Windows ARM: ignore calling conventions as described on MSDN

Summary:
MSDN says that fastcall, stdcall, thiscall, and vectorcall are all
accepted but ignored on ARM and X64.
https://msdn.microsoft.com/en-us/library/984x0h58.aspx

MSDN also says cdecl is also accepted and typically ignored
This patch brings ARM in line with how we ignore them for X64

Reviewers: rnk

Subscribers: compnerd, cfe-commits

Differential Revision: http://reviews.llvm.org/D12034

llvm-svn: 245076

1 files changed, 13 insertions, 0 deletions

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index f942eebdea9..8d1966e8f3d 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -4959,6 +4959,19 @@ public:
   BuiltinVaListKind getBuiltinVaListKind() const override {
     return TargetInfo::CharPtrBuiltinVaList;
   }
+  CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
+    switch (CC) {
+    case CC_X86StdCall:
+    case CC_X86ThisCall:
+    case CC_X86FastCall:
+    case CC_X86VectorCall:
+      return CCCR_Ignore;
+    case CC_C:
+      return CCCR_OK;
+    default:
+      return CCCR_Warning;
+    }
+  }
 };
 
 // Windows ARM + Itanium C++ ABI Target