patch to fix PR56144

[Vladimir Makarov]

The following patch fixes

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56144

The patch was successfully bootstrapped and tested on x86/x86-64.

Committed as rev. 195582.

2013-01-30  Vladimir Makarov  <vmaka...@redhat.com>

        PR rtl-optimization/56144
        * lra-constraints.c (get_reload_reg): Don't reuse reload pseudo
        for values with side effects.

2013-01-30  Vladimir Makarov  <vmaka...@redhat.com>

        PR rtl-optimization/56144
        * gcc.dg/pr56144.c: New.




Index: lra-constraints.c
===================================================================
--- lra-constraints.c   (revision 195581)
+++ lra-constraints.c   (working copy)
@@ -414,24 +414,26 @@ get_reload_reg (enum op_type type, enum
        = lra_create_new_reg_with_unique_value (mode, original, rclass, title);
       return true;
     }
-  for (i = 0; i < curr_insn_input_reloads_num; i++)
-    if (rtx_equal_p (curr_insn_input_reloads[i].input, original)
-       && in_class_p (curr_insn_input_reloads[i].reg, rclass, &new_class))
-      {
-       lra_assert (! side_effects_p (original));
-       *result_reg = curr_insn_input_reloads[i].reg;
-       regno = REGNO (*result_reg);
-       if (lra_dump_file != NULL)
-         {
-           fprintf (lra_dump_file, "    Reuse r%d for reload ", regno);
-           dump_value_slim (lra_dump_file, original, 1);
-         }
-       if (new_class != lra_get_allocno_class (regno))
-         change_class (regno, new_class, ", change", false);
-       if (lra_dump_file != NULL)
-         fprintf (lra_dump_file, "\n");
-       return false;
-      }
+  /* Prevent reuse value of expression with side effects,
+     e.g. volatile memory.  */
+  if (! side_effects_p (original))
+    for (i = 0; i < curr_insn_input_reloads_num; i++)
+      if (rtx_equal_p (curr_insn_input_reloads[i].input, original)
+         && in_class_p (curr_insn_input_reloads[i].reg, rclass, &new_class))
+       {
+         *result_reg = curr_insn_input_reloads[i].reg;
+         regno = REGNO (*result_reg);
+         if (lra_dump_file != NULL)
+           {
+             fprintf (lra_dump_file, "  Reuse r%d for reload ", regno);
+             dump_value_slim (lra_dump_file, original, 1);
+           }
+         if (new_class != lra_get_allocno_class (regno))
+           change_class (regno, new_class, ", change", false);
+         if (lra_dump_file != NULL)
+           fprintf (lra_dump_file, "\n");
+         return false;
+       }
   *result_reg = lra_create_new_reg (mode, original, rclass, title);
   lra_assert (curr_insn_input_reloads_num < LRA_MAX_INSN_RELOADS);
   curr_insn_input_reloads[curr_insn_input_reloads_num].input = original;