When generating llvm.used, we may need an addrspacecast instead of a bitcast.

Summary:
This is especially important for targets that use multiple address spaces,
and commonly place global variables in address spaces other than zero.

Fixes PR22383

Test Plan: New test case added: llvm-used.cu

Reviewers: jingyue

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7345

llvm-svn: 227861

clang/lib/CodeGen/CodeGenModule.cpp

@@ -935,8 +935,8 @@ static void emitUsed(CodeGenModule &CGM, StringRef Name,
   UsedArray.resize(List.size());
   for (unsigned i = 0, e = List.size(); i != e; ++i) {
     UsedArray[i] =
-     llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(&*List[i]),
-                                    CGM.Int8PtrTy);
+        llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(
+            cast<llvm::Constant>(&*List[i]), CGM.Int8PtrTy);
   }
 
   if (UsedArray.empty())