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Subject: [Bug middle-end/53695] [4.8 Regression] ICE: in dfs_enumerate_from, at cfganal.c:1221 with -O2 -ftracer and labels/gotos
Date: Thu, 23 Aug 2012 07:37:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53695

--- Comment #11 from rguenther at suse dot de <rguenther at suse dot de> 2012-08-23 07:36:46 UTC ---
On Wed, 22 Aug 2012, steven at gcc dot gnu.org wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53695
> 
> --- Comment #9 from Steven Bosscher <steven at gcc dot gnu.org> 2012-08-22 21:33:18 UTC ---
> I think the right fix for this bug is to use disambiguate_multiple_latches in
> the loop updating code (fix_loop_structure), but I'm not sure where to put it.

Not sure - we can handle multiple latches just fine (loop->latch will
be NULL).  But I see the loop state does not reflect that.  Maybe

Index: gcc/cfgloopmanip.c
===================================================================
--- gcc/cfgloopmanip.c  (revision 190613)
+++ gcc/cfgloopmanip.c  (working copy)
@@ -1715,6 +1716,9 @@ fix_loop_structure (bitmap changed_bbs)
        }
     }

+  if (!loop_state_satisfies_p (LOOPS_MAY_HAVE_MULTIPLE_LATCHES))
+    disambiguate_loops_with_multiple_latches ();
+
   if (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS))
     create_preheaders (CP_SIMPLE_PREHEADERS);

which matches the order in which loop_optimizer_init calls it.

Richard.