[Bug target/114607] New: aarch64: Incorrect expansion of svsudot

[Bug target/114607] New: aarch64: Incorrect expansion of svsudot

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114607

            Bug ID: 114607
           Summary: aarch64: Incorrect expansion of svsudot
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rsandifo at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64*-*-*

svsudot is supposed to expand to USDOT with the second and third arguments
swapped.  However, there is a thinko in the code that does the reversal, making
it a no-op.  Unfortunately, the tests simply accept the buggy form. :-(

For example, gcc.target/aarch64/sve/acle/asm/sudot_s32.c contains:

/*
** sudot_s32_tied1:
**      usdot   z0\.s, z2\.b, z4\.b
**      ret
*/
TEST_TRIPLE_Z (sudot_s32_tied1, svint32_t, svint8_t, svuint8_t,
               z0 = svsudot_s32 (z0, z2, z4),
               z0 = svsudot (z0, z2, z4))

where the usdot z2 and z4 operands should be in the opposite order.

[Bug target/114607] aarch64: Incorrect expansion of svsudot

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114607

Richard Sandiford <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |rsandifo at gcc dot gnu.org
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2024-04-05
     Ever confirmed|0                           |1

[Bug target/114607] aarch64: Incorrect expansion of svsudot

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114607

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

https://gcc.gnu.org/g:2c1c2485a4b1aca746ac693041e51ea6da5c64ca

commit r14-9836-g2c1c2485a4b1aca746ac693041e51ea6da5c64ca
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Mon Apr 8 16:53:32 2024 +0100

    aarch64: Fix expansion of svsudot [PR114607]

    Not sure how this happend, but: svsudot is supposed to be expanded
    as USDOT with the operands swapped.  However, a thinko in the
    expansion of svsudot meant that the arguments weren't in fact
    swapped; the attempted swap was just a no-op.  And the testcases
    blithely accepted that.

    gcc/
            PR target/114607
            * config/aarch64/aarch64-sve-builtins-base.cc
            (svusdot_impl::expand): Fix botched attempt to swap the operands
            for svsudot.

    gcc/testsuite/
            PR target/114607
            * gcc.target/aarch64/sve/acle/asm/sudot_s32.c: New test.

[Bug target/114607] aarch64: Incorrect expansion of svsudot

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114607

--- Comment #2 from Richard Sandiford <rsandifo at gcc dot gnu.org> ---
Fixed on trunk.  I'll backport in a few weeks if there's no fallout.