[Bug rtl-optimization/58831] [4.8/4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu in 64-bit mode

["ebotcazou at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58831

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|ebotcazou at gcc dot gnu.org       |
           Assignee|unassigned at gcc dot gnu.org      |ebotcazou at gcc dot gnu.org

--- Comment #6 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
Looking into it.  The non-deterministic behavior is cured by:

Index: recog.c
===================================================================
--- recog.c    (revision 203876)
+++ recog.c    (working copy)
@@ -3068,6 +3068,9 @@ peep2_reg_dead_p (int ofs, rtx reg)
   return 1;
 }

+/* Regno offset to be used in the register search.  */
+static int search_ofs;
+
 /* Try to find a hard register of mode MODE, matching the register class in
    CLASS_STR, which is available at the beginning of insn CURRENT_INSN and
    remains available until the end of LAST_INSN.  LAST_INSN may be NULL_RTX,
@@ -3083,7 +3086,6 @@ rtx
 peep2_find_free_register (int from, int to, const char *class_str,
               enum machine_mode mode, HARD_REG_SET *reg_set)
 {
-  static int search_ofs;
   enum reg_class cl;
   HARD_REG_SET live;
   df_ref *def_rec;
@@ -3548,6 +3550,7 @@ peephole2_optimize (void)
   /* Initialize the regsets we're going to use.  */
   for (i = 0; i < MAX_INSNS_PER_PEEP2 + 1; ++i)
     peep2_insn_data[i].live_before = BITMAP_ALLOC (&reg_obstack);
+  search_ofs = 0;
   live = BITMAP_ALLOC (&reg_obstack);

   FOR_EACH_BB_REVERSE (bb)

but there is something wrong in the alias.c machinery as well.