Satisfy C++ aliasing rules, per suggestion by Chandler.

llvm-svn: 158346

llvm/include/llvm/Support/ThreadLocal.h

@@ -28,7 +28,12 @@ namespace llvm {
       ///
       /// This is embedded in the class and we avoid malloc'ing/free'ing it,
       /// to make this class more safe for use along with CrashRecoveryContext.
-      ThreadLocalDataTy data;
+      union {
+        char data[sizeof(ThreadLocalDataTy)];
+        struct {
+          ThreadLocalDataTy align_data;
+        };
+      };
     public:
       ThreadLocalImpl();
       virtual ~ThreadLocalImpl();

llvm/lib/Support/ThreadLocal.cpp

@@ -40,7 +40,7 @@ void ThreadLocalImpl::removeInstance() { data = 0; }
 namespace llvm {
 using namespace sys;
 
-ThreadLocalImpl::ThreadLocalImpl() : data(0) {
+ThreadLocalImpl::ThreadLocalImpl() : data() {
   typedef int SIZE_TOO_BIG[sizeof(pthread_key_t) <= sizeof(data) ? 1 : -1];
   pthread_key_t* key = reinterpret_cast<pthread_key_t*>(&data);
   int errorcode = pthread_key_create(key, NULL);

llvm/lib/Support/Windows/ThreadLocal.inc

@@ -22,7 +22,7 @@
 namespace llvm {
 using namespace sys;
 
-ThreadLocalImpl::ThreadLocalImpl() : data(0) {
+ThreadLocalImpl::ThreadLocalImpl() : data() {
   typedef int SIZE_TOO_BIG[sizeof(DWORD) <= sizeof(data) ? 1 : -1];
   DWORD* tls = reinterpret_cast<DWORD*>(&data);
   *tls = TlsAlloc();