1 files changed, 48 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index c6a00b1dad1..f8e6c9d5ee4 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1037,6 +1037,8 @@ bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   default: return false;
   case X86::BI__builtin_cpu_supports:
     return SemaBuiltinCpuSupports(TheCall);
+  case X86::BI__builtin_ms_va_start:
+    return SemaBuiltinMSVAStart(TheCall);
   case X86::BI_mm_prefetch: i = 1; l = 0; u = 3; break;
   case X86::BI__builtin_ia32_sha1rnds4: i = 2, l = 0; u = 3; break;
   case X86::BI__builtin_ia32_vpermil2pd:
@@ -2317,9 +2319,10 @@ bool Sema::CheckObjCString(Expr *Arg) {
   return false;
 }
 
-/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
-/// Emit an error and return true on failure, return false on success.
-bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
+/// Check the arguments to '__builtin_va_start' or '__builtin_ms_va_start'
+/// for validity.  Emit an error and return true on failure; return false
+/// on success.
+bool Sema::SemaBuiltinVAStartImpl(CallExpr *TheCall) {
   Expr *Fn = TheCall->getCallee();
   if (TheCall->getNumArgs() > 2) {
     Diag(TheCall->getArg(2)->getLocStart(),
@@ -2397,6 +2400,48 @@ bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
   return false;
 }
 
+/// Check the arguments to '__builtin_va_start' for validity, and that
+/// it was called from a function of the native ABI.
+/// Emit an error and return true on failure; return false on success.
+bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
+  // On x86-64 Unix, don't allow this in Win64 ABI functions.
+  // On x64 Windows, don't allow this in System V ABI functions.
+  // (Yes, that means there's no corresponding way to support variadic
+  // System V ABI functions on Windows.)
+  if (Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86_64) {
+    unsigned OS = Context.getTargetInfo().getTriple().getOS();
+    clang::CallingConv CC = CC_C;
+    if (const FunctionDecl *FD = getCurFunctionDecl())
+      CC = FD->getType()->getAs<FunctionType>()->getCallConv();
+    if ((OS == llvm::Triple::Win32 && CC == CC_X86_64SysV) ||
+        (OS != llvm::Triple::Win32 && CC == CC_X86_64Win64))
+      return Diag(TheCall->getCallee()->getLocStart(),
+                  diag::err_va_start_used_in_wrong_abi_function)
+             << (OS != llvm::Triple::Win32);
+  }
+  return SemaBuiltinVAStartImpl(TheCall);
+}
+
+/// Check the arguments to '__builtin_ms_va_start' for validity, and that
+/// it was called from a Win64 ABI function.
+/// Emit an error and return true on failure; return false on success.
+bool Sema::SemaBuiltinMSVAStart(CallExpr *TheCall) {
+  // This only makes sense for x86-64.
+  const llvm::Triple &TT = Context.getTargetInfo().getTriple();
+  Expr *Callee = TheCall->getCallee();
+  if (TT.getArch() != llvm::Triple::x86_64)
+    return Diag(Callee->getLocStart(), diag::err_x86_builtin_32_bit_tgt);
+  // Don't allow this in System V ABI functions.
+  clang::CallingConv CC = CC_C;
+  if (const FunctionDecl *FD = getCurFunctionDecl())
+    CC = FD->getType()->getAs<FunctionType>()->getCallConv();
+  if (CC == CC_X86_64SysV ||
+      (TT.getOS() != llvm::Triple::Win32 && CC != CC_X86_64Win64))
+    return Diag(Callee->getLocStart(),
+                diag::err_ms_va_start_used_in_sysv_function);
+  return SemaBuiltinVAStartImpl(TheCall);
+}
+
 bool Sema::SemaBuiltinVAStartARM(CallExpr *Call) {
   // void __va_start(va_list *ap, const char *named_addr, size_t slot_size,
   //                 const char *named_addr);