[Bug c/51042] New: segfault

[Bug c/51042] New: segfault

[regehr at cs dot utah.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

             Bug #: 51042
           Summary: segfault
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: regehr@cs.utah.edu


Valgrind wasn't too helpful in narrowing this down, just says something generic
about a stack overflow.

[regehr@gamow tmp052]$ current-gcc -Ofast -w small.c

current-gcc: internal compiler error: Segmentation fault (program cc1)
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

[regehr@gamow tmp052]$ current-gcc -v

Using built-in specs.
COLLECT_GCC=current-gcc
COLLECT_LTO_WRAPPER=/uusoc/exports/scratch/regehr/z/compiler-install/gcc-r181147-install/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --with-libelf=/usr/local --enable-lto
--prefix=/home/regehr/z/compiler-install/gcc-r181147-install
--program-prefix=r181147- --enable-languages=c,c++
Thread model: posix
gcc version 4.7.0 20111108 (experimental) (GCC) 

[regehr@gamow tmp052]$ cat small.c 


int g_10;
int g_97;
int g_144;
int g_237;
int g_264[2][2];

int func_22 (p_25)
{
  for (; p_25;)
    {
      for (g_237 = 0; g_237 <= 1; g_237 = 1)
    if (g_264[g_144][g_10])
      break;
      for (g_97 = 0; g_97 <= 0; g_97 = 1)
    {
      g_264[g_144][g_10] = g_10;
      if (g_10)
        break;
    }
    }
  return 0;
}

[Bug tree-optimization/51042] [4.7 Regression] endless recursion in phi_translate

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-11-09
                 CC|                            |jakub at gcc dot gnu.org
          Component|c                           |tree-optimization
   Target Milestone|---                         |4.7.0
            Summary|segfault                    |[4.7 Regression] endless
                   |                            |recursion in phi_translate
     Ever Confirmed|0                           |1

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-11-09 08:59:47 UTC ---
Caused by http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=155360

int a, b, c, d, e[2][2];

void
foo (int x)
{
  while (x)
    {
      for (d = 0; d <= 1; d = 1)
        if (e[c][a])
          break;
      for (b = 0; b <= 0; b = 1)
        {
          e[c][a] = a;
          if (a)
            break;
        }
    }
}

[Bug tree-optimization/51042] [4.5/4.6/4.7 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
      Known to work|                            |4.4.6
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
   Target Milestone|4.7.0                       |4.5.4
            Summary|[4.7 Regression] endless    |[4.5/4.6/4.7 Regression]
                   |recursion in phi_translate  |endless recursion in
                   |                            |phi_translate

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-11-09 09:22:04 UTC ---
Mine.

[Bug tree-optimization/51042] [4.5/4.6/4.7 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-11-09 13:23:00 UTC ---
Even shorter testcase:

int a, b;

void
foo (int x)
{
  int e[2];
  int d; 
  while (x)
    {
      for (d = 0; d <= 1; d = 1)
        if (e[a])
          break;
      for (b = 0; b <= 0; b = 1)
        {
          e[a] = a;
          if (a)
            break;
        }
    }
}

[Bug tree-optimization/51042] [4.5/4.6/4.7 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-11-09 14:33:14 UTC ---
The clean () code does not work properly for memory references it seems.  We
fail to prune expressions that are not available (the tricks we play with
dominance tests for virtual operands are not effective once we translate
them).

[Bug tree-optimization/51042] [4.5/4.6/4.7 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-11-10 12:50:51 UTC ---
Of course in principle the issue is that an SSA name can have an expression
leader that references the SSA name itself.

[Bug tree-optimization/51042] [4.5/4.6/4.7 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

--- Comment #6 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-11-10 15:29:01 UTC ---
Author: rguenth
Date: Thu Nov 10 15:28:57 2011
New Revision: 181256

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=181256
Log:
2011-11-10  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/51042
    * tree-ssa-pre.c (phi_translate_1): Avoid recursing on
    self-referential expressions.  Refactor code to avoid duplication.

    * gcc.dg/torture/pr51042.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr51042.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-pre.c

[Bug tree-optimization/51042] [4.5/4.6 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |4.7.0
            Summary|[4.5/4.6/4.7 Regression]    |[4.5/4.6 Regression]
                   |endless recursion in        |endless recursion in
                   |phi_translate               |phi_translate

--- Comment #7 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-11-10 15:29:39 UTC ---
Fixed on trunk sofar.

[Bug tree-optimization/51042] [4.5/4.6 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

--- Comment #8 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-03 14:46:08 UTC ---
Author: rguenth
Date: Tue Jan  3 14:46:03 2012
New Revision: 182848

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182848
Log:
2012-01-03  Richard Guenther  <rguenther@suse.de>

    Backport from mainline
    2011-11-10  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/51042
    * tree-ssa-pre.c (phi_translate_1): Avoid recursing on
    self-referential expressions.  Refactor code to avoid duplication.

    * gcc.dg/torture/pr51042.c: New testcase.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/gcc.dg/torture/pr51042.c
Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_6-branch/gcc/tree-ssa-pre.c

[Bug tree-optimization/51042] [4.5 Regression] endless recursion in phi_translate

[liujiangning at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

--- Comment #9 from Jiangning Liu <liujiangning at gcc dot gnu.org> 2012-06-12 09:53:57 UTC ---
Author: liujiangning
Date: Tue Jun 12 09:53:53 2012
New Revision: 188433

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188433
Log:
2011-06-12  Jiangning Liu  <jiangning.liu@arm.com>                              

    Backport r181256 from mainline
    2011-11-10  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/51042
    * tree-ssa-pre.c (phi_translate_1): Avoid recursing on
    self-referential expressions.  Refactor code to avoid duplication.

2011-06-12  Jiangning Liu  <jiangning.liu@arm.com>                              

    Backport r181256 from mainline
    2011-11-10  Richard Guenther  <rguenther@suse.de>


Added:
    branches/ARM/embedded-4_6-branch/gcc/testsuite/gcc.dg/torture/pr51042.c
Modified:
    branches/ARM/embedded-4_6-branch/gcc/ChangeLog.arm
    branches/ARM/embedded-4_6-branch/gcc/testsuite/ChangeLog.arm
    branches/ARM/embedded-4_6-branch/gcc/tree-ssa-pre.c

[Bug tree-optimization/51042] [4.5 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug tree-optimization/51042] [4.5 Regression] endless recursion in phi_translate

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51042

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|4.5.4                       |4.6.3

--- Comment #10 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-07-02 10:16:20 UTC ---
Fixed in 4.6.3.