Fix builtinvalistkind

Author: Prabhuk

clang/lib/Basic/Targets/X86.h

@@ -857,6 +857,10 @@ class LLVM_LIBRARY_VISIBILITY UEFIX86_64TargetInfo
                           "i64:64-i128:128-f80:128-n8:16:32:64-S128");
   }
 
+  BuiltinVaListKind getBuiltinVaListKind() const override {
+    return TargetInfo::CharPtrBuiltinVaList;
+  }
+
   CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
     switch (CC) {
     case CC_C:

clang/lib/CodeGen/Targets/X86.cpp

@@ -3038,8 +3038,30 @@ static Address EmitX86_64VAArgFromMemory(CodeGenFunction &CGF,
   return Address(Res, LTy, Align);
 }
 
+static RValue EmitMSABIVAArg(CodeGenFunction &CGF, Address VAListAddr,
+                             QualType Ty, AggValueSlot Slot,
+                             ASTContext &context) {
+  // MS x64 ABI requirement: "Any argument that doesn't fit in 8 bytes, or is
+  // not 1, 2, 4, or 8 bytes, must be passed by reference."
+  uint64_t Width = context.getTypeSize(Ty);
+  bool IsIndirect = Width > 64 || !llvm::isPowerOf2_64(Width);
+
+  return emitVoidPtrVAArg(CGF, VAListAddr, Ty, IsIndirect,
+                          CGF.getContext().getTypeInfoInChars(Ty),
+                          CharUnits::fromQuantity(8),
+                          /*allowHigherAlign*/ false, Slot);
+}
+
 RValue X86_64ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
                                 QualType Ty, AggValueSlot Slot) const {
+
+  // Emit MS ABI compliant va_list for X86_64 targets which use Microsoft CXX
+  // ABI and CharPtrBuiltinVaList.
+  if (CGF.getTarget().getCXXABI().isMicrosoft() &&
+      CGF.getTarget().getBuiltinVaListKind() ==
+          clang::TargetInfo::CharPtrBuiltinVaList)
+    return EmitMSABIVAArg(CGF, VAListAddr, Ty, Slot, getContext());
+
   // Assume that va_list type is correct; should be pointer to LLVM type:
   // struct {
   //   i32 gp_offset;
@@ -3486,15 +3508,7 @@ void WinX86_64ABIInfo::computeInfo(CGFunctionInfo &FI) const {
 
 RValue WinX86_64ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
                                    QualType Ty, AggValueSlot Slot) const {
-  // MS x64 ABI requirement: "Any argument that doesn't fit in 8 bytes, or is
-  // not 1, 2, 4, or 8 bytes, must be passed by reference."
-  uint64_t Width = getContext().getTypeSize(Ty);
-  bool IsIndirect = Width > 64 || !llvm::isPowerOf2_64(Width);
-
-  return emitVoidPtrVAArg(CGF, VAListAddr, Ty, IsIndirect,
-                          CGF.getContext().getTypeInfoInChars(Ty),
-                          CharUnits::fromQuantity(8),
-                          /*allowHigherAlign*/ false, Slot);
+  return EmitMSABIVAArg(CGF, VAListAddr, Ty, Slot, getContext());
 }
 
 std::unique_ptr<TargetCodeGenInfo> CodeGen::createX86_32TargetCodeGenInfo(