Make variable argument intrinsics behave correctly in a Win64 CC function.

Summary:
This change makes the variable argument intrinsics, `llvm.va_start` and
`llvm.va_copy`, and the `va_arg` instruction behave as they do on Windows
inside a `CallingConv::X86_64_Win64` function. It's needed for a Clang patch
I have to add support for GCC's `__builtin_ms_va_list` constructs.

Reviewers: nadav, asl, eugenis

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1622

llvm-svn: 245990

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index d296474abe1..eb2a5b3653c 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -2863,6 +2863,8 @@ struct VarArgAMD64Helper : public VarArgHelper {
   }
 
   void visitVAStartInst(VAStartInst &I) override {
+    if (F.getCallingConv() == CallingConv::X86_64_Win64)
+      return;
     IRBuilder<> IRB(&I);
     VAStartInstrumentationList.push_back(&I);
     Value *VAListTag = I.getArgOperand(0);
@@ -2875,6 +2877,8 @@ struct VarArgAMD64Helper : public VarArgHelper {
   }
 
   void visitVACopyInst(VACopyInst &I) override {
+    if (F.getCallingConv() == CallingConv::X86_64_Win64)
+      return;
     IRBuilder<> IRB(&I);
     Value *VAListTag = I.getArgOperand(0);
     Value *ShadowPtr = MSV.getShadowPtr(VAListTag, IRB.getInt8Ty(), IRB);