[Bug tree-optimization/116609] New: Live lane vectorization does not support SLP with loop masking

[Bug tree-optimization/116609] New: Live lane vectorization does not support SLP with loop masking

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116609

            Bug ID: 116609
           Summary: Live lane vectorization does not support SLP with loop
                    masking
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---

It should be trivial to support for single-lane SLP (testing a patch for that)
but also multi-lane might be supportable, for example using slide up/down
or easier when the number of lanes is power-of-two use a larger element
lastb extract.

In general when SLP discovery gets us multi-lanes and that fails we currently
scrap the respective SLP instance but we might want to split it up to a set
of single-lane instances (also avoiding re-discovery).

[Bug tree-optimization/116609] Live lane vectorization does not support SLP with loop masking

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116609

--- Comment #1 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:116bfbc806a7aa3f1ae2a3b3eb38d6bb65e0d0a7

commit r15-3506-g116bfbc806a7aa3f1ae2a3b3eb38d6bb65e0d0a7
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Sep 5 10:46:58 2024 +0200

    tree-optimization/116609 - SLP live lane vectorization with partial vectors

    The following implements the simple case of single-lane SLP when
    using partial vectors which can use the VEC_EXTRACT_LAST code
    generation without changes.  I'll keep the PR open for further
    enhancements.

    This avoids FAILs of gcc.target/aarch64/sve/live_1.c when using
    single-lane SLP for non-grouped stores.

            PR tree-optimization/116609
            * tree-vect-loop.cc (vectorizable_live_operation_1): Support
            partial vectors for single-lane SLP.

[Bug tree-optimization/116609] Live lane vectorization does not support SLP with loop masking

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116609

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-09-06
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
It should now work for single-lane SLP when also using the SLP equivalent
of ncopies == 1.  Both is overly restrictive of course, so keeping open.