Add bloaty package

This package can be used by other binary generator to gather the section
sizes at build time. It uses bloaty_merger to export all the measured
data into a single proto file.

Bug: 172339742
Test: m out/soong/binary_sizes.pb
Change-Id: I0ca87cdb2fb8b77226e79d9dcd762abe64aeea51

bloaty/Android.bp

@@ -1,3 +1,16 @@
+bootstrap_go_package {
+    name: "soong-bloaty",
+    pkgPath: "android/soong/bloaty",
+    deps: [
+        "blueprint",
+        "soong-android",
+    ],
+    srcs: [
+        "bloaty.go",
+    ],
+    pluginFor: ["soong_build"],
+}
+
 python_test_host {
     name: "bloaty_merger_test",
     srcs: [

bloaty/bloaty.go

@@ -0,0 +1,92 @@
+// 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 bloaty implements a singleton that measures binary (e.g. ELF
+// executable, shared library or Rust rlib) section sizes at build time.
+package bloaty
+
+import (
+	"android/soong/android"
+
+	"github.com/google/blueprint"
+)
+
+const bloatyDescriptorExt = "bloaty.csv"
+
+var (
+	fileSizeMeasurerKey blueprint.ProviderKey
+	pctx                = android.NewPackageContext("android/soong/bloaty")
+
+	// bloaty is used to measure a binary section sizes.
+	bloaty = pctx.AndroidStaticRule("bloaty",
+		blueprint.RuleParams{
+			Command:     "${bloaty} -n 0 --csv ${in} > ${out}",
+			CommandDeps: []string{"${bloaty}"},
+		})
+
+	// The bloaty merger script is used to combine the outputs from bloaty
+	// into a single protobuf.
+	bloatyMerger = pctx.AndroidStaticRule("bloatyMerger",
+		blueprint.RuleParams{
+			Command:        "${bloatyMerger} ${out}.lst ${out}",
+			CommandDeps:    []string{"${bloatyMerger}"},
+			Rspfile:        "${out}.lst",
+			RspfileContent: "${in}",
+		})
+)
+
+func init() {
+	pctx.VariableConfigMethod("hostPrebuiltTag", android.Config.PrebuiltOS)
+	pctx.SourcePathVariable("bloaty", "prebuilts/build-tools/${hostPrebuiltTag}/bin/bloaty")
+	pctx.HostBinToolVariable("bloatyMerger", "bloaty_merger")
+	android.RegisterSingletonType("file_metrics", fileSizesSingleton)
+	fileSizeMeasurerKey = blueprint.NewProvider(android.ModuleOutPath{})
+}
+
+// MeasureSizeForPath should be called by binary producers (e.g. in builder.go).
+func MeasureSizeForPath(ctx android.ModuleContext, filePath android.WritablePath) {
+	ctx.SetProvider(fileSizeMeasurerKey, filePath)
+}
+
+type sizesSingleton struct{}
+
+func fileSizesSingleton() android.Singleton {
+	return &sizesSingleton{}
+}
+
+func (singleton *sizesSingleton) GenerateBuildActions(ctx android.SingletonContext) {
+	var deps android.Paths
+	// Visit all modules. If the size provider give us a binary path to measure,
+	// create the rule to measure it.
+	ctx.VisitAllModules(func(m android.Module) {
+		if !ctx.ModuleHasProvider(m, fileSizeMeasurerKey) {
+			return
+		}
+		filePath := ctx.ModuleProvider(m, fileSizeMeasurerKey).(android.ModuleOutPath)
+		sizeFile := filePath.ReplaceExtension(ctx, bloatyDescriptorExt)
+		ctx.Build(pctx, android.BuildParams{
+			Rule:        bloaty,
+			Description: "bloaty " + filePath.Rel(),
+			Input:       filePath,
+			Output:      sizeFile,
+		})
+		deps = append(deps, sizeFile)
+	})
+
+	ctx.Build(pctx, android.BuildParams{
+		Rule:   bloatyMerger,
+		Inputs: android.SortedUniquePaths(deps),
+		Output: android.PathForOutput(ctx, "binary_sizes.pb"),
+	})
+}