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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/62025] [4.9/4.10 Regression] Miscompilation of openssl sha512.c
Date: Tue, 12 Aug 2014 12:17:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62025

--- Comment #15 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, what about this completely untested fix?  Unfortunately the scheduler
change has been committed with no testcases.  I guess I'll do a
bootstrap/regtest with some printout where this patch changes things and where
we consider it at all.

--- gcc/sched-deps.c.jj    2014-08-06 10:34:13.000000000 +0200
+++ gcc/sched-deps.c    2014-08-12 14:12:06.625193731 +0200
@@ -4751,6 +4751,24 @@ find_inc (struct mem_inc_info *mii, bool
                "inc conflicts with store failure.\n");
         goto next;
           }
+
+      /* The inc instruction could have clobbers, make sure those
+         registers are not used in mem insn.  */
+      FOR_EACH_INSN_DEF (def, mii->inc_insn)
+        if (!reg_overlap_mentioned_p (DF_REF_REG (def), mii->mem_reg0))
+          {
+        df_ref use;
+        FOR_EACH_INSN_USE (use, mii->mem_insn)
+          if (reg_overlap_mentioned_p (DF_REF_REG (def),
+                           DF_REF_REG (use)))
+            {
+              if (sched_verbose >= 5)
+            fprintf (sched_dump,
+                 "inc clobber used in store failure.\n");
+              goto next;
+            }
+          }
+
       newaddr = mii->inc_input;
       if (mii->mem_index != NULL_RTX)
         newaddr = gen_rtx_PLUS (GET_MODE (newaddr), newaddr,