[Bug tree-optimization/116142] vec_widen_smult_{odd,even}_M ineffective for a simple widening dot product (vect_used_by_reduction is not set?)

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116142

--- Comment #14 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Xi Ruoyao <xry...@gcc.gnu.org>:

https://gcc.gnu.org/g:2083389a18d36684a88d9e2653bacc87ad894b50

commit r15-2791-g2083389a18d36684a88d9e2653bacc87ad894b50
Author: Xi Ruoyao <xry...@xry111.site>
Date:   Tue Aug 6 17:48:42 2024 +0800

    vect: Fix vect_reduction_def check for odd/even widen mult [PR116142]

    The check was implemented incorrectly, so vec_widen_smult_{even,odd}_M
    was never used.  This is not good for targets with native even/odd
    widening multiplication but not lo/hi multiplication.

    The fix is actually developed by Richard Biener.

    gcc/ChangeLog:

            PR tree-optimization/116142
            * tree-vect-stmts.cc (supportable_widening_operation): Remove an
            redundant and incorrect vect_reduction_def check, and fix the
            operand of another vect_reduction_def check.

    gcc/testsuite/ChangeLog:

            PR tree-optimization/116142
            * gcc.target/i386/pr116142.c: New test.

    Co-authored-by: Richard Biener <rguent...@suse.de>