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From: "steven at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug rtl-optimization/48549] [4.6/4.7 Regression] Combiner ICE with -g
Date: Fri, 30 Nov 2012 13:54:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48549

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steven at gcc dot gnu.org

--- Comment #7 from Steven Bosscher <steven at gcc dot gnu.org> 2012-11-30 13:54:10 UTC ---
A patch to get rid of BARRIERs runs into this one. Here's an alternative fix:

Index: combine.c
===================================================================
--- combine.c   (revision 193989)
+++ combine.c   (working copy)
@@ -1223,11 +1223,10 @@ combine_instructions (rtx f, unsigned int nregs)
          if (NONDEBUG_INSN_P (insn))
            {
              while (last_combined_insn
-                    && INSN_DELETED_P (last_combined_insn))
+                    && INSN_DELETED_P (last_combined_insn)
+                    && last_combined_insn != BB_HEAD (this_basic_block))
                last_combined_insn = PREV_INSN (last_combined_insn);
              if (last_combined_insn == NULL_RTX
-                 || BARRIER_P (last_combined_insn)
-                 || BLOCK_FOR_INSN (last_combined_insn) != this_basic_block
                  || DF_INSN_LUID (last_combined_insn) <= DF_INSN_LUID (insn))
                last_combined_insn = insn;