Implement sseregparm.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46764 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CallingConv.h

@@ -57,7 +57,11 @@ namespace CallingConv {
     /// X86_FastCall - 'fast' analog of X86_StdCall. Passes first two arguments
     /// in ECX:EDX registers, others - via stack. Callee is responsible for
     /// stack cleaning.
-    X86_FastCall = 65
+    X86_FastCall = 65,
+
+    /// X86_SSEreg - The standard convention except that float and double
+    /// values are returned in XMM0 if SSE support is available.
+    X86_SSECall = 66
   };
 } // End CallingConv namespace