diff --git a/dexpreopt/class_loader_context.go b/dexpreopt/class_loader_context.go
index d0a6a39..7bc9ab2 100644
--- a/dexpreopt/class_loader_context.go
+++ b/dexpreopt/class_loader_context.go
@@ -196,10 +196,6 @@
 	// If the library is optional or required.
 	Optional bool
 
-	// If the library is implicitly infered by Soong (as opposed to explicitly added via `uses_libs`
-	// or `optional_uses_libs`.
-	Implicit bool
-
 	// On-host build path to the library dex file (used in dex2oat argument --class-loader-context).
 	Host android.Path
 
@@ -290,9 +286,8 @@
 const AnySdkVersion int = android.FutureApiLevelInt
 
 // Add class loader context for the given library to the map entry for the given SDK version.
-func (clcMap ClassLoaderContextMap) addContext(ctx android.ModuleInstallPathContext, sdkVer int,
-	lib string, optional, implicit bool, hostPath, installPath android.Path,
-	nestedClcMap ClassLoaderContextMap) error {
+func (clcMap ClassLoaderContextMap) addContext(ctx android.ModuleInstallPathContext, sdkVer int, lib string,
+	optional bool, hostPath, installPath android.Path, nestedClcMap ClassLoaderContextMap) error {
 
 	// For prebuilts, library should have the same name as the source module.
 	lib = android.RemoveOptionalPrebuiltPrefix(lib)
@@ -341,7 +336,6 @@
 	clcMap[sdkVer] = append(clcMap[sdkVer], &ClassLoaderContext{
 		Name:        lib,
 		Optional:    optional,
-		Implicit:    implicit,
 		Host:        hostPath,
 		Device:      devicePath,
 		Subcontexts: subcontexts,
@@ -354,10 +348,9 @@
 // about paths). For the subset of libraries that are used in dexpreopt, their build/install paths
 // are validated later before CLC is used (in validateClassLoaderContext).
 func (clcMap ClassLoaderContextMap) AddContext(ctx android.ModuleInstallPathContext, sdkVer int,
-	lib string, optional, implicit bool, hostPath, installPath android.Path,
-	nestedClcMap ClassLoaderContextMap) {
+	lib string, optional bool, hostPath, installPath android.Path, nestedClcMap ClassLoaderContextMap) {
 
-	err := clcMap.addContext(ctx, sdkVer, lib, optional, implicit, hostPath, installPath, nestedClcMap)
+	err := clcMap.addContext(ctx, sdkVer, lib, optional, hostPath, installPath, nestedClcMap)
 	if err != nil {
 		ctx.ModuleErrorf(err.Error())
 	}
@@ -401,15 +394,13 @@
 // included). This is the list of libraries that should be in the <uses-library> tags in the
 // manifest. Some of them may be present in the source manifest, others are added by manifest_fixer.
 // Required and optional libraries are in separate lists.
-func (clcMap ClassLoaderContextMap) usesLibs(implicit bool) (required []string, optional []string) {
+func (clcMap ClassLoaderContextMap) UsesLibs() (required []string, optional []string) {
 	if clcMap != nil {
 		clcs := clcMap[AnySdkVersion]
 		required = make([]string, 0, len(clcs))
 		optional = make([]string, 0, len(clcs))
 		for _, clc := range clcs {
-			if implicit && !clc.Implicit {
-				// Skip, this is an explicit library and we need only the implicit ones.
-			} else if clc.Optional {
+			if clc.Optional {
 				optional = append(optional, clc.Name)
 			} else {
 				required = append(required, clc.Name)
@@ -419,14 +410,6 @@
 	return required, optional
 }
 
-func (clcMap ClassLoaderContextMap) UsesLibs() ([]string, []string) {
-	return clcMap.usesLibs(false)
-}
-
-func (clcMap ClassLoaderContextMap) ImplicitUsesLibs() ([]string, []string) {
-	return clcMap.usesLibs(true)
-}
-
 func (clcMap ClassLoaderContextMap) Dump() string {
 	jsonCLC := toJsonClassLoaderContext(clcMap)
 	bytes, err := json.MarshalIndent(jsonCLC, "", "  ")
@@ -631,7 +614,6 @@
 type jsonClassLoaderContext struct {
 	Name        string
 	Optional    bool
-	Implicit    bool
 	Host        string
 	Device      string
 	Subcontexts []*jsonClassLoaderContext
@@ -664,7 +646,6 @@
 		clcs = append(clcs, &ClassLoaderContext{
 			Name:        clc.Name,
 			Optional:    clc.Optional,
-			Implicit:    clc.Implicit,
 			Host:        constructPath(ctx, clc.Host),
 			Device:      clc.Device,
 			Subcontexts: fromJsonClassLoaderContextRec(ctx, clc.Subcontexts),
@@ -700,7 +681,6 @@
 		jClcs[i] = &jsonClassLoaderContext{
 			Name:        clc.Name,
 			Optional:    clc.Optional,
-			Implicit:    clc.Implicit,
 			Host:        host,
 			Device:      clc.Device,
 			Subcontexts: toJsonClassLoaderContextRec(clc.Subcontexts),
diff --git a/dexpreopt/class_loader_context_test.go b/dexpreopt/class_loader_context_test.go
index 614681f..8b3c013 100644
--- a/dexpreopt/class_loader_context_test.go
+++ b/dexpreopt/class_loader_context_test.go
@@ -50,34 +50,33 @@
 	ctx := testContext()
 
 	optional := false
-	implicit := true
 
 	m := make(ClassLoaderContextMap)
 
-	m.AddContext(ctx, AnySdkVersion, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
-	m.AddContext(ctx, AnySdkVersion, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
-	m.AddContext(ctx, AnySdkVersion, "c", optional, implicit, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
+	m.AddContext(ctx, AnySdkVersion, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+	m.AddContext(ctx, AnySdkVersion, "b", optional, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+	m.AddContext(ctx, AnySdkVersion, "c", optional, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
 
 	// Add some libraries with nested subcontexts.
 
 	m1 := make(ClassLoaderContextMap)
-	m1.AddContext(ctx, AnySdkVersion, "a1", optional, implicit, buildPath(ctx, "a1"), installPath(ctx, "a1"), nil)
-	m1.AddContext(ctx, AnySdkVersion, "b1", optional, implicit, buildPath(ctx, "b1"), installPath(ctx, "b1"), nil)
+	m1.AddContext(ctx, AnySdkVersion, "a1", optional, buildPath(ctx, "a1"), installPath(ctx, "a1"), nil)
+	m1.AddContext(ctx, AnySdkVersion, "b1", optional, buildPath(ctx, "b1"), installPath(ctx, "b1"), nil)
 
 	m2 := make(ClassLoaderContextMap)
-	m2.AddContext(ctx, AnySdkVersion, "a2", optional, implicit, buildPath(ctx, "a2"), installPath(ctx, "a2"), nil)
-	m2.AddContext(ctx, AnySdkVersion, "b2", optional, implicit, buildPath(ctx, "b2"), installPath(ctx, "b2"), nil)
-	m2.AddContext(ctx, AnySdkVersion, "c2", optional, implicit, buildPath(ctx, "c2"), installPath(ctx, "c2"), m1)
+	m2.AddContext(ctx, AnySdkVersion, "a2", optional, buildPath(ctx, "a2"), installPath(ctx, "a2"), nil)
+	m2.AddContext(ctx, AnySdkVersion, "b2", optional, buildPath(ctx, "b2"), installPath(ctx, "b2"), nil)
+	m2.AddContext(ctx, AnySdkVersion, "c2", optional, buildPath(ctx, "c2"), installPath(ctx, "c2"), m1)
 
 	m3 := make(ClassLoaderContextMap)
-	m3.AddContext(ctx, AnySdkVersion, "a3", optional, implicit, buildPath(ctx, "a3"), installPath(ctx, "a3"), nil)
-	m3.AddContext(ctx, AnySdkVersion, "b3", optional, implicit, buildPath(ctx, "b3"), installPath(ctx, "b3"), nil)
+	m3.AddContext(ctx, AnySdkVersion, "a3", optional, buildPath(ctx, "a3"), installPath(ctx, "a3"), nil)
+	m3.AddContext(ctx, AnySdkVersion, "b3", optional, buildPath(ctx, "b3"), installPath(ctx, "b3"), nil)
 
-	m.AddContext(ctx, AnySdkVersion, "d", optional, implicit, buildPath(ctx, "d"), installPath(ctx, "d"), m2)
+	m.AddContext(ctx, AnySdkVersion, "d", optional, buildPath(ctx, "d"), installPath(ctx, "d"), m2)
 	// When the same library is both in conditional and unconditional context, it should be removed
 	// from conditional context.
-	m.AddContext(ctx, 42, "f", optional, implicit, buildPath(ctx, "f"), installPath(ctx, "f"), nil)
-	m.AddContext(ctx, AnySdkVersion, "f", optional, implicit, buildPath(ctx, "f"), installPath(ctx, "f"), nil)
+	m.AddContext(ctx, 42, "f", optional, buildPath(ctx, "f"), installPath(ctx, "f"), nil)
+	m.AddContext(ctx, AnySdkVersion, "f", optional, buildPath(ctx, "f"), installPath(ctx, "f"), nil)
 
 	// Merge map with implicit root library that is among toplevel contexts => does nothing.
 	m.AddContextMap(m1, "c")
@@ -86,12 +85,12 @@
 	m.AddContextMap(m3, "m_g")
 
 	// Compatibility libraries with unknown install paths get default paths.
-	m.AddContext(ctx, 29, AndroidHidlManager, optional, implicit, buildPath(ctx, AndroidHidlManager), nil, nil)
-	m.AddContext(ctx, 29, AndroidHidlBase, optional, implicit, buildPath(ctx, AndroidHidlBase), nil, nil)
+	m.AddContext(ctx, 29, AndroidHidlManager, optional, buildPath(ctx, AndroidHidlManager), nil, nil)
+	m.AddContext(ctx, 29, AndroidHidlBase, optional, buildPath(ctx, AndroidHidlBase), nil, nil)
 
 	// Add "android.test.mock" to conditional CLC, observe that is gets removed because it is only
 	// needed as a compatibility library if "android.test.runner" is in CLC as well.
-	m.AddContext(ctx, 30, AndroidTestMock, optional, implicit, buildPath(ctx, AndroidTestMock), nil, nil)
+	m.AddContext(ctx, 30, AndroidTestMock, optional, buildPath(ctx, AndroidTestMock), nil, nil)
 
 	valid, validationError := validateClassLoaderContext(m)
 
@@ -165,12 +164,11 @@
 func TestCLCJson(t *testing.T) {
 	ctx := testContext()
 	optional := false
-	implicit := true
 	m := make(ClassLoaderContextMap)
-	m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
-	m.AddContext(ctx, 29, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
-	m.AddContext(ctx, 30, "c", optional, implicit, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
-	m.AddContext(ctx, AnySdkVersion, "d", optional, implicit, buildPath(ctx, "d"), installPath(ctx, "d"), nil)
+	m.AddContext(ctx, 28, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+	m.AddContext(ctx, 29, "b", optional, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+	m.AddContext(ctx, 30, "c", optional, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
+	m.AddContext(ctx, AnySdkVersion, "d", optional, buildPath(ctx, "d"), installPath(ctx, "d"), nil)
 	jsonCLC := toJsonClassLoaderContext(m)
 	restored := fromJsonClassLoaderContext(ctx, jsonCLC)
 	android.AssertIntEquals(t, "The size of the maps should be the same.", len(m), len(restored))
@@ -191,13 +189,12 @@
 func testCLCUnknownPath(t *testing.T, whichPath string) {
 	ctx := testContext()
 	optional := false
-	implicit := true
 
 	m := make(ClassLoaderContextMap)
 	if whichPath == "build" {
-		m.AddContext(ctx, AnySdkVersion, "a", optional, implicit, nil, nil, nil)
+		m.AddContext(ctx, AnySdkVersion, "a", optional, nil, nil, nil)
 	} else {
-		m.AddContext(ctx, AnySdkVersion, "a", optional, implicit, buildPath(ctx, "a"), nil, nil)
+		m.AddContext(ctx, AnySdkVersion, "a", optional, buildPath(ctx, "a"), nil, nil)
 	}
 
 	// The library should be added to <uses-library> tags by the manifest_fixer.
@@ -232,11 +229,10 @@
 func TestCLCNestedConditional(t *testing.T) {
 	ctx := testContext()
 	optional := false
-	implicit := true
 	m1 := make(ClassLoaderContextMap)
-	m1.AddContext(ctx, 42, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+	m1.AddContext(ctx, 42, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
 	m := make(ClassLoaderContextMap)
-	err := m.addContext(ctx, AnySdkVersion, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), m1)
+	err := m.addContext(ctx, AnySdkVersion, "b", optional, buildPath(ctx, "b"), installPath(ctx, "b"), m1)
 	checkError(t, err, "nested class loader context shouldn't have conditional part")
 }
 
@@ -245,12 +241,11 @@
 func TestCLCSdkVersionOrder(t *testing.T) {
 	ctx := testContext()
 	optional := false
-	implicit := true
 	m := make(ClassLoaderContextMap)
-	m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
-	m.AddContext(ctx, 29, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
-	m.AddContext(ctx, 30, "c", optional, implicit, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
-	m.AddContext(ctx, AnySdkVersion, "d", optional, implicit, buildPath(ctx, "d"), installPath(ctx, "d"), nil)
+	m.AddContext(ctx, 28, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+	m.AddContext(ctx, 29, "b", optional, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+	m.AddContext(ctx, 30, "c", optional, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
+	m.AddContext(ctx, AnySdkVersion, "d", optional, buildPath(ctx, "d"), installPath(ctx, "d"), nil)
 
 	valid, validationError := validateClassLoaderContext(m)
 
@@ -287,7 +282,6 @@
 func TestCLCMExcludeLibs(t *testing.T) {
 	ctx := testContext()
 	const optional = false
-	const implicit = true
 
 	excludeLibs := func(t *testing.T, m ClassLoaderContextMap, excluded_libs ...string) ClassLoaderContextMap {
 		// Dump the CLCM before creating a new copy that excludes a specific set of libraries.
@@ -305,7 +299,7 @@
 
 	t.Run("exclude nothing", func(t *testing.T) {
 		m := make(ClassLoaderContextMap)
-		m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+		m.AddContext(ctx, 28, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
 
 		a := excludeLibs(t, m)
 
@@ -314,7 +308,6 @@
     {
       "Name": "a",
       "Optional": false,
-      "Implicit": true,
       "Host": "out/soong/a.jar",
       "Device": "/system/a.jar",
       "Subcontexts": []
@@ -325,8 +318,8 @@
 
 	t.Run("one item from list", func(t *testing.T) {
 		m := make(ClassLoaderContextMap)
-		m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
-		m.AddContext(ctx, 28, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+		m.AddContext(ctx, 28, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+		m.AddContext(ctx, 28, "b", optional, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
 
 		a := excludeLibs(t, m, "a")
 
@@ -335,7 +328,6 @@
     {
       "Name": "b",
       "Optional": false,
-      "Implicit": true,
       "Host": "out/soong/b.jar",
       "Device": "/system/b.jar",
       "Subcontexts": []
@@ -347,8 +339,8 @@
 
 	t.Run("all items from a list", func(t *testing.T) {
 		m := make(ClassLoaderContextMap)
-		m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
-		m.AddContext(ctx, 28, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+		m.AddContext(ctx, 28, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+		m.AddContext(ctx, 28, "b", optional, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
 
 		a := excludeLibs(t, m, "a", "b")
 
@@ -357,11 +349,11 @@
 
 	t.Run("items from a subcontext", func(t *testing.T) {
 		s := make(ClassLoaderContextMap)
-		s.AddContext(ctx, AnySdkVersion, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
-		s.AddContext(ctx, AnySdkVersion, "c", optional, implicit, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
+		s.AddContext(ctx, AnySdkVersion, "b", optional, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+		s.AddContext(ctx, AnySdkVersion, "c", optional, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
 
 		m := make(ClassLoaderContextMap)
-		m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), s)
+		m.AddContext(ctx, 28, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), s)
 
 		a := excludeLibs(t, m, "b")
 
@@ -370,14 +362,12 @@
     {
       "Name": "a",
       "Optional": false,
-      "Implicit": true,
       "Host": "out/soong/a.jar",
       "Device": "/system/a.jar",
       "Subcontexts": [
         {
           "Name": "c",
           "Optional": false,
-          "Implicit": true,
           "Host": "out/soong/c.jar",
           "Device": "/system/c.jar",
           "Subcontexts": []
@@ -393,16 +383,14 @@
 func TestCLCtoJSON(t *testing.T) {
 	ctx := testContext()
 	optional := false
-	implicit := true
 	m := make(ClassLoaderContextMap)
-	m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
-	m.AddContext(ctx, AnySdkVersion, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+	m.AddContext(ctx, 28, "a", optional, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+	m.AddContext(ctx, AnySdkVersion, "b", optional, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
 	android.AssertStringEquals(t, "output CLCM ", `{
   "28": [
     {
       "Name": "a",
       "Optional": false,
-      "Implicit": true,
       "Host": "out/soong/a.jar",
       "Device": "/system/a.jar",
       "Subcontexts": []
@@ -412,7 +400,6 @@
     {
       "Name": "b",
       "Optional": false,
-      "Implicit": true,
       "Host": "out/soong/b.jar",
       "Device": "/system/b.jar",
       "Subcontexts": []
diff --git a/java/android_manifest.go b/java/android_manifest.go
index 3fa3520..a297b2c 100644
--- a/java/android_manifest.go
+++ b/java/android_manifest.go
@@ -96,9 +96,9 @@
 	}
 
 	if params.ClassLoaderContexts != nil {
-		// manifest_fixer should add only the implicit SDK libraries inferred by Soong, not those added
-		// explicitly via `uses_libs`/`optional_uses_libs`.
-		requiredUsesLibs, optionalUsesLibs := params.ClassLoaderContexts.ImplicitUsesLibs()
+		// Libraries propagated via `uses_libs`/`optional_uses_libs` are also added (they may be
+		// propagated from dependencies).
+		requiredUsesLibs, optionalUsesLibs := params.ClassLoaderContexts.UsesLibs()
 
 		for _, usesLib := range requiredUsesLibs {
 			args = append(args, "--uses-library", usesLib)
diff --git a/java/app.go b/java/app.go
index d0a1db0..768d9e9 100755
--- a/java/app.go
+++ b/java/app.go
@@ -1227,28 +1227,17 @@
 
 func (u *usesLibrary) deps(ctx android.BottomUpMutatorContext, hasFrameworkLibs bool) {
 	if !ctx.Config().UnbundledBuild() || ctx.Config().UnbundledBuildImage() {
-		reqTag := makeUsesLibraryDependencyTag(dexpreopt.AnySdkVersion, false, false)
-		ctx.AddVariationDependencies(nil, reqTag, u.usesLibraryProperties.Uses_libs...)
-
-		optTag := makeUsesLibraryDependencyTag(dexpreopt.AnySdkVersion, true, false)
-		ctx.AddVariationDependencies(nil, optTag, u.presentOptionalUsesLibs(ctx)...)
-
+		ctx.AddVariationDependencies(nil, usesLibReqTag, u.usesLibraryProperties.Uses_libs...)
+		ctx.AddVariationDependencies(nil, usesLibOptTag, u.presentOptionalUsesLibs(ctx)...)
 		// Only add these extra dependencies if the module depends on framework libs. This avoids
 		// creating a cyclic dependency:
 		//     e.g. framework-res -> org.apache.http.legacy -> ... -> framework-res.
 		if hasFrameworkLibs {
-			// Add implicit <uses-library> dependencies on compatibility libraries. Some of them are
-			// optional, and some required --- this depends on the most common usage of the library
-			// and may be wrong for some apps (they need explicit `uses_libs`/`optional_uses_libs`).
-
-			compat28OptTag := makeUsesLibraryDependencyTag(28, true, true)
-			ctx.AddVariationDependencies(nil, compat28OptTag, dexpreopt.OptionalCompatUsesLibs28...)
-
-			compat29ReqTag := makeUsesLibraryDependencyTag(29, false, true)
-			ctx.AddVariationDependencies(nil, compat29ReqTag, dexpreopt.CompatUsesLibs29...)
-
-			compat30OptTag := makeUsesLibraryDependencyTag(30, true, true)
-			ctx.AddVariationDependencies(nil, compat30OptTag, dexpreopt.OptionalCompatUsesLibs30...)
+			// Dexpreopt needs paths to the dex jars of these libraries in order to construct
+			// class loader context for dex2oat. Add them as a dependency with a special tag.
+			ctx.AddVariationDependencies(nil, usesLibCompat29ReqTag, dexpreopt.CompatUsesLibs29...)
+			ctx.AddVariationDependencies(nil, usesLibCompat28OptTag, dexpreopt.OptionalCompatUsesLibs28...)
+			ctx.AddVariationDependencies(nil, usesLibCompat30OptTag, dexpreopt.OptionalCompatUsesLibs30...)
 		}
 	}
 }
@@ -1307,7 +1296,7 @@
 				replaceInList(u.usesLibraryProperties.Uses_libs, dep, libName)
 				replaceInList(u.usesLibraryProperties.Optional_uses_libs, dep, libName)
 			}
-			clcMap.AddContext(ctx, tag.sdkVersion, libName, tag.optional, tag.implicit,
+			clcMap.AddContext(ctx, tag.sdkVersion, libName, tag.optional,
 				lib.DexJarBuildPath().PathOrNil(), lib.DexJarInstallPath(),
 				lib.ClassLoaderContexts())
 		} else if ctx.Config().AllowMissingDependencies() {
diff --git a/java/app_test.go b/java/app_test.go
index 6a4508c..8324dff 100644
--- a/java/app_test.go
+++ b/java/app_test.go
@@ -2505,12 +2505,20 @@
 	prebuilt := result.ModuleForTests("prebuilt", "android_common")
 
 	// Test that implicit dependencies on java_sdk_library instances are passed to the manifest.
-	// This should not include explicit `uses_libs`/`optional_uses_libs` entries.
+	// These also include explicit `uses_libs`/`optional_uses_libs` entries, as they may be
+	// propagated from dependencies.
 	actualManifestFixerArgs := app.Output("manifest_fixer/AndroidManifest.xml").Args["args"]
 	expectManifestFixerArgs := `--extract-native-libs=true ` +
 		`--uses-library qux ` +
 		`--uses-library quuz ` +
-		`--uses-library runtime-library`
+		`--uses-library foo ` +
+		`--uses-library com.non.sdk.lib ` +
+		`--uses-library runtime-library ` +
+		`--uses-library runtime-required-x ` +
+		`--uses-library runtime-required-y ` +
+		`--optional-uses-library bar ` +
+		`--optional-uses-library runtime-optional-x ` +
+		`--optional-uses-library runtime-optional-y`
 	android.AssertStringDoesContain(t, "manifest_fixer args", actualManifestFixerArgs, expectManifestFixerArgs)
 
 	// Test that all libraries are verified (library order matters).
diff --git a/java/base.go b/java/base.go
index ff1ce85..e60e54e 100644
--- a/java/base.go
+++ b/java/base.go
@@ -724,8 +724,10 @@
 			if component, ok := dep.(SdkLibraryComponentDependency); ok {
 				if lib := component.OptionalSdkLibraryImplementation(); lib != nil {
 					// Add library as optional if it's one of the optional compatibility libs.
-					optional := android.InList(*lib, dexpreopt.OptionalCompatUsesLibs)
-					tag := makeUsesLibraryDependencyTag(dexpreopt.AnySdkVersion, optional, true)
+					tag := usesLibReqTag
+					if android.InList(*lib, dexpreopt.OptionalCompatUsesLibs) {
+						tag = usesLibOptTag
+					}
 					ctx.AddVariationDependencies(nil, tag, *lib)
 				}
 			}
diff --git a/java/dexpreopt.go_v1 b/java/dexpreopt.go_v1
new file mode 100644
index 0000000..0adaf99
--- /dev/null
+++ b/java/dexpreopt.go_v1
@@ -0,0 +1,404 @@
+// Copyright 2018 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 java
+
+import (
+	"path/filepath"
+	"strings"
+
+	"android/soong/android"
+	"android/soong/dexpreopt"
+)
+
+type DexpreopterInterface interface {
+	IsInstallable() bool // Structs that embed dexpreopter must implement this.
+	dexpreoptDisabled(ctx android.BaseModuleContext) bool
+	DexpreoptBuiltInstalledForApex() []dexpreopterInstall
+	AndroidMkEntriesForApex() []android.AndroidMkEntries
+}
+
+type dexpreopterInstall struct {
+	// A unique name to distinguish an output from others for the same java library module. Usually in
+	// the form of `<arch>-<encoded-path>.odex/vdex/art`.
+	name string
+
+	// The name of the input java module.
+	moduleName string
+
+	// The path to the dexpreopt output on host.
+	outputPathOnHost android.Path
+
+	// The directory on the device for the output to install to.
+	installDirOnDevice android.InstallPath
+
+	// The basename (the last segment of the path) for the output to install as.
+	installFileOnDevice string
+}
+
+// The full module name of the output in the makefile.
+func (install *dexpreopterInstall) FullModuleName() string {
+	return install.moduleName + install.SubModuleName()
+}
+
+// The sub-module name of the output in the makefile (the name excluding the java module name).
+func (install *dexpreopterInstall) SubModuleName() string {
+	return "-dexpreopt-" + install.name
+}
+
+// Returns Make entries for installing the file.
+//
+// This function uses a value receiver rather than a pointer receiver to ensure that the object is
+// safe to use in `android.AndroidMkExtraEntriesFunc`.
+func (install dexpreopterInstall) ToMakeEntries() android.AndroidMkEntries {
+	return android.AndroidMkEntries{
+		Class:      "ETC",
+		SubName:    install.SubModuleName(),
+		OutputFile: android.OptionalPathForPath(install.outputPathOnHost),
+		ExtraEntries: []android.AndroidMkExtraEntriesFunc{
+			func(ctx android.AndroidMkExtraEntriesContext, entries *android.AndroidMkEntries) {
+				entries.SetString("LOCAL_MODULE_PATH", install.installDirOnDevice.String())
+				entries.SetString("LOCAL_INSTALLED_MODULE_STEM", install.installFileOnDevice)
+				entries.SetString("LOCAL_NOT_AVAILABLE_FOR_PLATFORM", "false")
+			},
+		},
+	}
+}
+
+type dexpreopter struct {
+	dexpreoptProperties DexpreoptProperties
+
+	installPath         android.InstallPath
+	uncompressedDex     bool
+	isSDKLibrary        bool
+	isApp               bool
+	isTest              bool
+	isPresignedPrebuilt bool
+	preventInstall      bool
+
+	manifestFile        android.Path
+	statusFile          android.WritablePath
+	enforceUsesLibs     bool
+	classLoaderContexts dexpreopt.ClassLoaderContextMap
+
+	// See the `dexpreopt` function for details.
+	builtInstalled        string
+	builtInstalledForApex []dexpreopterInstall
+
+	// The config is used for two purposes:
+	// - Passing dexpreopt information about libraries from Soong to Make. This is needed when
+	//   a <uses-library> is defined in Android.bp, but used in Android.mk (see dex_preopt_config_merger.py).
+	//   Note that dexpreopt.config might be needed even if dexpreopt is disabled for the library itself.
+	// - Dexpreopt post-processing (using dexpreopt artifacts from a prebuilt system image to incrementally
+	//   dexpreopt another partition).
+	configPath android.WritablePath
+}
+
+type DexpreoptProperties struct {
+	Dex_preopt struct {
+		// If false, prevent dexpreopting.  Defaults to true.
+		Enabled *bool
+
+		// If true, generate an app image (.art file) for this module.
+		App_image *bool
+
+		// If true, use a checked-in profile to guide optimization.  Defaults to false unless
+		// a matching profile is set or a profile is found in PRODUCT_DEX_PREOPT_PROFILE_DIR
+		// that matches the name of this module, in which case it is defaulted to true.
+		Profile_guided *bool
+
+		// If set, provides the path to profile relative to the Android.bp file.  If not set,
+		// defaults to searching for a file that matches the name of this module in the default
+		// profile location set by PRODUCT_DEX_PREOPT_PROFILE_DIR, or empty if not found.
+		Profile *string `android:"path"`
+	}
+}
+
+func init() {
+	dexpreopt.DexpreoptRunningInSoong = true
+}
+
+func isApexVariant(ctx android.BaseModuleContext) bool {
+	apexInfo := ctx.Provider(android.ApexInfoProvider).(android.ApexInfo)
+	return !apexInfo.IsForPlatform()
+}
+
+func forPrebuiltApex(ctx android.BaseModuleContext) bool {
+	apexInfo := ctx.Provider(android.ApexInfoProvider).(android.ApexInfo)
+	return apexInfo.ForPrebuiltApex
+}
+
+func moduleName(ctx android.BaseModuleContext) string {
+	// Remove the "prebuilt_" prefix if the module is from a prebuilt because the prefix is not
+	// expected by dexpreopter.
+	return android.RemoveOptionalPrebuiltPrefix(ctx.ModuleName())
+}
+
+func (d *dexpreopter) dexpreoptDisabled(ctx android.BaseModuleContext) bool {
+	if !ctx.Device() {
+		return true
+	}
+
+	if d.isTest {
+		return true
+	}
+
+	if !BoolDefault(d.dexpreoptProperties.Dex_preopt.Enabled, true) {
+		return true
+	}
+
+	// If the module is from a prebuilt APEX, it shouldn't be installable, but it can still be
+	// dexpreopted.
+	if !ctx.Module().(DexpreopterInterface).IsInstallable() && !forPrebuiltApex(ctx) {
+		return true
+	}
+
+	if !android.IsModulePreferred(ctx.Module()) {
+		return true
+	}
+
+	global := dexpreopt.GetGlobalConfig(ctx)
+
+	if global.DisablePreopt {
+		return true
+	}
+
+	if inList(moduleName(ctx), global.DisablePreoptModules) {
+		return true
+	}
+
+	isApexSystemServerJar := global.AllApexSystemServerJars(ctx).ContainsJar(moduleName(ctx))
+	if isApexVariant(ctx) {
+		// Don't preopt APEX variant module unless the module is an APEX system server jar and we are
+		// building the entire system image.
+		if !isApexSystemServerJar || ctx.Config().UnbundledBuild() {
+			return true
+		}
+	} else {
+		// Don't preopt the platform variant of an APEX system server jar to avoid conflicts.
+		if isApexSystemServerJar {
+			return true
+		}
+	}
+
+	// TODO: contains no java code
+
+	return false
+}
+
+func dexpreoptToolDepsMutator(ctx android.BottomUpMutatorContext) {
+	if d, ok := ctx.Module().(DexpreopterInterface); !ok || d.dexpreoptDisabled(ctx) {
+		return
+	}
+	dexpreopt.RegisterToolDeps(ctx)
+}
+
+func (d *dexpreopter) odexOnSystemOther(ctx android.ModuleContext, installPath android.InstallPath) bool {
+	return dexpreopt.OdexOnSystemOtherByName(moduleName(ctx), android.InstallPathToOnDevicePath(ctx, installPath), dexpreopt.GetGlobalConfig(ctx))
+}
+
+// Returns the install path of the dex jar of a module.
+//
+// Do not rely on `ApexInfo.ApexVariationName` because it can be something like "apex1000", rather
+// than the `name` in the path `/apex/<name>` as suggested in its comment.
+//
+// This function is on a best-effort basis. It cannot handle the case where an APEX jar is not a
+// system server jar, which is fine because we currently only preopt system server jars for APEXes.
+func (d *dexpreopter) getInstallPath(
+	ctx android.ModuleContext, defaultInstallPath android.InstallPath) android.InstallPath {
+	global := dexpreopt.GetGlobalConfig(ctx)
+	if global.AllApexSystemServerJars(ctx).ContainsJar(moduleName(ctx)) {
+		dexLocation := dexpreopt.GetSystemServerDexLocation(ctx, global, moduleName(ctx))
+		return android.PathForModuleInPartitionInstall(ctx, "", strings.TrimPrefix(dexLocation, "/"))
+	}
+	if !d.dexpreoptDisabled(ctx) && isApexVariant(ctx) &&
+		filepath.Base(defaultInstallPath.PartitionDir()) != "apex" {
+		ctx.ModuleErrorf("unable to get the install path of the dex jar for dexpreopt")
+	}
+	return defaultInstallPath
+}
+
+func (d *dexpreopter) dexpreopt(ctx android.ModuleContext, dexJarFile android.WritablePath) {
+	global := dexpreopt.GetGlobalConfig(ctx)
+
+	// TODO(b/148690468): The check on d.installPath is to bail out in cases where
+	// the dexpreopter struct hasn't been fully initialized before we're called,
+	// e.g. in aar.go. This keeps the behaviour that dexpreopting is effectively
+	// disabled, even if installable is true.
+	if d.installPath.Base() == "." {
+		return
+	}
+
+	dexLocation := android.InstallPathToOnDevicePath(ctx, d.installPath)
+
+	providesUsesLib := moduleName(ctx)
+	if ulib, ok := ctx.Module().(ProvidesUsesLib); ok {
+		name := ulib.ProvidesUsesLib()
+		if name != nil {
+			providesUsesLib = *name
+		}
+	}
+
+	// If it is test, make config files regardless of its dexpreopt setting.
+	// The config files are required for apps defined in make which depend on the lib.
+	if d.isTest && d.dexpreoptDisabled(ctx) {
+		return
+	}
+
+	isSystemServerJar := global.AllSystemServerJars(ctx).ContainsJar(moduleName(ctx))
+
+	bootImage := defaultBootImageConfig(ctx)
+	dexFiles, dexLocations := bcpForDexpreopt(ctx, global.PreoptWithUpdatableBcp)
+
+	targets := ctx.MultiTargets()
+	if len(targets) == 0 {
+		// assume this is a java library, dexpreopt for all arches for now
+		for _, target := range ctx.Config().Targets[android.Android] {
+			if target.NativeBridge == android.NativeBridgeDisabled {
+				targets = append(targets, target)
+			}
+		}
+		if isSystemServerJar && !d.isSDKLibrary {
+			// If the module is not an SDK library and it's a system server jar, only preopt the primary arch.
+			targets = targets[:1]
+		}
+	}
+
+	var archs []android.ArchType
+	var images android.Paths
+	var imagesDeps []android.OutputPaths
+	for _, target := range targets {
+		archs = append(archs, target.Arch.ArchType)
+		variant := bootImage.getVariant(target)
+		images = append(images, variant.imagePathOnHost)
+		imagesDeps = append(imagesDeps, variant.imagesDeps)
+	}
+	// The image locations for all Android variants are identical.
+	hostImageLocations, deviceImageLocations := bootImage.getAnyAndroidVariant().imageLocations()
+
+	var profileClassListing android.OptionalPath
+	var profileBootListing android.OptionalPath
+	profileIsTextListing := false
+	if BoolDefault(d.dexpreoptProperties.Dex_preopt.Profile_guided, true) {
+		// If dex_preopt.profile_guided is not set, default it based on the existence of the
+		// dexprepot.profile option or the profile class listing.
+		if String(d.dexpreoptProperties.Dex_preopt.Profile) != "" {
+			profileClassListing = android.OptionalPathForPath(
+				android.PathForModuleSrc(ctx, String(d.dexpreoptProperties.Dex_preopt.Profile)))
+			profileBootListing = android.ExistentPathForSource(ctx,
+				ctx.ModuleDir(), String(d.dexpreoptProperties.Dex_preopt.Profile)+"-boot")
+			profileIsTextListing = true
+		} else if global.ProfileDir != "" {
+			profileClassListing = android.ExistentPathForSource(ctx,
+				global.ProfileDir, moduleName(ctx)+".prof")
+		}
+	}
+
+	// Full dexpreopt config, used to create dexpreopt build rules.
+	dexpreoptConfig := &dexpreopt.ModuleConfig{
+		Name:            moduleName(ctx),
+		DexLocation:     dexLocation,
+		BuildPath:       android.PathForModuleOut(ctx, "dexpreopt", moduleName(ctx)+".jar").OutputPath,
+		DexPath:         dexJarFile,
+		ManifestPath:    android.OptionalPathForPath(d.manifestFile),
+		UncompressedDex: d.uncompressedDex,
+		HasApkLibraries: false,
+		PreoptFlags:     nil,
+
+		ProfileClassListing:  profileClassListing,
+		ProfileIsTextListing: profileIsTextListing,
+		ProfileBootListing:   profileBootListing,
+
+		EnforceUsesLibrariesStatusFile: dexpreopt.UsesLibrariesStatusFile(ctx),
+		EnforceUsesLibraries:           d.enforceUsesLibs,
+		ProvidesUsesLibrary:            providesUsesLib,
+		ClassLoaderContexts:            d.classLoaderContexts,
+
+		Archs:                           archs,
+		DexPreoptImagesDeps:             imagesDeps,
+		DexPreoptImageLocationsOnHost:   hostImageLocations,
+		DexPreoptImageLocationsOnDevice: deviceImageLocations,
+
+		PreoptBootClassPathDexFiles:     dexFiles.Paths(),
+		PreoptBootClassPathDexLocations: dexLocations,
+
+		PreoptExtractedApk: false,
+
+		NoCreateAppImage:    !BoolDefault(d.dexpreoptProperties.Dex_preopt.App_image, true),
+		ForceCreateAppImage: BoolDefault(d.dexpreoptProperties.Dex_preopt.App_image, false),
+
+		PresignedPrebuilt: d.isPresignedPrebuilt,
+	}
+
+	d.configPath = android.PathForModuleOut(ctx, "dexpreopt", "dexpreopt.config")
+	dexpreopt.WriteModuleConfig(ctx, dexpreoptConfig, d.configPath)
+
+	if d.dexpreoptDisabled(ctx) {
+		return
+	}
+
+	globalSoong := dexpreopt.GetGlobalSoongConfig(ctx)
+
+	dexpreoptRule, err := dexpreopt.GenerateDexpreoptRule(ctx, globalSoong, global, dexpreoptConfig)
+	if err != nil {
+		ctx.ModuleErrorf("error generating dexpreopt rule: %s", err.Error())
+		return
+	}
+
+	dexpreoptRule.Build("dexpreopt", "dexpreopt")
+
+	isApexSystemServerJar := global.AllApexSystemServerJars(ctx).ContainsJar(moduleName(ctx))
+
+	for _, install := range dexpreoptRule.Installs() {
+		// Remove the "/" prefix because the path should be relative to $ANDROID_PRODUCT_OUT.
+		installDir := strings.TrimPrefix(filepath.Dir(install.To), "/")
+		installBase := filepath.Base(install.To)
+		arch := filepath.Base(installDir)
+		installPath := android.PathForModuleInPartitionInstall(ctx, "", installDir)
+
+		if isApexSystemServerJar {
+			// APEX variants of java libraries are hidden from Make, so their dexpreopt
+			// outputs need special handling. Currently, for APEX variants of java
+			// libraries, only those in the system server classpath are handled here.
+			// Preopting of boot classpath jars in the ART APEX are handled in
+			// java/dexpreopt_bootjars.go, and other APEX jars are not preopted.
+			// The installs will be handled by Make as sub-modules of the java library.
+			d.builtInstalledForApex = append(d.builtInstalledForApex, dexpreopterInstall{
+				name:                arch + "-" + installBase,
+				moduleName:          moduleName(ctx),
+				outputPathOnHost:    install.From,
+				installDirOnDevice:  installPath,
+				installFileOnDevice: installBase,
+			})
+		} else if !d.preventInstall {
+			ctx.InstallFile(installPath, installBase, install.From)
+		}
+	}
+
+	if !isApexSystemServerJar {
+		d.builtInstalled = dexpreoptRule.Installs().String()
+	}
+}
+
+func (d *dexpreopter) DexpreoptBuiltInstalledForApex() []dexpreopterInstall {
+	return d.builtInstalledForApex
+}
+
+func (d *dexpreopter) AndroidMkEntriesForApex() []android.AndroidMkEntries {
+	var entries []android.AndroidMkEntries
+	for _, install := range d.builtInstalledForApex {
+		entries = append(entries, install.ToMakeEntries())
+	}
+	return entries
+}
diff --git a/java/dexpreopt_bootjars.go_v1 b/java/dexpreopt_bootjars.go_v1
new file mode 100644
index 0000000..07a357b
--- /dev/null
+++ b/java/dexpreopt_bootjars.go_v1
@@ -0,0 +1,952 @@
+// Copyright 2019 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 java
+
+import (
+	"path/filepath"
+	"strings"
+
+	"android/soong/android"
+	"android/soong/dexpreopt"
+
+	"github.com/google/blueprint/proptools"
+)
+
+// =================================================================================================
+// WIP - see http://b/177892522 for details
+//
+// The build support for boot images is currently being migrated away from singleton to modules so
+// the documentation may not be strictly accurate. Rather than update the documentation at every
+// step which will create a lot of churn the changes that have been made will be listed here and the
+// documentation will be updated once it is closer to the final result.
+//
+// Changes:
+// 1) dex_bootjars is now a singleton module and not a plain singleton.
+// 2) Boot images are now represented by the boot_image module type.
+// 3) The art boot image is called "art-boot-image", the framework boot image is called
+//    "framework-boot-image".
+// 4) They are defined in art/build/boot/Android.bp and frameworks/base/boot/Android.bp
+//    respectively.
+// 5) Each boot_image retrieves the appropriate boot image configuration from the map returned by
+//    genBootImageConfigs() using the image_name specified in the boot_image module.
+// =================================================================================================
+
+// This comment describes:
+//   1. ART boot images in general (their types, structure, file layout, etc.)
+//   2. build system support for boot images
+//
+// 1. ART boot images
+// ------------------
+//
+// A boot image in ART is a set of files that contain AOT-compiled native code and a heap snapshot
+// of AOT-initialized classes for the bootclasspath Java libraries. A boot image is compiled from a
+// set of DEX jars by the dex2oat compiler. A boot image is used for two purposes: 1) it is
+// installed on device and loaded at runtime, and 2) other Java libraries and apps are compiled
+// against it (compilation may take place either on host, known as "dexpreopt", or on device, known
+// as "dexopt").
+//
+// A boot image is not a single file, but a collection of interrelated files. Each boot image has a
+// number of components that correspond to the Java libraries that constitute it. For each component
+// there are multiple files:
+//   - *.oat or *.odex file with native code (architecture-specific, one per instruction set)
+//   - *.art file with pre-initialized Java classes (architecture-specific, one per instruction set)
+//   - *.vdex file with verification metadata for the DEX bytecode (architecture independent)
+//
+// *.vdex files for the boot images do not contain the DEX bytecode itself, because the
+// bootclasspath DEX files are stored on disk in uncompressed and aligned form. Consequently a boot
+// image is not self-contained and cannot be used without its DEX files. To simplify the management
+// of boot image files, ART uses a certain naming scheme and associates the following metadata with
+// each boot image:
+//   - A stem, which is a symbolic name that is prepended to boot image file names.
+//   - A location (on-device path to the boot image files).
+//   - A list of boot image locations (on-device paths to dependency boot images).
+//   - A set of DEX locations (on-device paths to the DEX files, one location for one DEX file used
+//     to compile the boot image).
+//
+// There are two kinds of boot images:
+//   - primary boot images
+//   - boot image extensions
+//
+// 1.1. Primary boot images
+// ------------------------
+//
+// A primary boot image is compiled for a core subset of bootclasspath Java libraries. It does not
+// depend on any other images, and other boot images may depend on it.
+//
+// For example, assuming that the stem is "boot", the location is /apex/com.android.art/javalib/,
+// the set of core bootclasspath libraries is A B C, and the boot image is compiled for ARM targets
+// (32 and 64 bits), it will have three components with the following files:
+//   - /apex/com.android.art/javalib/{arm,arm64}/boot.{art,oat,vdex}
+//   - /apex/com.android.art/javalib/{arm,arm64}/boot-B.{art,oat,vdex}
+//   - /apex/com.android.art/javalib/{arm,arm64}/boot-C.{art,oat,vdex}
+//
+// The files of the first component are special: they do not have the component name appended after
+// the stem. This naming convention dates back to the times when the boot image was not split into
+// components, and there were just boot.oat and boot.art. The decision to split was motivated by
+// licensing reasons for one of the bootclasspath libraries.
+//
+// As of November 2020 the only primary boot image in Android is the image in the ART APEX
+// com.android.art. The primary ART boot image contains the Core libraries that are part of the ART
+// module. When the ART module gets updated, the primary boot image will be updated with it, and all
+// dependent images will get invalidated (the checksum of the primary image stored in dependent
+// images will not match), unless they are updated in sync with the ART module.
+//
+// 1.2. Boot image extensions
+// --------------------------
+//
+// A boot image extension is compiled for a subset of bootclasspath Java libraries (in particular,
+// this subset does not include the Core bootclasspath libraries that go into the primary boot
+// image). A boot image extension depends on the primary boot image and optionally some other boot
+// image extensions. Other images may depend on it. In other words, boot image extensions can form
+// acyclic dependency graphs.
+//
+// The motivation for boot image extensions comes from the Mainline project. Consider a situation
+// when the list of bootclasspath libraries is A B C, and both A and B are parts of the Android
+// platform, but C is part of an updatable APEX com.android.C. When the APEX is updated, the Java
+// code for C might have changed compared to the code that was used to compile the boot image.
+// Consequently, the whole boot image is obsolete and invalidated (even though the code for A and B
+// that does not depend on C is up to date). To avoid this, the original monolithic boot image is
+// split in two parts: the primary boot image that contains A B, and the boot image extension that
+// contains C and depends on the primary boot image (extends it).
+//
+// For example, assuming that the stem is "boot", the location is /system/framework, the set of
+// bootclasspath libraries is D E (where D is part of the platform and is located in
+// /system/framework, and E is part of a non-updatable APEX com.android.E and is located in
+// /apex/com.android.E/javalib), and the boot image is compiled for ARM targets (32 and 64 bits),
+// it will have two components with the following files:
+//   - /system/framework/{arm,arm64}/boot-D.{art,oat,vdex}
+//   - /system/framework/{arm,arm64}/boot-E.{art,oat,vdex}
+//
+// As of November 2020 the only boot image extension in Android is the Framework boot image
+// extension. It extends the primary ART boot image and contains Framework libraries and other
+// bootclasspath libraries from the platform and non-updatable APEXes that are not included in the
+// ART image. The Framework boot image extension is updated together with the platform. In the
+// future other boot image extensions may be added for some updatable modules.
+//
+//
+// 2. Build system support for boot images
+// ---------------------------------------
+//
+// The primary ART boot image needs to be compiled with one dex2oat invocation that depends on DEX
+// jars for the core libraries. Framework boot image extension needs to be compiled with one dex2oat
+// invocation that depends on the primary ART boot image and all bootclasspath DEX jars except the
+// core libraries as they are already part of the primary ART boot image.
+//
+// 2.1. Libraries that go in the boot images
+// -----------------------------------------
+//
+// The contents of each boot image are determined by the PRODUCT variables. The primary ART APEX
+// boot image contains libraries listed in the ART_APEX_JARS variable in the AOSP makefiles. The
+// Framework boot image extension contains libraries specified in the PRODUCT_BOOT_JARS and
+// PRODUCT_BOOT_JARS_EXTRA variables. The AOSP makefiles specify some common Framework libraries,
+// but more product-specific libraries can be added in the product makefiles.
+//
+// Each component of the PRODUCT_BOOT_JARS and PRODUCT_BOOT_JARS_EXTRA variables is a
+// colon-separated pair <apex>:<library>, where <apex> is the variant name of a non-updatable APEX,
+// "platform" if the library is a part of the platform in the system partition, or "system_ext" if
+// it's in the system_ext partition.
+//
+// In these variables APEXes are identified by their "variant names", i.e. the names they get
+// mounted as in /apex on device. In Soong modules that is the name set in the "apex_name"
+// properties, which default to the "name" values. For example, many APEXes have both
+// com.android.xxx and com.google.android.xxx modules in Soong, but take the same place
+// /apex/com.android.xxx at runtime. In these cases the variant name is always com.android.xxx,
+// regardless which APEX goes into the product. See also android.ApexInfo.ApexVariationName and
+// apex.apexBundleProperties.Apex_name.
+//
+// A related variable PRODUCT_APEX_BOOT_JARS contains bootclasspath libraries that are in APEXes.
+// They are not included in the boot image. The only exception here are ART jars and core-icu4j.jar
+// that have been historically part of the boot image and are now in apexes; they are in boot images
+// and core-icu4j.jar is generally treated as being part of PRODUCT_BOOT_JARS.
+//
+// One exception to the above rules are "coverage" builds (a special build flavor which requires
+// setting environment variable EMMA_INSTRUMENT_FRAMEWORK=true). In coverage builds the Java code in
+// boot image libraries is instrumented, which means that the instrumentation library (jacocoagent)
+// needs to be added to the list of bootclasspath DEX jars.
+//
+// In general, there is a requirement that the source code for a boot image library must be
+// available at build time (e.g. it cannot be a stub that has a separate implementation library).
+//
+// 2.2. Static configs
+// -------------------
+//
+// Because boot images are used to dexpreopt other Java modules, the paths to boot image files must
+// be known by the time dexpreopt build rules for the dependent modules are generated. Boot image
+// configs are constructed very early during the build, before build rule generation. The configs
+// provide predefined paths to boot image files (these paths depend only on static build
+// configuration, such as PRODUCT variables, and use hard-coded directory names).
+//
+// 2.3. Singleton
+// --------------
+//
+// Build rules for the boot images are generated with a Soong singleton. Because a singleton has no
+// dependencies on other modules, it has to find the modules for the DEX jars using VisitAllModules.
+// Soong loops through all modules and compares each module against a list of bootclasspath library
+// names. Then it generates build rules that copy DEX jars from their intermediate module-specific
+// locations to the hard-coded locations predefined in the boot image configs.
+//
+// It would be possible to use a module with proper dependencies instead, but that would require
+// changes in the way Soong generates variables for Make: a singleton can use one MakeVars() method
+// that writes variables to out/soong/make_vars-*.mk, which is included early by the main makefile,
+// but module(s) would have to use out/soong/Android-*.mk which has a group of LOCAL_* variables
+// for each module, and is included later.
+//
+// 2.4. Install rules
+// ------------------
+//
+// The primary boot image and the Framework extension are installed in different ways. The primary
+// boot image is part of the ART APEX: it is copied into the APEX intermediate files, packaged
+// together with other APEX contents, extracted and mounted on device. The Framework boot image
+// extension is installed by the rules defined in makefiles (make/core/dex_preopt_libart.mk). Soong
+// writes out a few DEXPREOPT_IMAGE_* variables for Make; these variables contain boot image names,
+// paths and so on.
+//
+
+var artApexNames = []string{
+	"com.android.art",
+	"com.android.art.debug",
+	"com.android.art.testing",
+	"com.google.android.art",
+	"com.google.android.art.debug",
+	"com.google.android.art.testing",
+}
+
+func init() {
+	RegisterDexpreoptBootJarsComponents(android.InitRegistrationContext)
+}
+
+// Target-independent description of a boot image.
+type bootImageConfig struct {
+	// If this image is an extension, the image that it extends.
+	extends *bootImageConfig
+
+	// Image name (used in directory names and ninja rule names).
+	name string
+
+	// Basename of the image: the resulting filenames are <stem>[-<jar>].{art,oat,vdex}.
+	stem string
+
+	// Output directory for the image files.
+	dir android.OutputPath
+
+	// Output directory for the image files with debug symbols.
+	symbolsDir android.OutputPath
+
+	// Subdirectory where the image files are installed.
+	installDirOnHost string
+
+	// Subdirectory where the image files on device are installed.
+	installDirOnDevice string
+
+	// Install path of the boot image profile if it needs to be installed in the APEX, or empty if not
+	// needed.
+	profileInstallPathInApex string
+
+	// A list of (location, jar) pairs for the Java modules in this image.
+	modules android.ConfiguredJarList
+
+	// File paths to jars.
+	dexPaths     android.WritablePaths // for this image
+	dexPathsDeps android.WritablePaths // for the dependency images and in this image
+
+	// Map from module name (without prebuilt_ prefix) to the predefined build path.
+	dexPathsByModule map[string]android.WritablePath
+
+	// File path to a zip archive with all image files (or nil, if not needed).
+	zip android.WritablePath
+
+	// Rules which should be used in make to install the outputs.
+	profileInstalls android.RuleBuilderInstalls
+
+	// Path to the license metadata file for the module that built the profile.
+	profileLicenseMetadataFile android.OptionalPath
+
+	// Path to the image profile file on host (or empty, if profile is not generated).
+	profilePathOnHost android.Path
+
+	// Target-dependent fields.
+	variants []*bootImageVariant
+
+	// Path of the preloaded classes file.
+	preloadedClassesFile string
+}
+
+// Target-dependent description of a boot image.
+type bootImageVariant struct {
+	*bootImageConfig
+
+	// Target for which the image is generated.
+	target android.Target
+
+	// The "locations" of jars.
+	dexLocations     []string // for this image
+	dexLocationsDeps []string // for the dependency images and in this image
+
+	// Paths to image files.
+	imagePathOnHost   android.OutputPath // first image file path on host
+	imagePathOnDevice string             // first image file path on device
+
+	// All the files that constitute this image variant, i.e. .art, .oat and .vdex files.
+	imagesDeps android.OutputPaths
+
+	// The path to the primary image variant's imagePathOnHost field, where primary image variant
+	// means the image variant that this extends.
+	//
+	// This is only set for a variant of an image that extends another image.
+	primaryImages android.OutputPath
+
+	// The paths to the primary image variant's imagesDeps field, where primary image variant
+	// means the image variant that this extends.
+	//
+	// This is only set for a variant of an image that extends another image.
+	primaryImagesDeps android.Paths
+
+	// Rules which should be used in make to install the outputs on host.
+	installs           android.RuleBuilderInstalls
+	vdexInstalls       android.RuleBuilderInstalls
+	unstrippedInstalls android.RuleBuilderInstalls
+
+	// Rules which should be used in make to install the outputs on device.
+	deviceInstalls android.RuleBuilderInstalls
+
+	// Path to the license metadata file for the module that built the image.
+	licenseMetadataFile android.OptionalPath
+}
+
+// Get target-specific boot image variant for the given boot image config and target.
+func (image bootImageConfig) getVariant(target android.Target) *bootImageVariant {
+	for _, variant := range image.variants {
+		if variant.target.Os == target.Os && variant.target.Arch.ArchType == target.Arch.ArchType {
+			return variant
+		}
+	}
+	return nil
+}
+
+// Return any (the first) variant which is for the device (as opposed to for the host).
+func (image bootImageConfig) getAnyAndroidVariant() *bootImageVariant {
+	for _, variant := range image.variants {
+		if variant.target.Os == android.Android {
+			return variant
+		}
+	}
+	return nil
+}
+
+// Return the name of a boot image module given a boot image config and a component (module) index.
+// A module name is a combination of the Java library name, and the boot image stem (that is stored
+// in the config).
+func (image bootImageConfig) moduleName(ctx android.PathContext, idx int) string {
+	// The first module of the primary boot image is special: its module name has only the stem, but
+	// not the library name. All other module names are of the form <stem>-<library name>
+	m := image.modules.Jar(idx)
+	name := image.stem
+	if idx != 0 || image.extends != nil {
+		name += "-" + android.ModuleStem(m)
+	}
+	return name
+}
+
+// Return the name of the first boot image module, or stem if the list of modules is empty.
+func (image bootImageConfig) firstModuleNameOrStem(ctx android.PathContext) string {
+	if image.modules.Len() > 0 {
+		return image.moduleName(ctx, 0)
+	} else {
+		return image.stem
+	}
+}
+
+// Return filenames for the given boot image component, given the output directory and a list of
+// extensions.
+func (image bootImageConfig) moduleFiles(ctx android.PathContext, dir android.OutputPath, exts ...string) android.OutputPaths {
+	ret := make(android.OutputPaths, 0, image.modules.Len()*len(exts))
+	for i := 0; i < image.modules.Len(); i++ {
+		name := image.moduleName(ctx, i)
+		for _, ext := range exts {
+			ret = append(ret, dir.Join(ctx, name+ext))
+		}
+	}
+	return ret
+}
+
+// apexVariants returns a list of all *bootImageVariant that could be included in an apex.
+func (image *bootImageConfig) apexVariants() []*bootImageVariant {
+	variants := []*bootImageVariant{}
+	for _, variant := range image.variants {
+		// We also generate boot images for host (for testing), but we don't need those in the apex.
+		// TODO(b/177892522) - consider changing this to check Os.OsClass = android.Device
+		if variant.target.Os == android.Android {
+			variants = append(variants, variant)
+		}
+	}
+	return variants
+}
+
+// Returns true if the boot image should be installed in the APEX.
+func (image *bootImageConfig) shouldInstallInApex() bool {
+	return strings.HasPrefix(image.installDirOnDevice, "apex/")
+}
+
+// Return boot image locations (as a list of symbolic paths).
+//
+// The image "location" is a symbolic path that, with multiarchitecture support, doesn't really
+// exist on the device. Typically it is /apex/com.android.art/javalib/boot.art and should be the
+// same for all supported architectures on the device. The concrete architecture specific files
+// actually end up in architecture-specific sub-directory such as arm, arm64, x86, or x86_64.
+//
+// For example a physical file /apex/com.android.art/javalib/x86/boot.art has "image location"
+// /apex/com.android.art/javalib/boot.art (which is not an actual file).
+//
+// For a primary boot image the list of locations has a single element.
+//
+// For a boot image extension the list of locations contains a location for all dependency images
+// (including the primary image) and the location of the extension itself. For example, for the
+// Framework boot image extension that depends on the primary ART boot image the list contains two
+// elements.
+//
+// The location is passed as an argument to the ART tools like dex2oat instead of the real path.
+// ART tools will then reconstruct the architecture-specific real path.
+//
+func (image *bootImageVariant) imageLocations() (imageLocationsOnHost []string, imageLocationsOnDevice []string) {
+	if image.extends != nil {
+		imageLocationsOnHost, imageLocationsOnDevice = image.extends.getVariant(image.target).imageLocations()
+	}
+	return append(imageLocationsOnHost, dexpreopt.PathToLocation(image.imagePathOnHost, image.target.Arch.ArchType)),
+		append(imageLocationsOnDevice, dexpreopt.PathStringToLocation(image.imagePathOnDevice, image.target.Arch.ArchType))
+}
+
+func dexpreoptBootJarsFactory() android.SingletonModule {
+	m := &dexpreoptBootJars{}
+	android.InitAndroidModule(m)
+	return m
+}
+
+func RegisterDexpreoptBootJarsComponents(ctx android.RegistrationContext) {
+	ctx.RegisterSingletonModuleType("dex_bootjars", dexpreoptBootJarsFactory)
+}
+
+func SkipDexpreoptBootJars(ctx android.PathContext) bool {
+	return dexpreopt.GetGlobalConfig(ctx).DisablePreoptBootImages
+}
+
+// Singleton module for generating boot image build rules.
+type dexpreoptBootJars struct {
+	android.SingletonModuleBase
+
+	// Default boot image config (currently always the Framework boot image extension). It should be
+	// noted that JIT-Zygote builds use ART APEX image instead of the Framework boot image extension,
+	// but the switch is handled not here, but in the makefiles (triggered with
+	// DEXPREOPT_USE_ART_IMAGE=true).
+	defaultBootImage *bootImageConfig
+
+	// Build path to a config file that Soong writes for Make (to be used in makefiles that install
+	// the default boot image).
+	dexpreoptConfigForMake android.WritablePath
+}
+
+// Provide paths to boot images for use by modules that depend upon them.
+//
+// The build rules are created in GenerateSingletonBuildActions().
+func (d *dexpreoptBootJars) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// Placeholder for now.
+}
+
+// Generate build rules for boot images.
+func (d *dexpreoptBootJars) GenerateSingletonBuildActions(ctx android.SingletonContext) {
+	if SkipDexpreoptBootJars(ctx) {
+		return
+	}
+	if dexpreopt.GetCachedGlobalSoongConfig(ctx) == nil {
+		// No module has enabled dexpreopting, so we assume there will be no boot image to make.
+		return
+	}
+
+	d.dexpreoptConfigForMake = android.PathForOutput(ctx, ctx.Config().DeviceName(), "dexpreopt.config")
+	writeGlobalConfigForMake(ctx, d.dexpreoptConfigForMake)
+
+	global := dexpreopt.GetGlobalConfig(ctx)
+	if !shouldBuildBootImages(ctx.Config(), global) {
+		return
+	}
+
+	defaultImageConfig := defaultBootImageConfig(ctx)
+	d.defaultBootImage = defaultImageConfig
+}
+
+// shouldBuildBootImages determines whether boot images should be built.
+func shouldBuildBootImages(config android.Config, global *dexpreopt.GlobalConfig) bool {
+	// Skip recompiling the boot image for the second sanitization phase. We'll get separate paths
+	// and invalidate first-stage artifacts which are crucial to SANITIZE_LITE builds.
+	// Note: this is technically incorrect. Compiled code contains stack checks which may depend
+	//       on ASAN settings.
+	if len(config.SanitizeDevice()) == 1 && config.SanitizeDevice()[0] == "address" && global.SanitizeLite {
+		return false
+	}
+	return true
+}
+
+// copyBootJarsToPredefinedLocations generates commands that will copy boot jars to predefined
+// paths in the global config.
+func copyBootJarsToPredefinedLocations(ctx android.ModuleContext, srcBootDexJarsByModule bootDexJarByModule, dstBootJarsByModule map[string]android.WritablePath) {
+	// Create the super set of module names.
+	names := []string{}
+	names = append(names, android.SortedStringKeys(srcBootDexJarsByModule)...)
+	names = append(names, android.SortedStringKeys(dstBootJarsByModule)...)
+	names = android.SortedUniqueStrings(names)
+	for _, name := range names {
+		src := srcBootDexJarsByModule[name]
+		dst := dstBootJarsByModule[name]
+
+		if src == nil {
+			// A dex boot jar should be provided by the source java module. It needs to be installable or
+			// have compile_dex=true - cf. assignments to java.Module.dexJarFile.
+			//
+			// However, the source java module may be either replaced or overridden (using prefer:true) by
+			// a prebuilt java module with the same name. In that case the dex boot jar needs to be
+			// provided by the corresponding prebuilt APEX module. That APEX is the one that refers
+			// through a exported_(boot|systemserver)classpath_fragments property to a
+			// prebuilt_(boot|systemserver)classpath_fragment module, which in turn lists the prebuilt
+			// java module in the contents property. If that chain is broken then this dependency will
+			// fail.
+			if !ctx.Config().AllowMissingDependencies() {
+				ctx.ModuleErrorf("module %s does not provide a dex boot jar (see comment next to this message in Soong for details)", name)
+			} else {
+				ctx.AddMissingDependencies([]string{name})
+			}
+		} else if dst == nil {
+			ctx.ModuleErrorf("module %s is not part of the boot configuration", name)
+		} else {
+			ctx.Build(pctx, android.BuildParams{
+				Rule:   android.Cp,
+				Input:  src,
+				Output: dst,
+			})
+		}
+	}
+}
+
+// buildBootImageVariantsForAndroidOs generates rules to build the boot image variants for the
+// android.Android OsType and returns a map from the architectures to the paths of the generated
+// boot image files.
+//
+// The paths are returned because they are needed elsewhere in Soong, e.g. for populating an APEX.
+func buildBootImageVariantsForAndroidOs(ctx android.ModuleContext, image *bootImageConfig, profile android.WritablePath) bootImageFilesByArch {
+	return buildBootImageForOsType(ctx, image, profile, android.Android)
+}
+
+// buildBootImageVariantsForBuildOs generates rules to build the boot image variants for the
+// config.BuildOS OsType, i.e. the type of OS on which the build is being running.
+//
+// The files need to be generated into their predefined location because they are used from there
+// both within Soong and outside, e.g. for ART based host side testing and also for use by some
+// cloud based tools. However, they are not needed by callers of this function and so the paths do
+// not need to be returned from this func, unlike the buildBootImageVariantsForAndroidOs func.
+func buildBootImageVariantsForBuildOs(ctx android.ModuleContext, image *bootImageConfig, profile android.WritablePath) {
+	buildBootImageForOsType(ctx, image, profile, ctx.Config().BuildOS)
+}
+
+// buildBootImageForOsType takes a bootImageConfig, a profile file and an android.OsType
+// boot image files are required for and it creates rules to build the boot image
+// files for all the required architectures for them.
+//
+// It returns a map from android.ArchType to the predefined paths of the boot image files.
+func buildBootImageForOsType(ctx android.ModuleContext, image *bootImageConfig, profile android.WritablePath, requiredOsType android.OsType) bootImageFilesByArch {
+	filesByArch := bootImageFilesByArch{}
+	for _, variant := range image.variants {
+		if variant.target.Os == requiredOsType {
+			buildBootImageVariant(ctx, variant, profile)
+			filesByArch[variant.target.Arch.ArchType] = variant.imagesDeps.Paths()
+		}
+	}
+
+	return filesByArch
+}
+
+// buildBootImageZipInPredefinedLocation generates a zip file containing all the boot image files.
+//
+// The supplied filesByArch is nil when the boot image files have not been generated. Otherwise, it
+// is a map from android.ArchType to the predefined locations.
+func buildBootImageZipInPredefinedLocation(ctx android.ModuleContext, image *bootImageConfig, filesByArch bootImageFilesByArch) {
+	if filesByArch == nil {
+		return
+	}
+
+	// Compute the list of files from all the architectures.
+	zipFiles := android.Paths{}
+	for _, archType := range android.ArchTypeList() {
+		zipFiles = append(zipFiles, filesByArch[archType]...)
+	}
+
+	rule := android.NewRuleBuilder(pctx, ctx)
+	rule.Command().
+		BuiltTool("soong_zip").
+		FlagWithOutput("-o ", image.zip).
+		FlagWithArg("-C ", image.dir.Join(ctx, android.Android.String()).String()).
+		FlagWithInputList("-f ", zipFiles, " -f ")
+
+	rule.Build("zip_"+image.name, "zip "+image.name+" image")
+}
+
+// Generate boot image build rules for a specific target.
+func buildBootImageVariant(ctx android.ModuleContext, image *bootImageVariant, profile android.Path) {
+
+	globalSoong := dexpreopt.GetGlobalSoongConfig(ctx)
+	global := dexpreopt.GetGlobalConfig(ctx)
+
+	arch := image.target.Arch.ArchType
+	os := image.target.Os.String() // We need to distinguish host-x86 and device-x86.
+	symbolsDir := image.symbolsDir.Join(ctx, os, image.installDirOnHost, arch.String())
+	symbolsFile := symbolsDir.Join(ctx, image.stem+".oat")
+	outputDir := image.dir.Join(ctx, os, image.installDirOnHost, arch.String())
+	outputPath := outputDir.Join(ctx, image.stem+".oat")
+	oatLocation := dexpreopt.PathToLocation(outputPath, arch)
+	imagePath := outputPath.ReplaceExtension(ctx, "art")
+
+	rule := android.NewRuleBuilder(pctx, ctx)
+
+	rule.Command().Text("mkdir").Flag("-p").Flag(symbolsDir.String())
+	rule.Command().Text("rm").Flag("-f").
+		Flag(symbolsDir.Join(ctx, "*.art").String()).
+		Flag(symbolsDir.Join(ctx, "*.oat").String()).
+		Flag(symbolsDir.Join(ctx, "*.invocation").String())
+	rule.Command().Text("rm").Flag("-f").
+		Flag(outputDir.Join(ctx, "*.art").String()).
+		Flag(outputDir.Join(ctx, "*.oat").String()).
+		Flag(outputDir.Join(ctx, "*.invocation").String())
+
+	cmd := rule.Command()
+
+	extraFlags := ctx.Config().Getenv("ART_BOOT_IMAGE_EXTRA_ARGS")
+	if extraFlags == "" {
+		// Use ANDROID_LOG_TAGS to suppress most logging by default...
+		cmd.Text(`ANDROID_LOG_TAGS="*:e"`)
+	} else {
+		// ...unless the boot image is generated specifically for testing, then allow all logging.
+		cmd.Text(`ANDROID_LOG_TAGS="*:v"`)
+	}
+
+	invocationPath := outputPath.ReplaceExtension(ctx, "invocation")
+
+	cmd.Tool(globalSoong.Dex2oat).
+		Flag("--avoid-storing-invocation").
+		FlagWithOutput("--write-invocation-to=", invocationPath).ImplicitOutput(invocationPath).
+		Flag("--runtime-arg").FlagWithArg("-Xms", global.Dex2oatImageXms).
+		Flag("--runtime-arg").FlagWithArg("-Xmx", global.Dex2oatImageXmx)
+
+	if profile != nil {
+		cmd.FlagWithInput("--profile-file=", profile)
+	}
+
+	dirtyImageFile := "frameworks/base/config/dirty-image-objects"
+	dirtyImagePath := android.ExistentPathForSource(ctx, dirtyImageFile)
+	if dirtyImagePath.Valid() {
+		cmd.FlagWithInput("--dirty-image-objects=", dirtyImagePath.Path())
+	}
+
+	if image.extends != nil {
+		// It is a boot image extension, so it needs the boot image it depends on (in this case the
+		// primary ART APEX image).
+		artImage := image.primaryImages
+		cmd.
+			Flag("--runtime-arg").FlagWithInputList("-Xbootclasspath:", image.dexPathsDeps.Paths(), ":").
+			Flag("--runtime-arg").FlagWithList("-Xbootclasspath-locations:", image.dexLocationsDeps, ":").
+			// Add the path to the first file in the boot image with the arch specific directory removed,
+			// dex2oat will reconstruct the path to the actual file when it needs it. As the actual path
+			// to the file cannot be passed to the command make sure to add the actual path as an Implicit
+			// dependency to ensure that it is built before the command runs.
+			FlagWithArg("--boot-image=", dexpreopt.PathToLocation(artImage, arch)).Implicit(artImage).
+			// Similarly, the dex2oat tool will automatically find the paths to other files in the base
+			// boot image so make sure to add them as implicit dependencies to ensure that they are built
+			// before this command is run.
+			Implicits(image.primaryImagesDeps)
+	} else {
+		// It is a primary image, so it needs a base address.
+		cmd.FlagWithArg("--base=", ctx.Config().LibartImgDeviceBaseAddress())
+	}
+
+	// We always expect a preloaded classes file to be available. However, if we cannot find it, it's
+	// OK to not pass the flag to dex2oat.
+	preloadedClassesPath := android.ExistentPathForSource(ctx, image.preloadedClassesFile)
+	if preloadedClassesPath.Valid() {
+		cmd.FlagWithInput("--preloaded-classes=", preloadedClassesPath.Path())
+	}
+
+	cmd.
+		FlagForEachInput("--dex-file=", image.dexPaths.Paths()).
+		FlagForEachArg("--dex-location=", image.dexLocations).
+		Flag("--generate-debug-info").
+		Flag("--generate-build-id").
+		Flag("--image-format=lz4hc").
+		FlagWithArg("--oat-symbols=", symbolsFile.String()).
+		Flag("--strip").
+		FlagWithArg("--oat-file=", outputPath.String()).
+		FlagWithArg("--oat-location=", oatLocation).
+		FlagWithArg("--image=", imagePath.String()).
+		FlagWithArg("--instruction-set=", arch.String()).
+		FlagWithArg("--android-root=", global.EmptyDirectory).
+		FlagWithArg("--no-inline-from=", "core-oj.jar").
+		Flag("--force-determinism").
+		Flag("--abort-on-hard-verifier-error")
+
+	// Use the default variant/features for host builds.
+	// The map below contains only device CPU info (which might be x86 on some devices).
+	if image.target.Os == android.Android {
+		cmd.FlagWithArg("--instruction-set-variant=", global.CpuVariant[arch])
+		cmd.FlagWithArg("--instruction-set-features=", global.InstructionSetFeatures[arch])
+	}
+
+	if global.BootFlags != "" {
+		cmd.Flag(global.BootFlags)
+	}
+
+	if extraFlags != "" {
+		cmd.Flag(extraFlags)
+	}
+
+	cmd.Textf(`|| ( echo %s ; false )`, proptools.ShellEscape(failureMessage))
+
+	installDir := filepath.Join("/", image.installDirOnHost, arch.String())
+
+	var vdexInstalls android.RuleBuilderInstalls
+	var unstrippedInstalls android.RuleBuilderInstalls
+	var deviceInstalls android.RuleBuilderInstalls
+
+	for _, artOrOat := range image.moduleFiles(ctx, outputDir, ".art", ".oat") {
+		cmd.ImplicitOutput(artOrOat)
+
+		// Install the .oat and .art files
+		rule.Install(artOrOat, filepath.Join(installDir, artOrOat.Base()))
+	}
+
+	for _, vdex := range image.moduleFiles(ctx, outputDir, ".vdex") {
+		cmd.ImplicitOutput(vdex)
+
+		// Note that the vdex files are identical between architectures.
+		// Make rules will create symlinks to share them between architectures.
+		vdexInstalls = append(vdexInstalls,
+			android.RuleBuilderInstall{vdex, filepath.Join(installDir, vdex.Base())})
+	}
+
+	for _, unstrippedOat := range image.moduleFiles(ctx, symbolsDir, ".oat") {
+		cmd.ImplicitOutput(unstrippedOat)
+
+		// Install the unstripped oat files.  The Make rules will put these in $(TARGET_OUT_UNSTRIPPED)
+		unstrippedInstalls = append(unstrippedInstalls,
+			android.RuleBuilderInstall{unstrippedOat, filepath.Join(installDir, unstrippedOat.Base())})
+	}
+
+	if image.installDirOnHost != image.installDirOnDevice && !image.shouldInstallInApex() && !ctx.Config().UnbundledBuild() {
+		installDirOnDevice := filepath.Join("/", image.installDirOnDevice, arch.String())
+		for _, file := range image.moduleFiles(ctx, outputDir, ".art", ".oat", ".vdex") {
+			deviceInstalls = append(deviceInstalls,
+				android.RuleBuilderInstall{file, filepath.Join(installDirOnDevice, file.Base())})
+		}
+	}
+
+	rule.Build(image.name+"JarsDexpreopt_"+image.target.String(), "dexpreopt "+image.name+" jars "+arch.String())
+
+	// save output and installed files for makevars
+	image.installs = rule.Installs()
+	image.vdexInstalls = vdexInstalls
+	image.unstrippedInstalls = unstrippedInstalls
+	image.deviceInstalls = deviceInstalls
+	image.licenseMetadataFile = android.OptionalPathForPath(ctx.LicenseMetadataFile())
+}
+
+const failureMessage = `ERROR: Dex2oat failed to compile a boot image.
+It is likely that the boot classpath is inconsistent.
+Rebuild with ART_BOOT_IMAGE_EXTRA_ARGS="--runtime-arg -verbose:verifier" to see verification errors.`
+
+func bootImageProfileRule(ctx android.ModuleContext, image *bootImageConfig) android.WritablePath {
+	globalSoong := dexpreopt.GetGlobalSoongConfig(ctx)
+	global := dexpreopt.GetGlobalConfig(ctx)
+
+	if global.DisableGenerateProfile {
+		return nil
+	}
+
+	defaultProfile := "frameworks/base/config/boot-image-profile.txt"
+
+	rule := android.NewRuleBuilder(pctx, ctx)
+
+	var bootImageProfile android.Path
+	if len(global.BootImageProfiles) > 1 {
+		combinedBootImageProfile := image.dir.Join(ctx, "boot-image-profile.txt")
+		rule.Command().Text("cat").Inputs(global.BootImageProfiles).Text(">").Output(combinedBootImageProfile)
+		bootImageProfile = combinedBootImageProfile
+	} else if len(global.BootImageProfiles) == 1 {
+		bootImageProfile = global.BootImageProfiles[0]
+	} else if path := android.ExistentPathForSource(ctx, defaultProfile); path.Valid() {
+		bootImageProfile = path.Path()
+	} else {
+		// No profile (not even a default one, which is the case on some branches
+		// like master-art-host that don't have frameworks/base).
+		// Return nil and continue without profile.
+		return nil
+	}
+
+	profile := image.dir.Join(ctx, "boot.prof")
+
+	rule.Command().
+		Text(`ANDROID_LOG_TAGS="*:e"`).
+		Tool(globalSoong.Profman).
+		Flag("--output-profile-type=boot").
+		FlagWithInput("--create-profile-from=", bootImageProfile).
+		FlagForEachInput("--apk=", image.dexPathsDeps.Paths()).
+		FlagForEachArg("--dex-location=", image.getAnyAndroidVariant().dexLocationsDeps).
+		FlagWithOutput("--reference-profile-file=", profile)
+
+	if image == defaultBootImageConfig(ctx) {
+		rule.Install(profile, "/system/etc/boot-image.prof")
+		image.profileInstalls = append(image.profileInstalls, rule.Installs()...)
+		image.profileLicenseMetadataFile = android.OptionalPathForPath(ctx.LicenseMetadataFile())
+	}
+
+	rule.Build("bootJarsProfile", "profile boot jars")
+
+	image.profilePathOnHost = profile
+
+	return profile
+}
+
+// bootFrameworkProfileRule generates the rule to create the boot framework profile and
+// returns a path to the generated file.
+func bootFrameworkProfileRule(ctx android.ModuleContext, image *bootImageConfig) android.WritablePath {
+	globalSoong := dexpreopt.GetGlobalSoongConfig(ctx)
+	global := dexpreopt.GetGlobalConfig(ctx)
+
+	if global.DisableGenerateProfile || ctx.Config().UnbundledBuild() {
+		return nil
+	}
+
+	defaultProfile := "frameworks/base/config/boot-profile.txt"
+	bootFrameworkProfile := android.PathForSource(ctx, defaultProfile)
+
+	profile := image.dir.Join(ctx, "boot.bprof")
+
+	rule := android.NewRuleBuilder(pctx, ctx)
+	rule.Command().
+		Text(`ANDROID_LOG_TAGS="*:e"`).
+		Tool(globalSoong.Profman).
+		Flag("--output-profile-type=bprof").
+		FlagWithInput("--create-profile-from=", bootFrameworkProfile).
+		FlagForEachInput("--apk=", image.dexPathsDeps.Paths()).
+		FlagForEachArg("--dex-location=", image.getAnyAndroidVariant().dexLocationsDeps).
+		FlagWithOutput("--reference-profile-file=", profile)
+
+	rule.Install(profile, "/system/etc/boot-image.bprof")
+	rule.Build("bootFrameworkProfile", "profile boot framework jars")
+	image.profileInstalls = append(image.profileInstalls, rule.Installs()...)
+	image.profileLicenseMetadataFile = android.OptionalPathForPath(ctx.LicenseMetadataFile())
+
+	return profile
+}
+
+func dumpOatRules(ctx android.ModuleContext, image *bootImageConfig) {
+	var allPhonies android.Paths
+	for _, image := range image.variants {
+		arch := image.target.Arch.ArchType
+		suffix := arch.String()
+		// Host and target might both use x86 arch. We need to ensure the names are unique.
+		if image.target.Os.Class == android.Host {
+			suffix = "host-" + suffix
+		}
+		// Create a rule to call oatdump.
+		output := android.PathForOutput(ctx, "boot."+suffix+".oatdump.txt")
+		rule := android.NewRuleBuilder(pctx, ctx)
+		imageLocationsOnHost, _ := image.imageLocations()
+		rule.Command().
+			BuiltTool("oatdump").
+			FlagWithInputList("--runtime-arg -Xbootclasspath:", image.dexPathsDeps.Paths(), ":").
+			FlagWithList("--runtime-arg -Xbootclasspath-locations:", image.dexLocationsDeps, ":").
+			FlagWithArg("--image=", strings.Join(imageLocationsOnHost, ":")).Implicits(image.imagesDeps.Paths()).
+			FlagWithOutput("--output=", output).
+			FlagWithArg("--instruction-set=", arch.String())
+		rule.Build("dump-oat-boot-"+suffix, "dump oat boot "+arch.String())
+
+		// Create a phony rule that depends on the output file and prints the path.
+		phony := android.PathForPhony(ctx, "dump-oat-boot-"+suffix)
+		rule = android.NewRuleBuilder(pctx, ctx)
+		rule.Command().
+			Implicit(output).
+			ImplicitOutput(phony).
+			Text("echo").FlagWithArg("Output in ", output.String())
+		rule.Build("phony-dump-oat-boot-"+suffix, "dump oat boot "+arch.String())
+
+		allPhonies = append(allPhonies, phony)
+	}
+
+	phony := android.PathForPhony(ctx, "dump-oat-boot")
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        android.Phony,
+		Output:      phony,
+		Inputs:      allPhonies,
+		Description: "dump-oat-boot",
+	})
+}
+
+func writeGlobalConfigForMake(ctx android.SingletonContext, path android.WritablePath) {
+	data := dexpreopt.GetGlobalConfigRawData(ctx)
+
+	android.WriteFileRule(ctx, path, string(data))
+}
+
+// Define Make variables for boot image names, paths, etc. These variables are used in makefiles
+// (make/core/dex_preopt_libart.mk) to generate install rules that copy boot image files to the
+// correct output directories.
+func (d *dexpreoptBootJars) MakeVars(ctx android.MakeVarsContext) {
+	if d.dexpreoptConfigForMake != nil {
+		ctx.Strict("DEX_PREOPT_CONFIG_FOR_MAKE", d.dexpreoptConfigForMake.String())
+		ctx.Strict("DEX_PREOPT_SOONG_CONFIG_FOR_MAKE", android.PathForOutput(ctx, "dexpreopt_soong.config").String())
+	}
+
+	image := d.defaultBootImage
+	if image == nil {
+		return
+	}
+
+	ctx.Strict("DEXPREOPT_IMAGE_PROFILE_BUILT_INSTALLED", image.profileInstalls.String())
+	if image.profileLicenseMetadataFile.Valid() {
+		ctx.Strict("DEXPREOPT_IMAGE_PROFILE_LICENSE_METADATA", image.profileLicenseMetadataFile.String())
+	}
+
+	global := dexpreopt.GetGlobalConfig(ctx)
+	dexPaths, dexLocations := bcpForDexpreopt(ctx, global.PreoptWithUpdatableBcp)
+	ctx.Strict("DEXPREOPT_BOOTCLASSPATH_DEX_FILES", strings.Join(dexPaths.Strings(), " "))
+	ctx.Strict("DEXPREOPT_BOOTCLASSPATH_DEX_LOCATIONS", strings.Join(dexLocations, " "))
+
+	for _, variant := range image.variants {
+		suffix := ""
+		if variant.target.Os.Class == android.Host {
+			suffix = "_host"
+		}
+		sfx := suffix + "_" + variant.target.Arch.ArchType.String()
+		ctx.Strict("DEXPREOPT_IMAGE_VDEX_BUILT_INSTALLED_"+sfx, variant.vdexInstalls.String())
+		ctx.Strict("DEXPREOPT_IMAGE_"+sfx, variant.imagePathOnHost.String())
+		ctx.Strict("DEXPREOPT_IMAGE_DEPS_"+sfx, strings.Join(variant.imagesDeps.Strings(), " "))
+		ctx.Strict("DEXPREOPT_IMAGE_BUILT_INSTALLED_"+sfx, variant.installs.String())
+		ctx.Strict("DEXPREOPT_IMAGE_UNSTRIPPED_BUILT_INSTALLED_"+sfx, variant.unstrippedInstalls.String())
+		if variant.licenseMetadataFile.Valid() {
+			ctx.Strict("DEXPREOPT_IMAGE_LICENSE_METADATA_"+sfx, variant.licenseMetadataFile.String())
+		}
+	}
+	imageLocationsOnHost, imageLocationsOnDevice := image.getAnyAndroidVariant().imageLocations()
+	ctx.Strict("DEXPREOPT_IMAGE_LOCATIONS_ON_HOST", strings.Join(imageLocationsOnHost, ":"))
+	ctx.Strict("DEXPREOPT_IMAGE_LOCATIONS_ON_DEVICE", strings.Join(imageLocationsOnDevice, ":"))
+	ctx.Strict("DEXPREOPT_IMAGE_ZIP", image.zip.String())
+
+	// There used to be multiple images for JIT-Zygote mode, not there's only one.
+	ctx.Strict("DEXPREOPT_IMAGE_NAMES", image.name)
+}
diff --git a/java/dexpreopt_config.go_v1 b/java/dexpreopt_config.go_v1
new file mode 100644
index 0000000..d71e2bb
--- /dev/null
+++ b/java/dexpreopt_config.go_v1
@@ -0,0 +1,215 @@
+// Copyright 2019 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 java
+
+import (
+	"path/filepath"
+	"strings"
+
+	"android/soong/android"
+	"android/soong/dexpreopt"
+)
+
+// dexpreoptTargets returns the list of targets that are relevant to dexpreopting, which excludes architectures
+// supported through native bridge.
+func dexpreoptTargets(ctx android.PathContext) []android.Target {
+	var targets []android.Target
+	for _, target := range ctx.Config().Targets[android.Android] {
+		if target.NativeBridge == android.NativeBridgeDisabled {
+			targets = append(targets, target)
+		}
+	}
+	// We may also need the images on host in order to run host-based tests.
+	for _, target := range ctx.Config().Targets[ctx.Config().BuildOS] {
+		targets = append(targets, target)
+	}
+
+	return targets
+}
+
+var (
+	bootImageConfigKey     = android.NewOnceKey("bootImageConfig")
+	bootImageConfigRawKey  = android.NewOnceKey("bootImageConfigRaw")
+	artBootImageName       = "art"
+	frameworkBootImageName = "boot"
+)
+
+func genBootImageConfigRaw(ctx android.PathContext) map[string]*bootImageConfig {
+	return ctx.Config().Once(bootImageConfigRawKey, func() interface{} {
+		global := dexpreopt.GetGlobalConfig(ctx)
+
+		artModules := global.ArtApexJars
+		frameworkModules := global.BootJars.RemoveList(artModules)
+
+		// ART config for the primary boot image in the ART apex.
+		// It includes the Core Libraries.
+		artCfg := bootImageConfig{
+			name:                     artBootImageName,
+			stem:                     "boot",
+			installDirOnHost:         "apex/art_boot_images/javalib",
+			installDirOnDevice:       "system/framework",
+			profileInstallPathInApex: "etc/boot-image.prof",
+			modules:                  artModules,
+			preloadedClassesFile:     "art/build/boot/preloaded-classes",
+		}
+
+		// Framework config for the boot image extension.
+		// It includes framework libraries and depends on the ART config.
+		frameworkSubdir := "system/framework"
+		frameworkCfg := bootImageConfig{
+			extends:              &artCfg,
+			name:                 frameworkBootImageName,
+			stem:                 "boot",
+			installDirOnHost:     frameworkSubdir,
+			installDirOnDevice:   frameworkSubdir,
+			modules:              frameworkModules,
+			preloadedClassesFile: "frameworks/base/config/preloaded-classes",
+		}
+
+		return map[string]*bootImageConfig{
+			artBootImageName:       &artCfg,
+			frameworkBootImageName: &frameworkCfg,
+		}
+	}).(map[string]*bootImageConfig)
+}
+
+// Construct the global boot image configs.
+func genBootImageConfigs(ctx android.PathContext) map[string]*bootImageConfig {
+	return ctx.Config().Once(bootImageConfigKey, func() interface{} {
+		targets := dexpreoptTargets(ctx)
+		deviceDir := android.PathForOutput(ctx, ctx.Config().DeviceName())
+
+		configs := genBootImageConfigRaw(ctx)
+		artCfg := configs[artBootImageName]
+		frameworkCfg := configs[frameworkBootImageName]
+
+		// common to all configs
+		for _, c := range configs {
+			c.dir = deviceDir.Join(ctx, "dex_"+c.name+"jars")
+			c.symbolsDir = deviceDir.Join(ctx, "dex_"+c.name+"jars_unstripped")
+
+			// expands to <stem>.art for primary image and <stem>-<1st module>.art for extension
+			imageName := c.firstModuleNameOrStem(ctx) + ".art"
+
+			// The path to bootclasspath dex files needs to be known at module
+			// GenerateAndroidBuildAction time, before the bootclasspath modules have been compiled.
+			// Set up known paths for them, the singleton rules will copy them there.
+			// TODO(b/143682396): use module dependencies instead
+			inputDir := deviceDir.Join(ctx, "dex_"+c.name+"jars_input")
+			c.dexPaths = c.modules.BuildPaths(ctx, inputDir)
+			c.dexPathsByModule = c.modules.BuildPathsByModule(ctx, inputDir)
+			c.dexPathsDeps = c.dexPaths
+
+			// Create target-specific variants.
+			for _, target := range targets {
+				arch := target.Arch.ArchType
+				imageDir := c.dir.Join(ctx, target.Os.String(), c.installDirOnHost, arch.String())
+				variant := &bootImageVariant{
+					bootImageConfig:   c,
+					target:            target,
+					imagePathOnHost:   imageDir.Join(ctx, imageName),
+					imagePathOnDevice: filepath.Join("/", c.installDirOnDevice, arch.String(), imageName),
+					imagesDeps:        c.moduleFiles(ctx, imageDir, ".art", ".oat", ".vdex"),
+					dexLocations:      c.modules.DevicePaths(ctx.Config(), target.Os),
+				}
+				variant.dexLocationsDeps = variant.dexLocations
+				c.variants = append(c.variants, variant)
+			}
+
+			c.zip = c.dir.Join(ctx, c.name+".zip")
+		}
+
+		// specific to the framework config
+		frameworkCfg.dexPathsDeps = append(artCfg.dexPathsDeps, frameworkCfg.dexPathsDeps...)
+		for i := range targets {
+			frameworkCfg.variants[i].primaryImages = artCfg.variants[i].imagePathOnHost
+			frameworkCfg.variants[i].primaryImagesDeps = artCfg.variants[i].imagesDeps.Paths()
+			frameworkCfg.variants[i].dexLocationsDeps = append(artCfg.variants[i].dexLocations, frameworkCfg.variants[i].dexLocationsDeps...)
+		}
+
+		return configs
+	}).(map[string]*bootImageConfig)
+}
+
+func defaultBootImageConfig(ctx android.PathContext) *bootImageConfig {
+	return genBootImageConfigs(ctx)[frameworkBootImageName]
+}
+
+// Apex boot config allows to access build/install paths of apex boot jars without going
+// through the usual trouble of registering dependencies on those modules and extracting build paths
+// from those dependencies.
+type apexBootConfig struct {
+	// A list of apex boot jars.
+	modules android.ConfiguredJarList
+
+	// A list of predefined build paths to apex boot jars. They are configured very early,
+	// before the modules for these jars are processed and the actual paths are generated, and
+	// later on a singleton adds commands to copy actual jars to the predefined paths.
+	dexPaths android.WritablePaths
+
+	// Map from module name (without prebuilt_ prefix) to the predefined build path.
+	dexPathsByModule map[string]android.WritablePath
+
+	// A list of dex locations (a.k.a. on-device paths) to the boot jars.
+	dexLocations []string
+}
+
+var updatableBootConfigKey = android.NewOnceKey("apexBootConfig")
+
+// Returns apex boot config.
+func GetApexBootConfig(ctx android.PathContext) apexBootConfig {
+	return ctx.Config().Once(updatableBootConfigKey, func() interface{} {
+		apexBootJars := dexpreopt.GetGlobalConfig(ctx).ApexBootJars
+
+		dir := android.PathForOutput(ctx, ctx.Config().DeviceName(), "apex_bootjars")
+		dexPaths := apexBootJars.BuildPaths(ctx, dir)
+		dexPathsByModuleName := apexBootJars.BuildPathsByModule(ctx, dir)
+
+		dexLocations := apexBootJars.DevicePaths(ctx.Config(), android.Android)
+
+		return apexBootConfig{apexBootJars, dexPaths, dexPathsByModuleName, dexLocations}
+	}).(apexBootConfig)
+}
+
+// Returns a list of paths and a list of locations for the boot jars used in dexpreopt (to be
+// passed in -Xbootclasspath and -Xbootclasspath-locations arguments for dex2oat).
+func bcpForDexpreopt(ctx android.PathContext, withUpdatable bool) (android.WritablePaths, []string) {
+	// Non-updatable boot jars (they are used both in the boot image and in dexpreopt).
+	bootImage := defaultBootImageConfig(ctx)
+	dexPaths := bootImage.dexPathsDeps
+	// The dex locations for all Android variants are identical.
+	dexLocations := bootImage.getAnyAndroidVariant().dexLocationsDeps
+
+	if withUpdatable {
+		// Apex boot jars (they are used only in dexpreopt, but not in the boot image).
+		apexBootConfig := GetApexBootConfig(ctx)
+		dexPaths = append(dexPaths, apexBootConfig.dexPaths...)
+		dexLocations = append(dexLocations, apexBootConfig.dexLocations...)
+	}
+
+	return dexPaths, dexLocations
+}
+
+var defaultBootclasspathKey = android.NewOnceKey("defaultBootclasspath")
+
+var copyOf = android.CopyOf
+
+func init() {
+	android.RegisterMakeVarsProvider(pctx, dexpreoptConfigMakevars)
+}
+
+func dexpreoptConfigMakevars(ctx android.MakeVarsContext) {
+	ctx.Strict("DEXPREOPT_BOOT_JARS_MODULES", strings.Join(defaultBootImageConfig(ctx).modules.CopyOfApexJarPairs(), ":"))
+}
diff --git a/java/java.go b/java/java.go
index 4e7e14c..13f4c80 100644
--- a/java/java.go
+++ b/java/java.go
@@ -300,19 +300,11 @@
 
 type usesLibraryDependencyTag struct {
 	dependencyTag
-
-	// SDK version in which the library appared as a standalone library.
-	sdkVersion int
-
-	// If the dependency is optional or required.
-	optional bool
-
-	// Whether this is an implicit dependency inferred by Soong, or an explicit one added via
-	// `uses_libs`/`optional_uses_libs` properties.
-	implicit bool
+	sdkVersion int  // SDK version in which the library appared as a standalone library.
+	optional   bool // If the dependency is optional or required.
 }
 
-func makeUsesLibraryDependencyTag(sdkVersion int, optional bool, implicit bool) usesLibraryDependencyTag {
+func makeUsesLibraryDependencyTag(sdkVersion int, optional bool) usesLibraryDependencyTag {
 	return usesLibraryDependencyTag{
 		dependencyTag: dependencyTag{
 			name:          fmt.Sprintf("uses-library-%d", sdkVersion),
@@ -320,7 +312,6 @@
 		},
 		sdkVersion: sdkVersion,
 		optional:   optional,
-		implicit:   implicit,
 	}
 }
 
@@ -351,6 +342,11 @@
 	syspropPublicStubDepTag = dependencyTag{name: "sysprop public stub"}
 	jniInstallTag           = installDependencyTag{name: "jni install"}
 	binaryInstallTag        = installDependencyTag{name: "binary install"}
+	usesLibReqTag           = makeUsesLibraryDependencyTag(dexpreopt.AnySdkVersion, false)
+	usesLibOptTag           = makeUsesLibraryDependencyTag(dexpreopt.AnySdkVersion, true)
+	usesLibCompat28OptTag   = makeUsesLibraryDependencyTag(28, true)
+	usesLibCompat29ReqTag   = makeUsesLibraryDependencyTag(29, false)
+	usesLibCompat30OptTag   = makeUsesLibraryDependencyTag(30, true)
 )
 
 func IsLibDepTag(depTag blueprint.DependencyTag) bool {
@@ -1996,10 +1992,8 @@
 	depTag := ctx.OtherModuleDependencyTag(depModule)
 	if depTag == libTag {
 		// Ok, propagate <uses-library> through non-static library dependencies.
-	} else if tag, ok := depTag.(usesLibraryDependencyTag); ok &&
-		tag.sdkVersion == dexpreopt.AnySdkVersion && tag.implicit {
-		// Ok, propagate <uses-library> through non-compatibility implicit <uses-library>
-		// dependencies.
+	} else if tag, ok := depTag.(usesLibraryDependencyTag); ok && tag.sdkVersion == dexpreopt.AnySdkVersion {
+		// Ok, propagate <uses-library> through non-compatibility <uses-library> dependencies.
 	} else if depTag == staticLibTag {
 		// Propagate <uses-library> through static library dependencies, unless it is a component
 		// library (such as stubs). Component libraries have a dependency on their SDK library,
@@ -2017,7 +2011,7 @@
 	// <uses_library> and should not be added to CLC, but the transitive <uses-library> dependencies
 	// from its CLC should be added to the current CLC.
 	if sdkLib != nil {
-		clcMap.AddContext(ctx, dexpreopt.AnySdkVersion, *sdkLib, false, true,
+		clcMap.AddContext(ctx, dexpreopt.AnySdkVersion, *sdkLib, false,
 			dep.DexJarBuildPath().PathOrNil(), dep.DexJarInstallPath(), dep.ClassLoaderContexts())
 	} else {
 		clcMap.AddContextMap(dep.ClassLoaderContexts(), depName)