From 9723e338ee143a4daff826a521ecd3672adf1b32 Mon Sep 17 00:00:00 2001
From: Yi Kong <yikong@google.com>
Date: Mon, 4 Dec 2023 14:52:53 +0900
Subject: [PATCH] Do not perform AFDO or optimizing LTO for eng builds

Afdo creates more variants to build, and optimizing LTO is costly to
perform. Turn off these two optimizations for eng builds for a faster
build speed.

This reduces total C/C++ invocation time for aosp_arm64-eng by 6.28%.

Test: presubmit
Bug: 307753064
Change-Id: Ibac4269c66a64e896dba2074b607d71a2da37546
---
 cc/afdo.go | 7 +++++++
 cc/cc.go   | 3 +++
 cc/lto.go  | 3 ++-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/cc/afdo.go b/cc/afdo.go
index 91cf0b8a2..e7dea0e0d 100644
--- a/cc/afdo.go
+++ b/cc/afdo.go
@@ -64,6 +64,13 @@ func (afdo *afdo) props() []interface{} {
 	return []interface{}{&afdo.Properties}
 }
 
+func (afdo *afdo) begin(ctx BaseModuleContext) {
+	// Disable on eng builds for faster build.
+	if ctx.Config().Eng() {
+		afdo.Properties.Afdo = false
+	}
+}
+
 // afdoEnabled returns true for binaries and shared libraries
 // that set afdo prop to True and there is a profile available
 func (afdo *afdo) afdoEnabled() bool {
diff --git a/cc/cc.go b/cc/cc.go
index 867a59c03..2e42761c4 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -2401,6 +2401,9 @@ func (c *Module) begin(ctx BaseModuleContext) {
 	if c.coverage != nil {
 		c.coverage.begin(ctx)
 	}
+	if c.afdo != nil {
+		c.afdo.begin(ctx)
+	}
 	if c.lto != nil {
 		c.lto.begin(ctx)
 	}
diff --git a/cc/lto.go b/cc/lto.go
index d2a43d27b..8b0880cf0 100644
--- a/cc/lto.go
+++ b/cc/lto.go
@@ -116,7 +116,8 @@ func (lto *lto) flags(ctx BaseModuleContext, flags Flags) Flags {
 		// better dead code elimination and CFG simplification, but do
 		// not perform costly optimizations for a balance between compile
 		// time, binary size and performance.
-		if !lto.ThinLTO() {
+		// Apply the same for Eng builds as well.
+		if !lto.ThinLTO() || ctx.Config().Eng() {
 			ltoLdFlags = append(ltoLdFlags, "-Wl,--lto-O0")
 		}