From 1613e5541fd5aa5d22f093d8a53787b503aed624 Mon Sep 17 00:00:00 2001
From: Jiyong Park <jiyong@google.com>
Date: Mon, 14 Sep 2020 19:43:17 +0900
Subject: [PATCH 1/2] HostCross is an attribute of a Target, not OsType

A host target is considered as being cross-compiled when the target
can't run natively on the build machine. For example, linux_glibc/x86_64
is a non-cross target on a standard x86/Linux machine, but is a cross
host on Mac. Previously, whether cross or not was a static attribute of
an OsType. For example, Windows was always considered as cross host,
while linux_bionic was not. This becomes a problem when we support more
host targets like linux_bionic/arm64 which should be cross-host on
standard x86/Linux machines.

This change removes HostCross from the OsClass type and instead adds a
property HostCross to the Target type. When a target is being added, it
is initialized to true when the target can't run natively on the current
build machine.

Bug: 168086242
Test: m
Change-Id: Ic37c8db918873ddf324c86b12b5412952b0f2be2
---
 android/androidmk.go     | 35 ++++++++++++---------
 android/arch.go          | 68 ++++++++++++++++++++++++++--------------
 android/config.go        | 20 ++++++------
 android/module.go        | 48 +++++++++++++++-------------
 android/prebuilt_test.go |  2 +-
 apex/androidmk.go        | 15 ++++-----
 cc/cc.go                 |  4 +--
 java/app.go              |  2 +-
 python/binary.go         |  2 +-
 python/library.go        |  2 +-
 sdk/testing.go           |  6 ++--
 sdk/update.go            | 12 +++----
 12 files changed, 124 insertions(+), 92 deletions(-)

diff --git a/android/androidmk.go b/android/androidmk.go
index fafbfd61e..e90e5f0e0 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -304,15 +304,16 @@ func (a *AndroidMkEntries) fillInEntries(config Config, bpPath string, mod bluep
 	host := false
 	switch amod.Os().Class {
 	case Host:
-		// Make cannot identify LOCAL_MODULE_HOST_ARCH:= common.
-		if amod.Arch().ArchType != Common {
-			a.SetString("LOCAL_MODULE_HOST_ARCH", archStr)
-		}
-		host = true
-	case HostCross:
-		// Make cannot identify LOCAL_MODULE_HOST_CROSS_ARCH:= common.
-		if amod.Arch().ArchType != Common {
-			a.SetString("LOCAL_MODULE_HOST_CROSS_ARCH", archStr)
+		if amod.Target().HostCross {
+			// Make cannot identify LOCAL_MODULE_HOST_CROSS_ARCH:= common.
+			if amod.Arch().ArchType != Common {
+				a.SetString("LOCAL_MODULE_HOST_CROSS_ARCH", archStr)
+			}
+		} else {
+			// Make cannot identify LOCAL_MODULE_HOST_ARCH:= common.
+			if amod.Arch().ArchType != Common {
+				a.SetString("LOCAL_MODULE_HOST_ARCH", archStr)
+			}
 		}
 		host = true
 	case Device:
@@ -359,9 +360,11 @@ func (a *AndroidMkEntries) fillInEntries(config Config, bpPath string, mod bluep
 	if amod.ArchSpecific() {
 		switch amod.Os().Class {
 		case Host:
-			prefix = "HOST_"
-		case HostCross:
-			prefix = "HOST_CROSS_"
+			if amod.Target().HostCross {
+				prefix = "HOST_CROSS_"
+			} else {
+				prefix = "HOST_"
+			}
 		case Device:
 			prefix = "TARGET_"
 
@@ -563,9 +566,11 @@ func translateAndroidModule(ctx SingletonContext, w io.Writer, mod blueprint.Mod
 	if amod.ArchSpecific() {
 		switch amod.Os().Class {
 		case Host:
-			prefix = "HOST_"
-		case HostCross:
-			prefix = "HOST_CROSS_"
+			if amod.Target().HostCross {
+				prefix = "HOST_CROSS_"
+			} else {
+				prefix = "HOST_"
+			}
 		case Device:
 			prefix = "TARGET_"
 
diff --git a/android/arch.go b/android/arch.go
index 414113893..655257076 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -578,7 +578,7 @@ var (
 	Linux       = NewOsType("linux_glibc", Host, false)
 	Darwin      = NewOsType("darwin", Host, false)
 	LinuxBionic = NewOsType("linux_bionic", Host, false)
-	Windows     = NewOsType("windows", HostCross, true)
+	Windows     = NewOsType("windows", Host, true)
 	Android     = NewOsType("android", Device, false)
 	Fuchsia     = NewOsType("fuchsia", Device, false)
 
@@ -609,7 +609,6 @@ const (
 	Generic OsClass = iota
 	Device
 	Host
-	HostCross
 )
 
 func (class OsClass) String() string {
@@ -620,8 +619,6 @@ func (class OsClass) String() string {
 		return "device"
 	case Host:
 		return "host"
-	case HostCross:
-		return "host cross"
 	default:
 		panic(fmt.Errorf("unknown class %d", class))
 	}
@@ -681,6 +678,11 @@ type Target struct {
 	NativeBridge             NativeBridgeSupport
 	NativeBridgeHostArchName string
 	NativeBridgeRelativePath string
+
+	// HostCross is true when the target cannot run natively on the current build host.
+	// For example, linux_glibc_x86 returns true on a regular x86/i686/Linux machines, but returns false
+	// on Mac (different OS), or on 64-bit only i686/Linux machines (unsupported arch).
+	HostCross bool
 }
 
 func (target Target) String() string {
@@ -739,26 +741,15 @@ func osMutator(bpctx blueprint.BottomUpMutatorContext) {
 		return
 	}
 
-	osClasses := base.OsClassSupported()
-
 	var moduleOSList []OsType
 
 	for _, os := range OsTypeList {
-		supportedClass := false
-		for _, osClass := range osClasses {
-			if os.Class == osClass {
-				supportedClass = true
+		for _, t := range mctx.Config().Targets[os] {
+			if base.supportsTarget(t, mctx.Config()) {
+				moduleOSList = append(moduleOSList, os)
+				break
 			}
 		}
-		if !supportedClass {
-			continue
-		}
-
-		if len(mctx.Config().Targets[os]) == 0 {
-			continue
-		}
-
-		moduleOSList = append(moduleOSList, os)
 	}
 
 	if len(moduleOSList) == 0 {
@@ -913,7 +904,7 @@ func archMutator(bpctx blueprint.BottomUpMutatorContext) {
 
 	prefer32 := false
 	if base.prefer32 != nil {
-		prefer32 = base.prefer32(mctx, base, os.Class)
+		prefer32 = base.prefer32(mctx, base, os)
 	}
 
 	multilib, extraMultilib := decodeMultilib(base, os.Class)
@@ -964,7 +955,7 @@ func decodeMultilib(base *ModuleBase, class OsClass) (multilib, extraMultilib st
 	switch class {
 	case Device:
 		multilib = String(base.commonProperties.Target.Android.Compile_multilib)
-	case Host, HostCross:
+	case Host:
 		multilib = String(base.commonProperties.Target.Host.Compile_multilib)
 	}
 	if multilib == "" {
@@ -1240,7 +1231,7 @@ func (m *ModuleBase) setOSProperties(ctx BottomUpMutatorContext) {
 			//         key: value,
 			//     },
 			// },
-			if os.Class == Host || os.Class == HostCross {
+			if os.Class == Host {
 				field := "Host"
 				prefix := "target.host"
 				m.appendProperties(ctx, genProps, targetProp, field, prefix)
@@ -1280,7 +1271,7 @@ func (m *ModuleBase) setOSProperties(ctx BottomUpMutatorContext) {
 			prefix := "target." + os.Name
 			m.appendProperties(ctx, genProps, targetProp, field, prefix)
 
-			if (os.Class == Host || os.Class == HostCross) && os != Windows {
+			if os.Class == Host && os != Windows {
 				field := "Not_windows"
 				prefix := "target.not_windows"
 				m.appendProperties(ctx, genProps, targetProp, field, prefix)
@@ -1508,6 +1499,36 @@ func decodeTargetProductVariables(config *config) (map[OsType][]Target, error) {
 			nativeBridgeRelativePathStr = arch.ArchType.String()
 		}
 
+		// A target is considered as HostCross if it's a host target which can't run natively on
+		// the currently configured build machine (either because the OS is different or because of
+		// the unsupported arch)
+		hostCross := false
+		if os.Class == Host {
+			var osSupported bool
+			if os == BuildOs {
+				osSupported = true
+			} else if BuildOs.Linux() && os.Linux() {
+				// LinuxBionic and Linux are compatible
+				osSupported = true
+			} else {
+				osSupported = false
+			}
+
+			var archSupported bool
+			if arch.ArchType == Common {
+				archSupported = true
+			} else if arch.ArchType.Name == *variables.HostArch {
+				archSupported = true
+			} else if variables.HostSecondaryArch != nil && arch.ArchType.Name == *variables.HostSecondaryArch {
+				archSupported = true
+			} else {
+				archSupported = false
+			}
+			if !osSupported || !archSupported {
+				hostCross = true
+			}
+		}
+
 		targets[os] = append(targets[os],
 			Target{
 				Os:                       os,
@@ -1515,6 +1536,7 @@ func decodeTargetProductVariables(config *config) (map[OsType][]Target, error) {
 				NativeBridge:             nativeBridgeEnabled,
 				NativeBridgeHostArchName: nativeBridgeHostArchNameStr,
 				NativeBridgeRelativePath: nativeBridgeRelativePathStr,
+				HostCross:                hostCross,
 			})
 	}
 
diff --git a/android/config.go b/android/config.go
index 1c06e8c55..f8c8821fa 100644
--- a/android/config.go
+++ b/android/config.go
@@ -260,10 +260,10 @@ func TestArchConfigNativeBridge(buildDir string, env map[string]string, bp strin
 	config := testConfig.config
 
 	config.Targets[Android] = []Target{
-		{Android, Arch{ArchType: X86_64, ArchVariant: "silvermont", Abi: []string{"arm64-v8a"}}, NativeBridgeDisabled, "", ""},
-		{Android, Arch{ArchType: X86, ArchVariant: "silvermont", Abi: []string{"armeabi-v7a"}}, NativeBridgeDisabled, "", ""},
-		{Android, Arch{ArchType: Arm64, ArchVariant: "armv8-a", Abi: []string{"arm64-v8a"}}, NativeBridgeEnabled, "x86_64", "arm64"},
-		{Android, Arch{ArchType: Arm, ArchVariant: "armv7-a-neon", Abi: []string{"armeabi-v7a"}}, NativeBridgeEnabled, "x86", "arm"},
+		{Android, Arch{ArchType: X86_64, ArchVariant: "silvermont", Abi: []string{"arm64-v8a"}}, NativeBridgeDisabled, "", "", false},
+		{Android, Arch{ArchType: X86, ArchVariant: "silvermont", Abi: []string{"armeabi-v7a"}}, NativeBridgeDisabled, "", "", false},
+		{Android, Arch{ArchType: Arm64, ArchVariant: "armv8-a", Abi: []string{"arm64-v8a"}}, NativeBridgeEnabled, "x86_64", "arm64", false},
+		{Android, Arch{ArchType: Arm, ArchVariant: "armv7-a-neon", Abi: []string{"armeabi-v7a"}}, NativeBridgeEnabled, "x86", "arm", false},
 	}
 
 	return testConfig
@@ -275,10 +275,10 @@ func TestArchConfigFuchsia(buildDir string, env map[string]string, bp string, fs
 
 	config.Targets = map[OsType][]Target{
 		Fuchsia: []Target{
-			{Fuchsia, Arch{ArchType: Arm64, ArchVariant: "", Abi: []string{"arm64-v8a"}}, NativeBridgeDisabled, "", ""},
+			{Fuchsia, Arch{ArchType: Arm64, ArchVariant: "", Abi: []string{"arm64-v8a"}}, NativeBridgeDisabled, "", "", false},
 		},
 		BuildOs: []Target{
-			{BuildOs, Arch{ArchType: X86_64}, NativeBridgeDisabled, "", ""},
+			{BuildOs, Arch{ArchType: X86_64}, NativeBridgeDisabled, "", "", false},
 		},
 	}
 
@@ -292,12 +292,12 @@ func TestArchConfig(buildDir string, env map[string]string, bp string, fs map[st
 
 	config.Targets = map[OsType][]Target{
 		Android: []Target{
-			{Android, Arch{ArchType: Arm64, ArchVariant: "armv8-a", Abi: []string{"arm64-v8a"}}, NativeBridgeDisabled, "", ""},
-			{Android, Arch{ArchType: Arm, ArchVariant: "armv7-a-neon", Abi: []string{"armeabi-v7a"}}, NativeBridgeDisabled, "", ""},
+			{Android, Arch{ArchType: Arm64, ArchVariant: "armv8-a", Abi: []string{"arm64-v8a"}}, NativeBridgeDisabled, "", "", false},
+			{Android, Arch{ArchType: Arm, ArchVariant: "armv7-a-neon", Abi: []string{"armeabi-v7a"}}, NativeBridgeDisabled, "", "", false},
 		},
 		BuildOs: []Target{
-			{BuildOs, Arch{ArchType: X86_64}, NativeBridgeDisabled, "", ""},
-			{BuildOs, Arch{ArchType: X86}, NativeBridgeDisabled, "", ""},
+			{BuildOs, Arch{ArchType: X86_64}, NativeBridgeDisabled, "", "", false},
+			{BuildOs, Arch{ArchType: X86}, NativeBridgeDisabled, "", "", false},
 		},
 	}
 
diff --git a/android/module.go b/android/module.go
index 5bc7a17b6..e1b98f657 100644
--- a/android/module.go
+++ b/android/module.go
@@ -923,7 +923,7 @@ type ModuleBase struct {
 	initRcPaths         Paths
 	vintfFragmentsPaths Paths
 
-	prefer32 func(ctx BaseModuleContext, base *ModuleBase, class OsClass) bool
+	prefer32 func(ctx BaseModuleContext, base *ModuleBase, os OsType) bool
 }
 
 func (m *ModuleBase) ComponentDepsMutator(BottomUpMutatorContext) {}
@@ -950,7 +950,7 @@ func (m *ModuleBase) VariablesForTests() map[string]string {
 	return m.variables
 }
 
-func (m *ModuleBase) Prefer32(prefer32 func(ctx BaseModuleContext, base *ModuleBase, class OsClass) bool) {
+func (m *ModuleBase) Prefer32(prefer32 func(ctx BaseModuleContext, base *ModuleBase, os OsType) bool) {
 	m.prefer32 = prefer32
 }
 
@@ -1046,7 +1046,7 @@ func (m *ModuleBase) Os() OsType {
 }
 
 func (m *ModuleBase) Host() bool {
-	return m.Os().Class == Host || m.Os().Class == HostCross
+	return m.Os().Class == Host
 }
 
 func (m *ModuleBase) Device() bool {
@@ -1066,28 +1066,28 @@ func (m *ModuleBase) IsCommonOSVariant() bool {
 	return m.commonProperties.CommonOSVariant
 }
 
-func (m *ModuleBase) OsClassSupported() []OsClass {
+func (m *ModuleBase) supportsTarget(target Target, config Config) bool {
 	switch m.commonProperties.HostOrDeviceSupported {
 	case HostSupported:
-		return []OsClass{Host, HostCross}
+		return target.Os.Class == Host
 	case HostSupportedNoCross:
-		return []OsClass{Host}
+		return target.Os.Class == Host && !target.HostCross
 	case DeviceSupported:
-		return []OsClass{Device}
+		return target.Os.Class == Device
 	case HostAndDeviceSupported, HostAndDeviceDefault:
-		var supported []OsClass
+		supported := false
 		if Bool(m.hostAndDeviceProperties.Host_supported) ||
 			(m.commonProperties.HostOrDeviceSupported == HostAndDeviceDefault &&
 				m.hostAndDeviceProperties.Host_supported == nil) {
-			supported = append(supported, Host, HostCross)
+			supported = supported || target.Os.Class == Host
 		}
 		if m.hostAndDeviceProperties.Device_supported == nil ||
 			*m.hostAndDeviceProperties.Device_supported {
-			supported = append(supported, Device)
+			supported = supported || target.Os.Class == Device
 		}
 		return supported
 	default:
-		return nil
+		return false
 	}
 }
 
@@ -2075,7 +2075,7 @@ func (b *baseModuleContext) Os() OsType {
 }
 
 func (b *baseModuleContext) Host() bool {
-	return b.os.Class == Host || b.os.Class == HostCross
+	return b.os.Class == Host
 }
 
 func (b *baseModuleContext) Device() bool {
@@ -2535,30 +2535,36 @@ func (c *buildTargetSingleton) GenerateBuildActions(ctx SingletonContext) {
 	}
 
 	// Create (host|host-cross|target)-<OS> phony rules to build a reduced checkbuild.
-	osDeps := map[OsType]Paths{}
+	type osAndCross struct {
+		os        OsType
+		hostCross bool
+	}
+	osDeps := map[osAndCross]Paths{}
 	ctx.VisitAllModules(func(module Module) {
 		if module.Enabled() {
-			os := module.Target().Os
-			osDeps[os] = append(osDeps[os], module.base().checkbuildFiles...)
+			key := osAndCross{os: module.Target().Os, hostCross: module.Target().HostCross}
+			osDeps[key] = append(osDeps[key], module.base().checkbuildFiles...)
 		}
 	})
 
 	osClass := make(map[string]Paths)
-	for os, deps := range osDeps {
+	for key, deps := range osDeps {
 		var className string
 
-		switch os.Class {
+		switch key.os.Class {
 		case Host:
-			className = "host"
-		case HostCross:
-			className = "host-cross"
+			if key.hostCross {
+				className = "host-cross"
+			} else {
+				className = "host"
+			}
 		case Device:
 			className = "target"
 		default:
 			continue
 		}
 
-		name := className + "-" + os.Name
+		name := className + "-" + key.os.Name
 		osClass[className] = append(osClass[className], PathForPhony(ctx, name))
 
 		ctx.Phony(name, deps...)
diff --git a/android/prebuilt_test.go b/android/prebuilt_test.go
index 6c3cd9eef..854395e64 100644
--- a/android/prebuilt_test.go
+++ b/android/prebuilt_test.go
@@ -285,7 +285,7 @@ func TestPrebuilts(t *testing.T) {
 				t.Errorf("windows is assumed to be disabled by default")
 			}
 			config.config.Targets[Windows] = []Target{
-				{Windows, Arch{ArchType: X86_64}, NativeBridgeDisabled, "", ""},
+				{Windows, Arch{ArchType: X86_64}, NativeBridgeDisabled, "", "", true},
 			}
 
 			ctx := NewTestArchContext()
diff --git a/apex/androidmk.go b/apex/androidmk.go
index 1b53a672b..c4fe3a36a 100644
--- a/apex/androidmk.go
+++ b/apex/androidmk.go
@@ -157,13 +157,14 @@ func (a *apexBundle) androidMkForFiles(w io.Writer, apexBundleName, apexName, mo
 			host := false
 			switch fi.module.Target().Os.Class {
 			case android.Host:
-				if fi.module.Target().Arch.ArchType != android.Common {
-					fmt.Fprintln(w, "LOCAL_MODULE_HOST_ARCH :=", archStr)
-				}
-				host = true
-			case android.HostCross:
-				if fi.module.Target().Arch.ArchType != android.Common {
-					fmt.Fprintln(w, "LOCAL_MODULE_HOST_CROSS_ARCH :=", archStr)
+				if fi.module.Target().HostCross {
+					if fi.module.Target().Arch.ArchType != android.Common {
+						fmt.Fprintln(w, "LOCAL_MODULE_HOST_CROSS_ARCH :=", archStr)
+					}
+				} else {
+					if fi.module.Target().Arch.ArchType != android.Common {
+						fmt.Fprintln(w, "LOCAL_MODULE_HOST_ARCH :=", archStr)
+					}
 				}
 				host = true
 			case android.Device:
diff --git a/cc/cc.go b/cc/cc.go
index 6584380aa..d0d6427bd 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -950,9 +950,9 @@ func (c *Module) Init() android.Module {
 		c.AddProperties(feature.props()...)
 	}
 
-	c.Prefer32(func(ctx android.BaseModuleContext, base *android.ModuleBase, class android.OsClass) bool {
+	c.Prefer32(func(ctx android.BaseModuleContext, base *android.ModuleBase, os android.OsType) bool {
 		// Windows builds always prefer 32-bit
-		return class == android.HostCross
+		return os == android.Windows
 	})
 	android.InitAndroidArchModule(c, c.hod, c.multilib)
 	android.InitApexModule(c)
diff --git a/java/app.go b/java/app.go
index ae7373fc7..9ffb6b4a1 100755
--- a/java/app.go
+++ b/java/app.go
@@ -678,7 +678,7 @@ func (a *AndroidApp) noticeBuildActions(ctx android.ModuleContext) {
 		seenModules[child] = true
 
 		// Skip host modules.
-		if child.Target().Os.Class == android.Host || child.Target().Os.Class == android.HostCross {
+		if child.Target().Os.Class == android.Host {
 			return false
 		}
 
diff --git a/python/binary.go b/python/binary.go
index 5a7492648..1d2400efd 100644
--- a/python/binary.go
+++ b/python/binary.go
@@ -79,7 +79,7 @@ func NewBinary(hod android.HostOrDeviceSupported) (*Module, *binaryDecorator) {
 }
 
 func PythonBinaryHostFactory() android.Module {
-	module, _ := NewBinary(android.HostSupportedNoCross)
+	module, _ := NewBinary(android.HostSupported)
 
 	return module.Init()
 }
diff --git a/python/library.go b/python/library.go
index 65c1352e7..0c8d61313 100644
--- a/python/library.go
+++ b/python/library.go
@@ -26,7 +26,7 @@ func init() {
 }
 
 func PythonLibraryHostFactory() android.Module {
-	module := newModule(android.HostSupportedNoCross, android.MultilibFirst)
+	module := newModule(android.HostSupported, android.MultilibFirst)
 
 	return module.Init()
 }
diff --git a/sdk/testing.go b/sdk/testing.go
index b53558d9f..e57f1f79d 100644
--- a/sdk/testing.go
+++ b/sdk/testing.go
@@ -68,14 +68,14 @@ func testSdkContext(bp string, fs map[string][]byte, extraOsTypes []android.OsTy
 	// Add windows as a default disable OS to test behavior when some OS variants
 	// are disabled.
 	config.Targets[android.Windows] = []android.Target{
-		{android.Windows, android.Arch{ArchType: android.X86_64}, android.NativeBridgeDisabled, "", ""},
+		{android.Windows, android.Arch{ArchType: android.X86_64}, android.NativeBridgeDisabled, "", "", true},
 	}
 
 	for _, extraOsType := range extraOsTypes {
 		switch extraOsType {
 		case android.LinuxBionic:
 			config.Targets[android.LinuxBionic] = []android.Target{
-				{android.LinuxBionic, android.Arch{ArchType: android.X86_64}, android.NativeBridgeDisabled, "", ""},
+				{android.LinuxBionic, android.Arch{ArchType: android.X86_64}, android.NativeBridgeDisabled, "", "", false},
 			}
 		}
 	}
@@ -89,7 +89,7 @@ func testSdkContext(bp string, fs map[string][]byte, extraOsTypes []android.OsTy
 	android.RegisterAndroidMkBuildComponents(ctx)
 	android.SetInMakeForTests(config)
 	config.Targets[android.CommonOS] = []android.Target{
-		{android.CommonOS, android.Arch{ArchType: android.Common}, android.NativeBridgeDisabled, "", ""},
+		{android.CommonOS, android.Arch{ArchType: android.Common}, android.NativeBridgeDisabled, "", "", true},
 	}
 
 	// from android package
diff --git a/sdk/update.go b/sdk/update.go
index 537ab13cb..3c4309cf3 100644
--- a/sdk/update.go
+++ b/sdk/update.go
@@ -371,8 +371,7 @@ func (s *sdk) buildSnapshot(ctx android.ModuleContext, sdkVariants []*sdk) andro
 			osPropertySet := targetPropertySet.AddPropertySet(sdkVariant.Target().Os.Name)
 
 			// Enable the variant explicitly when we've disabled it by default on host.
-			if hasHostOsDependentMember &&
-				(osType.Class == android.Host || osType.Class == android.HostCross) {
+			if hasHostOsDependentMember && osType.Class == android.Host {
 				osPropertySet.AddProperty("enabled", true)
 			}
 
@@ -731,7 +730,7 @@ func (s *snapshotBuilder) AddPrebuiltModule(member android.SdkMember, moduleType
 
 	for _, variant := range member.Variants() {
 		osClass := variant.Target().Os.Class
-		if osClass == android.Host || osClass == android.HostCross {
+		if osClass == android.Host {
 			hostSupported = true
 		} else if osClass == android.Device {
 			deviceSupported = true
@@ -1061,8 +1060,7 @@ func (osInfo *osTypeSpecificInfo) addToPropertySet(ctx *memberContext, bpModule
 		archPropertySet = targetPropertySet
 
 		// Enable the variant explicitly when we've disabled it by default on host.
-		if ctx.memberType.IsHostOsDependent() &&
-			(osType.Class == android.Host || osType.Class == android.HostCross) {
+		if ctx.memberType.IsHostOsDependent() && osType.Class == android.Host {
 			osPropertySet.AddProperty("enabled", true)
 		}
 
@@ -1086,7 +1084,7 @@ func (osInfo *osTypeSpecificInfo) addToPropertySet(ctx *memberContext, bpModule
 
 func (osInfo *osTypeSpecificInfo) isHostVariant() bool {
 	osClass := osInfo.osType.Class
-	return osClass == android.Host || osClass == android.HostCross
+	return osClass == android.Host
 }
 
 var _ isHostVariant = (*osTypeSpecificInfo)(nil)
@@ -1323,7 +1321,7 @@ func (s *sdk) getPossibleOsTypes() []android.OsType {
 			}
 		}
 		if s.HostSupported() {
-			if osType.Class == android.Host || osType.Class == android.HostCross {
+			if osType.Class == android.Host {
 				osTypes = append(osTypes, osType)
 			}
 		}

From 22101981293b1b8bc150f3187630baf5727f1314 Mon Sep 17 00:00:00 2001
From: Jiyong Park <jiyong@google.com>
Date: Thu, 17 Sep 2020 19:09:58 +0900
Subject: [PATCH 2/2] linux_bionic_arm64 is added when Host_bionic_arm64 is
 true

linux_bionic_arm64 is the new host target using Bionic as libc.  This
change adds a new Soong config Host_bionic_arm64 that enables the
target.

This change also amends firstTarget() function to handle the case when
the available targets for an OS have different arch families. In that
case, first target is selected for each of the arch family. This is
needed in the (rare) care when both linux_bionic_x86_64 and
linux_bionic_arm64 targets are enabled.

Bug: 159685774
Test: add "Host_bionic_arm64": true to out/soong/soong.config and run
./build/soong/soong_ui.bash --make-mode --skip-make
out/soong/host/linux_bionic-arm64/bin/aarch64-linux-bionic/crosvm

Change-Id: I0885e49379f6ee216c6e82adbb1230655171a7a5
---
 android/arch.go   | 18 +++++++++++++++---
 android/config.go |  5 +++--
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/android/arch.go b/android/arch.go
index 655257076..d115b3fe7 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -1553,6 +1553,9 @@ func decodeTargetProductVariables(config *config) (map[OsType][]Target, error) {
 	if Bool(config.Host_bionic) {
 		addTarget(LinuxBionic, "x86_64", nil, nil, nil, NativeBridgeDisabled, nil, nil)
 	}
+	if Bool(config.Host_bionic_arm64) {
+		addTarget(LinuxBionic, "arm64", nil, nil, nil, NativeBridgeDisabled, nil, nil)
+	}
 
 	if String(variables.CrossHost) != "" {
 		crossHostOs := osByName(*variables.CrossHost)
@@ -1793,13 +1796,22 @@ func getCommonTargets(targets []Target) []Target {
 }
 
 func firstTarget(targets []Target, filters ...string) []Target {
+	// find the first target from each OS
+	var ret []Target
+	hasHost := false
+	set := make(map[OsType]bool)
+
 	for _, filter := range filters {
 		buildTargets := filterMultilibTargets(targets, filter)
-		if len(buildTargets) > 0 {
-			return buildTargets[:1]
+		for _, t := range buildTargets {
+			if _, found := set[t.Os]; !found {
+				hasHost = hasHost || (t.Os.Class == Host)
+				set[t.Os] = true
+				ret = append(ret, t)
+			}
 		}
 	}
-	return nil
+	return ret
 }
 
 // Use the module multilib setting to select one or more targets from a target list
diff --git a/android/config.go b/android/config.go
index f8c8821fa..fd462c9a7 100644
--- a/android/config.go
+++ b/android/config.go
@@ -46,8 +46,9 @@ const productVariablesFileName = "soong.variables"
 // A FileConfigurableOptions contains options which can be configured by the
 // config file. These will be included in the config struct.
 type FileConfigurableOptions struct {
-	Mega_device *bool `json:",omitempty"`
-	Host_bionic *bool `json:",omitempty"`
+	Mega_device       *bool `json:",omitempty"`
+	Host_bionic       *bool `json:",omitempty"`
+	Host_bionic_arm64 *bool `json:",omitempty"`
 }
 
 func (f *FileConfigurableOptions) SetDefaultConfig() {