1 files changed, 17 insertions, 0 deletions
diff --git a/lib/CodeGen/TargetInfo.cpp b/lib/CodeGen/TargetInfo.cpp
index 434e202f2e..bad8a1d928 100644
--- a/lib/CodeGen/TargetInfo.cpp
+++ b/lib/CodeGen/TargetInfo.cpp
@@ -98,6 +98,14 @@ unsigned TargetCodeGenInfo::getSizeOfUnwindException() const {
   return 32;
 }
 
+bool TargetCodeGenInfo::isNoProtoCallVariadic(CallingConv CC) const {
+  // The following conventions are known to require this to be false:
+  //   x86_stdcall
+  //   MIPS
+  // For everything else, we just prefer false unless we opt out.
+  return false;
+}
+
 static bool isEmptyRecord(ASTContext &Context, QualType T, bool AllowArrays);
 
 /// isEmptyField - Return true iff a the field is "empty", that is it
@@ -959,6 +967,15 @@ public:
     return X86AdjustInlineAsmType(CGF, Constraint, Ty);
   }
 
+  bool isNoProtoCallVariadic(CallingConv CC) const {
+    // The default CC on x86-64 sets %al to the number of SSA
+    // registers used, and GCC sets this when calling an unprototyped
+    // function, so we override the default behavior.
+    if (CC == CC_Default || CC == CC_C) return true;
+
+    return TargetCodeGenInfo::isNoProtoCallVariadic(CC);
+  }
+
 };
 
 class WinX86_64TargetCodeGenInfo : public TargetCodeGenInfo {