[Bug target/110429] New: Redundant vector extract instruction on P9

[Bug target/110429] New: Redundant vector extract instruction on P9

[guihaoc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110429

            Bug ID: 110429
           Summary: Redundant vector extract instruction on P9
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: guihaoc at gcc dot gnu.org
  Target Milestone: ---

//test.c
#include <altivec.h>
void extract_int_2 (int *p, vector int a) { *p = vec_extract (a, 2); }

On P9 LE, it generates
        xxextractuw 34,34,4
        stxsiwx 34,0,3

The xxextractuw is unnecessary as the extracted int is just at word[1].

[Bug target/110429] Redundant vector extract instruction on P9

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110429

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by HaoChen Gui <guihaoc@gcc.gnu.org>:

https://gcc.gnu.org/g:d471bdb0453de7b738f49148b66d57cb5871937d

commit r14-3237-gd471bdb0453de7b738f49148b66d57cb5871937d
Author: Haochen Gui <guihaoc@gcc.gnu.org>
Date:   Wed Aug 16 14:29:36 2023 +0800

    rs6000: Skip unnecessary vector extract for certain elements.

    If the extracted element index is:
      - for byte, 7 on BE while 8 on LE;
      - for half word, 3 on BE while 4 on LE;

    the element to be stored is already in the corresponding place for
    stxsi[hb]x. We don't need a redundant vector extraction at all.

    gcc/
            PR target/110429
            * config/rs6000/vsx.md (*vsx_extract_<mode>_store_p9): Skip vector
            extract when the element is 7 on BE while 8 on LE for byte or 3 on
            BE while 4 on LE for halfword.

    gcc/testsuite/
            PR target/110429
            * gcc.target/powerpc/pr110429.c: New.

[Bug target/110429] Redundant vector extract instruction on P9

[guihaoc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110429

HaoChen Gui <guihaoc at gcc dot gnu.org> changed:

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

--- Comment #2 from HaoChen Gui <guihaoc at gcc dot gnu.org> ---
Fixed