Add support for -fpcc-struct-return.  Patch by Arthur O'Dwyer!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184166 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 4e62fda..1407e10 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -478,6 +478,15 @@
       Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Val;
   }
 
+  if (Arg *A = Args.getLastArg(OPT_fpcc_struct_return, OPT_freg_struct_return)) {
+    if (A->getOption().matches(OPT_fpcc_struct_return)) {
+      Opts.setStructReturnConvention(CodeGenOptions::SRCK_OnStack);
+    } else {
+      assert(A->getOption().matches(OPT_freg_struct_return));
+      Opts.setStructReturnConvention(CodeGenOptions::SRCK_InRegs);
+    }
+  }
+
   return Success;
 }