2 files changed, 21 insertions, 6 deletions
diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index 03cd853d66e..a7c8413dd9f 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -3626,19 +3626,31 @@ public:
     IntPtrType = SignedLongLong;
     this->UserLabelPrefix = "";
   }
+
   void getTargetDefines(const LangOptions &Opts,
                                 MacroBuilder &Builder) const override {
     WindowsTargetInfo<X86_64TargetInfo>::getTargetDefines(Opts, Builder);
     Builder.defineMacro("_WIN64");
   }
+
   BuiltinVaListKind getBuiltinVaListKind() const override {
     return TargetInfo::CharPtrBuiltinVaList;
   }
+
   CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
-    return (CC == CC_C ||
-            CC == CC_X86VectorCall ||
-            CC == CC_IntelOclBicc ||
-            CC == CC_X86_64SysV) ? CCCR_OK : CCCR_Warning;
+    switch (CC) {
+    case CC_X86StdCall:
+    case CC_X86ThisCall:
+    case CC_X86FastCall:
+      return CCCR_Ignore;
+    case CC_C:
+    case CC_X86VectorCall:
+    case CC_IntelOclBicc:
+    case CC_X86_64SysV:
+      return CCCR_OK;
+    default:
+      return CCCR_Warning;
+    }
   }
 };
 } // end anonymous namespace
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 7af4bd28d5c..4552ad9609e 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -3393,9 +3393,12 @@ bool Sema::CheckCallingConvAttr(const AttributeList &attr, CallingConv &CC,
 
   const TargetInfo &TI = Context.getTargetInfo();
   TargetInfo::CallingConvCheckResult A = TI.checkCallingConvention(CC);
-  if (A == TargetInfo::CCCR_Warning) {
-    Diag(attr.getLoc(), diag::warn_cconv_ignored) << attr.getName();
+  if (A != TargetInfo::CCCR_OK) {
+    if (A == TargetInfo::CCCR_Warning)
+      Diag(attr.getLoc(), diag::warn_cconv_ignored) << attr.getName();
 
+    // This convention is not valid for the target. Use the default function or
+    // method calling convention.
     TargetInfo::CallingConvMethodType MT = TargetInfo::CCMT_Unknown;
     if (FD)
       MT = FD->isCXXInstanceMember() ? TargetInfo::CCMT_Member :