Introduce afdo
A new configuration rule for sampling PGO. This differs from the
original pgo.go rule in the following ways:
* Automatic propagation to static dependencies
* Simpler configuration (just put `afdo: true` to optimsation targets)
http://go/android-afdo
Test: build
Bug: 79161490
Change-Id: Ie194824cd523bca19e10ced41d2078fc598f13b3
diff --git a/cc/afdo.go b/cc/afdo.go
new file mode 100644
index 0000000..022f283
--- /dev/null
+++ b/cc/afdo.go
@@ -0,0 +1,194 @@
+// 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"
+
+ "github.com/google/blueprint/proptools"
+
+ "android/soong/android"
+)
+
+var (
+ globalAfdoProfileProjects = []string{
+ "vendor/google_data/pgo_profile/sampling/",
+ "toolchain/pgo-profiles/sampling/",
+ }
+)
+
+var afdoProfileProjectsConfigKey = android.NewOnceKey("AfdoProfileProjects")
+
+const afdoCFlagsFormat = "-fprofile-sample-accurate -fprofile-sample-use=%s"
+
+func getAfdoProfileProjects(config android.DeviceConfig) []string {
+ return config.OnceStringSlice(afdoProfileProjectsConfigKey, func() []string {
+ return append(globalAfdoProfileProjects, config.AfdoAdditionalProfileDirs()...)
+ })
+}
+
+func recordMissingAfdoProfileFile(ctx BaseModuleContext, missing string) {
+ getNamedMapForConfig(ctx.Config(), modulesMissingProfileFileKey).Store(missing, true)
+}
+
+type AfdoProperties struct {
+ Afdo bool
+
+ AfdoTarget *string `blueprint:"mutated"`
+ AfdoDeps []string `blueprint:"mutated"`
+}
+
+type afdo struct {
+ Properties AfdoProperties
+}
+
+func (afdo *afdo) props() []interface{} {
+ return []interface{}{&afdo.Properties}
+}
+
+func (afdo *afdo) AfdoEnabled() bool {
+ return afdo != nil && afdo.Properties.Afdo && afdo.Properties.AfdoTarget != nil
+}
+
+// Get list of profile file names, ordered by level of specialisation. For example:
+// 1. libfoo_arm64.afdo
+// 2. libfoo.afdo
+// Add more specialisation as needed.
+func getProfileFiles(ctx BaseModuleContext, moduleName string) []string {
+ var files []string
+ files = append(files, moduleName+"_"+ctx.Arch().ArchType.String()+".afdo")
+ files = append(files, moduleName+".afdo")
+ return files
+}
+
+func (props *AfdoProperties) getAfdoProfileFile(ctx BaseModuleContext, module string) android.OptionalPath {
+ // Test if the profile_file is present in any of the Afdo profile projects
+ for _, profileFile := range getProfileFiles(ctx, module) {
+ for _, profileProject := range getAfdoProfileProjects(ctx.DeviceConfig()) {
+ path := android.ExistentPathForSource(ctx, profileProject, profileFile)
+ if path.Valid() {
+ return path
+ }
+ }
+ }
+
+ // Record that this module's profile file is absent
+ missing := ctx.ModuleDir() + ":" + module
+ recordMissingAfdoProfileFile(ctx, missing)
+
+ return android.OptionalPathForPath(nil)
+}
+
+func (afdo *afdo) begin(ctx BaseModuleContext) {
+ if afdo.Properties.Afdo && !ctx.static() && !ctx.Host() {
+ module := ctx.ModuleName()
+ if afdo.Properties.getAfdoProfileFile(ctx, module).Valid() {
+ afdo.Properties.AfdoTarget = proptools.StringPtr(module)
+ }
+ }
+}
+
+func (afdo *afdo) flags(ctx ModuleContext, flags Flags) Flags {
+ if profile := afdo.Properties.AfdoTarget; profile != nil {
+ if profileFile := afdo.Properties.getAfdoProfileFile(ctx, *profile); profileFile.Valid() {
+ profileFilePath := profileFile.Path()
+
+ profileUseFlag := fmt.Sprintf(afdoCFlagsFormat, profileFile)
+ flags.Local.CFlags = append(flags.Local.CFlags, profileUseFlag)
+ flags.Local.LdFlags = append(flags.Local.LdFlags, profileUseFlag)
+ flags.Local.LdFlags = append(flags.Local.LdFlags, "-Wl,-mllvm,-no-warn-sample-unused=true")
+
+ // Update CFlagsDeps and LdFlagsDeps so the module is rebuilt
+ // if profileFile gets updated
+ flags.CFlagsDeps = append(flags.CFlagsDeps, profileFilePath)
+ flags.LdFlagsDeps = append(flags.LdFlagsDeps, profileFilePath)
+ }
+ }
+
+ return flags
+}
+
+// Propagate afdo requirements down from binaries
+func afdoDepsMutator(mctx android.TopDownMutatorContext) {
+ if m, ok := mctx.Module().(*Module); ok && m.afdo.AfdoEnabled() {
+ afdoTarget := *m.afdo.Properties.AfdoTarget
+ mctx.WalkDeps(func(dep android.Module, parent android.Module) bool {
+ tag := mctx.OtherModuleDependencyTag(dep)
+ libTag, isLibTag := tag.(libraryDependencyTag)
+
+ // Do not recurse down non-static dependencies
+ if isLibTag {
+ if !libTag.static() {
+ return false
+ }
+ } else {
+ if tag != objDepTag && tag != reuseObjTag {
+ return false
+ }
+ }
+
+ if dep, ok := dep.(*Module); ok {
+ dep.afdo.Properties.AfdoDeps = append(dep.afdo.Properties.AfdoDeps, afdoTarget)
+ }
+
+ return true
+ })
+ }
+}
+
+// Create afdo variants for modules that need them
+func afdoMutator(mctx android.BottomUpMutatorContext) {
+ if m, ok := mctx.Module().(*Module); ok && m.afdo != nil {
+ if m.afdo.AfdoEnabled() && !m.static() {
+ afdoTarget := *m.afdo.Properties.AfdoTarget
+ mctx.SetDependencyVariation(encodeTarget(afdoTarget))
+ }
+
+ variationNames := []string{""}
+ afdoDeps := android.FirstUniqueStrings(m.afdo.Properties.AfdoDeps)
+ for _, dep := range afdoDeps {
+ variationNames = append(variationNames, encodeTarget(dep))
+ }
+ if len(variationNames) > 1 {
+ modules := mctx.CreateVariations(variationNames...)
+ for i, name := range variationNames {
+ if name == "" {
+ continue
+ }
+ variation := modules[i].(*Module)
+ variation.Properties.PreventInstall = true
+ variation.Properties.HideFromMake = true
+ variation.afdo.Properties.AfdoTarget = proptools.StringPtr(decodeTarget(name))
+ }
+ }
+ }
+}
+
+// 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-")
+}