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Commit 7e53c57e authored by Yi Kong's avatar Yi Kong
Browse files

Disable inlining and loop unrolling in LTO without PGO profile 

Such optimisations may significantly increase the binary size when
compiler heuristics are off. Disabling these helps cut down the
binary sizes with negligible decrease in performance, but allows us to
be more comfortable enabling LTO across various projects.

Test: m
Test: dex2oat, hwui, skia benchmark
Bug: 62839002
Change-Id: Id63e8dd295df2972f76ae4e29ee367080fff8429
parent 51be632b

cc/cc.go

+12 −0
Original line number Diff line number Diff line
@@ -211,6 +211,7 @@ type ModuleContextIntf interface { 
	selectedStl() string

	baseModuleName() string

	getVndkExtendsModuleName() string

	isPgoCompile() bool

}



type ModuleContext interface {
@@ -408,6 +409,13 @@ func (c *Module) isVndk() bool { 
	return false

}



func (c *Module) isPgoCompile() bool {

	if pgo := c.pgo; pgo != nil {

		return pgo.Properties.PgoCompile

	}

	return false

}



func (c *Module) isVndkSp() bool {

	if vndkdep := c.vndkdep; vndkdep != nil {

		return vndkdep.isVndkSp()
@@ -507,6 +515,10 @@ func (ctx *moduleContextImpl) isVndk() bool { 
	return ctx.mod.isVndk()

}



func (ctx *moduleContextImpl) isPgoCompile() bool {

	return ctx.mod.isPgoCompile()

}



func (ctx *moduleContextImpl) isVndkSp() bool {

	return ctx.mod.isVndkSp()

}

cc/lto.go

+7 −0
Original line number Diff line number Diff line
@@ -87,6 +87,13 @@ func (lto *lto) flags(ctx BaseModuleContext, flags Flags) Flags { 
			flags.LdFlags = append(flags.LdFlags, "-Wl,-plugin-opt,-emulated-tls")

		}

		flags.ArGoldPlugin = true



		// If the module does not have a profile, be conservative and do not inline

		// or unroll loops during LTO, in order to prevent significant size bloat.

		if !ctx.isPgoCompile() {

			flags.LdFlags = append(flags.LdFlags, "-Wl,-plugin-opt,-inline-threshold=0")

			flags.LdFlags = append(flags.LdFlags, "-Wl,-plugin-opt,-unroll-threshold=0")

		}

	}

	return flags

}

cc/pgo.go

+9 −2
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ func getPgoProfileProjects(config android.DeviceConfig) []string { 
	})

}



func recordMissingProfileFile(ctx ModuleContext, missing string) {

func recordMissingProfileFile(ctx BaseModuleContext, missing string) {

	getNamedMapForConfig(ctx.Config(), modulesMissingProfileFile).Store(missing, true)

}
@@ -63,6 +63,7 @@ type PgoProperties struct { 


	PgoPresent          bool `blueprint:"mutated"`

	ShouldProfileModule bool `blueprint:"mutated"`

	PgoCompile          bool `blueprint:"mutated"`

}



type pgo struct {
@@ -98,7 +99,7 @@ func (props *PgoProperties) addProfileGatherFlags(ctx ModuleContext, flags Flags 
	return flags

}



func (props *PgoProperties) getPgoProfileFile(ctx ModuleContext) android.OptionalPath {

func (props *PgoProperties) getPgoProfileFile(ctx BaseModuleContext) android.OptionalPath {

	// Test if the profile_file is present in any of the PGO profile projects

	for _, profileProject := range getPgoProfileProjects(ctx.DeviceConfig()) {

		path := android.ExistentPathForSource(ctx, "", profileProject, *props.Pgo.Profile_file)
@@ -232,6 +233,12 @@ func (pgo *pgo) begin(ctx BaseModuleContext) { 
			}

		}

	}



	if !ctx.Config().IsEnvTrue("ANDROID_PGO_NO_PROFILE_USE") {

		if profileFile := pgo.Properties.getPgoProfileFile(ctx); profileFile.Valid() {

			pgo.Properties.PgoCompile = true

		}

	}

}



func (pgo *pgo) deps(ctx BaseModuleContext, deps Deps) Deps {