Add native_bridge target to Android.bp

This allows us to build guest libraries for the native bridge for
arm/arm64 architectures.

Bug: http://b/77159578
Test: make
Change-Id: I35520ca456105ddadd456c78a4eb1e6de39147c5
diff --git a/android/androidmk.go b/android/androidmk.go
index 2a3748e..2bbd452 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -28,6 +28,10 @@
 	"github.com/google/blueprint/bootstrap"
 )
 
+var (
+	NativeBridgeSuffix = ".native_bridge"
+)
+
 func init() {
 	RegisterSingletonType("androidmk", AndroidMkSingleton)
 }
@@ -161,6 +165,10 @@
 		}
 	}
 
+	if amod.Target().NativeBridge {
+		a.SubName += NativeBridgeSuffix
+	}
+
 	fmt.Fprintln(&a.header, "\ninclude $(CLEAR_VARS)")
 
 	// Collect make variable assignment entries.
@@ -190,7 +198,22 @@
 	case Device:
 		// Make cannot identify LOCAL_MODULE_TARGET_ARCH:= common.
 		if archStr != "common" {
-			a.SetString("LOCAL_MODULE_TARGET_ARCH", archStr)
+			if amod.Target().NativeBridge {
+				// TODO: Unhardcode these rules.
+				guestArchStr := archStr
+				hostArchStr := ""
+				if guestArchStr == "arm" {
+					hostArchStr = "x86"
+				} else if guestArchStr == "arm64" {
+					hostArchStr = "x86_64"
+				}
+
+				if hostArchStr != "" {
+					a.SetString("LOCAL_MODULE_TARGET_ARCH", hostArchStr)
+				}
+			} else {
+				a.SetString("LOCAL_MODULE_TARGET_ARCH", archStr)
+			}
 		}
 
 		a.AddStrings("LOCAL_INIT_RC", amod.commonProperties.Init_rc...)
diff --git a/android/arch.go b/android/arch.go
index 957a659..c68fe46 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -683,13 +683,25 @@
 	return NoOsType
 }
 
+type NativeBridgeSupport bool
+
+const (
+	NativeBridgeDisabled NativeBridgeSupport = false
+	NativeBridgeEnabled  NativeBridgeSupport = true
+)
+
 type Target struct {
-	Os   OsType
-	Arch Arch
+	Os           OsType
+	Arch         Arch
+	NativeBridge NativeBridgeSupport
 }
 
 func (target Target) String() string {
-	return target.Os.String() + "_" + target.Arch.String()
+	variant := ""
+	if target.NativeBridge {
+		variant = "native_bridge_"
+	}
+	return target.Os.String() + "_" + variant + target.Arch.String()
 }
 
 // archMutator splits a module into a variant for each Target requested by the module.  Target selection
@@ -750,6 +762,18 @@
 			continue
 		}
 
+		// Filter NativeBridge targets unless they are explicitly supported
+		if os == Android && !Bool(base.commonProperties.Native_bridge_supported) {
+			var targets []Target
+			for _, t := range osTargets {
+				if !t.NativeBridge {
+					targets = append(targets, t)
+				}
+			}
+
+			osTargets = targets
+		}
+
 		// only the primary arch in the recovery partition
 		if os == Android && module.InstallInRecovery() {
 			osTargets = []Target{osTargets[0]}
@@ -1378,7 +1402,8 @@
 	targets := make(map[OsType][]Target)
 	var targetErr error
 
-	addTarget := func(os OsType, archName string, archVariant, cpuVariant *string, abi []string) {
+	addTarget := func(os OsType, archName string, archVariant, cpuVariant *string, abi []string,
+		nativeBridgeEnabled NativeBridgeSupport) {
 		if targetErr != nil {
 			return
 		}
@@ -1391,8 +1416,9 @@
 
 		targets[os] = append(targets[os],
 			Target{
-				Os:   os,
-				Arch: arch,
+				Os:           os,
+				Arch:         arch,
+				NativeBridge: nativeBridgeEnabled,
 			})
 	}
 
@@ -1400,14 +1426,14 @@
 		return nil, fmt.Errorf("No host primary architecture set")
 	}
 
-	addTarget(BuildOs, *variables.HostArch, nil, nil, nil)
+	addTarget(BuildOs, *variables.HostArch, nil, nil, nil, NativeBridgeDisabled)
 
 	if variables.HostSecondaryArch != nil && *variables.HostSecondaryArch != "" {
-		addTarget(BuildOs, *variables.HostSecondaryArch, nil, nil, nil)
+		addTarget(BuildOs, *variables.HostSecondaryArch, nil, nil, nil, NativeBridgeDisabled)
 	}
 
 	if Bool(config.Host_bionic) {
-		addTarget(LinuxBionic, "x86_64", nil, nil, nil)
+		addTarget(LinuxBionic, "x86_64", nil, nil, nil, NativeBridgeDisabled)
 	}
 
 	if String(variables.CrossHost) != "" {
@@ -1420,10 +1446,10 @@
 			return nil, fmt.Errorf("No cross-host primary architecture set")
 		}
 
-		addTarget(crossHostOs, *variables.CrossHostArch, nil, nil, nil)
+		addTarget(crossHostOs, *variables.CrossHostArch, nil, nil, nil, NativeBridgeDisabled)
 
 		if variables.CrossHostSecondaryArch != nil && *variables.CrossHostSecondaryArch != "" {
-			addTarget(crossHostOs, *variables.CrossHostSecondaryArch, nil, nil, nil)
+			addTarget(crossHostOs, *variables.CrossHostSecondaryArch, nil, nil, nil, NativeBridgeDisabled)
 		}
 	}
 
@@ -1434,18 +1460,32 @@
 		}
 
 		addTarget(target, *variables.DeviceArch, variables.DeviceArchVariant,
-			variables.DeviceCpuVariant, variables.DeviceAbi)
+			variables.DeviceCpuVariant, variables.DeviceAbi, NativeBridgeDisabled)
 
 		if variables.DeviceSecondaryArch != nil && *variables.DeviceSecondaryArch != "" {
 			addTarget(Android, *variables.DeviceSecondaryArch,
 				variables.DeviceSecondaryArchVariant, variables.DeviceSecondaryCpuVariant,
-				variables.DeviceSecondaryAbi)
+				variables.DeviceSecondaryAbi, NativeBridgeDisabled)
 
 			deviceArches := targets[Android]
 			if deviceArches[0].Arch.ArchType.Multilib == deviceArches[1].Arch.ArchType.Multilib {
 				deviceArches[1].Arch.Native = false
 			}
 		}
+
+		if variables.NativeBridgeArch != nil && *variables.NativeBridgeArch != "" {
+			addTarget(Android, *variables.NativeBridgeArch,
+				variables.NativeBridgeArchVariant, variables.NativeBridgeCpuVariant,
+				variables.NativeBridgeAbi, NativeBridgeEnabled)
+		}
+
+		if variables.DeviceSecondaryArch != nil && *variables.DeviceSecondaryArch != "" &&
+			variables.NativeBridgeSecondaryArch != nil && *variables.NativeBridgeSecondaryArch != "" {
+			addTarget(Android, *variables.NativeBridgeSecondaryArch,
+				variables.NativeBridgeSecondaryArchVariant,
+				variables.NativeBridgeSecondaryCpuVariant,
+				variables.NativeBridgeSecondaryAbi, NativeBridgeEnabled)
+		}
 	}
 
 	if targetErr != nil {
diff --git a/android/config.go b/android/config.go
index 3495ad2..b142042 100644
--- a/android/config.go
+++ b/android/config.go
@@ -234,16 +234,36 @@
 	return Config{config}
 }
 
+func TestArchConfigNativeBridge(buildDir string, env map[string]string) Config {
+	testConfig := TestConfig(buildDir, env)
+	config := testConfig.config
+
+	config.Targets = map[OsType][]Target{
+		Android: []Target{
+			{Android, Arch{ArchType: X86_64, ArchVariant: "silvermont", Native: true, Abi: []string{"arm64-v8a"}}, NativeBridgeDisabled},
+			{Android, Arch{ArchType: X86, ArchVariant: "silvermont", Native: true, Abi: []string{"armeabi-v7a"}}, NativeBridgeDisabled},
+			{Android, Arch{ArchType: Arm64, ArchVariant: "armv8-a", Native: true, Abi: []string{"arm64-v8a"}}, NativeBridgeEnabled},
+			{Android, Arch{ArchType: Arm, ArchVariant: "armv7-a-neon", Native: true, Abi: []string{"armeabi-v7a"}}, NativeBridgeEnabled},
+		},
+		BuildOs: []Target{
+			{BuildOs, Arch{ArchType: X86_64}, NativeBridgeDisabled},
+			{BuildOs, Arch{ArchType: X86}, NativeBridgeDisabled},
+		},
+	}
+
+	return testConfig
+}
+
 func TestArchConfigFuchsia(buildDir string, env map[string]string) Config {
 	testConfig := TestConfig(buildDir, env)
 	config := testConfig.config
 
 	config.Targets = map[OsType][]Target{
 		Fuchsia: []Target{
-			{Fuchsia, Arch{ArchType: Arm64, ArchVariant: "", Native: true}},
+			{Fuchsia, Arch{ArchType: Arm64, ArchVariant: "", Native: true}, NativeBridgeDisabled},
 		},
 		BuildOs: []Target{
-			{BuildOs, Arch{ArchType: X86_64}},
+			{BuildOs, Arch{ArchType: X86_64}, NativeBridgeDisabled},
 		},
 	}
 
@@ -257,12 +277,12 @@
 
 	config.Targets = map[OsType][]Target{
 		Android: []Target{
-			{Android, Arch{ArchType: Arm64, ArchVariant: "armv8-a", Native: true, Abi: []string{"arm64-v8a"}}},
-			{Android, Arch{ArchType: Arm, ArchVariant: "armv7-a-neon", Native: true, Abi: []string{"armeabi-v7a"}}},
+			{Android, Arch{ArchType: Arm64, ArchVariant: "armv8-a", Native: true, Abi: []string{"arm64-v8a"}}, NativeBridgeDisabled},
+			{Android, Arch{ArchType: Arm, ArchVariant: "armv7-a-neon", Native: true, Abi: []string{"armeabi-v7a"}}, NativeBridgeDisabled},
 		},
 		BuildOs: []Target{
-			{BuildOs, Arch{ArchType: X86_64}},
-			{BuildOs, Arch{ArchType: X86}},
+			{BuildOs, Arch{ArchType: X86_64}, NativeBridgeDisabled},
+			{BuildOs, Arch{ArchType: X86}, NativeBridgeDisabled},
 		},
 	}
 
diff --git a/android/module.go b/android/module.go
index e3c37bb..fb5c00a 100644
--- a/android/module.go
+++ b/android/module.go
@@ -290,6 +290,9 @@
 	// Whether this module is installed to recovery partition
 	Recovery *bool
 
+	// Whether this module is built for non-native architecures (also known as native bridge binary)
+	Native_bridge_supported *bool `android:"arch_variant"`
+
 	// init.rc files to be installed if this module is installed
 	Init_rc []string `android:"path"`
 
diff --git a/android/variable.go b/android/variable.go
index d29ba73..c500671 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -165,6 +165,16 @@
 	DeviceSecondaryCpuVariant  *string  `json:",omitempty"`
 	DeviceSecondaryAbi         []string `json:",omitempty"`
 
+	NativeBridgeArch        *string  `json:",omitempty"`
+	NativeBridgeArchVariant *string  `json:",omitempty"`
+	NativeBridgeCpuVariant  *string  `json:",omitempty"`
+	NativeBridgeAbi         []string `json:",omitempty"`
+
+	NativeBridgeSecondaryArch        *string  `json:",omitempty"`
+	NativeBridgeSecondaryArchVariant *string  `json:",omitempty"`
+	NativeBridgeSecondaryCpuVariant  *string  `json:",omitempty"`
+	NativeBridgeSecondaryAbi         []string `json:",omitempty"`
+
 	HostArch          *string `json:",omitempty"`
 	HostSecondaryArch *string `json:",omitempty"`