[lld] r234628 - Fix minor threading issue.

[Rui Ueyama]

Author: ruiu
Date: Fri Apr 10 14:55:35 2015
New Revision: 234628

URL: http://llvm.org/viewvc/llvm-project?rev=234628&view=rev
Log:
Fix minor threading issue.

Because calls of applyRelocation is parallelized, all functions
called from that need to be thread-safe. This piece of code
didn't use any synchronization mechanism, so it was not safe.

Modified:
    lld/trunk/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h

Modified: lld/trunk/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h?rev=234628&r1=234627&r2=234628&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h (original)
+++ lld/trunk/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h Fri Apr 10 14:55:35 2015
@@ -82,17 +82,18 @@ public:
   Section<ELFT> *getSDataSection() const { return _sdataSection; }
 
   uint64_t getGOTSymAddr() {
-    if (!_gotSymAtom.hasValue())
-      _gotSymAtom = this->findAbsoluteAtom("_GLOBAL_OFFSET_TABLE_");
-    if (*_gotSymAtom)
-      return (*_gotSymAtom)->_virtualAddr;
-    return 0;
+    std::call_once(_gotOnce, [this]() {
+      if (AtomLayout *got = this->findAbsoluteAtom("_GLOBAL_OFFSET_TABLE_"))
+        _gotAddr = got->_virtualAddr;
+    });
+    return _gotAddr;
   }
 
 private:
   llvm::BumpPtrAllocator _alloc;
   SDataSection<ELFT> *_sdataSection = nullptr;
-  llvm::Optional<AtomLayout *> _gotSymAtom;
+  uint64_t _gotAddr = 0;
+  std::once_flag _gotOnce;
 };
 
 /// \brief TargetHandler for Hexagon