[Bug c/57584] New: ice: SSA corruption: Unable to coalesce ssa_names

[Bug c/57584] New: ice: SSA corruption: Unable to coalesce ssa_names

[dcb314 at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57584

            Bug ID: 57584
           Summary: ice: SSA corruption: Unable to coalesce ssa_names
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com

Created attachment 30289
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30289&action=edit
gzipped C source code

The attached source code causes the following crash
on gcc-4.9 trunk dated 20130605 on an AMD x86_64 box
when compiled with -O3.

Unable to coalesce ssa_names 45 and 3671 which are marked as MUST COALESCE.
sp_45(ab) and  sp_3671(ab)
In file included from vm.c:661:0:
vm-engine.c: In function ‘vm_debug_engine’:
vm-engine.c:39:1: internal compiler error: SSA corruption
0x9ca5bf fail_abnormal_edge_coalesce
    ../../src/trunk/gcc/tree-ssa-coalesce.c:898
0x9ca5bf coalesce_partitions
    ../../src/trunk/gcc/tree-ssa-coalesce.c:1200
0x9ca5bf coalesce_ssa_name()
    ../../src/trunk/gcc/tree-ssa-coalesce.c:1337
0x981cee remove_ssa_form
    ../../src/trunk/gcc/tree-outof-ssa.c:900
0x981cee rewrite_out_of_ssa(ssaexpand*)
    ../../src/trunk/gcc/tree-outof-ssa.c:1133
0x60c694 gimple_expand_cfg
    ../../src/trunk/gcc/cfgexpand.c:4541
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
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From: "dcb314 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/30604] Unable to coalesce ssa_names <x>  and <y>  which are marked as MUST COALESCE
Date: Tue, 11 Jun 2013 10:09:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id0604

--- Comment #17 from David Binderman <dcb314 at hotmail dot com> ---
(In reply to rguenther@suse.de from comment #16)
> Can you open a new bugreport please?  It's very likely a different
> reason than this one.

After a lot of fiddling about, please see #57584

Redhat package guile went to a lot of work to hide
the compiler command line ;-|

[Bug c/57584] ice: SSA corruption: Unable to coalesce ssa_names

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57584

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-06-11
             Blocks|                            |56982
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed, reducing.

[Bug tree-optimization/57584] [4.9 Regression] ice: SSA corruption: Unable to coalesce ssa_names

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57584

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |tree-optimization
   Target Milestone|---                         |4.9.0
            Summary|ice: SSA corruption: Unable |[4.9 Regression] ice: SSA
                   |to coalesce ssa_names       |corruption: Unable to
                   |                            |coalesce ssa_names

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's the vectorizer, thus fails at -O -ftree-vectorize already.

[Bug tree-optimization/57584] [4.9 Regression] ice: SSA corruption: Unable to coalesce ssa_names

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57584

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
niter analysis computes

 (((unsigned long) sp_35(ab) - (unsigned long) (sp_3(ab) + 8)) + 7) / 8))

which the vectorizer inserts, obviously breaking coalescing of sp_35 and sp_3.
It's expand_simple_operations done in niter analysis that breaks this and
I have a patch to fix that.

[Bug tree-optimization/57584] [4.9 Regression] ice: SSA corruption: Unable to coalesce ssa_names

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57584

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu Jun 20 10:22:33 2013
New Revision: 200237

URL: http://gcc.gnu.org/viewcvs?rev=200237&root=gcc&view=rev
Log:
2013-06-20  Richard Biener  <rguenther@suse.de>

    PR tree-optimization/57584
    * tree-ssa-loop-niter.c (expand_simple_operations): Avoid including
    SSA names into the expanded expression that take part in
    abnormal coalescing.

    * gcc.dg/torture/pr57584.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr57584.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-loop-niter.c