[Bug tree-optimization/58958] New: [4.9 Regression] Wrong aliasing info for variable index

[Bug tree-optimization/58958] New: [4.9 Regression] Wrong aliasing info for variable index

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58958

            Bug ID: 58958
           Summary: [4.9 Regression] Wrong aliasing info for variable
                    index
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glisse at gcc dot gnu.org

double a[10];
bool f(int n){
  a[3]=42;
  __builtin_memset(&a[n],3,sizeof(double));
  return a[3]==42;
}

is optimized to:

bool f(int) (int n)
{
  double * _4;

  <bb 2>:
  a[3] = 4.2e+1;
  _4 = &a[n_3(D)];
  __builtin_memset (_4, 3, 8);
  return 1;

}

This is the issue described here:
http://gcc.gnu.org/ml/gcc-patches/2013-10/msg02558.html

ao_ref_init_from_ptr_and_size makes an unsafe use of get_ref_base_and_extent.
Maybe relying on get_addr_base_and_unit_offset would be better?

The testcase is a regression, although the issue preexisted.

[Bug tree-optimization/58958] [4.9 Regression] Wrong aliasing info for variable index

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58958

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-11-04
   Target Milestone|---                         |4.9.0
     Ever confirmed|0                           |1

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

[Bug tree-optimization/58958] [4.9 Regression] Wrong aliasing info for variable index

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58958

--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Tue Nov  5 13:01:06 2013
New Revision: 204389

URL: http://gcc.gnu.org/viewcvs?rev=204389&root=gcc&view=rev
Log:
2013-11-05  Marc Glisse  <marc.glisse@inria.fr>

    PR tree-optimization/58958
gcc/
    * tree-ssa-alias.c (ao_ref_init_from_ptr_and_size): Use
    get_addr_base_and_unit_offset instead of get_ref_base_and_extent.

gcc/testsuite/
    * gcc.dg/tree-ssa/pr58958.c: New file.


Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr58958.c   (with props)
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-alias.c

Propchange: trunk/gcc/testsuite/gcc.dg/tree-ssa/pr58958.c
            ('svn:eol-style' added)

Propchange: trunk/gcc/testsuite/gcc.dg/tree-ssa/pr58958.c
            ('svn:keywords' added)

[Bug tree-optimization/58958] [4.9 Regression] Wrong aliasing info for variable index

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58958

Marc Glisse <glisse at gcc dot gnu.org> changed:

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

--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
.