IRgen/ObjC: Correctly construct the function info for variadic message sends.

This fixes some bad -O0 codegen and the unnecessary clearing of al on entry to objc_msgSend for most message sends.

<rdar://problem/7102824> [irgen] unnecessary xorb on calls to objc_msgSend on x86_64

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@82118 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGObjCGNU.cpp b/lib/CodeGen/CGObjCGNU.cpp
index c348123..893130c 100644
--- a/lib/CodeGen/CGObjCGNU.cpp
+++ b/lib/CodeGen/CGObjCGNU.cpp
@@ -380,7 +380,8 @@
 
   CodeGenTypes &Types = CGM.getTypes();
   const CGFunctionInfo &FnInfo = Types.getFunctionInfo(ResultType, ActualArgs);
-  const llvm::FunctionType *impType = Types.GetFunctionType(FnInfo, false);
+  const llvm::FunctionType *impType =
+    Types.GetFunctionType(FnInfo, Method ? Method->isVariadic() : false);
 
   llvm::Value *ReceiverClass = 0;
   if (isCategoryImpl) {
@@ -478,7 +479,8 @@
 
   CodeGenTypes &Types = CGM.getTypes();
   const CGFunctionInfo &FnInfo = Types.getFunctionInfo(ResultType, ActualArgs);
-  const llvm::FunctionType *impType = Types.GetFunctionType(FnInfo, false);
+  const llvm::FunctionType *impType =
+    Types.GetFunctionType(FnInfo, Method ? Method->isVariadic() : false);
 
   llvm::Value *imp;
   // For sender-aware dispatch, we pass the sender as the third argument to a