[Bug tree-optimization/94401] New: pr92420.c fails on aarch64 since r10-7415

[Bug tree-optimization/94401] New: pr92420.c fails on aarch64 since r10-7415

[clyon at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

            Bug ID: 94401
           Summary: pr92420.c fails on aarch64 since r10-7415
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: clyon at gcc dot gnu.org
  Target Milestone: ---

I've noticed that the fix for PR90332 caused a regression on aarch64:

FAIL: gcc.dg/vect/pr92420.c -flto -ffat-lto-objects execution test
FAIL: gcc.dg/vect/pr92420.c execution test

[Bug tree-optimization/94401] pr92420.c fails on aarch64 since r10-7415

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |linkw at gcc dot gnu.org
                 CC|                            |linkw at gcc dot gnu.org

--- Comment #1 from Kewen Lin <linkw at gcc dot gnu.org> ---
Thanks for reporting this! Do I need some special arch configuration options
for the gcc build to reproduce this on some aarch machine in CFarm? or fine
with default?

[Bug tree-optimization/94401] pr92420.c fails on aarch64 since r10-7415

[clyon at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

--- Comment #2 from Christophe Lyon <clyon at gcc dot gnu.org> ---
The defaults are OK (either native or cross aarch64)

[Bug tree-optimization/94401] [10 Regression] pr92420.c fails on aarch64 since r10-7415

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |aarch64
            Version|unknown                     |10.0
   Target Milestone|---                         |10.0
           Keywords|                            |wrong-code
           Priority|P3                          |P1
            Summary|pr92420.c fails on aarch64  |[10 Regression] pr92420.c
                   |since r10-7415              |fails on aarch64 since
                   |                            |r10-7415

[Bug tree-optimization/94401] [10 Regression] pr92420.c fails on aarch64 since r10-7415

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

Jeffrey A. Law <law at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-03-30
                 CC|                            |law at redhat dot com
             Status|UNCONFIRMED                 |NEW

--- Comment #3 from Jeffrey A. Law <law at redhat dot com> ---
Confirmed.  My tester tripped over this as well.

No special options are needed at configure time.

[Bug tree-optimization/94401] [10 Regression] pr92420.c fails on aarch64 since r10-7415

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |segher at gcc dot gnu.org,
                   |                            |wschmidt at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #4 from Kewen Lin <linkw at gcc dot gnu.org> ---
My commit extends the current scalar epilogue peeling for gaps 
elimination, it makes the case can make use of int for the construction. But it
reveals the existing handlings misses to handle VMAT_CONTIGUOUS_REVERSE case,
currently it assumes overrun happens on high address end, it's true for almost
all cases, but this case is on the low address end. So if we have to load the
high part and put it in the latter part of constructed vector for
VMAT_CONTIGUOUS_REVERSE.

The IR before/after the commit looks

good:
  vect__9.16_80 = MEM <vector(2) int> [(int *)vectp_y.14_78];
  vect__9.17_81 = VEC_PERM_EXPR <vect__9.16_80, vect__9.16_80, { 1, 0 }>;
  vect__9.18_82 = VEC_PERM_EXPR <vect__9.17_81, vect__9.17_81, { 0, 0 }>;

bad:
  _30 = MEM[(int *)vectp_y.12_34];
  _20 = {_30, 0};
  vect__9.14_19 = VIEW_CONVERT_EXPR<vector(2) int>(_20);
  vect__9.15_61 = VEC_PERM_EXPR <vect__9.14_19, vect__9.14_19, { 1, 0 }>;
  vect__9.16_54 = VEC_PERM_EXPR <vect__9.15_61, vect__9.15_61, { 0, 0 }>;

[Bug tree-optimization/94401] [10 Regression] pr92420.c fails on aarch64 since r10-7415

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

--- Comment #5 from Kewen Lin <linkw at gcc dot gnu.org> ---
Created attachment 48150
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48150&action=edit
untested patch

This can fix the REG failures on aarch64.

[Bug tree-optimization/94401] [10 Regression] pr92420.c fails on aarch64 since r10-7415

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Kewen Lin <linkw@gcc.gnu.org>:

https://gcc.gnu.org/g:81ce375d1fdd99f9d93b00f4895eab74c3d8b54a

commit r10-7519-g81ce375d1fdd99f9d93b00f4895eab74c3d8b54a
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Thu Apr 2 08:48:03 2020 -0500

    Fix PR94401 by considering reverse overrun

    The commit r10-7415 brings scalar type consideration
    to eliminate epilogue peeling for gaps, but it exposed
    one problem that the current handling doesn't consider
    the memory access type VMAT_CONTIGUOUS_REVERSE, for
    which the overrun happens on low address side.  This
    patch is to make the code take care of it by updating
    the offset and construction element order accordingly.

    Bootstrapped/regtested on powerpc64le-linux-gnu P8
    and aarch64-linux-gnu.

    2020-04-02  Kewen Lin  <linkw@gcc.gnu.org>

    gcc/ChangeLog

        PR tree-optimization/94401
        * tree-vect-loop.c (vectorizable_load): Handle VMAT_CONTIGUOUS_REVERSE
        access type when loading halves of vector to avoid peeling for gaps.

[Bug tree-optimization/94401] [10 Regression] pr92420.c fails on aarch64 since r10-7415

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94401

Kewen Lin <linkw at gcc dot gnu.org> changed:

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

--- Comment #7 from Kewen Lin <linkw at gcc dot gnu.org> ---
Should be fixed now.