Add convenient helper for win64 check. Simplify things slightly.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48691 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 933c33e..dd2d784 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1009,7 +1009,7 @@
   unsigned CC = cast<ConstantSDNode>(Op.getOperand(1))->getValue();
   
   if (Subtarget->is64Bit()) {
-    if (Subtarget->isTargetWindows() || Subtarget->isTargetMingw())
+    if (Subtarget->isTargetWin64())
       return CC_X86_Win64_C;
     else {
       if (CC == CallingConv::Fast && PerformTailCallOpt)