Fix byval arguments in the fastcc calling convention. The fastcc convention

delegates to the regular x86-32 convention which handles byval, but only
after it handles a few cases, and it's necessary to handle byval before
handling those cases. This fixes PR3122 (and rdar://6400815), llvm-gcc
miscompiling LLVM.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60453 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86CallingConv.td

@@ -321,6 +321,11 @@ def CC_X86_32_FastCall : CallingConv<[
 ]>;
 
 def CC_X86_32_FastCC : CallingConv<[
+  // Handles byval parameters.  Note that we can't rely on the delegation
+  // to CC_X86_32_Common for this because that happens after code that
+  // handles i32 arguments.
+  CCIfByVal<CCPassByVal<4, 4>>,
+
   // Promote i8/i16 arguments to i32.
   CCIfType<[i8, i16], CCPromoteToType<i32>>,