[Bug rtl-optimization/55489] New: [4.7 regression] insane PRE memory usage with PIE (translate.i)

[Bug rtl-optimization/55489] New: [4.7 regression] insane PRE memory usage with PIE (translate.i)

[bonzini at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55489

             Bug #: 55489
           Summary: [4.7 regression] insane PRE memory usage with PIE
                    (translate.i)
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Keywords: memory-hog
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: bonzini@gnu.org


Created attachment 28793
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28793
gzipped preprocessed source

Yet another evil testcase, this time for RTL GCSE.  Compile with:

$ gcc ~/translate.i -g -O2 -fPIE

gcc 4.4.6:
 PRE :   3.83 (24%) usr   0.15 (17%) sys   3.99 (24%) wall  267307 kB (33%) ggc

gcc 4.7.2:
 PRE :   7.95 (41%) usr   0.40 (40%) sys   8.31 (41%) wall  821017 kB (80%) ggc

Fixed, or latent in trunk:

gcc 4.8.0:
 PRE :   6.94 (26%) usr   0.02 ( 4%) sys   6.98 (26%) wall     731 kB ( 0%) ggc

[Bug rtl-optimization/55489] [4.7 regression] insane PRE memory usage with PIE (translate.i)

[bonzini at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55489

Paolo Bonzini <bonzini at gnu dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-11-27
     Ever Confirmed|0                           |1

[Bug rtl-optimization/55489] [4.7 regression] insane PRE memory usage with PIE (translate.i)

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55489

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |4.4.6, 4.8.0
   Target Milestone|---                         |4.7.3
      Known to fail|                            |4.7.2

[Bug rtl-optimization/55489] [4.7/4.8 regression] insane PRE memory usage with PIE (translate.i)

[bonzini at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55489

Paolo Bonzini <bonzini at gnu dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|4.8.0                       |
            Summary|[4.7 regression] insane PRE |[4.7/4.8 regression] insane
                   |memory usage with PIE       |PRE memory usage with PIE
                   |(translate.i)               |(translate.i)
      Known to fail|                            |4.8.0

--- Comment #1 from Paolo Bonzini <bonzini at gnu dot org> 2012-11-27 15:50:44 UTC ---
Strictly not a regression, because the underlying bug is present since always. 
But something between 4.4.6 and 4.7.2 caused memory usage to become much worse.

Also, marking it as not-working in 4.8 because the allocation of
reg_known_value is wrong:

  vec_alloc (reg_known_value, maxreg - FIRST_PSEUDO_REGISTER);

and that's what causes the bug to be latent: set_reg_known_value becomes a
no-op, and get_reg_known_value always returns NULL.

[Bug rtl-optimization/55489] [4.7/4.8 regression] insane PRE memory usage with PIE (translate.i)

[bonzini at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55489

--- Comment #2 from Paolo Bonzini <bonzini at gnu dot org> 2012-11-27 20:27:09 UTC ---
Author: bonzini
Date: Tue Nov 27 20:26:57 2012
New Revision: 193867

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=193867
Log:
2012-11-27  Paolo Bonzini  <pbonzini@redhat.com>

    PR rtl-optimization/55489
    * gcse.c (compute_transp): Precompute a canonical version
    of XEXP (x, 0), and pass it to canon_true_dependence.


Modified:
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/gcse.c

[Bug rtl-optimization/55489] [4.7/4.8 regression] insane PRE memory usage with PIE (translate.i)

[bonzini at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55489

--- Comment #3 from Paolo Bonzini <bonzini at gnu dot org> 2012-11-27 20:29:24 UTC ---
Author: bonzini
Date: Tue Nov 27 20:29:15 2012
New Revision: 193868

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=193868
Log:
2012-11-27  Paolo Bonzini  <pbonzini@redhat.com>

    PR rtl-optimization/55489
    * gcse.c (compute_transp): Precompute a canonical version
    of XEXP (x, 0), and pass it to canon_true_dependence.

    * alias.c (init_alias_analysis): Fix allocation of reg_known_value.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/alias.c
    trunk/gcc/gcse.c

[Bug rtl-optimization/55489] [4.7/4.8 regression] insane PRE memory usage with PIE (translate.i)

[bonzini at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55489

Paolo Bonzini <bonzini at gnu dot org> changed:

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

--- Comment #4 from Paolo Bonzini <bonzini at gnu dot org> 2012-11-28 09:29:50 UTC ---
fixed in 4.7 and 4.8 - present in other branches, but nowhere as bad as in 4.7
and newer.