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Commit ab58647b authored by Ivan Lozano's avatar Ivan Lozano
Browse files

rust: Add an option to disable LTO for Rust 

This adds an option to disable LTO when building a Rust module. This is
mostly intended to speedu p local prototyping, and LTO should not
normally be disabled for production builds.

Bug: 339628497
Test: m blueprint_tests && m rust
Change-Id: I21d5d4513a259a56f101ce8906e2bef7404e4efb
parent e8fcd377

rust/builder.go

+14 −4
Original line number Diff line number Diff line
@@ -158,7 +158,9 @@ func getTransformProperties(ctx ModuleContext, crateType string) transformProper 


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

	outputFile android.WritablePath) buildOutput {

	if ctx.RustModule().compiler.Thinlto() {

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

	}



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

}
@@ -212,20 +214,28 @@ func TransformRlibstoStaticlib(ctx android.ModuleContext, mainSrc android.Path, 


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

	outputFile android.WritablePath) buildOutput {

	if ctx.RustModule().compiler.Thinlto() {

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

	}



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

}



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

	outputFile android.WritablePath) buildOutput {

	if ctx.RustModule().compiler.Thinlto() {

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

	}



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

}



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

	outputFile android.WritablePath) buildOutput {

	if ctx.RustModule().compiler.Thinlto() {

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

	}



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

}

rust/compiler.go

+15 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ type compiler interface { 
	edition() string

	features() []string

	rustdoc(ctx ModuleContext, flags Flags, deps PathDeps) android.OptionalPath

	Thinlto() bool



	// Output directory in which source-generated code from dependencies is

	// copied. This is equivalent to Cargo's OUT_DIR variable.
@@ -231,6 +232,15 @@ type BaseCompilerProperties struct { 


	// If cargo_env_compat is true, sets the CARGO_PKG_VERSION env var to this value.

	Cargo_pkg_version *string



	// Control whether LTO is used for the final (Rust) linkage. This does not impact

	// cross-language LTO.

	Lto struct {

		// Whether thin LTO should be enabled. By default this is true.

		// LTO provides such a large code size benefit for Rust, this should always

		// be enabled for production builds unless there's a clear need to disable it.

		Thin *bool `android:"arch_variant"`

	} `android:"arch_variant"`

}



type baseCompiler struct {
@@ -273,6 +283,11 @@ func (compiler *baseCompiler) Disabled() bool { 
	return false

}



// Thin LTO is enabled by default.

func (compiler *baseCompiler) Thinlto() bool {

	return BoolDefault(compiler.Properties.Lto.Thin, true)

}



func (compiler *baseCompiler) SetDisabled() {

	panic("baseCompiler does not implement SetDisabled()")

}

rust/compiler_test.go

+29 −0
Original line number Diff line number Diff line
@@ -63,6 +63,35 @@ func TestCfgsToFlags(t *testing.T) { 
	}

}



func TestLtoFlag(t *testing.T) {

	ctx := testRust(t, `

		rust_library_host {

			name: "libfoo",

			srcs: ["foo.rs"],

			crate_name: "foo",

			lto: {

				thin: false,

			}

		}



		rust_library_host {

			name: "libfoo_lto",

			srcs: ["foo.rs"],

			crate_name: "foo",

		}

		`)



	libfoo := ctx.ModuleForTests("libfoo", "linux_glibc_x86_64_dylib").Rule("rustc")

	libfooLto := ctx.ModuleForTests("libfoo_lto", "linux_glibc_x86_64_dylib").Rule("rustc")



	if strings.Contains(libfoo.Args["rustcFlags"], "-C lto=thin") {

		t.Fatalf("libfoo expected to disable lto -- rustcFlags: %#v", libfoo.Args["rustcFlags"])

	}

	if !strings.Contains(libfooLto.Args["rustcFlags"], "-C lto=thin") {

		t.Fatalf("libfoo expected to enable lto by default -- rustcFlags: %#v", libfooLto.Args["rustcFlags"])

	}

}



// Test that we reject multiple source files.

func TestEnforceSingleSourceFile(t *testing.T) {