[lld] r308786 - Merging r308728:

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Fri Jul 21 14:36:54 2017
New Revision: 308786

URL: http://llvm.org/viewvc/llvm-project?rev=308786&view=rev
Log:
Merging r308728:
------------------------------------------------------------------------
r308728 | ikudrin | 2017-07-21 04:26:08 -0700 (Fri, 21 Jul 2017) | 3 lines

[ELF] Avoid data race in ObjectFile<ELFT>::getDILineInfo().

Differential Revision: https://reviews.llvm.org/D35537
------------------------------------------------------------------------

Modified:
    lld/branches/release_50/   (props changed)
    lld/branches/release_50/ELF/InputFiles.cpp
    lld/branches/release_50/ELF/InputFiles.h

Propchange: lld/branches/release_50/
------------------------------------------------------------------------------
    svn:mergeinfo = /lld/trunk:308728

Modified: lld/branches/release_50/ELF/InputFiles.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/branches/release_50/ELF/InputFiles.cpp?rev=308786&r1=308785&r2=308786&view=diff
==============================================================================
--- lld/branches/release_50/ELF/InputFiles.cpp (original)
+++ lld/branches/release_50/ELF/InputFiles.cpp Fri Jul 21 14:36:54 2017
@@ -91,8 +91,7 @@ template <class ELFT> void elf::ObjectFi
 template <class ELFT>
 Optional<DILineInfo> elf::ObjectFile<ELFT>::getDILineInfo(InputSectionBase *S,
                                                           uint64_t Offset) {
-  if (!DwarfLine)
-    initializeDwarfLine();
+  llvm::call_once(InitDwarfLine, [this]() { initializeDwarfLine(); });
 
   // The offset to CU is 0.
   const DWARFDebugLine::LineTable *Tbl = DwarfLine->getLineTable(0);

Modified: lld/branches/release_50/ELF/InputFiles.h
URL: http://llvm.org/viewvc/llvm-project/lld/branches/release_50/ELF/InputFiles.h?rev=308786&r1=308785&r2=308786&view=diff
==============================================================================
--- lld/branches/release_50/ELF/InputFiles.h (original)
+++ lld/branches/release_50/ELF/InputFiles.h Fri Jul 21 14:36:54 2017
@@ -24,6 +24,7 @@
 #include "llvm/Object/Archive.h"
 #include "llvm/Object/ELF.h"
 #include "llvm/Object/IRObjectFile.h"
+#include "llvm/Support/Threading.h"
 
 #include <map>
 
@@ -211,6 +212,7 @@ private:
   // single object file, so we cache debugging information in order to
   // parse it only once for each object file we link.
   std::unique_ptr<llvm::DWARFDebugLine> DwarfLine;
+  llvm::once_flag InitDwarfLine;
 };
 
 // LazyObjectFile is analogous to ArchiveFile in the sense that