platform_build_soong/android/bazel_overlay.go
Jingwen Chen 5ba7e479d1 Create a AOSP Bazel overlay workspace with Soong
The Bazel overlay is a directory at out/soong/bazel_overlay that
replicates the layout of the AOSP Soong module tree, but as a Bazel
workspace. Each Soong module variant is represented as a BUILD target
created with the `soong_module` rule.

To create this overlay, run `m bazel_overlay`.

A `soong_module` target can depend on other `soong_module` targets.
These dependencies replicate each module's `directDeps` in the Blueprint
graph, just before `PrepareBuildActions`.

This enables users to use bazel query as a way to introspect the Soong
module graph. For example,

- Direct reverse dependencies of //bionic/libc:generated_android_ids in
//bionic/libc/...:

$ bazel query 'rdeps(//bionic/libc/...,
//bionic/libc:generated_android_ids, 1)'
//bionic/libc:libc_bionic_ndk--android_recovery_arm_armv7-a-neon_static
//bionic/libc:libc_bionic_ndk--android_ramdisk_arm_armv7-a-neon_static
//bionic/libc:libc_bionic_ndk--android_arm_armv7-a-neon_static_com.android.runtime
//bionic/libc:libc_bionic_ndk--android_arm_armv7-a-neon_static
//bionic/libc:generated_android_ids

- Why does com.android.runtime depend on lzma?

$ bazel query
'somepath(//bionic/apex:com.android.runtime--android_common_com.android.runtime_image,
//external/lzma/...)'
//bionic/apex:com.android.runtime--android_common_com.android.runtime_image
//bionic/libc/malloc_debug:libc_malloc_debug--android_arm_armv7-a-neon_shared_com.android.runtime
//system/core/libunwindstack:libunwindstack--android_arm_armv7-a-neon_shared_com.android.runtime
//external/lzma/C:liblzma--android_arm_armv7-a-neon_shared_com.android.runtime

- What does the dep graph of //bionic/libc:crtbegin_so look like?

$ bazel query
'deps(//bionic/libc:crtbegin_so--android_arm_armv7-a-neon)'
--output=graph > graph.in && dot -Tpng < graph.in > graph.png

https://photos.app.goo.gl/DfsdoFRNsRjGwTmy8

Test:  croot && m bazel_overlay && cd out/soong/bazel_overlay && bazel
query //... && bazel query 'rdeps(//bionic/libc/...,
//bionic/libc:generated_android_ids, 1)'

Signed-off-by: Jingwen Chen <jingwen@google.com>
Change-Id: I3bf40309bfb2d963bb8a688706385a57ee304c37#
2020-08-06 10:24:21 +00:00

76 lines
2.5 KiB
Go

// Copyright 2020 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 android
import (
"fmt"
"os"
"strings"
"github.com/google/blueprint"
)
// The Bazel Overlay singleton is responsible for generating the Ninja actions
// for calling the soong_build primary builder in the main build.ninja file.
func init() {
RegisterSingletonType("bazel_overlay", BazelOverlaySingleton)
}
func BazelOverlaySingleton() Singleton {
return &bazelOverlaySingleton{}
}
type bazelOverlaySingleton struct{}
func (c *bazelOverlaySingleton) GenerateBuildActions(ctx SingletonContext) {
// Create a build and rule statement, using the Bazel overlay's WORKSPACE
// file as the output file marker.
var deps Paths
moduleListFilePath := pathForBuildToolDep(ctx, ctx.Config().moduleListFile)
deps = append(deps, moduleListFilePath)
deps = append(deps, pathForBuildToolDep(ctx, ctx.Config().ProductVariablesFileName))
bazelOverlayDirectory := PathForOutput(ctx, "bazel_overlay")
bazelOverlayWorkspaceFile := bazelOverlayDirectory.Join(ctx, "WORKSPACE")
primaryBuilder := primaryBuilderPath(ctx)
bazelOverlay := ctx.Rule(pctx, "bazelOverlay",
blueprint.RuleParams{
Command: fmt.Sprintf(
"rm -rf ${outDir}/* && %s --bazel_overlay_dir ${outDir} %s && echo WORKSPACE: `cat %s` > ${outDir}/.overlay-depfile.d",
primaryBuilder.String(),
strings.Join(os.Args[1:], " "),
moduleListFilePath.String(), // Use the contents of Android.bp.list as the depfile.
),
CommandDeps: []string{primaryBuilder.String()},
Description: fmt.Sprintf(
"Creating the Bazel overlay workspace with %s at $outDir",
primaryBuilder.Base()),
Deps: blueprint.DepsGCC,
Depfile: "${outDir}/.overlay-depfile.d",
},
"outDir")
ctx.Build(pctx, BuildParams{
Rule: bazelOverlay,
Output: bazelOverlayWorkspaceFile,
Inputs: deps,
Args: map[string]string{
"outDir": bazelOverlayDirectory.String(),
},
})
// Add a phony target for building the bazel overlay
ctx.Phony("bazel_overlay", bazelOverlayWorkspaceFile)
}