[Bug tree-optimization/53516] New: Vectorization and memset recognition miscompile bitfield stores

[Bug tree-optimization/53516] New: Vectorization and memset recognition miscompile bitfield stores

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53516

             Bug #: 53516
           Summary: Vectorization and memset recognition miscompile
                    bitfield stores
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: rguenth@gcc.gnu.org
        ReportedBy: rguenth@gcc.gnu.org


The following is miscompiled at -O3.

extern void abort (void);

struct Foo
{
  char a : 1;
  char b : 7;
};

struct Foo x[256];
int y[256];

void __attribute__((noinline,noclone)) bar (int n)
{
  int i;
  for (i = 0; i < n; ++i)
    {
      x[i].a = 0;
      y[i] = 3;
    }
}

int main()
{
  x[5].b = 7;
  bar (256);
  if (x[5].b != 7)
    abort ();
  return 0;
}

[Bug tree-optimization/53516] [4.6/4.7/4.8 Regression] Vectorization and memset recognition miscompile bitfield stores

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53516

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-05-29
      Known to work|                            |4.5.3
   Target Milestone|---                         |4.6.4
            Summary|Vectorization and memset    |[4.6/4.7/4.8 Regression]
                   |recognition miscompile      |Vectorization and memset
                   |bitfield stores             |recognition miscompile
                   |                            |bitfield stores
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-05-29 13:13:42 UTC ---
4.5 works.

[Bug tree-optimization/53516] [4.6/4.7/4.8 Regression] Vectorization and memset recognition miscompile bitfield stores

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53516

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

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

[Bug tree-optimization/53516] [4.6/4.7/4.8 Regression] Vectorization and memset recognition miscompile bitfield stores

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53516

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-05-29 14:40:23 UTC ---
Author: rguenth
Date: Tue May 29 14:40:16 2012
New Revision: 187961

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=187961
Log:
2012-05-29  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/53516
    * tree-data-ref.c (stmt_with_adjacent_zero_store_dr_p): Reject
    bitfield accesses.
    * tree-vect-data-refs.c (vect_analyze_data_refs): Likewise.

    * gcc.dg/torture/pr53516.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr53516.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-data-ref.c
    trunk/gcc/tree-vect-data-refs.c

[Bug tree-optimization/53516] [4.6/4.7/4.8 Regression] Vectorization and memset recognition miscompile bitfield stores

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53516

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-05-29 14:44:13 UTC ---
Author: rguenth
Date: Tue May 29 14:44:08 2012
New Revision: 187964

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=187964
Log:
2012-05-29  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/53516
    * tree-data-ref.c (stmt_with_adjacent_zero_store_dr_p): Reject
    bitfield accesses.
    * tree-vect-data-refs.c (vect_analyze_data_refs): Likewise.

    * gcc.dg/torture/pr53516.c: New testcase.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/gcc.dg/torture/pr53516.c
Modified:
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_7-branch/gcc/tree-data-ref.c
    branches/gcc-4_7-branch/gcc/tree-vect-data-refs.c

[Bug tree-optimization/53516] [4.6 Regression] Vectorization and memset recognition miscompile bitfield stores

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53516

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P2                          |P3
      Known to work|                            |4.7.1, 4.8.0
            Summary|[4.6/4.7/4.8 Regression]    |[4.6 Regression]
                   |Vectorization and memset    |Vectorization and memset
                   |recognition miscompile      |recognition miscompile
                   |bitfield stores             |bitfield stores
      Known to fail|                            |4.6.3, 4.7.0

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-05-29 14:44:50 UTC ---
Fixed on the trunk and the 4.7 branch for now.

[Bug tree-optimization/53516] [4.6 Regression] Vectorization and memset recognition miscompile bitfield stores

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53516

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|4.6.4                       |4.7.1

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-04-12 16:25:40 UTC ---
The 4.6 branch has been closed, fixed in GCC 4.7.1.