[Bug regression/53729] New: [4.8 regression] PR53636 fix caused bb-slp-16.c to FAIL on sparc64 and powerpc64

[Bug regression/53729] New: [4.8 regression] PR53636 fix caused bb-slp-16.c to FAIL on sparc64 and powerpc64

[mikpe at it dot uu.se]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53729

             Bug #: 53729
           Summary: [4.8 regression] PR53636 fix caused bb-slp-16.c to
                    FAIL on sparc64 and powerpc64
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: mikpe@it.uu.se


The PR53636 fix caused

FAIL: gcc.dg/vect/bb-slp-16.c scan-tree-dump-times slp "basic block vectorized
using SLP" 1

on sparc64-linux.  Comparing the pre and post patch dumps for that file shows

 22: vect_compute_data_ref_alignment:
 22: misalign = 4 bytes of ref MEM[(unsigned int *)pout_90 + 28B]
 22: vect_compute_data_ref_alignment:
-22: force alignment of arr[i_87]
-22: misalign = 0 bytes of ref arr[i_87]
+22: SLP: step doesn't divide the vector-size.
+22: Unknown alignment for access: arr

(lots of stuff that's simply gone)

-22: BASIC BLOCK VECTORIZED
-
-22: basic block vectorized using SLP
+22: not vectorized: unsupported unaligned store.arr[i_87]
+22: not vectorized: unsupported alignment in basic block.

The same new FAIL also appears on powerpc64-linux.

[Bug regression/53729] [4.8 regression] PR53636 fix caused bb-slp-16.c to FAIL on sparc64 and powerpc64

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53729

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu.org,
                   |                            |uweigand at gcc dot gnu.org
   Target Milestone|---                         |4.8.0

[Bug regression/53729] [4.8 regression] PR53636 fix caused bb-slp-16.c to FAIL on sparc64 and powerpc64

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53729

Ulrich Weigand <uweigand at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-06-20
         AssignedTo|unassigned at gcc dot       |uweigand at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #1 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2012-06-20 15:22:45 UTC ---
The problem is that SLP tests *all* accesses within the basic block for
alignment, even those that aren't actually part of a SLP instance.

This is of course broken, but that bug had been hidden by the PR53636 problem
(due to which accesses were considered aligned that actually are not).

The fix for this problem is to only check *relevant* accesses for alignment. 
(This requires moving the alignment check until after relevant statements are
actually marked ...)

I'm testing a fix.

[Bug regression/53729] [4.8 regression] PR53636 fix caused bb-slp-16.c to FAIL on sparc64 and powerpc64

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53729

--- Comment #2 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2012-06-26 09:05:55 UTC ---
Author: uweigand
Date: Tue Jun 26 09:05:48 2012
New Revision: 188979

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188979
Log:
    PR tree-optimization/53729
    PR tree-optimization/53636
    * tree-vect-slp.c (vect_slp_analyze_bb_1): Delay call to
    vect_verify_datarefs_alignment until after statements have
    been marked as relevant/irrelevant.
    * tree-vect-data-refs.c (vect_verify_datarefs_alignment):
    Skip irrelevant statements.
    (vect_enhance_data_refs_alignment): Use STMT_VINFO_RELEVANT_P
    instead of STMT_VINFO_RELEVANT.
    (vect_get_data_access_cost): Do not check for supportable
    alignment before calling vect_get_load_cost/vect_get_store_cost.
    * tree-vect-stmts.c (vect_get_store_cost): Do not abort when
    handling unsupported alignment.
    (vect_get_load_cost): Likewise.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/tree-vect-data-refs.c
    trunk/gcc/tree-vect-slp.c
    trunk/gcc/tree-vect-stmts.c

[Bug regression/53729] [4.8 regression] PR53636 fix caused bb-slp-16.c to FAIL on sparc64 and powerpc64

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53729

Ulrich Weigand <uweigand at gcc dot gnu.org> changed:

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

--- Comment #3 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2012-06-26 09:09:28 UTC ---
Fixed.