From 5007c4a06d7452c7b8dbed2910665d6719d0d390 Mon Sep 17 00:00:00 2001
From: Mitch Phillips <mitchp@google.com>
Date: Wed, 2 Mar 2022 01:25:22 +0000
Subject: [PATCH] Revert "[cc_fuzz] Revert 'disable LTO' patches."

Revert submission 1976512-revert-nolto-fuzzing

Reason for revert: b/222160662
Reverted Changes:
Iacee4fa29:[cc_fuzz] Revert 'disable LTO' patches.
Ic509b00a1:[cc_fuzz] Revert 'disable LTO' patches.
If85931f09:[cc_fuzz] Revert 'disable LTO' patches.

Change-Id: I84e01a4f84145e3331c2955836c8cc9bfa05c36b
---
 cc/lto.go      |  6 ++++++
 cc/sanitize.go | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/cc/lto.go b/cc/lto.go
index a48a12ce4..6d555790c 100644
--- a/cc/lto.go
+++ b/cc/lto.go
@@ -82,6 +82,12 @@ func (lto *lto) useClangLld(ctx BaseModuleContext) bool {
 }
 
 func (lto *lto) flags(ctx BaseModuleContext, flags Flags) Flags {
+	// TODO(b/131771163): Disable LTO when using explicit fuzzing configurations.
+	// LTO breaks fuzzer builds.
+	if inList("-fsanitize=fuzzer-no-link", flags.Local.CFlags) {
+		return flags
+	}
+
 	if lto.LTO(ctx) {
 		var ltoCFlag string
 		var ltoLdFlag string
diff --git a/cc/sanitize.go b/cc/sanitize.go
index 9e047d5d1..6c6882217 100644
--- a/cc/sanitize.go
+++ b/cc/sanitize.go
@@ -540,6 +540,12 @@ func (sanitize *sanitize) begin(ctx BaseModuleContext) {
 		s.Address = nil
 		s.Thread = nil
 	}
+
+	// TODO(b/131771163): CFI transiently depends on LTO, and thus Fuzzer is
+	// mutually incompatible.
+	if Bool(s.Fuzzer) {
+		s.Cfi = nil
+	}
 }
 
 func toDisableImplicitIntegerChange(flags []string) bool {
@@ -642,6 +648,12 @@ func (sanitize *sanitize) flags(ctx ModuleContext, flags Flags) Flags {
 	if Bool(sanitize.Properties.Sanitize.Fuzzer) {
 		flags.Local.CFlags = append(flags.Local.CFlags, "-fsanitize=fuzzer-no-link")
 
+		// TODO(b/131771163): LTO and Fuzzer support is mutually incompatible.
+		_, flags.Local.LdFlags = removeFromList("-flto", flags.Local.LdFlags)
+		_, flags.Local.CFlags = removeFromList("-flto", flags.Local.CFlags)
+		flags.Local.LdFlags = append(flags.Local.LdFlags, "-fno-lto")
+		flags.Local.CFlags = append(flags.Local.CFlags, "-fno-lto")
+
 		// TODO(b/142430592): Upstream linker scripts for sanitizer runtime libraries
 		// discard the sancov_lowest_stack symbol, because it's emulated TLS (and thus
 		// doesn't match the linker script due to the "__emutls_v." prefix).