[Bug tree-optimization/43434] Missed vectorization: "not vectorized: data ref analysis": pointer incremented by a parameter

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43434

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2013-03-27
             Blocks|                            |37021
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-27 12:45:02 UTC ---
Confirmed.  We for example have

t.c:39: note: Build SLP failed: not grouped load _46 = *pix_1;

as we fail to detect groups for

  _46 = *pix_1;
  _49 = MEM[(unsigned char *)pix_1 + 1B];
  _52 = MEM[(unsigned char *)pix_1 + 2B];
...

as the step is not integral.  That is, this is a strided-load SLP group.

I am working on a patch for this.  This is one reason why PR37021 is not
vectorized in the best possible way.