[Bug tree-optimization/123002] [15/16 regression] WIDEN_MULT_EXPR are incorrectly vectorized since r15-3189-gd3e71b99194bff

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123002

--- Comment #4 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:1da0e5c1405e87e9f2a11ed358b40dff21085657

commit r16-5902-g1da0e5c1405e87e9f2a11ed358b40dff21085657
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Aug 21 13:46:06 2025 +0200

    Move even/odd validity check from supportable_widening_operation to caller

    The following moves the incomplete validity check to use
    WIDEN_MULT_{EVEN,ODD} to the caller of supportable_widening_operation
    where we have access to more (but not enough) information.  I have
    made the test conservative enough I hope.  For the testcase what was
    broken is that it uses a SLP reduction where lane-swizzling isn't
    valid.

            PR tree-optimization/123002
            * tree-vectorizer.h (supportable_widening_operation): Remove
            vinfo and stmt_info parameters, add flag to indicate whether
            the context would allow OP_{EVEN,ODD}.
            * tree-vect-patterns.cc (vect_recog_abd_pattern): Adjust
            and pass false.
            (vect_recog_widen_op_pattern): Likewise.
            (vect_recog_widen_abd_pattern): Likewise.
            * tree-vect-stmts.cc (vectorizable_conversion): Move
            even/odd validity check here, from supportable_widening_operation.
            Adjust it to be conservative.
            (supportable_widening_operation): Get flag whether even/odd
            is OK to use and remove then unused parameters and code.

            * gcc.dg/vect/vect-pr123002.c: New testcase.