Refactor LTO (895d2410) · Commits · e / os / android_build_soong

cc/lto.go

+49 −45

Original line number	Diff line number	Diff line
		@@ -46,11 +46,11 @@ type LTOProperties struct {
		Thin *bool `android:"arch_variant"`
		} `android:"arch_variant"`

		LtoEnabled bool `blueprint:"mutated"`

		// Dep properties indicate that this module needs to be built with LTO
		// since it is an object dependency of an LTO module.
		ThinEnabled bool `blueprint:"mutated"`
		NoLtoEnabled bool `blueprint:"mutated"`
		ThinDep bool `blueprint:"mutated"`
		LtoDep bool `blueprint:"mutated"`
		NoLtoDep bool `blueprint:"mutated"`

		// Use -fwhole-program-vtables cflag.
		@@ -66,19 +66,16 @@ func (lto *lto) props() []interface{} {
		}

		func (lto *lto) begin(ctx BaseModuleContext) {
		if ctx.Config().IsEnvTrue("DISABLE_LTO") {
		lto.Properties.NoLtoEnabled = true
		}
		lto.Properties.LtoEnabled = lto.LTO(ctx)
		}

		func (lto *lto) flags(ctx BaseModuleContext, flags Flags) Flags {
		// TODO(b/131771163): Disable LTO when using explicit fuzzing configurations.
		// LTO breaks fuzzer builds.
		if ctx.isFuzzer() {
		// TODO(b/131771163): CFI and Fuzzer controls LTO flags by themselves.
		// This has be checked late because these properties can be mutated.
		if ctx.isCfi() \|\| ctx.isFuzzer() {
		return flags
		}

		if lto.LTO(ctx) {
		if lto.Properties.LtoEnabled {
		var ltoCFlag string
		var ltoLdFlag string
		if lto.ThinLTO() {
		@@ -97,7 +94,7 @@ func (lto *lto) flags(ctx BaseModuleContext, flags Flags) Flags {
		flags.Local.CFlags = append(flags.Local.CFlags, "-fwhole-program-vtables")
		}

		if (lto.DefaultThinLTO(ctx) \|\| lto.ThinLTO()) && ctx.Config().IsEnvTrue("USE_THINLTO_CACHE") {
		if ctx.Config().IsEnvTrue("USE_THINLTO_CACHE") {
		// Set appropriate ThinLTO cache policy
		cacheDirFormat := "-Wl,--thinlto-cache-dir="
		cacheDir := android.PathForOutput(ctx, "thinlto-cache").String()
		@@ -120,30 +117,40 @@ func (lto *lto) flags(ctx BaseModuleContext, flags Flags) Flags {
		return flags
		}

		// Determine which LTO mode to use for the given module.
		func (lto *lto) LTO(ctx BaseModuleContext) bool {
		return lto.ThinLTO() \|\| lto.DefaultThinLTO(ctx)
		if lto.Never() {
		return false
		}
		if ctx.Config().IsEnvTrue("DISABLE_LTO") {
		return false
		}
		// Module explicitly requests for LTO.
		if lto.ThinLTO() {
		return true
		}

		func (lto *lto) DefaultThinLTO(ctx BaseModuleContext) bool {
		// LP32 has many subtle issues and less test coverage.
		lib32 := ctx.Arch().ArchType.Multilib == "lib32"
		// CFI adds LTO flags by itself.
		cfi := ctx.isCfi()
		if ctx.Arch().ArchType.Multilib == "lib32" {
		return false
		}
		// Performance and binary size are less important for host binaries and tests.
		host := ctx.Host()
		test := ctx.testBinary() \|\| ctx.testLibrary()
		if ctx.Host() \|\| ctx.testBinary() \|\| ctx.testLibrary() {
		return false
		}
		// FIXME: ThinLTO for VNDK produces different output.
		// b/169217596
		vndk := ctx.isVndk()
		return GlobalThinLTO(ctx) && !lto.Never() && !lib32 && !cfi && !host && !test && !vndk
		if ctx.isVndk() {
		return false
		}
		return GlobalThinLTO(ctx)
		}

		func (lto *lto) ThinLTO() bool {
		return lto != nil && (proptools.Bool(lto.Properties.Lto.Thin) \|\| lto.Properties.ThinEnabled)
		return lto != nil && proptools.Bool(lto.Properties.Lto.Thin)
		}

		func (lto *lto) Never() bool {
		return lto != nil && (proptools.Bool(lto.Properties.Lto.Never) \|\| lto.Properties.NoLtoEnabled)
		return lto != nil && proptools.Bool(lto.Properties.Lto.Never)
		}

		func GlobalThinLTO(ctx android.BaseModuleContext) bool {
		@@ -152,11 +159,12 @@ func GlobalThinLTO(ctx android.BaseModuleContext) bool {

		// Propagate lto requirements down from binaries
		func ltoDepsMutator(mctx android.TopDownMutatorContext) {
		globalThinLTO := GlobalThinLTO(mctx)
		defaultLTOMode := GlobalThinLTO(mctx)

		if m, ok := mctx.Module().(*Module); ok {
		thin := m.lto.ThinLTO()
		never := m.lto.Never()
		if m.lto == nil \|\| m.lto.Properties.LtoEnabled == defaultLTOMode {
		return
		}

		mctx.WalkDeps(func(dep android.Module, parent android.Module) bool {
		tag := mctx.OtherModuleDependencyTag(dep)
		@@ -174,10 +182,9 @@ func ltoDepsMutator(mctx android.TopDownMutatorContext) {
		}

		if dep, ok := dep.(*Module); ok {
		if !globalThinLTO && thin && !dep.lto.ThinLTO() {
		dep.lto.Properties.ThinDep = true
		}
		if globalThinLTO && never && !dep.lto.Never() {
		if m.lto.Properties.LtoEnabled {
		dep.lto.Properties.LtoDep = true
		} else {
		dep.lto.Properties.NoLtoDep = true
		}
		}
		@@ -196,22 +203,19 @@ func ltoMutator(mctx android.BottomUpMutatorContext) {
		// Create variations for LTO types required as static
		// dependencies
		variationNames := []string{""}
		if !globalThinLTO && m.lto.Properties.ThinDep && !m.lto.ThinLTO() {
		if m.lto.Properties.LtoDep {
		variationNames = append(variationNames, "lto-thin")
		}
		if globalThinLTO && m.lto.Properties.NoLtoDep && !m.lto.Never() {
		if m.lto.Properties.NoLtoDep {
		variationNames = append(variationNames, "lto-none")
		}

		// Use correct dependencies if LTO property is explicitly set
		// (mutually exclusive)
		if !globalThinLTO && m.lto.ThinLTO() {
		mctx.SetDependencyVariation("lto-thin")
		}
		// Never must be the last, it overrides Thin.
		if globalThinLTO && m.lto.Never() {
		if globalThinLTO && !m.lto.Properties.LtoEnabled {
		mctx.SetDependencyVariation("lto-none")
		}
		if !globalThinLTO && m.lto.Properties.LtoEnabled {
		mctx.SetDependencyVariation("lto-thin")
		}

		if len(variationNames) > 1 {
		modules := mctx.CreateVariations(variationNames...)
		@@ -226,14 +230,14 @@ func ltoMutator(mctx android.BottomUpMutatorContext) {

		// LTO properties for dependencies
		if name == "lto-thin" {
		variation.lto.Properties.ThinEnabled = true
		variation.lto.Properties.LtoEnabled = true
		}
		if name == "lto-none" {
		variation.lto.Properties.NoLtoEnabled = true
		variation.lto.Properties.LtoEnabled = false
		}
		variation.Properties.PreventInstall = true
		variation.Properties.HideFromMake = true
		variation.lto.Properties.ThinDep = false
		variation.lto.Properties.LtoDep = false
		variation.lto.Properties.NoLtoDep = false
		}
		}