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Commit 6146cf4b authored by Chris Wailes's avatar Chris Wailes
Browse files

Make building Rust targets faster in eng builds 

This CL makes the following changes when building an eng variant to
speed up compilation, possibly at the expense of the performance of the
generated binary:
* Disables LTO
* Enables incremental compilation
* Sets codegen units to 256 to increase parallelism (default set when
  enabling incremental compilation)

These changes reduce the time taken to compile all of Android's Rust
code from 16m20s to 12m10s.

Test: lunch aosp_oriole-eng && m clean && m rust
Bug: https://b.corp.google.com/issues/289094772
Change-Id: I97f1675c67ded69120b0c0e0fb5608aa9314a866
parent 7d7d94ff

rust/builder.go

+15 −15
Original line number Diff line number Diff line
@@ -122,8 +122,6 @@ func init() { 


func TransformSrcToBinary(ctx ModuleContext, mainSrc android.Path, deps PathDeps, flags Flags,

	outputFile android.WritablePath) buildOutput {

	flags.GlobalRustFlags = append(flags.GlobalRustFlags, "-C lto=thin")



	return transformSrctoCrate(ctx, mainSrc, deps, flags, outputFile, "bin")

}
@@ -134,20 +132,16 @@ func TransformSrctoRlib(ctx ModuleContext, mainSrc android.Path, deps PathDeps, 


func TransformSrctoDylib(ctx ModuleContext, mainSrc android.Path, deps PathDeps, flags Flags,

	outputFile android.WritablePath) buildOutput {

	flags.GlobalRustFlags = append(flags.GlobalRustFlags, "-C lto=thin")



	return transformSrctoCrate(ctx, mainSrc, deps, flags, outputFile, "dylib")

}



func TransformSrctoStatic(ctx ModuleContext, mainSrc android.Path, deps PathDeps, flags Flags,

	outputFile android.WritablePath) buildOutput {

	flags.GlobalRustFlags = append(flags.GlobalRustFlags, "-C lto=thin")

	return transformSrctoCrate(ctx, mainSrc, deps, flags, outputFile, "staticlib")

}



func TransformSrctoShared(ctx ModuleContext, mainSrc android.Path, deps PathDeps, flags Flags,

	outputFile android.WritablePath) buildOutput {

	flags.GlobalRustFlags = append(flags.GlobalRustFlags, "-C lto=thin")

	return transformSrctoCrate(ctx, mainSrc, deps, flags, outputFile, "cdylib")

}
@@ -263,6 +257,21 @@ func transformSrctoCrate(ctx ModuleContext, main android.Path, deps PathDeps, fl 


	inputs = append(inputs, main)



	if ctx.Config().Eng() {

		// Per https://doc.rust-lang.org/rustc/codegen-options/index.html#codegen-units

		// incremental building implies codegen-units=256

		incrementalPath := android.PathForModuleOut(ctx, "rustc-incremental").String()

		flags.GlobalRustFlags = append(flags.GlobalRustFlags, "-C incremental="+incrementalPath)



	} else {

		flags.GlobalRustFlags = append(flags.GlobalRustFlags, "-C codegen-units=1")



		if !(ctx.RustModule().Rlib() || ctx.RustModule().ProcMacro()) {

			flags.GlobalRustFlags = append(flags.GlobalRustFlags, "-Z dylib-lto")

			flags.GlobalRustFlags = append(flags.GlobalRustFlags, "-C lto=thin")

		}

	}



	// Collect rustc flags

	rustcFlags = append(rustcFlags, flags.GlobalRustFlags...)

	rustcFlags = append(rustcFlags, flags.RustFlags...)
@@ -278,15 +287,6 @@ func transformSrctoCrate(ctx ModuleContext, main android.Path, deps PathDeps, fl 
	// Suppress an implicit sysroot

	rustcFlags = append(rustcFlags, "--sysroot=/dev/null")



	// Enable incremental compilation if requested by user

	if ctx.Config().IsEnvTrue("SOONG_RUSTC_INCREMENTAL") {

		incrementalPath := android.PathForOutput(ctx, "rustc").String()



		rustcFlags = append(rustcFlags, "-C incremental="+incrementalPath)

	} else {

		rustcFlags = append(rustcFlags, "-C codegen-units=1")

	}



	// Disallow experimental features

	modulePath := ctx.ModuleDir()

	if !(android.IsThirdPartyPath(modulePath) || strings.HasPrefix(modulePath, "prebuilts")) {