[PATCH] PR49452, prevent post reload combining cross blockage insn

[Carrot Wei]

Hi

We should not combine insns cross volatile insns. Combine.c already does this
check, postreload should also do so.

Bootstrapped and regtested on x86_64-unknown-linux-gnu.
Regtested on arm qemu.

thanks
Carrot


ChangeLog:
2011-09-19  Wei Guozhi  <car...@google.com>

        PR 49452
        * postreload.c (reload_combine): Invalidate use information when across
        volatile insn.


Index: postreload.c
===================================================================
--- postreload.c        (revision 178938)
+++ postreload.c        (working copy)
@@ -1312,7 +1312,8 @@ reload_combine (void)
         is and then later disable any optimization that would cross it.  */
       if (LABEL_P (insn))
        last_label_ruid = reload_combine_ruid;
-      else if (BARRIER_P (insn))
+      else if (BARRIER_P (insn)
+              || (INSN_P (insn) && volatile_insn_p (PATTERN (insn))))
        for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
          if (! fixed_regs[r])
              reg_state[r].use_index = RELOAD_COMBINE_MAX_USES;