From ebb0ebff4b78e4a1de410cfc86597885d58a3e86 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@google.com>
Date: Sat, 19 Sep 2015 23:14:51 +0000
Subject: [PATCH] COFF: Fix thread-safety bug.

LTOModule doesn't seem to be thread-safe, so guard that with mutex.

llvm-svn: 248102
---
 lld/COFF/InputFiles.cpp | 5 +++++
 lld/COFF/InputFiles.h   | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp
index df92c432b6a9..6fdb8e265352 100644
--- a/lld/COFF/InputFiles.cpp
+++ b/lld/COFF/InputFiles.cpp
@@ -310,6 +310,9 @@ void ImportFile::parse() {
 }
 
 void BitcodeFile::parse() {
+  // Usually parse() is thread-safe, but bitcode file is an exception.
+  std::lock_guard<std::mutex> Lock(Mu);
+
   std::string Err;
   M.reset(LTOModule::createFromBuffer(MB.getBufferStart(),
                                       MB.getBufferSize(),
@@ -356,5 +359,7 @@ MachineTypes BitcodeFile::getMachineType() {
   }
 }
 
+std::mutex BitcodeFile::Mu;
+
 } // namespace coff
 } // namespace lld
diff --git a/lld/COFF/InputFiles.h b/lld/COFF/InputFiles.h
index 4f93a6749dfc..ca9ed3f5ddb4 100644
--- a/lld/COFF/InputFiles.h
+++ b/lld/COFF/InputFiles.h
@@ -17,6 +17,7 @@
 #include "llvm/Object/COFF.h"
 #include "llvm/Support/StringSaver.h"
 #include <memory>
+#include <mutex>
 #include <set>
 #include <vector>
 
@@ -213,6 +214,7 @@ private:
   std::vector<SymbolBody *> SymbolBodies;
   llvm::BumpPtrAllocator Alloc;
   std::unique_ptr<LTOModule> M;
+  static std::mutex Mu;
 };
 
 } // namespace coff