[backport from gcc-4.9/trunk r197036 <mikpe@it.uu.se>]

List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>
From: Eric Botcazou <ebotcazou at adacore dot com>
Subject: Fix bug with simple returns on cc0 targets
Date: Mon, 25 Mar 2013 12:24:15 +0100

Hi,

for a private port which both is a cc0 target and has conditional returns, 
emit_use_return_register_into_block will try to emit the use return register 
sequence between a cc0 setter and a cc0 user.

Fixed thusly, tested on x86_64-suse-linux, applied on the mainline.

gcc/

2013-03-25  Eric Botcazou  <ebotcazou@adacore.com>

	* function.c (emit_use_return_register_into_block): On cc0 targets,
	do not emit the sequence between cc0 setter and user.

--- gcc-4.8.0/gcc/function.c.~1~	2013-03-09 08:54:02.000000000 +0100
+++ gcc-4.8.0/gcc/function.c	2013-03-29 14:03:35.822981791 +0100
@@ -5597,12 +5597,17 @@ prepare_shrink_wrap (basic_block entry_b
 static void
 emit_use_return_register_into_block (basic_block bb)
 {
-  rtx seq;
+  rtx seq, insn;
   start_sequence ();
   use_return_register ();
   seq = get_insns ();
   end_sequence ();
-  emit_insn_before (seq, BB_END (bb));
+  insn = BB_END (bb);
+#ifdef HAVE_cc0
+  if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
+    insn = prev_cc0_setter (insn);
+#endif
+  emit_insn_before (seq, insn);
 }