patches/ANDROID-Do-not-record-function-addresses-if-value-profiling-is-disabled.patch

From ba72e3476bfd8f588c288f87048199a5e6f7a0ee Mon Sep 17 00:00:00 2001
From: Pirama Arumuga Nainar <pirama@google.com>
Date: Wed, 12 Feb 2020 10:40:09 -0800
Subject: [ANDROID] Do not record function addresses if value profiling is
 disabled

Temporary change until a proper fix is merged to upstream.

Don't recording function addresses in __llvm_prf_data when value
profiling is turned off.  This is safe for Android, where we don't use
value profiling.

Functional change: needs -mllvm -enable-value-profiling to work with LTO

The proper fix is to use associated metadata to link a __llvm_prf_data
of a function with the function itself so the linker can discard the
__llvm_prf_data if the function itself is discarded.  See
http://lists.llvm.org/pipermail/llvm-dev/2019-December/137363.html for
more details.

Change-Id: Ifcb04349e71e20ae3ef4bb82ebf8ac064fc59169
---
 clang/lib/CodeGen/CodeGenPGO.cpp                       | 5 +----
 llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp | 8 ++++++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/clang/lib/CodeGen/CodeGenPGO.cpp b/clang/lib/CodeGen/CodeGenPGO.cpp
index e525abe979e..fee33883ac0 100644
--- a/clang/lib/CodeGen/CodeGenPGO.cpp
+++ b/clang/lib/CodeGen/CodeGenPGO.cpp
@@ -21,10 +21,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MD5.h"
 
-static llvm::cl::opt<bool>
-    EnableValueProfiling("enable-value-profiling", llvm::cl::ZeroOrMore,
-                         llvm::cl::desc("Enable value profiling"),
-                         llvm::cl::Hidden, llvm::cl::init(false));
+extern llvm::cl::opt<bool> EnableValueProfiling;
 
 using namespace clang;
 using namespace CodeGen;
diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 63c2b807896..6aba06fbb65 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -71,6 +71,11 @@ cl::opt<unsigned> MemOPSizeLarge(
              "Value of 0 disables the large value profiling."),
     cl::init(8192));
 
+llvm::cl::opt<bool>
+    EnableValueProfiling("enable-value-profiling", llvm::cl::ZeroOrMore,
+                         llvm::cl::desc("Enable value profiling"),
+                         llvm::cl::Hidden, llvm::cl::init(false));
+
 namespace {
 
 cl::opt<bool> DoNameCompression("enable-name-compression",
@@ -678,6 +683,9 @@ static std::string getVarName(InstrProfIncrementInst *Inc, StringRef Prefix) {
 }
 
 static inline bool shouldRecordFunctionAddr(Function *F) {
+  if (!EnableValueProfiling)
+    return false;
+
   // Check the linkage
   bool HasAvailableExternallyLinkage = F->hasAvailableExternallyLinkage();
   if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage() &&
-- 
2.25.0.225.g125e21ebc7-goog