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// Copyright 2021 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cc
import (
"fmt"
"strings"
"android/soong/android"
"github.com/google/blueprint"
)
// This flag needs to be in both CFlags and LdFlags to ensure correct symbol ordering
const afdoFlagsFormat = "-fprofile-sample-use=%s -fprofile-sample-accurate"
type AfdoProperties struct {
// Afdo allows developers self-service enroll for
// automatic feedback-directed optimization using profile data.
Afdo bool
AfdoDep bool `blueprint:"mutated"`
}
type afdo struct {
Properties AfdoProperties
}
func (afdo *afdo) props() []interface{} {
return []interface{}{&afdo.Properties}
}
func (afdo *afdo) begin(ctx BaseModuleContext) {
// Disable on eng builds for faster build.
if ctx.Config().Eng() {
afdo.Properties.Afdo = false
}
}
// afdoEnabled returns true for binaries and shared libraries
// that set afdo prop to True.
func (afdo *afdo) afdoEnabled() bool {
return afdo != nil && afdo.Properties.Afdo
}
func (afdo *afdo) isAfdoCompile(ctx ModuleContext) bool {
fdoProfilePath := getFdoProfilePathFromDep(ctx)
return !ctx.Host() && (afdo.Properties.Afdo || afdo.Properties.AfdoDep) && (fdoProfilePath != "")
}
func getFdoProfilePathFromDep(ctx ModuleContext) string {
fdoProfileDeps := ctx.GetDirectDepsWithTag(FdoProfileTag)
if len(fdoProfileDeps) > 0 && fdoProfileDeps[0] != nil {
if info, ok := android.OtherModuleProvider(ctx, fdoProfileDeps[0], FdoProfileProvider); ok {
return info.Path.String()
}
}
return ""
}
func (afdo *afdo) flags(ctx ModuleContext, flags Flags) Flags {
if ctx.Host() {
return flags
}
if afdo.Properties.Afdo || afdo.Properties.AfdoDep {
// We use `-funique-internal-linkage-names` to associate profiles to the right internal
// functions. This option should be used before generating a profile. Because a profile
// generated for a binary without unique names doesn't work well building a binary with
// unique names (they have different internal function names).
// To avoid a chicken-and-egg problem, we enable `-funique-internal-linkage-names` when
// `afdo=true`, whether a profile exists or not.
// The profile can take effect in three steps:
// 1. Add `afdo: true` in Android.bp, and build the binary.
// 2. Collect an AutoFDO profile for the binary.
// 3. Make the profile searchable by the build system. So it's used the next time the binary
// is built.
flags.Local.CFlags = append([]string{"-funique-internal-linkage-names"}, flags.Local.CFlags...)
// Flags for Flow Sensitive AutoFDO
flags.Local.CFlags = append([]string{"-mllvm", "-enable-fs-discriminator=true"}, flags.Local.CFlags...)
// TODO(b/266595187): Remove the following feature once it is enabled in LLVM by default.
flags.Local.CFlags = append([]string{"-mllvm", "-improved-fs-discriminator=true"}, flags.Local.CFlags...)
}
if fdoProfilePath := getFdoProfilePathFromDep(ctx); fdoProfilePath != "" {
// The flags are prepended to allow overriding.
profileUseFlag := fmt.Sprintf(afdoFlagsFormat, fdoProfilePath)
flags.Local.CFlags = append([]string{profileUseFlag}, flags.Local.CFlags...)
flags.Local.LdFlags = append([]string{profileUseFlag, "-Wl,-mllvm,-no-warn-sample-unused=true"}, flags.Local.LdFlags...)
// Update CFlagsDeps and LdFlagsDeps so the module is rebuilt
// if profileFile gets updated
pathForSrc := android.PathForSource(ctx, fdoProfilePath)
flags.CFlagsDeps = append(flags.CFlagsDeps, pathForSrc)
flags.LdFlagsDeps = append(flags.LdFlagsDeps, pathForSrc)
}
return flags
}
func (a *afdo) addDep(ctx android.BottomUpMutatorContext, fdoProfileTarget string) {
if fdoProfileName, err := ctx.DeviceConfig().AfdoProfile(fdoProfileTarget); fdoProfileName != "" && err == nil {
ctx.AddFarVariationDependencies(
[]blueprint.Variation{
{Mutator: "arch", Variation: ctx.Target().ArchVariation()},
{Mutator: "os", Variation: "android"},
},
FdoProfileTag,
fdoProfileName)
}
}
func afdoPropagateViaDepTag(tag blueprint.DependencyTag) bool {
libTag, isLibTag := tag.(libraryDependencyTag)
// Do not recurse down non-static dependencies
if isLibTag {
return libTag.static()
} else {
return tag == objDepTag || tag == reuseObjTag || tag == staticVariantTag
}
}
// afdoTransitionMutator creates afdo variants of cc modules.
type afdoTransitionMutator struct{}
func (a *afdoTransitionMutator) Split(ctx android.BaseModuleContext) []string {
return []string{""}
}
func (a *afdoTransitionMutator) OutgoingTransition(ctx android.OutgoingTransitionContext, sourceVariation string) string {
if ctx.Host() {
return ""
}
if m, ok := ctx.Module().(*Module); ok && m.afdo != nil {
if !afdoPropagateViaDepTag(ctx.DepTag()) {
return ""
}
if sourceVariation != "" {
return sourceVariation
}
if !m.afdo.afdoEnabled() {
return ""
}
// TODO(b/324141705): this is designed to prevent propagating AFDO from static libraries that have afdo: true set, but
// it should be m.static() && !m.staticBinary() so that static binaries use AFDO variants of dependencies.
if m.static() {
return ""
}
return encodeTarget(ctx.Module().Name())
}
return ""
}
func (a *afdoTransitionMutator) IncomingTransition(ctx android.IncomingTransitionContext, incomingVariation string) string {
if m, ok := ctx.Module().(*Module); ok && m.afdo != nil {
return incomingVariation
}
return ""
}
func (a *afdoTransitionMutator) Mutate(ctx android.BottomUpMutatorContext, variation string) {
if m, ok := ctx.Module().(*Module); ok && m.afdo != nil {
if variation == "" {
// The empty variation is either a module that has enabled AFDO for itself, or the non-AFDO
// variant of a dependency.
if m.afdo.afdoEnabled() && !(m.static() && !m.staticBinary()) && !m.Host() {
m.afdo.addDep(ctx, ctx.ModuleName())
}
} else {
// The non-empty variation is the AFDO variant of a dependency of a module that enabled AFDO
// for itself.
m.Properties.PreventInstall = true
m.Properties.HideFromMake = true
m.afdo.Properties.AfdoDep = true
m.afdo.addDep(ctx, decodeTarget(variation))
}
}
}
// Encode target name to variation name.
func encodeTarget(target string) string {
if target == "" {
return ""
}
return "afdo-" + target
}
// Decode target name from variation name.
func decodeTarget(variation string) string {
if variation == "" {
return ""
}
return strings.TrimPrefix(variation, "afdo-")
}
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