Add toolchain cflags that are always used

Some cflags are part of the toolchain selection and should not be
removed by no_default_compiler_flags = true, for example -m32 for x86
compiles.  Removing all the cflags results in hacks such as in crt.mk
where the bare minimum cflags are reinserted.

Add new toolchain interface functions ToolchainCflags, ToolchainLdflags
and ToolchainClangCflags that will always be used.

Change-Id: I0ba02d7611e2afb9ad913319740e00c1bb2d654c

cc/arm_device.go

@@ -8,6 +8,10 @@ import (
 )
 
 var (
+	armToolchainCflags = []string{
+		"-mthumb-interwork",
+	}
+
 	armCflags = []string{
 		"-fno-exceptions", // from build/core/combo/select.mk
 		"-Wno-multichar",  // from build/core/combo/select.mk
@@ -26,8 +30,6 @@ var (
 		"-fno-builtin-sin",
 		"-fno-strict-volatile-bitfields",
 
-		"-mthumb-interwork",
-
 		// TARGET_RELEASE_CFLAGS
 		"-DNDEBUG",
 		"-g",
@@ -139,6 +141,7 @@ func init() {
 
 	pctx.StaticVariable("armGccTriple", "arm-linux-androideabi")
 
+	pctx.StaticVariable("armToolchainCflags", strings.Join(armToolchainCflags, " "))
 	pctx.StaticVariable("armCflags", strings.Join(armCflags, " "))
 	pctx.StaticVariable("armLdflags", strings.Join(armLdflags, " "))
 	pctx.StaticVariable("armCppflags", strings.Join(armCppflags, " "))
@@ -168,6 +171,7 @@ func init() {
 	pctx.StaticVariable("armCortexA15Cflags", strings.Join(armCpuVariantCflags["cortex-a15"], " "))
 
 	// Clang cflags
+	pctx.StaticVariable("armToolchainClangCflags", strings.Join(clangFilterUnknownCflags(armToolchainCflags), " "))
 	pctx.StaticVariable("armClangCflags", strings.Join(clangFilterUnknownCflags(armCflags), " "))
 	pctx.StaticVariable("armClangLdflags", strings.Join(clangFilterUnknownCflags(armLdflags), " "))
 	pctx.StaticVariable("armClangCppflags", strings.Join(clangFilterUnknownCflags(armCppflags), " "))
@@ -233,7 +237,8 @@ var (
 
 type toolchainArm struct {
 	toolchain32Bit
-	cflags, ldflags, clangCflags string
+	ldflags                               string
+	toolchainCflags, toolchainClangCflags string
 }
 
 func (t *toolchainArm) Name() string {
@@ -252,8 +257,12 @@ func (t *toolchainArm) GccVersion() string {
 	return "${armGccVersion}"
 }
 
+func (t *toolchainArm) ToolchainCflags() string {
+	return t.toolchainCflags
+}
+
 func (t *toolchainArm) Cflags() string {
-	return t.cflags
+	return "${armCflags}"
 }
 
 func (t *toolchainArm) Cppflags() string {
@@ -283,8 +292,12 @@ func (t *toolchainArm) ClangTriple() string {
 	return "${armGccTriple}"
 }
 
+func (t *toolchainArm) ToolchainClangCflags() string {
+	return t.toolchainClangCflags
+}
+
 func (t *toolchainArm) ClangCflags() string {
-	return t.clangCflags
+	return "${armClangCflags}"
 }
 
 func (t *toolchainArm) ClangCppflags() string {
@@ -317,8 +330,8 @@ func armToolchainFactory(arch common.Arch) Toolchain {
 	}
 
 	return &toolchainArm{
-		cflags: strings.Join([]string{
+		toolchainCflags: strings.Join([]string{
-			"${armCflags}",
+			"${armToolchainCflags}",
 			armArchVariantCflagsVar[arch.ArchVariant],
 			armCpuVariantCflagsVar[arch.CpuVariant],
 		}, " "),
@@ -326,8 +339,8 @@ func armToolchainFactory(arch common.Arch) Toolchain {
 			"${armLdflags}",
 			fixCortexA8,
 		}, " "),
-		clangCflags: strings.Join([]string{
+		toolchainClangCflags: strings.Join([]string{
-			"${armClangCflags}",
+			"${armToolchainClangCflags}",
 			armClangArchVariantCflagsVar[arch.ArchVariant],
 			armClangCpuVariantCflagsVar[arch.CpuVariant],
 		}, " "),

cc/cc.go

@@ -590,6 +590,13 @@ func (c *CCBase) collectFlags(ctx common.AndroidModuleContext, toolchain Toolcha
 		}
 	}
 
+	if flags.Clang {
+		flags.GlobalFlags = append(flags.GlobalFlags, toolchain.ToolchainClangCflags())
+	} else {
+		flags.GlobalFlags = append(flags.GlobalFlags, toolchain.ToolchainCflags())
+		flags.LdFlags = append(flags.LdFlags, toolchain.ToolchainLdflags())
+	}
+
 	flags = c.ccModuleType().flags(ctx, flags)
 
 	if c.Properties.Sdk_version == "" {

cc/toolchain.go

@@ -39,6 +39,8 @@ type Toolchain interface {
 	GccRoot() string
 	GccTriple() string
 	GccVersion() string
+	ToolchainCflags() string
+	ToolchainLdflags() string
 	Cflags() string
 	Cppflags() string
 	Ldflags() string
@@ -46,6 +48,7 @@ type Toolchain interface {
 	InstructionSetFlags(string) (string, error)
 
 	ClangTriple() string
+	ToolchainClangCflags() string
 	ClangCflags() string
 	ClangCppflags() string
 	ClangLdflags() string
@@ -71,6 +74,18 @@ func (toolchainBase) ClangInstructionSetFlags(s string) (string, error) {
 	return "", nil
 }
 
+func (toolchainBase) ToolchainCflags() string {
+	return ""
+}
+
+func (toolchainBase) ToolchainLdflags() string {
+	return ""
+}
+
+func (toolchainBase) ToolchainClangCflags() string {
+	return ""
+}
+
 type toolchain64Bit struct {
 	toolchainBase
 }