToPlatform := am.AvailableFor(android.AvailableToPlatform)
-
-		// If any of the dep is not available to platform, this module is also considered
-		// as being not available to platform even if it has "//apex_available:platform"
-		mctx.VisitDirectDeps(func(child android.Module) {
-			if !am.DepIsInSameApex(mctx, child) {
-				// if the dependency crosses apex boundary, don't consider it
-				return
-			}
-			if dep, ok := child.(android.ApexModule); ok && dep.NotAvailableForPlatform() {
-				availableToPlatform = false
-				// TODO(b/154889534) trigger an error when 'am' has "//apex_available:platform"
-			}
-		})
-
-		// Exception 1: stub libraries and native bridge libraries are always available to platform
-		if cc, ok := mctx.Module().(*cc.Module); ok &&
-			(cc.IsStubs() || cc.Target().NativeBridge == android.NativeBridgeEnabled) {
-			availableToPlatform = true
-		}
-
-		// Exception 2: bootstrap bionic libraries are also always available to platform
-		if cc.InstallToBootstrap(mctx.ModuleName(), mctx.Config()) {
-			availableToPlatform = true
-		}
-
-		if !availableToPlatform {
-			am.SetNotAvailableForPlatform()
-		}
-	}
-}
-
-// If a module in an APEX depends on a module from an SDK then it needs an APEX
-// specific variant created for it. Refer to sdk.sdkDepsReplaceMutator.
-func inAnySdk(module android.Module) bool {
-	if sa, ok := module.(android.SdkAware); ok {
-		return sa.IsInAnySdk()
-	}
-
-	return false
-}
-
-// Create apex variations if a module is included in APEX(s).
-func apexMutator(mctx android.BottomUpMutatorContext) {
-	if !mctx.Module().Enabled() {
-		return
-	}
-
-	if am, ok := mctx.Module().(android.ApexModule); ok && am.CanHaveApexVariants() {
-		android.CreateApexVariations(mctx, am)
-	} else if a, ok := mctx.Module().(*apexBundle); ok && !a.vndkApex {
-		// apex bundle itself is mutated so that it and its modules have same
-		// apex variant.
-		apexBundleName := mctx.ModuleName()
-		mctx.CreateVariations(apexBundleName)
-	} else if o, ok := mctx.Module().(*OverrideApex); ok {
-		apexBundleName := o.GetOverriddenModuleName()
-		if apexBundleName == "" {
-			mctx.ModuleErrorf("base property is not set")
-			return
-		}
-		mctx.CreateVariations(apexBundleName)
-	}
-
-}
-
-func apexDirectlyInAnyMutator(mctx android.BottomUpMutatorContext) {
-	if !mctx.Module().Enabled() {
-		return
-	}
-	if am, ok := mctx.Module().(android.ApexModule); ok {
-		android.UpdateDirectlyInAnyApex(mctx, am)
-	}
-}
-
-func apexFlattenedMutator(mctx android.BottomUpMutatorContext) {
-	if !mctx.Module().Enabled() {
-		return
-	}
-	if ab, ok := mctx.Module().(*apexBundle); ok {
-		var variants []string
-		switch proptools.StringDefault(ab.properties.Payload_type, "image") {
-		case "image":
-			variants = append(variants, imageApexType, flattenedApexType)
-		case "zip":
-			variants = append(variants, zipApexType)
-		case "both":
-			variants = append(variants, imageApexType, zipApexType, flattenedApexType)
-		default:
-			mctx.PropertyErrorf("type", "%q is not one of \"image\", \"zip\", or \"both\".", *ab.properties.Payload_type)
-			return
-		}
-
-		modules := mctx.CreateLocalVariations(variants...)
-
-		for i, v := range variants {
-			switch v {
-			case imageApexType:
-				modules[i].(*apexBundle).properties.ApexType = imageApex
-			case zipApexType:
-				modules[i].(*apexBundle).properties.ApexType = zipApex
-			case flattenedApexType:
-				modules[i].(*apexBundle).properties.ApexType = flattenedApex
-				if !mctx.Config().FlattenApex() && ab.Platform() {
-					modules[i].(*apexBundle).MakeAsSystemExt()
-				}
-			}
-		}
-	} else if _, ok := mctx.Module().(*OverrideApex); ok {
-		mctx.CreateVariations(imageApexType, flattenedApexType)
-	}
-}
-
-var (
-	useVendorAllowListKey = android.NewOnceKey("useVendorAllowList")
-)
-
-// useVendorAllowList returns the list of APEXes which are allowed to use_vendor.
-// When use_vendor is used, native modules are built with __ANDROID_VNDK__ and __ANDROID_APEX__,
-// which may cause compatibility issues. (e.g. libbinder)
-// Even though libbinder restricts its availability via 'apex_available' property and relies on
-// yet another macro __ANDROID_APEX_<NAME>__, we restrict usage of "use_vendor:" from other APEX modules
-// to avoid similar problems.
-func useVendorAllowList(config android.Config) []string {
-	return config.Once(useVendorAllowListKey, func() interface{} {
-		return []string{
-			// swcodec uses "vendor" variants for smaller size
-			"com.android.media.swcodec",
-			"test_com.android.media.swcodec",
-		}
-	}).([]string)
-}
-
-// setUseVendorAllowListForTest overrides useVendorAllowList and must be
-// called before the first call to useVendorAllowList()
-func setUseVendorAllowListForTest(config android.Config, allowList []string) {
-	config.Once(useVendorAllowListKey, func() interface{} {
-		return allowList
-	})
-}
-
-type ApexNativeDependencies struct {
-	// List of native libraries
-	Native_shared_libs []string
-
-	// List of JNI libraries
-	Jni_libs []string
-
-	// List of native executables
-	Binaries []string
-
-	// List of native tests
-	Tests []string
-}
-
-type apexMultilibProperties struct {
-	// Native dependencies whose compile_multilib is "first"
-	First ApexNativeDependencies
-
-	// Native dependencies whose compile_multilib is "both"
-	Both ApexNativeDependencies
-
-	// Native dependencies whose compile_multilib is "prefer32"
-	Prefer32 ApexNativeDependencies
-
-	// Native dependencies whose compile_multilib is "32"
-	Lib32 ApexNativeDependencies
-
-	// Native dependencies whose compile_multilib is "64"
-	Lib64 ApexNativeDependencies
-}
-
-type apexBundleProperties struct {
-	// Json manifest file describing meta info of this APEX bundle. Default:
-	// "apex_manifest.json"
-	Manifest *string `android:"path"`
-
-	// AndroidManifest.xml file used for the zip container of this APEX bundle.
-	// If unspecified, a default one is automatically generated.
-	AndroidManifest *string `android:"path"`
-
-	// Canonical name of the APEX bundle. Used to determine the path to the activated APEX on
-	// device (/apex/<apex_name>).
-	// If unspecified, defaults to the value of name.
-	Apex_name *string
-
-	// Determines the file contexts file for setting security context to each file in this APEX bundle.
-	// For platform APEXes, this should points to a file under /system/sepolicy
-	// Default: /system/sepolicy/apex/<module_name>_file_contexts.
-	File_contexts *string `android:"path"`
-
-	ApexNativeDependencies
-
-	// List of java libraries that are embedded inside this APEX bundle
-	Java_libs []string
-
-	// List of prebuilt files that are embedded inside this APEX bundle
-	Prebuilts []string
-
-	// List of BPF programs inside APEX
-	Bpfs []string
-
-	// Name of the apex_key module that provides the private key to sign APEX
-	Key *string
-
-	// The type of APEX to build. Controls what the APEX payload is. Either
-	// 'image', 'zip' or 'both'. Default: 'image'.
-	Payload_type *string
-
-	// The name of a certificate in the default certificate directory, blank to use the default product certificate,
-	// or an android_app_certificate module name in the form ":module".
-	Certificate *string
-
-	// Whether this APEX is installable to one of the partitions. Default: true.
-	Installable *bool
-
-	// For native libraries and binaries, use the vendor variant instead of the core (platform) variant.
-	// Default is false.
-	Use_vendor *bool
-
-	// For telling the apex to ignore special handling for system libraries such as bionic. Default is false.
-	Ignore_system_library_special_case *bool
-
-	Multilib apexMultilibProperties
-
-	// List of sanitizer names that this APEX is enabled for
-	SanitizerNames []string `blueprint:"mutated"`
-
-	PreventInstall bool `blueprint:"mutated"`
-
-	HideFromMake bool `blueprint:"mutated"`
-
-	// package format of this apex variant; could be non-flattened, flattened, or zip.
-	// imageApex, zipApex or flattened
-	ApexType apexPackaging `blueprint:"mutated"`
-
-	// List of SDKs that are used to build this APEX. A reference to an SDK should be either
-	// `name#version` or `name` which is an alias for `name#current`. If left empty, `platform#current`
-	// is implied. This value affects all modules included in this APEX. In other words, they are
-	// also built with the SDKs specified here.
-	Uses_sdks []string
-
-	// Whenever apex_payload.img of the APEX should include dm-verity hashtree.
-	// Should be only used in tests#.
-	Test_only_no_hashtree *bool
-
-	// Whenever apex_payload.img of the APEX should not be dm-verity signed.
-	// Should be only used in tests#.
-	Test_only_unsigned_payload *bool
-
-	IsCoverageVariant bool `blueprint:"mutated"`
-
-	// Whether this APEX is considered updatable or not. When set to true, this will enforce additional
-	// rules for making sure that the APEX is truly updatable.
-	// - To be updatable, min_sdk_version should be set as well
-	// This will also disable the size optimizations like symlinking to the system libs.
-	// Default is false.
-	Updatable *bool
-
-	// The minimum SDK version that this apex must be compatibile with.
-	Min_sdk_version *string
-
-	// If set true, VNDK libs are considered as stable libs and are not included in this apex.
-	// Should be only used in non-system apexes (e.g. vendor: true).
-	// Default is false.
-	Use_vndk_as_stable *bool
-
-	// The type of filesystem to use for an image apex. Either 'ext4' or 'f2fs'.
-	// Default 'ext4'.
-	Payload_fs_type *string
-}
-
-type ApexBundleInfo struct {
-	Contents *android.ApexContents
-}
-
-var ApexBundleInfoProvider = blueprint.NewMutatorProvider(ApexBundleInfo{}, "apex_deps")
-
-type apexTargetBundleProperties struct {
-	Target struct {
-		// Multilib properties only for android.
-		Android struct {
-			Multilib apexMultilibProperties
-		}
-
-		// Multilib properties only for host.
-		Host struct {
-			Multilib apexMultilibProperties
-		}
-
-		// Multilib properties only for host linux_bionic.
-		Linux_bionic struct {
-			Multilib apexMultilibProperties
-		}
-
-		// Multilib properties only for host linux_glibc.
-		Linux_glibc struct {
-			Multilib apexMultilibProperties
-		}
-	}
-}
-
-type overridableProperties struct {
-	// List of APKs to package inside APEX
-	Apps []string
-
-	// List of runtime resource overlays (RROs) inside APEX
-	Rros []string
-
-	// Names of modules to be overridden. Listed modules can only be other binaries
-	// (in Make or Soong).
-	// This does not completely prevent installation of the overridden binaries, but if both
-	// binaries would be installed by default (in PRODUCT_PACKAGES) the other binary will be removed
-	// from PRODUCT_PACKAGES.
-	Overrides []string
-
-	// Logging Parent value
-	Logging_parent string
-
-	// Apex Container Package Name.
-	// Override value for attribute package:name in AndroidManifest.xml
-	Package_name string
-
-	// A txt file containing list of files that are allowed to be included in this APEX.
-	Allowed_files *string `android:"path"`
-}
-
-type apexPackaging int
-
-const (
-	imageApex apexPackaging = iota
-	zipApex
-	flattenedApex
-)
-
-// The suffix for the output "file", not the module
-func (a apexPackaging) suffix() string {
-	switch a {
-	case imageApex:
-		return imageApexSuffix
-	case zipApex:
-		return zipApexSuffix
-	default:
-		panic(fmt.Errorf("unknown APEX type %d", a))
-	}
-}
-
-func (a apexPackaging) name() string {
-	switch a {
-	case imageApex:
-		return imageApexType
-	case zipApex:
-		return zipApexType
-	default:
-		panic(fmt.Errorf("unknown APEX type %d", a))
-	}
-}
-
-type apexFileClass int
-
-const (
-	etc apexFileClass = iota
-	nativeSharedLib
-	nativeExecutable
-	shBinary
-	pyBinary
-	goBinary
-	javaSharedLib
-	nativeTest
-	app
-	appSet
-)
-
-func (class apexFileClass) NameInMake() string {
-	switch class {
-	case etc:
-		return "ETC"
-	case nativeSharedLib:
-		return "SHARED_LIBRARIES"
-	case nativeExecutable, shBinary, pyBinary, goBinary:
-		return "EXECUTABLES"
-	case javaSharedLib:
-		return "JAVA_LIBRARIES"
-	case nativeTest:
-		return "NATIVE_TESTS"
-	case app, appSet:
-		// b/142537672 Why isn't this APP? We want to have full control over
-		// the paths and file names of the apk file under the flattend APEX.
-		// If this is set to APP, then the paths and file names are modified
-		// by the Make build system. For example, it is installed to
-		// /system/apex/<apexname>/app/<Appname>/<apexname>.<Appname>/ instead of
-		// /system/apex/<apexname>/app/<Appname> because the build system automatically
-		// appends module name (which is <apexname>.<Appname> to the path.
-		return "ETC"
-	default:
-		panic(fmt.Errorf("unknown class %d", class))
-	}
-}
-
-// apexFile represents a file in an APEX bundle
-type apexFile struct {
-	builtFile android.Path
-	stem      string
-	// Module name of `module` in AndroidMk. Note the generated AndroidMk module for
-	// apexFile is named something like <AndroidMk module name>.<apex name>[<apex suffix>]
-	androidMkModuleName string
-	installDir          string
-	class               apexFileClass
-	module              android.Module
-	// list of symlinks that will be created in installDir that point to this apexFile
-	symlinks      []string
-	dataPaths     []android.DataPath
-	transitiveDep bool
-	moduleDir     string
-
-	requiredModuleNames       []string
-	targetRequiredModuleNames []string
-	hostRequiredModuleNames   []string
-
-	jacocoReportClassesFile android.Path     // only for javalibs and apps
-	lintDepSets             java.LintDepSets // only for javalibs and apps
-	certificate             java.Certificate // only for apps
-	overriddenPackageName   string           // only for apps
-
-	isJniLib bool
-
-	noticeFiles android.Paths
-}
-
-func newApexFile(ctx android.BaseModuleContext, builtFile android.Path, androidMkModuleName string, installDir string, class apexFileClass, module android.Module) apexFile {
-	ret := apexFile{
-		builtFile:           builtFile,
-		androidMkModuleName: androidMkModuleName,
-		installDir:          installDir,
-		class:               class,
-		module:              module,
-	}
-	if module != nil {
-		ret.moduleDir = ctx.OtherModuleDir(module)
-		ret.requiredModuleNames = module.RequiredModuleNames()
-		ret.targetRequiredModuleNames = module.TargetRequiredModuleNames()
-		ret.hostRequiredModuleNames = module.HostRequiredModuleNames()
-		ret.noticeFiles = module.NoticeFiles()
-	}
-	return ret
-}
-
-func (af *apexFile) Ok() bool {
-	return af.builtFile != nil && af.builtFile.String() != ""
-}
-
-func (af *apexFile) apexRelativePath(path string) string {
-	return filepath.Join(af.installDir, path)
-}
-
-// Path() returns path of this apex file relative to the APEX root
-func (af *apexFile) Path() string {
-	return af.apexRelativePath(af.Stem())
-}
-
-func (af *apexFile) Stem() string {
-	if af.stem != "" {
-		return af.stem
-	}
-	return af.builtFile.Base()
-}
-
-// SymlinkPaths() returns paths of the symlinks (if any) relative to the APEX root
-func (af *apexFile) SymlinkPaths() []string {
-	var ret []string
-	for _, symlink := range af.symlinks {
-		ret = append(ret, af.apexRelativePath(symlink))
-	}
-	return ret
-}
-
-func (af *apexFile) AvailableToPlatform() bool {
-	if af.module == nil {
-		return false
-	}
-	if am, ok := af.module.(android.ApexModule); ok {
-		return am.AvailableFor(android.AvailableToPlatform)
-	}
-	return false
-}
-
-type fsType int
-
-const (
-	ext4 fsType = iota
-	f2fs
-)
-
-func (f fsType) string() string {
-	switch f {
-	case ext4:
-		return ext4FsType
-	case f2fs:
-		return f2fsFsType
-	default:
-		panic(fmt.Errorf("unknown APEX payload type %d", f))
-	}
-}
-
-type apexBundle struct {
-	android.ModuleBase
-	android.DefaultableModuleBase
-	android.OverridableModuleBase
-	android.SdkBase
-
-	properties            apexBundleProperties
-	targetProperties      apexTargetBundleProperties
-	overridableProperties overridableProperties
-
-	// specific to apex_vndk modules
-	vndkProperties apexVndkProperties
-
-	bundleModuleFile android.WritablePath
-	outputFile       android.WritablePath
-	installDir       android.InstallPath
-
-	prebuiltFileToDelete string
-
-	public_key_file  android.Path
-	private_key_file android.Path
-
-	container_certificate_file android.Path
-	container_private_key_file android.Path
-
-	fileContexts android.WritablePath
-
-	// list of files to be included in this apex
-	filesInfo []apexFile
-
-	// list of module names that should be installed along with this APEX
-	requiredDeps []string
-
-	// list of module names that this APEX is including (to be shown via *-deps-info target)
-	android.ApexBundleDepsInfo
-
-	testApex        bool
-	vndkApex        bool
-	artApex         bool
-	primaryApexType bool
-
-	manifestJsonOut android.WritablePath
-	manifestPbOut   android.WritablePath
-
-	// list of commands to create symlinks for backward compatibility.
-	// these commands will be attached as LOCAL_POST_INSTALL_CMD to
-	// apex package itself(for unflattened build) or apex_manifest(for flattened build)
-	// so that compat symlinks are always installed regardless of TARGET_FLATTEN_APEX setting.
-	compatSymlinks []string
-
-	// Suffix of module name in Android.mk
-	// ".flattened", ".apex", ".zipapex", or ""
-	suffix string
-
-	installedFilesFile android.WritablePath
-
-	// Whether to create symlink to the system file instead of having a file
-	// inside the apex or not
-	linkToSystemLib bool
-
-	// Struct holding the merged notice file paths in different formats
-	mergedNotices android.NoticeOutputs
-
-	// Optional list of lint report zip files for apexes that contain java or app modules
-	lintReports android.Paths
-
-	payloadFsType fsType
-
-	distFiles android.TaggedDistFiles
-}
-
-func addDependenciesForNativeModules(ctx android.BottomUpMutatorContext,
-	nativeModules ApexNativeDependencies,
-	target android.Target, imageVariation string) {
-	// Use *FarVariation* to be able to depend on modules having
-	// conflicting variations with this module. This is required since
-	// arch variant of an APEX bundle is 'common' but it is 'arm' or 'arm64'
-	// for native shared libs.
-
-	binVariations := target.Variations()
-	libVariations := append(target.Variations(),
-		blueprint.Variation{Mutator: "link", Variation: "shared"})
-
-	if ctx.Device() {
-		binVariations = append(binVariations,
-			blueprint.Variation{Mutator: "image", Variation: imageVariation})
-		libVariations = append(libVariations,
-			blueprint.Variation{Mutator: "image", Variation: imageVariation},
-			blueprint.Variation{Mutator: "version", Variation: ""}) // "" is the non-stub variant
-	}
-
-	ctx.AddFarVariationDependencies(libVariations, sharedLibTag, nativeModules.Native_shared_libs...)
-
-	ctx.AddFarVariationDependencies(libVariations, jniLibTag, nativeModules.Jni_libs...)
-
-	ctx.AddFarVariationDependencies(binVariations, executableTag, nativeModules.Binaries...)
-
-	ctx.AddFarVariationDependencies(binVariations, testTag, nativeModules.Tests...)
-}
-
-func (a *apexBundle) combineProperties(ctx android.BottomUpMutatorContext) {
-	if ctx.Os().Class == android.Device {
-		proptools.AppendProperties(&a.properties.Multilib, &a.targetProperties.Target.Android.Multilib, nil)
-	} else {
-		proptools.AppendProperties(&a.properties.Multilib, &a.targetProperties.Target.Host.Multilib, nil)
-		if ctx.Os().Bionic() {
-			proptools.AppendProperties(&a.properties.Multilib, &a.targetProperties.Target.Linux_bionic.Multilib, nil)
-		} else {
-			proptools.AppendProperties(&a.properties.Multilib, &a.targetProperties.Target.Linux_glibc.Multilib, nil)
-		}
-	}
-}
-
-func (a *apexBundle) DepsMutator(ctx android.BottomUpMutatorContext) {
-	if proptools.Bool(a.properties.Use_vendor) && !android.InList(a.Name(), useVendorAllowList(ctx.Config())) {
-		ctx.PropertyErrorf("use_vendor", "not allowed to set use_vendor: true")
-	}
-
-	targets := ctx.MultiTargets()
-	config := ctx.DeviceConfig()
-	imageVariation := a.getImageVariation(ctx)
-
-	a.combineProperties(ctx)
-
-	has32BitTarget := false
-	for _, target := range targets {
-		if target.Arch.ArchType.Multilib == "lib32" {
-			has32BitTarget = true
-		}
-	}
-	for i, target := range targets {
-		if target.HostCross {
-			// Don't include artifats for the host cross targets because there is no way
-			// for us to run those artifacts natively on host
-			continue
-		}
-
-		// When multilib.* is omitted for native_shared_libs/jni_libs/tests, it implies
-		// multilib.both
-		addDependenciesForNativeModules(ctx,
-			ApexNativeDependencies{
-				Native_shared_libs: a.properties.Native_shared_libs,
-				Tests:              a.properties.Tests,
-				Jni_libs:           a.properties.Jni_libs,
-				Binaries:           nil,
-			},
-			target, imageVariation)
-
-		// Add native modules targetting both ABIs
-		addDependenciesForNativeModules(ctx,
-			a.properties.Multilib.Both,
-			target,
-			imageVariation)
-
-		isPrimaryAbi := i == 0
-		if isPrimaryAbi {
-			// When multilib.* is omitted for binaries, it implies
-			// multilib.first
-			addDependenciesForNativeModules(ctx,
-				ApexNativeDependencies{
-					Native_shared_libs: nil,
-					Tests:              nil,
-					Jni_libs:           nil,
-					Binaries:           a.properties.Binaries,
-				},
-				target, imageVariation)
-
-			// Add native modules targetting the first ABI
-			addDependenciesForNativeModules(ctx,
-				a.properties.Multilib.First,
-				target,
-				imageVariation)
-		}
-
-		switch target.Arch.ArchType.Multilib {
-		case "lib32":
-			// Add native modules targetting 32-bit ABI
-			addDependenciesForNativeModules(ctx,
-				a.properties.Multilib.Lib32,
-				target,
-				imageVariation)
-
-			addDependenciesForNativeModules(ctx,
-				a.properties.Multilib.Prefer32,
-				target,
-				imageVariation)
-		case "lib64":
-			// Add native modules targetting 64-bit ABI
-			addDependenciesForNativeModules(ctx,
-				a.properties.Multilib.Lib64,
-				target,
-				imageVariation)
-
-			if !has32BitTarget {
-				addDependenciesForNativeModules(ctx,
-					a.properties.Multilib.Prefer32,
-					target,
-					imageVariation)
-			}
-		}
-	}
-
-	// For prebuilt_etc, use the first variant (64 on 64/32bit device,
-	// 32 on 32bit device) regardless of the TARGET_PREFER_* setting.
-	// b/144532908
-	archForPrebuiltEtc := config.Arches()[0]
-	for _, arch := range config.Arches() {
-		// Prefer 64-bit arch if there is any
-		if arch.ArchType.Multilib == "lib64" {
-			archForPrebuiltEtc = arch
-			break
-		}
-	}
-	ctx.AddFarVariationDependencies([]blueprint.Variation{
-		{Mutator: "os", Variation: ctx.Os().String()},
-		{Mutator: "arch", Variation: archForPrebuiltEtc.String()},
-	}, prebuiltTag, a.properties.Prebuilts...)
-
-	ctx.AddFarVariationDependencies(ctx.Config().AndroidCommonTarget.Variations(),
-		javaLibTag, a.properties.Java_libs...)
-
-	ctx.AddFarVariationDependencies(ctx.Config().AndroidCommonTarget.Variations(),
-		bpfTag, a.properties.Bpfs...)
-
-	// With EMMA_INSTRUMENT_FRAMEWORK=true the ART boot image includes jacoco library.
-	if a.artApex && ctx.Config().IsEnvTrue("EMMA_INSTRUMENT_FRAMEWORK") {
-		ctx.AddFarVariationDependencies(ctx.Config().AndroidCommonTarget.Variations(),
-			javaLibTag, "jacocoagent")
-	}
-
-	if String(a.properties.Key) == "" {
-		ctx.ModuleErrorf("key is missing")
-		return
-	}
-	ctx.AddDependency(ctx.Module(), keyTag, String(a.properties.Key))
-
-	cert := android.SrcIsModule(a.getCertString(ctx))
-	if cert != "" {
-		ctx.AddDependency(ctx.Module(), certificateTag, cert)
-	}
-
-	// TODO(jiyong): ensure that all apexes are with non-empty uses_sdks
-	if len(a.properties.Uses_sdks) > 0 {
-		sdkRefs := []android.SdkRef{}
-		for _, str := range a.properties.Uses_sdks {
-			parsed := android.ParseSdkRef(ctx, str, "uses_sdks")
-			sdkRefs = append(sdkRefs, parsed)
-		}
-		a.BuildWithSdks(sdkRefs)
-	}
-}
-
-func (a *apexBundle) OverridablePropertiesDepsMutator(ctx android.BottomUpMutatorContext) {
-	if a.overridableProperties.Allowed_files != nil {
-		android.ExtractSourceDeps(ctx, a.overridableProperties.Allowed_files)
-	}
-	ctx.AddFarVariationDependencies(ctx.Config().AndroidCommonTarget.Variations(),
-		androidAppTag, a.overridableProperties.Apps...)
-	ctx.AddFarVariationDependencies(ctx.Config().AndroidCommonTarget.Variations(),
-		rroTag, a.overridableProperties.Rros...)
-}
-
-func (a *apexBundle) DepIsInSameApex(ctx android.BaseModuleContext, dep android.Module) bool {
-	// direct deps of an APEX bundle are all part of the APEX bundle
-	return true
-}
-
-func (a *apexBundle) getCertString(ctx android.BaseModuleContext) string {
-	moduleName := ctx.ModuleName()
-	// VNDK APEXes share the same certificate. To avoid adding a new VNDK version to the OVERRIDE_* list,
-	// we check with the pseudo module name to see if its certificate is overridden.
-	if a.vndkApex {
-		moduleName = vndkApexName
-	}
-	certificate, overridden := ctx.DeviceConfig().OverrideCertificateFor(moduleName)
-	if overridden {
-		return ":" + certificate
-	}
-	return String(a.properties.Certificate)
-}
-
-func (a *apexBundle) OutputFiles(tag string) (android.Paths, error) {
-	switch tag {
-	case "":
-		return android.Paths{a.outputFile}, nil
-	default:
-		return nil, fmt.Errorf("unsupported module reference tag %q", tag)
-	}
-}
-
-func (a *apexBundle) installable() bool {
-	return !a.properties.PreventInstall && (a.properties.Installable == nil || proptools.Bool(a.properties.Installable))
-}
-
-func (a *apexBundle) testOnlyShouldSkipHashtreeGeneration() bool {
-	return proptools.Bool(a.properties.Test_only_no_hashtree)
-}
-
-func (a *apexBundle) testOnlyShouldSkipPayloadSign() bool {
-	return proptools.Bool(a.properties.Test_only_unsigned_payload)
-}
-
-func (a *apexBundle) getImageVariation(ctx android.BottomUpMutatorContext) string {
-	deviceConfig := ctx.DeviceConfig()
-	if a.vndkApex {
-		return cc.VendorVariationPrefix + a.vndkVersion(deviceConfig)
-	}
-
-	var prefix string
-	var vndkVersion string
-	if deviceConfig.VndkVersion() != "" {
-		if proptools.Bool(a.properties.Use_vendor) {
-			prefix = cc.VendorVariationPrefix
-			vndkVersion = deviceConfig.PlatformVndkVersion()
-		} else if a.SocSpecific() || a.DeviceSpecific() {
-			prefix = cc.VendorVariationPrefix
-			vndkVersion = deviceConfig.VndkVersion()
-		} else if a.ProductSpecific() {
-			prefix = cc.ProductVariationPrefix
-			vndkVersion = deviceConfig.ProductVndkVersion()
-		}
-	}
-	if vndkVersion == "current" {
-		vndkVersion = deviceConfig.PlatformVndkVersion()
-	}
-	if vndkVersion != "" {
-		return prefix + vndkVersion
-	}
-	return android.CoreVariation
-}
-
-func (a *apexBundle) EnableSanitizer(sanitizerName string) {
-	if !android.InList(sanitizerName, a.properties.SanitizerNames) {
-		a.properties.SanitizerNames = append(a.properties.SanitizerNames, sanitizerName)
-	}
-}
-
-func (a *apexBundle) IsSanitizerEnabled(ctx android.BaseModuleContext, sanitizerName string) bool {
-	if android.InList(sanitizerName, a.properties.SanitizerNames) {
-		return true
-	}
-
-	// Then follow the global setting
-	globalSanitizerNames := []string{}
-	if a.Host() {
-		globalSanitizerNames = ctx.Config().SanitizeHost()
-	} else {
-		arches := ctx.Config().SanitizeDeviceArch()
-		if len(arches) == 0 || android.InList(a.Arch().ArchType.Name, arches) {
-			globalSanitizerNames = ctx.Config().SanitizeDevice()
-		}
-	}
-	return android.InList(sanitizerName, globalSanitizerNames)
-}
-
-func (a *apexBundle) AddSanitizerDependencies(ctx android.BottomUpMutatorContext, sanitizerName string) {
-	if ctx.Device() && sanitizerName == "hwaddress" && strings.HasPrefix(a.Name(), "com.android.runtime") {
-		for _, target := range ctx.MultiTargets() {
-			if target.Arch.ArchType.Multilib == "lib64" {
-				ctx.AddFarVariationDependencies(append(target.Variations(), []blueprint.Variation{
-					{Mutator: "image", Variation: a.getImageVariation(ctx)},
-					{Mutator: "link", Variation: "shared"},
-					{Mutator: "version", Variation: ""}, // "" is the non-stub variant
-				}...), sharedLibTag, "libclang_rt.hwasan-aarch64-android")
-				break
-			}
-		}
-	}
-}
-
-var _ cc.Coverage = (*apexBundle)(nil)
-
-func (a *apexBundle) IsNativeCoverageNeeded(ctx android.BaseModuleContext) bool {
-	return ctx.Device() && ctx.DeviceConfig().NativeCoverageEnabled()
-}
-
-func (a *apexBundle) PreventInstall() {
-	a.properties.PreventInstall = true
-}
-
-func (a *apexBundle) HideFromMake() {
-	a.properties.HideFromMake = true
-}
-
-func (a *apexBundle) MarkAsCoverageVariant(coverage bool) {
-	a.properties.IsCoverageVariant = coverage
-}
-
-func (a *apexBundle) EnableCoverageIfNeeded() {}
-
-// TODO(jiyong) move apexFileFor* close to the apexFile type definition
-func apexFileForNativeLibrary(ctx android.BaseModuleContext, ccMod *cc.Module, handleSpecialLibs bool) apexFile {
-	// Decide the APEX-local directory by the multilib of the library
-	// In the future, we may query this to the module.
-	var dirInApex string
-	switch ccMod.Arch().ArchType.Multilib {
-	case "lib32":
-		dirInApex = "lib"
-	case "lib64":
-		dirInApex = "lib64"
-	}
-	if ccMod.Target().NativeBridge == android.NativeBridgeEnabled {
-		dirInApex = filepath.Join(dirInApex, ccMod.Target().NativeBridgeRelativePath)
-	}
-	dirInApex = filepath.Join(dirInApex, ccMod.RelativeInstallPath())
-	if handleSpecialLibs && cc.InstallToBootstrap(ccMod.BaseModuleName(), ctx.Config()) {
-		// Special case for Bionic libs and other libs installed with them. This is
-		// to prevent those libs from being included in the search path
-		// /apex/com.android.runtime/${LIB}. This exclusion is required because
-		// those libs in the Runtime APEX are available via the legacy paths in
-		// /system/lib/. By the init process, the libs in the APEX are bind-mounted
-		// to the legacy paths and thus will be loaded into the default linker
-		// namespace (aka "platform" namespace). If the libs are directly in
-		// /apex/com.android.runtime/${LIB} then the same libs will be loaded again
-		// into the runtime linker namespace, which will result in double loading of
-		// them, which isn't supported.
-		dirInApex = filepath.Join(dirInApex, "bionic")
-	}
-
-	fileToCopy := ccMod.OutputFile().Path()
-	androidMkModuleName := ccMod.BaseModuleName() + ccMod.Properties.SubName
-	return newApexFile(ctx, fileToCopy, androidMkModuleName, dirInApex, nativeSharedLib, ccMod)
-}
-
-func apexFileForExecutable(ctx android.BaseModuleContext, cc *cc.Module) apexFile {
-	dirInApex := "bin"
-	if cc.Target().NativeBridge == android.NativeBridgeEnabled {
-		dirInApex = filepath.Join(dirInApex, cc.Target().NativeBridgeRelativePath)
-	}
-	dirInApex = filepath.Join(dirInApex, cc.RelativeInstallPath())
-	fileToCopy := cc.OutputFile().Path()
-	androidMkModuleName := cc.BaseModuleName() + cc.Properties.SubName
-	af := newApexFile(ctx, fileToCopy, androidMkModuleName, dirInApex, nativeExecutable, cc)
-	af.symlinks = cc.Symlinks()
-	af.dataPaths = cc.DataPaths()
-	return af
-}
-
-func apexFileForPyBinary(ctx android.BaseModuleContext, py *python.Module) apexFile {
-	dirInApex := "bin"
-	fileToCopy := py.HostToolPath().Path()
-	return newApexFile(ctx, fileToCopy, py.BaseModuleName(), dirInApex, pyBinary, py)
-}
-func apexFileForGoBinary(ctx android.BaseModuleContext, depName string, gb bootstrap.GoBinaryTool) apexFile {
-	dirInApex := "bin"
-	s, err := filepath.Rel(android.PathForOutput(ctx).String(), gb.InstallPath())
-	if err != nil {
-		ctx.ModuleErrorf("Unable to use compiled binary at %s", gb.InstallPath())
-		return apexFile{}
-	}
-	fileToCopy := android.PathForOutput(ctx, s)
-	// NB: Since go binaries are static we don't need the module for anything here, which is
-	// good since the go tool is a blueprint.Module not an android.Module like we would
-	// normally use.
-	return newApexFile(ctx, fileToCopy, depName, dirInApex, goBinary, nil)
-}
-
-func apexFileForShBinary(ctx android.BaseModuleContext, sh *sh.ShBinary) apexFile {
-	dirInApex := filepath.Join("bin", sh.SubDir())
-	fileToCopy := sh.OutputFile()
-	af := newApexFile(ctx, fileToCopy, sh.BaseModuleName(), dirInApex, shBinary, sh)
-	af.symlinks = sh.Symlinks()
-	return af
-}
-
-type javaModule interface {
-	android.Module
-	BaseModuleName() string
-	DexJarBuildPath() android.Path
-	JacocoReportClassesFile() android.Path
-	LintDepSets() java.LintDepSets
-
-	Stem() string
-}
-
-var _ javaModule = (*java.Library)(nil)
-var _ javaModule = (*java.SdkLibrary)(nil)
-var _ javaModule = (*java.DexImport)(nil)
-var _ javaModule = (*java.SdkLibraryImport)(nil)
-
-func apexFileForJavaLibrary(ctx android.BaseModuleContext, module javaModule) apexFile {
-	dirInApex := "javalib"
-	fileToCopy := module.DexJarBuildPath()
-	af := newApexFile(ctx, fileToCopy, module.BaseModuleName(), dirInApex, javaSharedLib, module)
-	af.jacocoReportClassesFile = module.JacocoReportClassesFile()
-	af.lintDepSets = module.LintDepSets()
-	af.stem = module.Stem() + ".jar"
-	return af
-}
-
-func apexFileForPrebuiltEtc(ctx android.BaseModuleContext, prebuilt prebuilt_etc.PrebuiltEtcModule, depName string) apexFile {
-	dirInApex := filepath.Join(prebuilt.BaseDir(), prebuilt.SubDir())
-	fileToCopy := prebuilt.OutputFile()
-	return newApexFile(ctx, fileToCopy, depName, dirInApex, etc, prebuilt)
-}
-
-func apexFileForCompatConfig(ctx android.BaseModuleContext, config java.PlatformCompatConfigIntf, depName string) apexFile {
-	dirInApex := filepath.Join("etc", config.SubDir())
-	fileToCopy := config.CompatConfig()
-	return newApexFile(ctx, fileToCopy, depName, dirInApex, etc, config)
-}
-
-func apexFileForAndroidApp(ctx android.BaseModuleContext, aapp interface {
-	android.Module
-	Privileged() bool
-	InstallApkName() string
-	OutputFile() android.Path
-	JacocoReportClassesFile() android.Path
-	Certificate() java.Certificate
-	BaseModuleName() string
-}) apexFile {
-	appDir := "app"
-	if aapp.Privileged() {
-		appDir = "priv-app"
-	}
-	dirInApex := filepath.Join(appDir, aapp.InstallApkName())
-	fileToCopy := aapp.OutputFile()
-	af := newApexFile(ctx, fileToCopy, aapp.BaseModuleName(), dirInApex, app, aapp)
-	af.jacocoReportClassesFile = aapp.JacocoReportClassesFile()
-	af.certificate = aapp.Certificate()
-
-	if app, ok := aapp.(interface {
-		OverriddenManifestPackageName() string
-	}); ok {
-		af.overriddenPackageName = app.OverriddenManifestPackageName()
-	}
-	return af
-}
-
-func apexFileForRuntimeResourceOverlay(ctx android.BaseModuleContext, rro java.RuntimeResourceOverlayModule) apexFile {
-	rroDir := "overlay"
-	dirInApex := filepath.Join(rroDir, rro.Theme())
-	fileToCopy := rro.OutputFile()
-	af := newApexFile(ctx, fileToCopy, rro.Name(), dirInApex, app, rro)
-	af.certificate = rro.Certificate()
-
-	if a, ok := rro.(interface {
-		OverriddenManifestPackageName() string
-	}); ok {
-		af.overriddenPackageName = a.OverriddenManifestPackageName()
-	}
-	return af
-}
-
-func apexFileForBpfProgram(ctx android.BaseModuleContext, builtFile android.Path, bpfProgram bpf.BpfModule) apexFile {
-	dirInApex := filepath.Join("etc", "bpf")
-	return newApexFile(ctx, builtFile, builtFile.Base(), dirInApex, etc, bpfProgram)
-}
-
-// Context "decorator", overriding the InstallBypassMake method to always reply `true`.
-type flattenedApexContext struct {
-	android.ModuleContext
-}
-
-func (c *flattenedApexContext) InstallBypassMake() bool {
-	return true
-}
-
-// Visit dependencies that contributes to the payload of this APEX
-func (a *apexBundle) WalkPayloadDeps(ctx android.ModuleContext, do android.PayloadDepsCallback) {
-	ctx.WalkDeps(func(child, parent android.Module) bool {
-		am, ok := child.(android.ApexModule)
-		if !ok || !am.CanHaveApexVariants() {
-			return false
-		}
-
-		childApexInfo := ctx.OtherModuleProvider(child, android.ApexInfoProvider).(android.ApexInfo)
-
-		dt := ctx.OtherModuleDependencyTag(child)
-
-		if _, ok := dt.(android.ExcludeFromApexContentsTag); ok {
-			return false
-		}
-
-		// Check for the direct dependencies that contribute to the payload
-		if adt, ok := dt.(dependencyTag); ok {
-			if adt.payload {
-				return do(ctx, parent, am, false /* externalDep */)
-			}
-			// As soon as the dependency graph crosses the APEX boundary, don't go further.
-			return false
-		}
-
-		// Check for the indirect dependencies if it is considered as part of the APEX
-		if android.InList(ctx.ModuleName(), childApexInfo.InApexes) {
-			return do(ctx, parent, am, false /* externalDep */)
-		}
-
-		return do(ctx, parent, am, true /* externalDep */)
-	})
-}
-
-func (a *apexBundle) minSdkVersion(ctx android.BaseModuleContext) android.ApiLevel {
-	ver := proptools.String(a.properties.Min_sdk_version)
-	if ver == "" {
-		return android.FutureApiLevel
-	}
-	apiLevel, err := android.ApiLevelFromUser(ctx, ver)
-	if err != nil {
-		ctx.PropertyErrorf("min_sdk_version", "%s", err.Error())
-		return android.NoneApiLevel
-	}
-	if apiLevel.IsPreview() {
-		// All codenames should build against "current".
-		return android.FutureApiLevel
-	}
-	return apiLevel
-}
-
-func (a *apexBundle) Updatable() bool {
-	return proptools.Bool(a.properties.Updatable)
-}
-
-var _ android.ApexBundleDepsInfoIntf = (*apexBundle)(nil)
-
-// Ensures that the dependencies are marked as available for this APEX
-func (a *apexBundle) checkApexAvailability(ctx android.ModuleContext) {
-	// Let's be practical. Availability for test, host, and the VNDK apex isn't important
-	if ctx.Host() || a.testApex || a.vndkApex {
-		return
-	}
-
-	// Because APEXes targeting other than system/system_ext partitions
-	// can't set apex_available, we skip checks for these APEXes
-	if a.SocSpecific() || a.DeviceSpecific() ||
-		(a.ProductSpecific() && ctx.Config().EnforceProductPartitionInterface()) {
-		return
-	}
-
-	// Coverage build adds additional dependencies for the coverage-only runtime libraries.
-	// Requiring them and their transitive depencies with apex_available is not right
-	// because they just add noise.
-	if ctx.Config().IsEnvTrue("EMMA_INSTRUMENT") || a.IsNativeCoverageNeeded(ctx) {
-		return
-	}
-
-	a.WalkPayloadDeps(ctx, func(ctx android.ModuleContext, from blueprint.Module, to android.ApexModule, externalDep bool) bool {
-		if externalDep {
-			// As soon as the dependency graph crosses the APEX boundary, don't go further.
-			return false
-		}
-
-		apexName := ctx.ModuleName()
-		fromName := ctx.OtherModuleName(from)
-		toName := ctx.OtherModuleName(to)
-
-		// If `to` is not actually in the same APEX as `from` then it does not need apex_available and neither
-		// do any of its dependencies.
-		if am, ok := from.(android.DepIsInSameApex); ok && !am.DepIsInSameApex(ctx, to) {
-			// As soon as the dependency graph crosses the APEX boundary, don't go further.
-			return false
-		}
-
-		if to.AvailableFor(apexName) || baselineApexAvailable(apexName, toName) {
-			return true
-		}
-		ctx.ModuleErrorf("%q requires %q that doesn't list the APEX under 'apex_available'. Dependency path:%s", fromName, toName, ctx.GetPathString(true))
-		// Visit this module's dependencies to check and report any issues with their availability.
-		return true
-	})
-}
-
-func (a *apexBundle) checkUpdatable(ctx android.ModuleContext) {
-	if a.Updatable() {
-		if String(a.properties.Min_sdk_version) == "" {
-			ctx.PropertyErrorf("updatable", "updatable APEXes should set min_sdk_version as well")
-		}
-
-		a.checkJavaStableSdkVersion(ctx)
-	}
-}
-
-func (a *apexBundle) checkMinSdkVersion(ctx android.ModuleContext) {
-	if a.testApex || a.vndkApex {
-		return
-	}
-	// Meaningless to check min_sdk_version when building use_vendor modules against non-Trebleized targets
-	if proptools.Bool(a.properties.Use_vendor) && ctx.DeviceConfig().VndkVersion() == "" {
-		return
-	}
-	// apexBundle::minSdkVersion reports its own errors.
-	minSdkVersion := a.minSdkVersion(ctx)
-	android.CheckMinSdkVersion(a, ctx, minSdkVersion)
-}
-
-// Ensures that a lib providing stub isn't statically linked
-func (a *apexBundle) checkStaticLinkingToStubLibraries(ctx android.ModuleContext) {
-	// Practically, we only care about regular APEXes on the device.
-	if ctx.Host() || a.testApex || a.vndkApex {
-		return
-	}
-
-	abInfo := ctx.Provider(ApexBundleInfoProvider).(ApexBundleInfo)
-
-	a.WalkPayloadDeps(ctx, func(ctx android.ModuleContext, from blueprint.Module, to android.ApexModule, externalDep bool) bool {
-		if ccm, ok := to.(*cc.Module); ok {
-			apexName := ctx.ModuleName()
-			fromName := ctx.OtherModuleName(from)
-			toName := ctx.OtherModuleName(to)
-
-			// If `to` is not actually in the same APEX as `from` then it does not need apex_available and neither
-			// do any of its dependencies.
-			if am, ok := from.(android.DepIsInSameApex); ok && !am.DepIsInSameApex(ctx, to) {
-				// As soon as the dependency graph crosses the APEX boundary, don't go further.
-				return false
-			}
-
-			// The dynamic linker and crash_dump tool in the runtime APEX is the only exception to this rule.
-			// It can't make the static dependencies dynamic because it can't
-			// do the dynamic linking for itself.
-			if apexName == "com.android.runtime" && (fromName == "linker" || fromName == "crash_dump") {
-				return false
-			}
-
-			isStubLibraryFromOtherApex := ccm.HasStubsVariants() && !abInfo.Contents.DirectlyInApex(toName)
-			if isStubLibraryFromOtherApex && !externalDep {
-				ctx.ModuleErrorf("%q required by %q is a native library providing stub. "+
-					"It shouldn't be included in this APEX via static linking. Dependency path: %s", to.String(), fromName, ctx.GetPathString(false))
-			}
-
-		}
-		return true
-	})
-}
-
-func (a *apexBundle) GenerateAndroidBuildActions(ctx android.ModuleContext) {
-	buildFlattenedAsDefault := ctx.Config().FlattenApex() && !ctx.Config().UnbundledBuildApps()
-	switch a.properties.ApexType {
-	case imageApex:
-		if buildFlattenedAsDefault {
-			a.suffix = imageApexSuffix
-		} else {
-			a.suffix = ""
-			a.primaryApexType = true
-
-			if ctx.Config().InstallExtraFlattenedApexes() {
-				a.requiredDeps = append(a.requiredDeps, a.Name()+flattenedSuffix)
-			}
-		}
-	case zipApex:
-		if proptools.String(a.properties.Payload_type) == "zip" {
-			a.suffix = ""
-			a.primaryApexType = true
-		} else {
-			a.suffix = zipApexSuffix
-		}
-	case flattenedApex:
-		if buildFlattenedAsDefault {
-			a.suffix = ""
-			a.primaryApexType = true
-		} else {
-			a.suffix = flattenedSuffix
-		}
-	}
-
-	if len(a.properties.Tests) > 0 && !a.testApex {
-		ctx.PropertyErrorf("tests", "property not allowed in apex module type")
-		return
-	}
-
-	a.checkApexAvailability(ctx)
-	a.checkUpdatable(ctx)
-	a.checkMinSdkVersion(ctx)
-	a.checkStaticLinkingToStubLibraries(ctx)
-
-	handleSpecialLibs := !android.Bool(a.properties.Ignore_system_library_special_case)
-
-	// native lib dependencies
-	var provideNativeLibs []string
-	var requireNativeLibs []string
-
-	var filesInfo []apexFile
-	// TODO(jiyong) do this using WalkPayloadDeps
-	ctx.WalkDepsBlueprint(func(child, parent blueprint.Module) bool {
-		depTag := ctx.OtherModuleDependencyTag(child)
-		if _, ok := depTag.(android.ExcludeFromApexContentsTag); ok {
-			return false
-		}
-		depName := ctx.OtherModuleName(child)
-		if _, isDirectDep := parent.(*apexBundle); isDirectDep {
-			switch depTag {
-			case sharedLibTag, jniLibTag:
-				isJniLib := depTag == jniLibTag
-				if c, ok := child.(*cc.Module); ok {
-					fi := apexFileForNativeLibrary(ctx, c, handleSpecialLibs)
-					fi.isJniLib = isJniLib
-					filesInfo = append(filesInfo, fi)
-					// Collect the list of stub-providing libs except:
-					// - VNDK libs are only for vendors
-					// - bootstrap bionic libs are treated as provided by system
-					if c.HasStubsVariants() && !a.vndkApex && !cc.InstallToBootstrap(c.BaseModuleName(), ctx.Config()) {
-						provideNativeLibs = append(provideNativeLibs, fi.Stem())
-					}
-					return true // track transitive dependencies
-				} else {
-					propertyName := "native_shared_libs"
-					if isJniLib {
-						propertyName = "jni_libs"
-					}
-					ctx.PropertyErrorf(propertyName, "%q is not a cc_library or cc_library_shared module", depName)
-				}
-			case executableTag:
-				if cc, ok := child.(*cc.Module); ok {
-					filesInfo = append(filesInfo, apexFileForExecutable(ctx, cc))
-					return true // track transitive dependencies
-				} else if sh, ok := child.(*sh.ShBinary); ok {
-					filesInfo = append(filesInfo, apexFileForShBinary(ctx, sh))
-				} else if py, ok := child.(*python.Module); ok && py.HostToolPath().Valid() {
-					filesInfo = append(filesInfo, apexFileForPyBinary(ctx, py))
-				} else if gb, ok := child.(bootstrap.GoBinaryTool); ok && a.Host() {
-					filesInfo = append(filesInfo, apexFileForGoBinary(ctx, depName, gb))
-				} else {
-					ctx.PropertyErrorf("binaries", "%q is neither cc_binary, (embedded) py_binary, (host) blueprint_go_binary, (host) bootstrap_go_binary, nor sh_binary", depName)
-				}
-			case javaLibTag:
-				switch child.(type) {
-				case *java.Library, *java.SdkLibrary, *java.DexImport, *java.SdkLibraryImport:
-					af := apexFileForJavaLibrary(ctx, child.(javaModule))
-					if !af.Ok() {
-						ctx.PropertyErrorf("java_libs", "%q is not configured to be compiled into dex", depName)
-						return false
-					}
-					filesInfo = append(filesInfo, af)
-					return true // track transitive dependencies
-				default:
-					ctx.PropertyErrorf("java_libs", "%q of type %q is not supported", depName, ctx.OtherModuleType(child))
-				}
-			case androidAppTag:
-				if ap, ok := child.(*java.AndroidApp); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
-					return true // track transitive dependencies
-				} else if ap, ok := child.(*java.AndroidAppImport); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
-				} else if ap, ok := child.(*java.AndroidTestHelperApp); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
-				} else if ap, ok := child.(*java.AndroidAppSet); ok {
-					appDir := "app"
-					if ap.Privileged() {
-						appDir = "priv-app"
-					}
-					af := newApexFile(ctx, ap.OutputFile(), ap.BaseModuleName(),
-						filepath.Join(appDir, ap.BaseModuleName()), appSet, ap)
-					af.certificate = java.PresignedCertificate
-					filesInfo = append(filesInfo, af)
-				} else {
-					ctx.PropertyErrorf("apps", "%q is not an android_app module", depName)
-				}
-			case rroTag:
-				if rro, ok := child.(java.RuntimeResourceOverlayModule); ok {
-					filesInfo = append(filesInfo, apexFileForRuntimeResourceOverlay(ctx, rro))
-				} else {
-					ctx.PropertyErrorf("rros", "%q is not an runtime_resource_overlay module", depName)
-				}
-			case bpfTag:
-				if bpfProgram, ok := child.(bpf.BpfModule); ok {
-					filesToCopy, _ := bpfProgram.OutputFiles("")
-					for _, bpfFile := range filesToCopy {
-						filesInfo = append(filesInfo, apexFileForBpfProgram(ctx, bpfFile, bpfProgram))
-					}
-				} else {
-					ctx.PropertyErrorf("bpfs", "%q is not a bpf module", depName)
-				}
-			case prebuiltTag:
-				if prebuilt, ok := child.(prebuilt_etc.PrebuiltEtcModule); ok {
-					filesInfo = append(filesInfo, apexFileForPrebuiltEtc(ctx, prebuilt, depName))
-				} else if prebuilt, ok := child.(java.PlatformCompatConfigIntf); ok {
-					filesInfo = append(filesInfo, apexFileForCompatConfig(ctx, prebuilt, depName))
-				} else {
-					ctx.PropertyErrorf("prebuilts", "%q is not a prebuilt_etc and not a platform_compat_config module", depName)
-				}
-			case testTag:
-				if ccTest, ok := child.(*cc.Module); ok {
-					if ccTest.IsTestPerSrcAllTestsVariation() {
-						// Multiple-output test module (where `test_per_src: true`).
-						//
-						// `ccTest` is the "" ("all tests") variation of a `test_per_src` module.
-						// We do not add this variation to `filesInfo`, as it has no output;
-						// however, we do add the other variations of this module as indirect
-						// dependencies (see below).
-					} else {
-						// Single-output test module (where `test_per_src: false`).
-						af := apexFileForExecutable(ctx, ccTest)
-						af.class = nativeTest
-						filesInfo = append(filesInfo, af)
-					}
-					return true // track transitive dependencies
-				} else {
-					ctx.PropertyErrorf("tests", "%q is not a cc module", depName)
-				}
-			case keyTag:
-				if key, ok := child.(*apexKey); ok {
-					a.private_key_file = key.private_key_file
-					a.public_key_file = key.public_key_file
-				} else {
-					ctx.PropertyErrorf("key", "%q is not an apex_key module", depName)
-				}
-				return false
-			case certificateTag:
-				if dep, ok := child.(*java.AndroidAppCertificate); ok {
-					a.container_certificate_file = dep.Certificate.Pem
-					a.container_private_key_file = dep.Certificate.Key
-				} else {
-					ctx.ModuleErrorf("certificate dependency %q must be an android_app_certificate module", depName)
-				}
-			case android.PrebuiltDepTag:
-				// If the prebuilt is force disabled, remember to delete the prebuilt file
-				// that might have been installed in the previous builds
-				if prebuilt, ok := child.(prebuilt); ok && prebuilt.isForceDisabled() {
-					a.prebuiltFileToDelete = prebuilt.InstallFilename()
-				}
-			}
-		} else if !a.vndkApex {
-			// indirect dependencies
-			if am, ok := child.(android.ApexModule); ok {
-				// We cannot use a switch statement on `depTag` here as the checked
-				// tags used below are private (e.g. `cc.sharedDepTag`).
-				if cc.IsSharedDepTag(depTag) || cc.IsRuntimeDepTag(depTag) {
-					if cc, ok := child.(*cc.Module); ok {
-						if cc.UseVndk() && proptools.Bool(a.properties.Use_vndk_as_stable) && cc.IsVndk() {
-							requireNativeLibs = append(requireNativeLibs, ":vndk")
-							return false
-						}
-						af := apexFileForNativeLibrary(ctx, cc, handleSpecialLibs)
-						af.transitiveDep = true
-						abInfo := ctx.Provider(ApexBundleInfoProvider).(ApexBundleInfo)
-						if !a.Host() && !abInfo.Contents.DirectlyInApex(depName) && (cc.IsStubs() || cc.HasStubsVariants()) {
-							// If the dependency is a stubs lib, don't include it in this APEX,
-							// but make sure that the lib is installed on the device.
-							// In case no APEX is having the lib, the lib is installed to the system
-							// partition.
-							//
-							// Always include if we are a host-apex however since those won't have any
-							// system libraries.
-							if !am.DirectlyInAnyApex() {
-								// we need a module name for Make
-								name := cc.ImplementationModuleName(ctx)
-
-								if !proptools.Bool(a.properties.Use_vendor) {
-									// we don't use subName(.vendor) for a "use_vendor: true" apex
-									// which is supposed to be installed in /system
-									name += cc.Properties.SubName
-								}
-								if !android.InList(name, a.requiredDeps) {
-									a.requiredDeps = append(a.requiredDeps, name)
-								}
-							}
-							requireNativeLibs = append(requireNativeLibs, af.Stem())
-							// Don't track further
-							return false
-						}
-						filesInfo = append(filesInfo, af)
-						return true // track transitive dependencies
-					}
-				} else if cc.IsTestPerSrcDepTag(depTag) {
-					if cc, ok := child.(*cc.Module); ok {
-						af := apexFileForExecutable(ctx, cc)
-						// Handle modules created as `test_per_src` variations of a single test module:
-						// use the name of the generated test binary (`fileToCopy`) instead of the name
-						// of the original test module (`depName`, shared by all `test_per_src`
-						// variations of that module).
-						af.androidMkModuleName = filepath.Base(af.builtFile.String())
-						// these are not considered transitive dep
-						af.transitiveDep = false
-						filesInfo = append(filesInfo, af)
-						return true // track transitive dependencies
-					}
-				} else if java.IsJniDepTag(depTag) {
-					// Because APK-in-APEX embeds jni_libs transitively, we don't need to track transitive deps
-					return false
-				} else if java.IsXmlPermissionsFileDepTag(depTag) {
-					if prebuilt, ok := child.(prebuilt_etc.PrebuiltEtcModule); ok {
-						filesInfo = append(filesInfo, apexFileForPrebuiltEtc(ctx, prebuilt, depName))
-					}
-				} else if _, ok := depTag.(android.CopyDirectlyInAnyApexTag); ok {
-					// nothing
-				} else if am.CanHaveApexVariants() && am.IsInstallableToApex() {
-					ctx.ModuleErrorf("unexpected tag %s for indirect dependency %q", android.PrettyPrintTag(depTag), depName)
-				}
-			}
-		}
-		return false
-	})
-
-	// Specific to the ART apex: dexpreopt artifacts for libcore Java libraries.
-	// Build rules are generated by the dexpreopt singleton, and here we access build artifacts
-	// via the global boot image config.
-	if a.artApex {
-		for arch, files := range java.DexpreoptedArtApexJars(ctx) {
-			dirInApex := filepath.Join("javalib", arch.String())
-			for _, f := range files {
-				localModule := "javalib_" + arch.String() + "_" + filepath.Base(f.String())
-				af := newApexFile(ctx, f, localModule, dirInApex, etc, nil)
-				filesInfo = append(filesInfo, af)
-			}
-		}
-	}
-
-	if a.private_key_file == nil {
-		ctx.PropertyErrorf("key", "private_key for %q could not be found", String(a.properties.Key))
-		return
-	}
-
-	// remove duplicates in filesInfo
-	removeDup := func(filesInfo []apexFile) []apexFile {
-		encountered := make(map[string]apexFile)
-		for _, f := range filesInfo {
-			dest := filepath.Join(f.installDir, f.builtFile.Base())
-			if e, ok := encountered[dest]; !ok {
-				encountered[dest] = f
-			} else {
-				// If a module is directly included and also transitively depended on
-				// consider it as directly included.
-				e.transitiveDep = e.transitiveDep && f.transitiveDep
-				encountered[dest] = e
-			}
-		}
-		var result []apexFile
-		for _, v := range encountered {
-			result = append(result, v)
-		}
-		return result
-	}
-	filesInfo = removeDup(filesInfo)
-
-	// to have consistent build rules
-	sort.Slice(filesInfo, func(i, j int) bool {
-		return filesInfo[i].builtFile.String() < filesInfo[j].builtFile.String()
-	})
-
-	a.installDir = android.PathForModuleInstall(ctx, "apex")
-	a.filesInfo = filesInfo
-
-	switch proptools.StringDefault(a.properties.Payload_fs_type, ext4FsType) {
-	case ext4FsType:
-		a.payloadFsType = ext4
-	case f2fsFsType:
-		a.payloadFsType = f2fs
-	default:
-		ctx.PropertyErrorf("payload_fs_type", "%q is not a valid filesystem for apex [ext4, f2fs]", *a.properties.Payload_fs_type)
-	}
-
-	// Optimization. If we are building bundled APEX, for the files that are gathered due to the
-	// transitive dependencies, don't place them inside the APEX, but place a symlink pointing
-	// the same library in the system partition, thus effectively sharing the same libraries
-	// across the APEX boundary. For unbundled APEX, all the gathered files are actually placed
-	// in the APEX.
-	a.linkToSystemLib = !ctx.Config().UnbundledBuild() &&
-		a.installable() &&
-		!proptools.Bool(a.properties.Use_vendor)
-
-	// APEXes targeting other than system/system_ext partitions use vendor/product variants.
-	// So we can't link them to /system/lib libs which are core variants.
-	if a.SocSpecific() || a.DeviceSpecific() ||
-		(a.ProductSpecific() && ctx.Config().EnforceProductPartitionInterface()) {
-		a.linkToSystemLib = false
-	}
-
-	// We don't need the optimization for updatable APEXes, as it might give false signal
-	// to the system health when the APEXes are still bundled (b/149805758)
-	if a.Updatable() && a.properties.ApexType == imageApex {
-		a.linkToSystemLib = false
-	}
-
-	// We also don't want the optimization for host APEXes, because it doesn't make sense.
-	if ctx.Host() {
-		a.linkToSystemLib = false
-	}
-
-	// prepare apex_manifest.json
-	a.buildManifest(ctx, provideNativeLibs, requireNativeLibs)
-
-	a.buildFileContexts(ctx)
-
-	a.setCertificateAndPrivateKey(ctx)
-	if a.properties.ApexType == flattenedApex {
-		a.buildFlattenedApex(ctx)
-	} else {
-		a.buildUnflattenedApex(ctx)
-	}
-
-	a.compatSymlinks = makeCompatSymlinks(a.BaseModuleName(), ctx)
-
-	a.buildApexDependencyInfo(ctx)
-
-	a.buildLintReports(ctx)
-
-	a.distFiles = a.GenerateTaggedDistFiles(ctx)
-}
-
-// Enforce that Java deps of the apex are using stable SDKs to compile
-func (a *apexBundle) checkJavaStableSdkVersion(ctx android.ModuleContext) {
-	// Visit direct deps only. As long as we guarantee top-level deps are using
-	// stable SDKs, java's checkLinkType guarantees correct usage for transitive deps
-	ctx.VisitDirectDepsBlueprint(func(module blueprint.Module) {
-		tag := ctx.OtherModuleDependencyTag(module)
-		switch tag {
-		case javaLibTag, androidAppTag:
-			if m, ok := module.(interface{ CheckStableSdkVersion() error }); ok {
-				if err := m.CheckStableSdkVersion(); err != nil {
-					ctx.ModuleErrorf("cannot depend on \"%v\": %v", ctx.OtherModuleName(module), err)
-				}
-			}
-		}
-	})
-}
-
-func baselineApexAvailable(apex, moduleName string) bool {
-	key := apex
-	moduleName = normalizeModuleName(moduleName)
-
-	if val, ok := apexAvailBaseline[key]; ok && android.InList(moduleName, val) {
-		return true
-	}
-
-	key = android.AvailableToAnyApex
-	if val, ok := apexAvailBaseline[key]; ok && android.InList(moduleName, val) {
-		return true
-	}
-
-	return false
-}
-
-func normalizeModuleName(moduleName string) string {
-	// Prebuilt modules (e.g. java_import, etc.) have "prebuilt_" prefix added by the build
-	// system. Trim the prefix for the check since they are confusing
-	moduleName = strings.TrimPrefix(moduleName, "prebuilt_")
-	if strings.HasPrefix(moduleName, "libclang_rt.") {
-		// This module has many arch variants that depend on the product being built.
-		// We don't want to list them all
-		moduleName = "libclang_rt"
-	}
-	if strings.HasPrefix(moduleName, "androidx.") {
-		// TODO(b/156996905) Set apex_available/min_sdk_version for androidx support libraries
-		moduleName = "androidx"
-	}
-	return moduleName
-}
-
-func newApexBundle() *apexBundle {
-	module := &apexBundle{}
-	module.AddProperties(&module.properties)
-	module.AddProperties(&module.targetProperties)
-	module.AddProperties(&module.overridableProperties)
-	android.InitAndroidMultiTargetsArchModule(module, android.HostAndDeviceSupported, android.MultilibCommon)
-	android.InitDefaultableModule(module)
-	android.InitSdkAwareModule(module)
-	android.InitOverridableModule(module, &module.overridableProperties.Overrides)
-	return module
-}
-
-func ApexBundleFactory(testApex bool, artApex bool) android.Module {
-	bundle := newApexBundle()
-	bundle.testApex = testApex
-	bundle.artApex = artApex
-	return bundle
-}
-
-// apex_test is an APEX for testing. The difference from the ordinary apex module type is that
-// certain compatibility checks such as apex_available are not done for apex_test.
-func testApexBundleFactory() android.Module {
-	bundle := newApexBundle()
-	bundle.testApex = true
-	return bundle
-}
-
-// apex packages other modules into an APEX file which is a packaging format for system-level
-// components like binaries, shared libraries, etc.
-func BundleFactory() android.Module {
-	return newApexBundle()
-}
-
-//
-// Defaults
-//
-type Defaults struct {
-	android.ModuleBase
-	android.DefaultsModuleBase
-}
-
-func defaultsFactory() android.Module {
-	return DefaultsFactory()
-}
-
-func DefaultsFactory(props ...interface{}) android.Module {
-	module := &Defaults{}
-
-	module.AddProperties(props...)
-	module.AddProperties(
-		&apexBundleProperties{},
-		&apexTargetBundleProperties{},
-		&overridableProperties{},
-	)
-
-	android.InitDefaultsModule(module)
-	return module
-}
-
-//
-// OverrideApex
-//
-type OverrideApex struct {
-	android.ModuleBase
-	android.OverrideModuleBase
-}
-
-func (o *OverrideApex) GenerateAndroidBuildActions(ctx android.ModuleContext) {
-	// All the overrides happen in the base module.
-}
-
-// override_apex is used to create an apex module based on another apex module
-// by overriding some of its properties.
-func overrideApexFactory() android.Module {
-	m := &OverrideApex{}
-	m.AddProperties(&overridableProperties{})
-
-	android.InitAndroidMultiTargetsArchModule(m, android.DeviceSupported, android.MultilibCommon)
-	android.InitOverrideModule(m)
-	return m
-}
diff --git a/apex/builder.go b/apex/builder.go
index acfb8c5..6f27dd1 100644
--- a/apex/builder.go
+++ b/apex/builder.go
@@ -195,8 +195,8 @@
 	// collect jniLibs. Notice that a.filesInfo is already sorted
 	var jniLibs []string
 	for _, fi := range a.filesInfo {
-		if fi.isJniLib && !android.InList(fi.Stem(), jniLibs) {
-			jniLibs = append(jniLibs, fi.Stem())
+		if fi.isJniLib && !android.InList(fi.stem(), jniLibs) {
+			jniLibs = append(jniLibs, fi.stem())
 		}
 	}
 	if len(jniLibs) > 0 {
@@ -363,7 +363,7 @@
 				config.Apex_config.Apex_embedded_apk_config,
 				ApkConfig{
 					Package_name: packageName,
-					Apk_path:     fi.Path(),
+					Apk_path:     fi.path(),
 				})
 		}
 	}
@@ -396,15 +396,15 @@
 	// TODO(jiyong): construct the copy rules using RuleBuilder
 	var copyCommands []string
 	for _, fi := range a.filesInfo {
-		destPath := android.PathForModuleOut(ctx, "image"+suffix, fi.Path()).String()
+		destPath := android.PathForModuleOut(ctx, "image"+suffix, fi.path()).String()
 		destPathDir := filepath.Dir(destPath)
 		if fi.class == appSet {
 			copyCommands = append(copyCommands, "rm -rf "+destPathDir)
 		}
 		copyCommands = append(copyCommands, "mkdir -p "+destPathDir)
-		if a.linkToSystemLib && fi.transitiveDep && fi.AvailableToPlatform() {
+		if a.linkToSystemLib && fi.transitiveDep && fi.availableToPlatform() {
 			// TODO(jiyong): pathOnDevice should come from fi.module, not being calculated here
-			pathOnDevice := filepath.Join("/system", fi.Path())
+			pathOnDevice := filepath.Join("/system", fi.path())
 			copyCommands = append(copyCommands, "ln -sfn "+pathOnDevice+" "+destPath)
 		} else {
 			if fi.class == appSet {
@@ -416,7 +416,7 @@
 			implicitInputs = append(implicitInputs, fi.builtFile)
 		}
 		// create additional symlinks pointing the file inside the APEX
-		for _, symlinkPath := range fi.SymlinkPaths() {
+		for _, symlinkPath := range fi.symlinkPaths() {
 			symlinkDest := android.PathForModuleOut(ctx, "image"+suffix, symlinkPath).String()
 			copyCommands = append(copyCommands, "ln -sfn "+filepath.Base(destPath)+" "+symlinkDest)
 		}
@@ -444,7 +444,7 @@
 		emitCommands = append(emitCommands, "echo ./apex_manifest.json >> "+imageContentFile.String())
 	}
 	for _, fi := range a.filesInfo {
-		emitCommands = append(emitCommands, "echo './"+fi.Path()+"' >> "+imageContentFile.String())
+		emitCommands = append(emitCommands, "echo './"+fi.path()+"' >> "+imageContentFile.String())
 	}
 	emitCommands = append(emitCommands, "sort -o "+imageContentFile.String()+" "+imageContentFile.String())
 	implicitInputs = append(implicitInputs, a.manifestPbOut)
@@ -489,7 +489,7 @@
 		var extractedAppSetPaths android.Paths
 		var extractedAppSetDirs []string
 		for _, f := range a.filesInfo {
-			pathInApex := f.Path()
+			pathInApex := f.path()
 			if f.installDir == "bin" || strings.HasPrefix(f.installDir, "bin/") {
 				executablePaths = append(executablePaths, pathInApex)
 				for _, d := range f.dataPaths {
@@ -697,6 +697,15 @@
 	a.installedFilesFile = a.buildInstalledFilesFile(ctx, a.outputFile, imageDir)
 }
 
+// Context "decorator", overriding the InstallBypassMake method to always reply `true`.
+type flattenedApexContext struct {
+	android.ModuleContext
+}
+
+func (c *flattenedApexContext) InstallBypassMake() bool {
+	return true
+}
+
 func (a *apexBundle) buildFlattenedApex(ctx android.ModuleContext) {
 	// Temporarily wrap the original `ctx` into a `flattenedApexContext` to have it
 	// reply true to `InstallBypassMake()` (thus making the call
@@ -742,7 +751,7 @@
 			apexBundleName := a.Name()
 			for _, fi := range a.filesInfo {
 				dir := filepath.Join("apex", apexBundleName, fi.installDir)
-				target := ctx.InstallFile(android.PathForModuleInstall(ctx, dir), fi.Stem(), fi.builtFile)
+				target := ctx.InstallFile(android.PathForModuleInstall(ctx, dir), fi.stem(), fi.builtFile)
 				for _, sym := range fi.symlinks {
 					ctx.InstallSymlink(android.PathForModuleInstall(ctx, dir), sym, target)
 				}
diff --git a/bazel/Android.bp b/bazel/Android.bp
new file mode 100644
index 0000000..0113726
--- /dev/null
+++ b/bazel/Android.bp
@@ -0,0 +1,10 @@
+bootstrap_go_package {
+    name: "soong-bazel",
+    pkgPath: "android/soong/bazel",
+    srcs: [
+        "properties.go",
+    ],
+    pluginFor: [
+        "soong_build",
+    ],
+}
diff --git a/bazel/properties.go b/bazel/properties.go
new file mode 100644
index 0000000..8bb1956
--- /dev/null
+++ b/bazel/properties.go
@@ -0,0 +1,27 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package bazel
+
+type bazelModuleProperties struct {
+	// The label of the Bazel target replacing this Soong module.
+	Label string
+}
+
+// Properties contains common module properties for migration purposes.
+type Properties struct {
+	// In USE_BAZEL_ANALYSIS=1 mode, this represents the Bazel target replacing
+	// this Soong module.
+	Bazel_module bazelModuleProperties
+}
diff --git a/cc/prebuilt_test.go b/cc/prebuilt_test.go
index 5bf334e..ee4de6e 100644
--- a/cc/prebuilt_test.go
+++ b/cc/prebuilt_test.go
@@ -32,7 +32,7 @@
 	// * Configure that we are inside make
 	// * Add CommonOS to ensure that androidmk processing works.
 	android.RegisterAndroidMkBuildComponents(ctx)
-	android.SetInMakeForTests(config)
+	android.SetKatiEnabledForTests(config)
 
 	for _, handler := range handlers {
 		handler(config)
diff --git a/cc/sanitize.go b/cc/sanitize.go
index eb61525..dbc52a5 100644
--- a/cc/sanitize.go
+++ b/cc/sanitize.go
@@ -172,6 +172,12 @@
 		No_recover       []string
 	}
 
+	// Sanitizers to run with flag configuration specified
+	Config struct {
+		// Enables CFI support flags for assembly-heavy libraries
+		Cfi_assembly_support *bool `android:"arch_variant"`
+	}
+
 	// value to pass to -fsanitize-recover=
 	Recover []string
 
@@ -543,6 +549,9 @@
 
 		flags.Local.CFlags = append(flags.Local.CFlags, cfiCflags...)
 		flags.Local.AsFlags = append(flags.Local.AsFlags, cfiAsflags...)
+		if Bool(sanitize.Properties.Sanitize.Config.Cfi_assembly_support) {
+			flags.Local.CFlags = append(flags.Local.CFlags, "-fno-sanitize-cfi-canonical-jump-tables")
+		}
 		// Only append the default visibility flag if -fvisibility has not already been set
 		// to hidden.
 		if !inList("-fvisibility=hidden", flags.Local.CFlags) {
diff --git a/cc/strip.go b/cc/strip.go
index 18150dc..f8814ea 100644
--- a/cc/strip.go
+++ b/cc/strip.go
@@ -35,8 +35,8 @@
 }
 
 func (stripper *Stripper) NeedsStrip(actx android.ModuleContext) bool {
-	// TODO(ccross): enable host stripping when embedded in make?  Make never had support for stripping host binaries.
-	return (!actx.Config().EmbeddedInMake() || actx.Device()) && !Bool(stripper.StripProperties.Strip.None)
+	// TODO(ccross): enable host stripping when Kati is enabled? Make never had support for stripping host binaries.
+	return (!actx.Config().KatiEnabled() || actx.Device()) && !Bool(stripper.StripProperties.Strip.None)
 }
 
 func (stripper *Stripper) strip(actx android.ModuleContext, in android.Path, out android.ModuleOutPath,
diff --git a/etc/prebuilt_etc.go b/etc/prebuilt_etc.go
index a6d1fcf..850c8f9 100644
--- a/etc/prebuilt_etc.go
+++ b/etc/prebuilt_etc.go
@@ -56,16 +56,19 @@
 	// Source file of this prebuilt. Can reference a genrule type module with the ":module" syntax.
 	Src *string `android:"path,arch_variant"`
 
-	// optional subdirectory under which this file is installed into, cannot be specified with relative_install_path, prefer relative_install_path
+	// Optional subdirectory under which this file is installed into, cannot be specified with
+	// relative_install_path, prefer relative_install_path.
 	Sub_dir *string `android:"arch_variant"`
 
-	// optional subdirectory under which this file is installed into, cannot be specified with sub_dir
+	// Optional subdirectory under which this file is installed into, cannot be specified with
+	// sub_dir.
 	Relative_install_path *string `android:"arch_variant"`
 
-	// optional name for the installed file. If unspecified, name of the module is used as the file name
+	// Optional name for the installed file. If unspecified, name of the module is used as the file
+	// name.
 	Filename *string `android:"arch_variant"`
 
-	// when set to true, and filename property is not set, the name for the installed file
+	// When set to true, and filename property is not set, the name for the installed file
 	// is the same as the file name of the source file.
 	Filename_from_src *bool `android:"arch_variant"`
 
@@ -95,8 +98,15 @@
 
 type PrebuiltEtcModule interface {
 	android.Module
+
+	// Returns the base install directory, such as "etc", "usr/share".
 	BaseDir() string
+
+	// Returns the sub install directory relative to BaseDir().
 	SubDir() string
+
+	// Returns an android.OutputPath to the intermeidate file, which is the renamed prebuilt source
+	// file.
 	OutputFile() android.OutputPath
 }
 
@@ -109,7 +119,8 @@
 	outputFilePath android.OutputPath
 	// The base install location, e.g. "etc" for prebuilt_etc, "usr/share" for prebuilt_usr_share.
 	installDirBase string
-	// The base install location when soc_specific property is set to true, e.g. "firmware" for prebuilt_firmware.
+	// The base install location when soc_specific property is set to true, e.g. "firmware" for
+	// prebuilt_firmware.
 	socInstallDirBase      string
 	installDirPath         android.InstallPath
 	additionalDependencies *android.Paths
@@ -179,14 +190,8 @@
 func (p *PrebuiltEtc) SetImageVariation(ctx android.BaseModuleContext, variation string, module android.Module) {
 }
 
-func (p *PrebuiltEtc) DepsMutator(ctx android.BottomUpMutatorContext) {
-	if p.properties.Src == nil {
-		ctx.PropertyErrorf("src", "missing prebuilt source file")
-	}
-}
-
 func (p *PrebuiltEtc) SourceFilePath(ctx android.ModuleContext) android.Path {
-	return android.PathForModuleSrc(ctx, android.String(p.properties.Src))
+	return android.PathForModuleSrc(ctx, proptools.String(p.properties.Src))
 }
 
 func (p *PrebuiltEtc) InstallDirPath() android.InstallPath {
@@ -215,36 +220,41 @@
 }
 
 func (p *PrebuiltEtc) Installable() bool {
-	return p.properties.Installable == nil || android.Bool(p.properties.Installable)
+	return p.properties.Installable == nil || proptools.Bool(p.properties.Installable)
 }
 
 func (p *PrebuiltEtc) GenerateAndroidBuildActions(ctx android.ModuleContext) {
-	p.sourceFilePath = android.PathForModuleSrc(ctx, android.String(p.properties.Src))
+	if p.properties.Src == nil {
+		ctx.PropertyErrorf("src", "missing prebuilt source file")
+		return
+	}
+	p.sourceFilePath = android.PathForModuleSrc(ctx, proptools.String(p.properties.Src))
 
 	// Determine the output file basename.
 	// If Filename is set, use the name specified by the property.
 	// If Filename_from_src is set, use the source file name.
 	// Otherwise use the module name.
-	filename := android.String(p.properties.Filename)
-	filename_from_src := android.Bool(p.properties.Filename_from_src)
-	if filename == "" {
-		if filename_from_src {
-			filename = p.sourceFilePath.Base()
-		} else {
-			filename = ctx.ModuleName()
+	filename := proptools.String(p.properties.Filename)
+	filenameFromSrc := proptools.Bool(p.properties.Filename_from_src)
+	if filename != "" {
+		if filenameFromSrc {
+			ctx.PropertyErrorf("filename_from_src", "filename is set. filename_from_src can't be true")
+			return
 		}
-	} else if filename_from_src {
-		ctx.PropertyErrorf("filename_from_src", "filename is set. filename_from_src can't be true")
-		return
+	} else if filenameFromSrc {
+		filename = p.sourceFilePath.Base()
+	} else {
+		filename = ctx.ModuleName()
 	}
 	p.outputFilePath = android.PathForModuleOut(ctx, filename).OutputPath
 
+	// Check that `sub_dir` and `relative_install_path` are not set at the same time.
 	if p.properties.Sub_dir != nil && p.properties.Relative_install_path != nil {
 		ctx.PropertyErrorf("sub_dir", "relative_install_path is set. Cannot set sub_dir")
 	}
 
-	// If soc install dir was specified and SOC specific is set, set the installDirPath to the specified
-	// socInstallDirBase.
+	// If soc install dir was specified and SOC specific is set, set the installDirPath to the
+	// specified socInstallDirBase.
 	installBaseDir := p.installDirBase
 	if p.SocSpecific() && p.socInstallDirBase != "" {
 		installBaseDir = p.socInstallDirBase
@@ -353,9 +363,10 @@
 	return module
 }
 
-// prebuilt_firmware installs a firmware file to <partition>/etc/firmware directory for system image.
-// If soc_specific property is set to true, the firmware file is installed to the vendor <partition>/firmware
-// directory for vendor image.
+// prebuilt_firmware installs a firmware file to <partition>/etc/firmware directory for system
+// image.
+// If soc_specific property is set to true, the firmware file is installed to the
+// vendor <partition>/firmware directory for vendor image.
 func PrebuiltFirmwareFactory() android.Module {
 	module := &PrebuiltEtc{}
 	module.socInstallDirBase = "firmware"
@@ -366,8 +377,8 @@
 }
 
 // prebuilt_dsp installs a DSP related file to <partition>/etc/dsp directory for system image.
-// If soc_specific property is set to true, the DSP related file is installed to the vendor <partition>/dsp
-// directory for vendor image.
+// If soc_specific property is set to true, the DSP related file is installed to the
+// vendor <partition>/dsp directory for vendor image.
 func PrebuiltDSPFactory() android.Module {
 	module := &PrebuiltEtc{}
 	module.socInstallDirBase = "dsp"
diff --git a/genrule/Android.bp b/genrule/Android.bp
index ff543a6..9690007 100644
--- a/genrule/Android.bp
+++ b/genrule/Android.bp
@@ -6,6 +6,7 @@
         "blueprint-pathtools",
         "soong",
         "soong-android",
+        "soong-bazel",
         "soong-shared",
     ],
     srcs: [
diff --git a/genrule/genrule.go b/genrule/genrule.go
index f85146c..0743e67 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -26,6 +26,7 @@
 	"github.com/google/blueprint/proptools"
 
 	"android/soong/android"
+	"android/soong/bazel"
 )
 
 func init() {
@@ -78,13 +79,6 @@
 	blueprint.BaseDependencyTag
 	label string
 }
-
-// TODO(cparsons): Move to a common location when there is more than just
-// genrule with a bazel_module property.
-type bazelModuleProperties struct {
-	Label string
-}
-
 type generatorProperties struct {
 	// The command to run on one or more input files. Cmd supports substitution of a few variables
 	//
@@ -118,8 +112,8 @@
 	// input files to exclude
 	Exclude_srcs []string `android:"path,arch_variant"`
 
-	// in bazel-enabled mode, the bazel label to evaluate instead of this module
-	Bazel_module bazelModuleProperties
+	// Properties for Bazel migration purposes.
+	bazel.Properties
 }
 type Module struct {
 	android.ModuleBase
diff --git a/java/hiddenapi_singleton.go b/java/hiddenapi_singleton.go
index 1f80e77..e57f323 100644
--- a/java/hiddenapi_singleton.go
+++ b/java/hiddenapi_singleton.go
@@ -255,7 +255,7 @@
 		FlagWithInput("--max-target-p ",
 			android.PathForSource(ctx, "frameworks/base/config/hiddenapi-max-target-p.txt")).
 		FlagWithInput("--max-target-o ", android.PathForSource(
-			ctx, "frameworks/base/config/hiddenapi-max-target-o.txt")).Flag("--ignore-conflicts ").
+			ctx, "frameworks/base/config/hiddenapi-max-target-o.txt")).Flag("--ignore-conflicts ").FlagWithArg("--tag ", "lo-prio").
 		FlagWithInput("--blocked ",
 			android.PathForSource(ctx, "frameworks/base/config/hiddenapi-force-blocked.txt")).
 		FlagWithInput("--blocked ",
diff --git a/java/java.go b/java/java.go
index c9a3819..3c9c92d 100644
--- a/java/java.go
+++ b/java/java.go
@@ -2358,7 +2358,7 @@
 
 func (j *Test) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	j.testConfig = tradefed.AutoGenJavaTestConfig(ctx, j.testProperties.Test_config, j.testProperties.Test_config_template,
-		j.testProperties.Test_suites, j.testProperties.Auto_gen_config)
+		j.testProperties.Test_suites, j.testProperties.Auto_gen_config, j.testProperties.Test_options.Unit_test)
 
 	j.data = android.PathsForModuleSrc(ctx, j.testProperties.Data)
 
@@ -2377,7 +2377,7 @@
 
 func (j *JavaTestImport) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	j.testConfig = tradefed.AutoGenJavaTestConfig(ctx, j.prebuiltTestProperties.Test_config, nil,
-		j.prebuiltTestProperties.Test_suites, nil)
+		j.prebuiltTestProperties.Test_suites, nil, nil)
 
 	j.Import.GenerateAndroidBuildActions(ctx)
 }
diff --git a/java/lint.go b/java/lint.go
index 3df582f..11f92e5 100644
--- a/java/lint.go
+++ b/java/lint.go
@@ -447,7 +447,7 @@
 	var outputs []*lintOutputs
 	var dirs []string
 	ctx.VisitAllModules(func(m android.Module) {
-		if ctx.Config().EmbeddedInMake() && !m.ExportedToMake() {
+		if ctx.Config().KatiEnabled() && !m.ExportedToMake() {
 			return
 		}
 
diff --git a/java/sdk_library.go b/java/sdk_library.go
index 4369ffc..603c808 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -435,8 +435,23 @@
 	// If set to true, the path of dist files is apistubs/core. Defaults to false.
 	Core_lib *bool
 
-	// don't create dist rules.
-	No_dist *bool `blueprint:"mutated"`
+	// If set to true then don't create dist rules.
+	No_dist *bool
+
+	// The stem for the artifacts that are copied to the dist, if not specified
+	// then defaults to the base module name.
+	//
+	// For each scope the following artifacts are copied to the apistubs/<scope>
+	// directory in the dist.
+	// * stubs impl jar -> <dist-stem>.jar
+	// * API specification file -> api/<dist-stem>.txt
+	// * Removed API specification file -> api/<dist-stem>-removed.txt
+	//
+	// Also used to construct the name of the filegroup (created by prebuilt_apis)
+	// that references the latest released API and remove API specification files.
+	// * API specification filegroup -> <dist-stem>.api.<scope>.latest
+	// * Removed API specification filegroup -> <dist-stem>-removed.api.<scope>.latest
+	Dist_stem *string
 
 	// indicates whether system and test apis should be generated.
 	Generate_system_and_test_apis bool `blueprint:"mutated"`
@@ -1117,12 +1132,16 @@
 	}
 }
 
+func (module *SdkLibrary) distStem() string {
+	return proptools.StringDefault(module.sdkLibraryProperties.Dist_stem, module.BaseModuleName())
+}
+
 func (module *SdkLibrary) latestApiFilegroupName(apiScope *apiScope) string {
-	return ":" + module.BaseModuleName() + ".api." + apiScope.name + ".latest"
+	return ":" + module.distStem() + ".api." + apiScope.name + ".latest"
 }
 
 func (module *SdkLibrary) latestRemovedApiFilegroupName(apiScope *apiScope) string {
-	return ":" + module.BaseModuleName() + "-removed.api." + apiScope.name + ".latest"
+	return ":" + module.distStem() + "-removed.api." + apiScope.name + ".latest"
 }
 
 func childModuleVisibility(childVisibility []string) []string {
@@ -1228,7 +1247,7 @@
 	// Dist the class jar artifact for sdk builds.
 	if !Bool(module.sdkLibraryProperties.No_dist) {
 		props.Dist.Targets = []string{"sdk", "win_sdk"}
-		props.Dist.Dest = proptools.StringPtr(fmt.Sprintf("%v.jar", module.BaseModuleName()))
+		props.Dist.Dest = proptools.StringPtr(fmt.Sprintf("%v.jar", module.distStem()))
 		props.Dist.Dir = proptools.StringPtr(module.apiDistPath(apiScope))
 		props.Dist.Tag = proptools.StringPtr(".jar")
 	}
@@ -1377,7 +1396,7 @@
 	// Dist the api txt artifact for sdk builds.
 	if !Bool(module.sdkLibraryProperties.No_dist) {
 		props.Dist.Targets = []string{"sdk", "win_sdk"}
-		props.Dist.Dest = proptools.StringPtr(fmt.Sprintf("%v.txt", module.BaseModuleName()))
+		props.Dist.Dest = proptools.StringPtr(fmt.Sprintf("%v.txt", module.distStem()))
 		props.Dist.Dir = proptools.StringPtr(path.Join(module.apiDistPath(apiScope), "api"))
 	}
 
@@ -1482,10 +1501,6 @@
 	return module.sdkJars(ctx, sdkVersion, false /*headerJars*/)
 }
 
-func (module *SdkLibrary) SetNoDist() {
-	module.sdkLibraryProperties.No_dist = proptools.BoolPtr(true)
-}
-
 var javaSdkLibrariesKey = android.NewOnceKey("javaSdkLibraries")
 
 func javaSdkLibraries(config android.Config) *[]string {
@@ -1513,12 +1528,10 @@
 	}
 
 	// If this builds against standard libraries (i.e. is not part of the core libraries)
-	// then assume it provides both system and test apis. Otherwise, assume it does not and
-	// also assume it does not contribute to the dist build.
+	// then assume it provides both system and test apis.
 	sdkDep := decodeSdkDep(mctx, sdkContext(&module.Library))
 	hasSystemAndTestApis := sdkDep.hasStandardLibs()
 	module.sdkLibraryProperties.Generate_system_and_test_apis = hasSystemAndTestApis
-	module.sdkLibraryProperties.No_dist = proptools.BoolPtr(!hasSystemAndTestApis)
 
 	missing_current_api := false
 
diff --git a/python/python.go b/python/python.go
index e4c8e94..d7b1bba 100644
--- a/python/python.go
+++ b/python/python.go
@@ -34,7 +34,7 @@
 }
 
 func RegisterPythonPreDepsMutators(ctx android.RegisterMutatorsContext) {
-	ctx.BottomUp("version_split", versionSplitMutator()).Parallel()
+	ctx.BottomUp("python_version", versionSplitMutator()).Parallel()
 }
 
 // the version properties that apply to python libraries and binaries.
@@ -86,6 +86,9 @@
 	// the test. the file extension can be arbitrary except for (.py).
 	Data []string `android:"path,arch_variant"`
 
+	// list of java modules that provide data that should be installed alongside the test.
+	Java_data []string
+
 	// list of the Python libraries compatible both with Python2 and Python3.
 	Libs []string `android:"arch_variant"`
 
@@ -216,6 +219,7 @@
 
 var (
 	pythonLibTag         = dependencyTag{name: "pythonLib"}
+	javaDataTag          = dependencyTag{name: "javaData"}
 	launcherTag          = dependencyTag{name: "launcher"}
 	launcherSharedLibTag = dependencyTag{name: "launcherSharedLib"}
 	pyIdentifierRegexp   = regexp.MustCompile(`^[a-zA-Z_][a-zA-Z0-9_-]*$`)
@@ -248,7 +252,7 @@
 				versionNames = append(versionNames, pyVersion2)
 				versionProps = append(versionProps, base.properties.Version.Py2)
 			}
-			modules := mctx.CreateVariations(versionNames...)
+			modules := mctx.CreateLocalVariations(versionNames...)
 			if len(versionNames) > 0 {
 				mctx.AliasVariation(versionNames[0])
 			}
@@ -306,16 +310,20 @@
 func (p *Module) DepsMutator(ctx android.BottomUpMutatorContext) {
 	android.ProtoDeps(ctx, &p.protoProperties)
 
-	if p.hasSrcExt(ctx, protoExt) && p.Name() != "libprotobuf-python" {
-		ctx.AddVariationDependencies(nil, pythonLibTag, "libprotobuf-python")
+	versionVariation := []blueprint.Variation{
+		{"python_version", p.properties.Actual_version},
 	}
-	ctx.AddVariationDependencies(nil, pythonLibTag, android.LastUniqueStrings(p.properties.Libs)...)
+
+	if p.hasSrcExt(ctx, protoExt) && p.Name() != "libprotobuf-python" {
+		ctx.AddVariationDependencies(versionVariation, pythonLibTag, "libprotobuf-python")
+	}
+	ctx.AddVariationDependencies(versionVariation, pythonLibTag, android.LastUniqueStrings(p.properties.Libs)...)
 
 	switch p.properties.Actual_version {
 	case pyVersion2:
 
 		if p.bootstrapper != nil && p.isEmbeddedLauncherEnabled() {
-			ctx.AddVariationDependencies(nil, pythonLibTag, "py2-stdlib")
+			ctx.AddVariationDependencies(versionVariation, pythonLibTag, "py2-stdlib")
 
 			launcherModule := "py2-launcher"
 			if p.bootstrapper.autorun() {
@@ -338,7 +346,7 @@
 	case pyVersion3:
 
 		if p.bootstrapper != nil && p.isEmbeddedLauncherEnabled() {
-			ctx.AddVariationDependencies(nil, pythonLibTag, "py3-stdlib")
+			ctx.AddVariationDependencies(versionVariation, pythonLibTag, "py3-stdlib")
 
 			launcherModule := "py3-launcher"
 			if p.bootstrapper.autorun() {
@@ -366,6 +374,11 @@
 		panic(fmt.Errorf("unknown Python Actual_version: %q for module: %q.",
 			p.properties.Actual_version, ctx.ModuleName()))
 	}
+
+	// Emulate the data property for java_data but with the arch variation overridden to "common"
+	// so that it can point to java modules.
+	javaDataVariation := []blueprint.Variation{{"arch", android.Common.String()}}
+	ctx.AddVariationDependencies(javaDataVariation, javaDataTag, p.properties.Java_data...)
 }
 
 func (p *Module) GenerateAndroidBuildActions(ctx android.ModuleContext) {
@@ -412,6 +425,11 @@
 	// expand data files from "data" property.
 	expandedData := android.PathsForModuleSrc(ctx, p.properties.Data)
 
+	// Emulate the data property for java_data dependencies.
+	for _, javaData := range ctx.GetDirectDepsWithTag(javaDataTag) {
+		expandedData = append(expandedData, android.OutputFilesForModule(ctx, javaData, "")...)
+	}
+
 	// sanitize pkg_path.
 	pkgPath := String(p.properties.Pkg_path)
 	if pkgPath != "" {
diff --git a/python/test.go b/python/test.go
index f9baa46..4df71c1 100644
--- a/python/test.go
+++ b/python/test.go
@@ -45,6 +45,9 @@
 	// the test
 	Data []string `android:"path,arch_variant"`
 
+	// list of java modules that provide data that should be installed alongside the test.
+	Java_data []string
+
 	// Test options.
 	Test_options TestOptions
 }
@@ -80,6 +83,13 @@
 	for _, dataSrcPath := range dataSrcPaths {
 		test.data = append(test.data, android.DataPath{SrcPath: dataSrcPath})
 	}
+
+	// Emulate the data property for java_data dependencies.
+	for _, javaData := range ctx.GetDirectDepsWithTag(javaDataTag) {
+		for _, javaDataSrcPath := range android.OutputFilesForModule(ctx, javaData, "") {
+			test.data = append(test.data, android.DataPath{SrcPath: javaDataSrcPath})
+		}
+	}
 }
 
 func NewTest(hod android.HostOrDeviceSupported) *Module {
diff --git a/scripts/build-aml-prebuilts.sh b/scripts/build-aml-prebuilts.sh
index 89fb1a5..0c868ea 100755
--- a/scripts/build-aml-prebuilts.sh
+++ b/scripts/build-aml-prebuilts.sh
@@ -12,7 +12,7 @@
 
 export OUT_DIR=${OUT_DIR:-out}
 
-if [ -e ${OUT_DIR}/soong/.soong.in_make ]; then
+if [ -e ${OUT_DIR}/soong/.soong.kati_enabled ]; then
   # If ${OUT_DIR} has been created without --skip-make, Soong will create an
   # ${OUT_DIR}/soong/build.ninja that leaves out many targets which are
   # expected to be supplied by the .mk files, and that might cause errors in
@@ -32,8 +32,8 @@
 
 my_get_build_var() {
   # get_build_var will run Soong in normal in-make mode where it creates
-  # .soong.in_make. That would clobber our real out directory, so we need to
-  # run it in a different one.
+  # .soong.kati_enabled. That would clobber our real out directory, so we need
+  # to run it in a different one.
   OUT_DIR=${OUT_DIR}/get_build_var get_build_var "$@"
 }
 
diff --git a/sdk/testing.go b/sdk/testing.go
index 5f520e5..91aa879 100644
--- a/sdk/testing.go
+++ b/sdk/testing.go
@@ -87,7 +87,7 @@
 	// * Configure that we are inside make
 	// * Add CommonOS to ensure that androidmk processing works.
 	android.RegisterAndroidMkBuildComponents(ctx)
-	android.SetInMakeForTests(config)
+	android.SetKatiEnabledForTests(config)
 	config.Targets[android.CommonOS] = []android.Target{
 		{android.CommonOS, android.Arch{ArchType: android.Common}, android.NativeBridgeDisabled, "", "", true},
 	}
diff --git a/tradefed/autogen.go b/tradefed/autogen.go
index b35f831..27d71e8 100644
--- a/tradefed/autogen.go
+++ b/tradefed/autogen.go
@@ -188,7 +188,7 @@
 }
 
 func AutoGenJavaTestConfig(ctx android.ModuleContext, testConfigProp *string, testConfigTemplateProp *string,
-	testSuites []string, autoGenConfig *bool) android.Path {
+	testSuites []string, autoGenConfig *bool, unitTest *bool) android.Path {
 	path, autogenPath := testConfigPath(ctx, testConfigProp, testSuites, autoGenConfig, testConfigTemplateProp)
 	if autogenPath != nil {
 		templatePath := getTestConfigTemplate(ctx, testConfigTemplateProp)
@@ -198,7 +198,11 @@
 			if ctx.Device() {
 				autogenTemplate(ctx, autogenPath, "${JavaTestConfigTemplate}", nil, "")
 			} else {
-				autogenTemplate(ctx, autogenPath, "${JavaHostTestConfigTemplate}", nil, "")
+				if Bool(unitTest) {
+					autogenTemplate(ctx, autogenPath, "${JavaHostUnitTestConfigTemplate}", nil, "")
+				} else {
+					autogenTemplate(ctx, autogenPath, "${JavaHostTestConfigTemplate}", nil, "")
+				}
 			}
 		}
 		return autogenPath
diff --git a/tradefed/config.go b/tradefed/config.go
index f7e8349..f3566a8 100644
--- a/tradefed/config.go
+++ b/tradefed/config.go
@@ -27,6 +27,7 @@
 	pctx.SourcePathVariable("InstrumentationTestConfigTemplate", "build/make/core/instrumentation_test_config_template.xml")
 	pctx.SourcePathVariable("JavaTestConfigTemplate", "build/make/core/java_test_config_template.xml")
 	pctx.SourcePathVariable("JavaHostTestConfigTemplate", "build/make/core/java_host_test_config_template.xml")
+	pctx.SourcePathVariable("JavaHostUnitTestConfigTemplate", "build/make/core/java_host_unit_test_config_template.xml")
 	pctx.SourcePathVariable("NativeBenchmarkTestConfigTemplate", "build/make/core/native_benchmark_test_config_template.xml")
 	pctx.SourcePathVariable("NativeHostTestConfigTemplate", "build/make/core/native_host_test_config_template.xml")
 	pctx.SourcePathVariable("NativeTestConfigTemplate", "build/make/core/native_test_config_template.xml")
diff --git a/ui/build/build.go b/ui/build/build.go
index 1cf2023..e9196a9 100644
--- a/ui/build/build.go
+++ b/ui/build/build.go
@@ -23,13 +23,20 @@
 	"android/soong/ui/metrics"
 )
 
-// Ensures the out directory exists, and has the proper files to prevent kati
-// from recursing into it.
+// SetupOutDir ensures the out directory exists, and has the proper files to
+// prevent kati from recursing into it.
 func SetupOutDir(ctx Context, config Config) {
 	ensureEmptyFileExists(ctx, filepath.Join(config.OutDir(), "Android.mk"))
 	ensureEmptyFileExists(ctx, filepath.Join(config.OutDir(), "CleanSpec.mk"))
 	if !config.SkipMake() {
-		ensureEmptyFileExists(ctx, filepath.Join(config.SoongOutDir(), ".soong.in_make"))
+		// Run soong_build with Kati for a hybrid build, e.g. running the
+		// AndroidMk singleton and postinstall commands. Communicate this to
+		// soong_build by writing an empty .soong.kati_enabled marker file in the
+		// soong_build output directory for the soong_build primary builder to
+		// know if the user wants to run Kati after.
+		//
+		// This does not preclude running Kati for *product configuration purposes*.
+		ensureEmptyFileExists(ctx, filepath.Join(config.SoongOutDir(), ".soong.kati_enabled"))
 	}
 	// The ninja_build file is used by our buildbots to understand that the output
 	// can be parsed as ninja output.
diff --git a/ui/build/kati.go b/ui/build/kati.go
index f6c0f52..06ec646 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -33,12 +33,18 @@
 const katiCleanspecSuffix = "-cleanspec"
 const katiPackageSuffix = "-package"
 
-// genKatiSuffix creates a suffix for kati-generated files so that we can cache
-// them based on their inputs. So this should encode all common changes to Kati
-// inputs. Currently that includes the TARGET_PRODUCT, kati-processed command
-// line arguments, and the directories specified by mm/mmm.
+// genKatiSuffix creates a filename suffix for kati-generated files so that we
+// can cache them based on their inputs. Such files include the generated Ninja
+// files and env.sh environment variable setup files.
+//
+// The filename suffix should encode all common changes to Kati inputs.
+// Currently that includes the TARGET_PRODUCT and kati-processed command line
+// arguments.
 func genKatiSuffix(ctx Context, config Config) {
+	// Construct the base suffix.
 	katiSuffix := "-" + config.TargetProduct()
+
+	// Append kati arguments to the suffix.
 	if args := config.KatiArgs(); len(args) > 0 {
 		katiSuffix += "-" + spaceSlashReplacer.Replace(strings.Join(args, "_"))
 	}
@@ -60,51 +66,101 @@
 	}
 }
 
+// Base function to construct and run the Kati command line with additional
+// arguments, and a custom function closure to mutate the environment Kati runs
+// in.
 func runKati(ctx Context, config Config, extraSuffix string, args []string, envFunc func(*Environment)) {
 	executable := config.PrebuiltBuildTool("ckati")
+	// cKati arguments.
 	args = append([]string{
+		// Instead of executing commands directly, generate a Ninja file.
 		"--ninja",
+		// Generate Ninja files in the output directory.
 		"--ninja_dir=" + config.OutDir(),
+		// Filename suffix of the generated Ninja file.
 		"--ninja_suffix=" + config.KatiSuffix() + extraSuffix,
+		// Remove common parts at the beginning of a Ninja file, like build_dir,
+		// local_pool and _kati_always_build_. Allows Kati to be run multiple
+		// times, with generated Ninja files combined in a single invocation
+		// using 'include'.
 		"--no_ninja_prelude",
+		// Support declaring phony outputs in AOSP Ninja.
 		"--use_ninja_phony_output",
+		// Support declaring symlink outputs in AOSP Ninja.
 		"--use_ninja_symlink_outputs",
+		// Regenerate the Ninja file if environment inputs have changed. e.g.
+		// CLI flags, .mk file timestamps, env vars, $(wildcard ..) and some
+		// $(shell ..) results.
 		"--regen",
+		// Skip '-include' directives starting with the specified path. Used to
+		// ignore generated .mk files.
 		"--ignore_optional_include=" + filepath.Join(config.OutDir(), "%.P"),
+		// Detect the use of $(shell echo ...).
 		"--detect_android_echo",
+		// Colorful ANSI-based warning and error messages.
 		"--color_warnings",
+		// Generate all targets, not just the top level requested ones.
 		"--gen_all_targets",
+		// Use the built-in emulator of GNU find for better file finding
+		// performance. Used with $(shell find ...).
 		"--use_find_emulator",
+		// Fail when the find emulator encounters problems.
 		"--werror_find_emulator",
+		// Do not provide any built-in rules.
 		"--no_builtin_rules",
+		// Fail when suffix rules are used.
 		"--werror_suffix_rules",
-		"--warn_real_to_phony",
-		"--warn_phony_looks_real",
+		// Fail when a real target depends on a phony target.
 		"--werror_real_to_phony",
-		"--werror_phony_looks_real",
-		"--werror_writable",
+		// Makes real_to_phony checks assume that any top-level or leaf
+		// dependencies that does *not* have a '/' in it is a phony target.
 		"--top_level_phony",
+		// Fail when a phony target contains slashes.
+		"--werror_phony_looks_real",
+		// Fail when writing to a read-only directory.
+		"--werror_writable",
+		// Print Kati's internal statistics, such as the number of variables,
+		// implicit/explicit/suffix rules, and so on.
 		"--kati_stats",
 	}, args...)
 
+	// Generate a minimal Ninja file.
+	//
+	// Used for build_test and multiproduct_kati, which runs Kati several
+	// hundred times for different configurations to test file generation logic.
+	// These can result in generating Ninja files reaching ~1GB or more,
+	// resulting in ~hundreds of GBs of writes.
+	//
+	// Since we don't care about executing the Ninja files in these test cases,
+	// generating the Ninja file content wastes time, so skip writing any
+	// information out with --empty_ninja_file.
+	//
+	// From https://github.com/google/kati/commit/87b8da7af2c8bea28b1d8ab17679453d859f96e5
 	if config.Environment().IsEnvTrue("EMPTY_NINJA_FILE") {
 		args = append(args, "--empty_ninja_file")
 	}
 
+	// Apply 'local_pool' to to all rules that don't specify a pool.
 	if config.UseRemoteBuild() {
 		args = append(args, "--default_pool=local_pool")
 	}
 
 	cmd := Command(ctx, config, "ckati", executable, args...)
+
+	// Set up the nsjail sandbox.
 	cmd.Sandbox = katiSandbox
+
+	// Set up stdout and stderr.
 	pipe, err := cmd.StdoutPipe()
 	if err != nil {
 		ctx.Fatalln("Error getting output pipe for ckati:", err)
 	}
 	cmd.Stderr = cmd.Stdout
 
+	// Apply the caller's function closure to mutate the environment variables.
 	envFunc(cmd.Environment)
 
+	// Pass on various build environment metadata to Kati.
 	if _, ok := cmd.Environment.Get("BUILD_USERNAME"); !ok {
 		username := "unknown"
 		if u, err := user.Current(); err == nil {
@@ -125,6 +181,8 @@
 	}
 
 	cmd.StartOrFatal()
+	// Set up the ToolStatus command line reader for Kati for a consistent UI
+	// for the user.
 	status.KatiReader(ctx.Status.StartTool(), pipe)
 	cmd.WaitOrFatal()
 }
@@ -134,35 +192,57 @@
 	defer ctx.EndTrace()
 
 	args := []string{
+		// Mark the output directory as writable.
 		"--writable", config.OutDir() + "/",
+		// Fail when encountering implicit rules. e.g.
+		// %.foo: %.bar
+		//   cp $< $@
 		"--werror_implicit_rules",
+		// Entry point for the Kati Ninja file generation.
 		"-f", "build/make/core/main.mk",
 	}
 
 	if !config.BuildBrokenDupRules() {
+		// Fail when redefining / duplicating a target.
 		args = append(args, "--werror_overriding_commands")
 	}
 
 	args = append(args, config.KatiArgs()...)
 
 	args = append(args,
+		// Location of the Make vars .mk file generated by Soong.
 		"SOONG_MAKEVARS_MK="+config.SoongMakeVarsMk(),
+		// Location of the Android.mk file generated by Soong. This
+		// file contains Soong modules represented as Kati modules,
+		// allowing Kati modules to depend on Soong modules.
 		"SOONG_ANDROID_MK="+config.SoongAndroidMk(),
+		// Directory containing outputs for the target device.
 		"TARGET_DEVICE_DIR="+config.TargetDeviceDir(),
+		// Directory containing .mk files for packaging purposes, such as
+		// the dist.mk file, containing dist-for-goals data.
 		"KATI_PACKAGE_MK_DIR="+config.KatiPackageMkDir())
 
 	runKati(ctx, config, katiBuildSuffix, args, func(env *Environment) {})
 
+	// compress and dist the main build ninja file.
 	distGzipFile(ctx, config, config.KatiBuildNinjaFile())
 
+	// Cleanup steps.
 	cleanCopyHeaders(ctx, config)
 	cleanOldInstalledFiles(ctx, config)
 }
 
+// Clean out obsolete header files on the disk that were *not copied* during the
+// build with BUILD_COPY_HEADERS and LOCAL_COPY_HEADERS.
+//
+// These should be increasingly uncommon, as it's a deprecated feature and there
+// isn't an equivalent feature in Soong.
 func cleanCopyHeaders(ctx Context, config Config) {
 	ctx.BeginTrace("clean", "clean copy headers")
 	defer ctx.EndTrace()
 
+	// Read and parse the list of copied headers from a file in the product
+	// output directory.
 	data, err := ioutil.ReadFile(filepath.Join(config.ProductOut(), ".copied_headers_list"))
 	if err != nil {
 		if os.IsNotExist(err) {
@@ -178,6 +258,8 @@
 	headerDir := headers[0]
 	headers = headers[1:]
 
+	// Walk the tree and remove any headers that are not in the list of copied
+	// headers in the current build.
 	filepath.Walk(headerDir,
 		func(path string, info os.FileInfo, err error) error {
 			if err != nil {
@@ -196,6 +278,8 @@
 		})
 }
 
+// Clean out any previously installed files from the disk that are not installed
+// in the current build.
 func cleanOldInstalledFiles(ctx Context, config Config) {
 	ctx.BeginTrace("clean", "clean old installed files")
 	defer ctx.EndTrace()
@@ -213,18 +297,27 @@
 	cleanOldFiles(ctx, config.HostOut(), ".installable_test_files")
 }
 
+// Generate the Ninja file containing the packaging command lines for the dist
+// dir.
 func runKatiPackage(ctx Context, config Config) {
 	ctx.BeginTrace(metrics.RunKati, "kati package")
 	defer ctx.EndTrace()
 
 	args := []string{
+		// Mark the dist dir as writable.
 		"--writable", config.DistDir() + "/",
+		// Fail when encountering implicit rules. e.g.
 		"--werror_implicit_rules",
+		// Fail when redefining / duplicating a target.
 		"--werror_overriding_commands",
+		// Entry point.
 		"-f", "build/make/packaging/main.mk",
+		// Directory containing .mk files for packaging purposes, such as
+		// the dist.mk file, containing dist-for-goals data.
 		"KATI_PACKAGE_MK_DIR=" + config.KatiPackageMkDir(),
 	}
 
+	// Run Kati against a restricted set of environment variables.
 	runKati(ctx, config, katiPackageSuffix, args, func(env *Environment) {
 		env.Allow([]string{
 			// Some generic basics
@@ -251,16 +344,21 @@
 		}
 	})
 
+	// Compress and dist the packaging Ninja file.
 	distGzipFile(ctx, config, config.KatiPackageNinjaFile())
 }
 
+// Run Kati on the cleanspec files to clean the build.
 func runKatiCleanSpec(ctx Context, config Config) {
 	ctx.BeginTrace(metrics.RunKati, "kati cleanspec")
 	defer ctx.EndTrace()
 
 	runKati(ctx, config, katiCleanspecSuffix, []string{
+		// Fail when encountering implicit rules. e.g.
 		"--werror_implicit_rules",
+		// Fail when redefining / duplicating a target.
 		"--werror_overriding_commands",
+		// Entry point.
 		"-f", "build/make/core/cleanbuild.mk",
 		"SOONG_MAKEVARS_MK=" + config.SoongMakeVarsMk(),
 		"TARGET_DEVICE_DIR=" + config.TargetDeviceDir(),
diff --git a/ui/build/ninja.go b/ui/build/ninja.go
index fa44cb1..ffd1ab9 100644
--- a/ui/build/ninja.go
+++ b/ui/build/ninja.go
@@ -27,10 +27,16 @@
 	"android/soong/ui/status"
 )
 
+// Constructs and runs the Ninja command line with a restricted set of
+// environment variables. It's important to restrict the environment Ninja runs
+// for hermeticity reasons, and to avoid spurious rebuilds.
 func runNinja(ctx Context, config Config) {
 	ctx.BeginTrace(metrics.PrimaryNinja, "ninja")
 	defer ctx.EndTrace()
 
+	// Sets up the FIFO status updater that reads the Ninja protobuf output, and
+	// translates it to the soong_ui status output, displaying real-time
+	// progress of the build.
 	fifo := filepath.Join(config.OutDir(), ".ninja_fifo")
 	nr := status.NewNinjaReader(ctx, ctx.Status.StartTool(), fifo)
 	defer nr.Close()
@@ -64,8 +70,12 @@
 		"-w", "missingdepfile=err")
 
 	cmd := Command(ctx, config, "ninja", executable, args...)
+
+	// Set up the nsjail sandbox Ninja runs in.
 	cmd.Sandbox = ninjaSandbox
 	if config.HasKatiSuffix() {
+		// Reads and executes a shell script from Kati that sets/unsets the
+		// environment Ninja runs in.
 		cmd.Environment.AppendFromKati(config.KatiEnvFile())
 	}
 
@@ -78,8 +88,8 @@
 		cmd.Args = append(cmd.Args, strings.Fields(extra)...)
 	}
 
-	logPath := filepath.Join(config.OutDir(), ".ninja_log")
 	ninjaHeartbeatDuration := time.Minute * 5
+	// Get the ninja heartbeat interval from the environment before it's filtered away later.
 	if overrideText, ok := cmd.Environment.Get("NINJA_HEARTBEAT_INTERVAL"); ok {
 		// For example, "1m"
 		overrideDuration, err := time.ParseDuration(overrideText)
@@ -88,18 +98,22 @@
 		}
 	}
 
-	// Filter the environment, as ninja does not rebuild files when environment variables change.
+	// Filter the environment, as ninja does not rebuild files when environment
+	// variables change.
 	//
-	// Anything listed here must not change the output of rules/actions when the value changes,
-	// otherwise incremental builds may be unsafe. Vars explicitly set to stable values
-	// elsewhere in soong_ui are fine.
+	// Anything listed here must not change the output of rules/actions when the
+	// value changes, otherwise incremental builds may be unsafe. Vars
+	// explicitly set to stable values elsewhere in soong_ui are fine.
 	//
-	// For the majority of cases, either Soong or the makefiles should be replicating any
-	// necessary environment variables in the command line of each action that needs it.
+	// For the majority of cases, either Soong or the makefiles should be
+	// replicating any necessary environment variables in the command line of
+	// each action that needs it.
 	if cmd.Environment.IsEnvTrue("ALLOW_NINJA_ENV") {
 		ctx.Println("Allowing all environment variables during ninja; incremental builds may be unsafe.")
 	} else {
 		cmd.Environment.Allow(append([]string{
+			// Set the path to a symbolizer (e.g. llvm-symbolizer) so ASAN-based
+			// tools can symbolize crashes.
 			"ASAN_SYMBOLIZER_PATH",
 			"HOME",
 			"JAVA_HOME",
@@ -108,14 +122,19 @@
 			"OUT_DIR",
 			"PATH",
 			"PWD",
+			// https://docs.python.org/3/using/cmdline.html#envvar-PYTHONDONTWRITEBYTECODE
 			"PYTHONDONTWRITEBYTECODE",
 			"TMPDIR",
 			"USER",
 
 			// TODO: remove these carefully
+			// Options for the address sanitizer.
 			"ASAN_OPTIONS",
+			// The list of Android app modules to be built in an unbundled manner.
 			"TARGET_BUILD_APPS",
+			// The variant of the product being built. e.g. eng, userdebug, debug.
 			"TARGET_BUILD_VARIANT",
+			// The product name of the product being built, e.g. aosp_arm, aosp_flame.
 			"TARGET_PRODUCT",
 			// b/147197813 - used by art-check-debug-apex-gen
 			"EMMA_INSTRUMENT_FRAMEWORK",
@@ -162,6 +181,7 @@
 	cmd.Environment.Set("DIST_DIR", config.DistDir())
 	cmd.Environment.Set("SHELL", "/bin/bash")
 
+	// Print the environment variables that Ninja is operating in.
 	ctx.Verboseln("Ninja environment: ")
 	envVars := cmd.Environment.Environ()
 	sort.Strings(envVars)
@@ -169,17 +189,21 @@
 		ctx.Verbosef("  %s", envVar)
 	}
 
-	// Poll the ninja log for updates; if it isn't updated enough, then we want to show some diagnostics
+	// Poll the Ninja log for updates regularly based on the heartbeat
+	// frequency. If it isn't updated enough, then we want to surface the
+	// possibility that Ninja is stuck, to the user.
 	done := make(chan struct{})
 	defer close(done)
 	ticker := time.NewTicker(ninjaHeartbeatDuration)
 	defer ticker.Stop()
-	checker := &statusChecker{}
+	ninjaChecker := &ninjaStucknessChecker{
+		logPath: filepath.Join(config.OutDir(), ".ninja_log"),
+	}
 	go func() {
 		for {
 			select {
 			case <-ticker.C:
-				checker.check(ctx, config, logPath)
+				ninjaChecker.check(ctx, config)
 			case <-done:
 				return
 			}
@@ -190,37 +214,36 @@
 	cmd.RunAndStreamOrFatal()
 }
 
-type statusChecker struct {
-	prevTime time.Time
+// A simple struct for checking if Ninja gets stuck, using timestamps.
+type ninjaStucknessChecker struct {
+	logPath     string
+	prevModTime time.Time
 }
 
-func (c *statusChecker) check(ctx Context, config Config, pathToCheck string) {
-	info, err := os.Stat(pathToCheck)
-	var newTime time.Time
+// Check that a file has been modified since the last time it was checked. If
+// the mod time hasn't changed, then assume that Ninja got stuck, and print
+// diagnostics for debugging.
+func (c *ninjaStucknessChecker) check(ctx Context, config Config) {
+	info, err := os.Stat(c.logPath)
+	var newModTime time.Time
 	if err == nil {
-		newTime = info.ModTime()
+		newModTime = info.ModTime()
 	}
-	if newTime == c.prevTime {
-		// ninja may be stuck
-		dumpStucknessDiagnostics(ctx, config, pathToCheck, newTime)
+	if newModTime == c.prevModTime {
+		// The Ninja file hasn't been modified since the last time it was
+		// checked, so Ninja could be stuck. Output some diagnostics.
+		ctx.Verbosef("ninja may be stuck; last update to %v was %v. dumping process tree...", c.logPath, newModTime)
+
+		// The "pstree" command doesn't exist on Mac, but "pstree" on Linux
+		// gives more convenient output than "ps" So, we try pstree first, and
+		// ps second
+		commandText := fmt.Sprintf("pstree -pal %v || ps -ef", os.Getpid())
+
+		cmd := Command(ctx, config, "dump process tree", "bash", "-c", commandText)
+		output := cmd.CombinedOutputOrFatal()
+		ctx.Verbose(string(output))
+
+		ctx.Verbosef("done\n")
 	}
-	c.prevTime = newTime
-}
-
-// dumpStucknessDiagnostics gets called when it is suspected that Ninja is stuck and we want to output some diagnostics
-func dumpStucknessDiagnostics(ctx Context, config Config, statusPath string, lastUpdated time.Time) {
-
-	ctx.Verbosef("ninja may be stuck; last update to %v was %v. dumping process tree...", statusPath, lastUpdated)
-
-	// The "pstree" command doesn't exist on Mac, but "pstree" on Linux gives more convenient output than "ps"
-	// So, we try pstree first, and ps second
-	pstreeCommandText := fmt.Sprintf("pstree -pal %v", os.Getpid())
-	psCommandText := "ps -ef"
-	commandText := pstreeCommandText + " || " + psCommandText
-
-	cmd := Command(ctx, config, "dump process tree", "bash", "-c", commandText)
-	output := cmd.CombinedOutputOrFatal()
-	ctx.Verbose(string(output))
-
-	ctx.Verbosef("done\n")
+	c.prevModTime = newModTime
 }
diff --git a/ui/build/path.go b/ui/build/path.go
index 6f5cf78..86e61c0 100644
--- a/ui/build/path.go
+++ b/ui/build/path.go
@@ -29,6 +29,9 @@
 	"android/soong/ui/metrics"
 )
 
+// parsePathDir returns the list of filenames of readable files in a directory.
+// This does not recurse into subdirectories, and does not contain subdirectory
+// names in the list.
 func parsePathDir(dir string) []string {
 	f, err := os.Open(dir)
 	if err != nil {
@@ -54,10 +57,12 @@
 	return ret
 }
 
-// A "lite" version of SetupPath used for dumpvars, or other places that need
-// minimal overhead (but at the expense of logging). If tmpDir is empty, the
-// default TMPDIR is used from config.
+// SetupLitePath is the "lite" version of SetupPath used for dumpvars, or other
+// places that does not need the full logging capabilities of path_interposer,
+// wants the minimal performance overhead, and still get the benefits of $PATH
+// hermeticity.
 func SetupLitePath(ctx Context, config Config, tmpDir string) {
+	// Don't replace the path twice.
 	if config.pathReplaced {
 		return
 	}
@@ -67,6 +72,7 @@
 
 	origPath, _ := config.Environment().Get("PATH")
 
+	// If tmpDir is empty, the default TMPDIR is used from config.
 	if tmpDir == "" {
 		tmpDir, _ = config.Environment().Get("TMPDIR")
 	}
@@ -74,8 +80,10 @@
 	ensureEmptyDirectoriesExist(ctx, myPath)
 
 	os.Setenv("PATH", origPath)
+	// Iterate over the ACL configuration of host tools for this build.
 	for name, pathConfig := range paths.Configuration {
 		if !pathConfig.Symlink {
+			// Excludes 'Forbidden' and 'LinuxOnlyPrebuilt' PathConfigs.
 			continue
 		}
 
@@ -88,6 +96,7 @@
 			continue
 		}
 
+		// Symlink allowed host tools into a directory for hermeticity.
 		err = os.Symlink(origExec, filepath.Join(myPath, name))
 		if err != nil {
 			ctx.Fatalln("Failed to create symlink:", err)
@@ -96,14 +105,26 @@
 
 	myPath, _ = filepath.Abs(myPath)
 
+	// Set up the checked-in prebuilts path directory for the current host OS.
 	prebuiltsPath, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86")
 	myPath = prebuiltsPath + string(os.PathListSeparator) + myPath
 
+	// Set $PATH to be the directories containing the host tool symlinks, and
+	// the prebuilts directory for the current host OS.
 	config.Environment().Set("PATH", myPath)
 	config.pathReplaced = true
 }
 
+// SetupPath uses the path_interposer to intercept calls to $PATH binaries, and
+// communicates with the interposer to validate allowed $PATH binaries at
+// runtime, using logs as a medium.
+//
+// This results in hermetic directories in $PATH containing only allowed host
+// tools for the build, and replaces $PATH to contain *only* these directories,
+// and enables an incremental restriction of tools allowed in the $PATH without
+// breaking existing use cases.
 func SetupPath(ctx Context, config Config) {
+	// Don't replace $PATH twice.
 	if config.pathReplaced {
 		return
 	}
@@ -112,9 +133,11 @@
 	defer ctx.EndTrace()
 
 	origPath, _ := config.Environment().Get("PATH")
+	// The directory containing symlinks from binaries in $PATH to the interposer.
 	myPath := filepath.Join(config.OutDir(), ".path")
 	interposer := myPath + "_interposer"
 
+	// Bootstrap the path_interposer Go binary with microfactory.
 	var cfg microfactory.Config
 	cfg.Map("android/soong", "build/soong")
 	cfg.TrimPath, _ = filepath.Abs(".")
@@ -122,15 +145,20 @@
 		ctx.Fatalln("Failed to build path interposer:", err)
 	}
 
+	// Save the original $PATH in a file.
 	if err := ioutil.WriteFile(interposer+"_origpath", []byte(origPath), 0777); err != nil {
 		ctx.Fatalln("Failed to write original path:", err)
 	}
 
+	// Communication with the path interposer works over log entries. Set up the
+	// listener channel for the log entries here.
 	entries, err := paths.LogListener(ctx.Context, interposer+"_log")
 	if err != nil {
 		ctx.Fatalln("Failed to listen for path logs:", err)
 	}
 
+	// Loop over all log entry listener channels to validate usage of only
+	// allowed PATH tools at runtime.
 	go func() {
 		for log := range entries {
 			curPid := os.Getpid()
@@ -140,6 +168,8 @@
 					break
 				}
 			}
+			// Compute the error message along with the process tree, including
+			// parents, for this log line.
 			procPrints := []string{
 				"See https://android.googlesource.com/platform/build/+/master/Changes.md#PATH_Tools for more information.",
 			}
@@ -150,6 +180,7 @@
 				}
 			}
 
+			// Validate usage against disallowed or missing PATH tools.
 			config := paths.GetConfig(log.Basename)
 			if config.Error {
 				ctx.Printf("Disallowed PATH tool %q used: %#v", log.Basename, log.Args)
@@ -165,8 +196,10 @@
 		}
 	}()
 
+	// Create the .path directory.
 	ensureEmptyDirectoriesExist(ctx, myPath)
 
+	// Compute the full list of binaries available in the original $PATH.
 	var execs []string
 	for _, pathEntry := range filepath.SplitList(origPath) {
 		if pathEntry == "" {
@@ -185,8 +218,14 @@
 		ctx.Fatalln("TEMPORARY_DISABLE_PATH_RESTRICTIONS was a temporary migration method, and is now obsolete.")
 	}
 
+	// Create symlinks from the path_interposer binary to all binaries for each
+	// directory in the original $PATH. This ensures that during the build,
+	// every call to a binary that's expected to be in the $PATH will be
+	// intercepted by the path_interposer binary, and validated with the
+	// LogEntry listener above at build time.
 	for _, name := range execs {
 		if !paths.GetConfig(name).Symlink {
+			// Ignore host tools that shouldn't be symlinked.
 			continue
 		}
 
@@ -200,11 +239,13 @@
 
 	myPath, _ = filepath.Abs(myPath)
 
-	// We put some prebuilts in $PATH, since it's infeasible to add dependencies for all of
-	// them.
+	// We put some prebuilts in $PATH, since it's infeasible to add dependencies
+	// for all of them.
 	prebuiltsPath, _ := filepath.Abs("prebuilts/build-tools/path/" + runtime.GOOS + "-x86")
 	myPath = prebuiltsPath + string(os.PathListSeparator) + myPath
 
+	// Replace the $PATH variable with the path_interposer symlinks, and
+	// checked-in prebuilts.
 	config.Environment().Set("PATH", myPath)
 	config.pathReplaced = true
 }