[patch RFA middle-end] Fix PR target/41993

[Kaz Kojima]

Hi,

The attached patch is to solve PR target/41993 which will affect
targets using MODE_EXIT.
Without it, we can't find all return registers for __builtin_return
in mode-switching.c:create_pre_exit.  See the trail #4 by Uros in
the PR for the details.  The patch is tested with bootstrap and
regtested on i686-pc-linux-gnu with no new failures.  It's also
tested on cross sh4-unknown-linux-gnu.
OK for trunk?

Regards,
        kaz
--
2012-11-05  Uros Bizjak  <ubiz...@gmail.com>
            Kaz Kojima  <kkoj...@gcc.gnu.org>

        PR target/41993
        * mode-switching.c (create_pre_exit): Set return_copy to
        last_insn when copy_start is a pseudo reg.

--- ORIG/trunk/gcc/mode-switching.c     2012-11-05 08:07:55.000000000 +0900
+++ trunk/gcc/mode-switching.c  2012-11-05 19:22:56.000000000 +0900
@@ -324,7 +324,10 @@ create_pre_exit (int n_entities, int *en
                    else
                      break;
                    if (copy_start >= FIRST_PSEUDO_REGISTER)
-                     break;
+                     {
+                       last_insn = return_copy;
+                       continue;
+                     }
                    copy_num
                      = hard_regno_nregs[copy_start][GET_MODE (copy_reg)];