[Bug tree-optimization/98602] Failure to optimise vector “x > -100 ? x : -100” to MAX_EXPR

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98602

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Naveen H.S <naveenh@gcc.gnu.org>:

https://gcc.gnu.org/g:729eb68a0021bd37acff6a07a505b89687b974b9

commit r17-3277-g729eb68a0021bd37acff6a07a505b89687b974b9
Author: Naveen <naveen.siddegowda@oss.qualcomm.com>
Date:   Thu Aug 13 22:00:54 2026 -0700

    tree-optimization: Fold canonicalized vector min/max conditionals [PR98602]

    The existing VEC_COND_EXPR min/max patterns require the comparison and
result
    constants to be equal so they do not recognize this canonicalized form.
    Add patterns for the GE/LT forms produced from negative signed maximum
    expressions and for the LE/GT forms produced from positive signed or
unsigned
    minimum expressions. Handle both normal and reversed conditional arms.
    The off-by-one check is performed elementwise so the transform is not
    restricted to uniform vector constants.

    This also handles non-uniform vector constants such as:
    X >= { -99, -98 } ? X : { -100, -99 }
    which can be folded to:
    MAX_EXPR <X, { -100, -99 }>
    when each comparison element is exactly one greater than the corresponding
    result element. Variable-length vector constants are handled when the two
    constants have matching VECTOR_CST encodings.

    gcc/ChangeLog:
            PR tree-optimization/98602
            * match.pd (vec_cond (cmp @0 VECTOR_CST@1) @0 VECTOR_CST@2):
            New simplification.
            (vec_cond (cmp @0 VECTOR_CST@1) VECTOR_CST@2 @0): Likewise.
            * tree.cc (record_uniform_integer_difference): New helper.
            (uniform_vector_difference_p): New function.
            * tree.h (uniform_vector_difference_p): Declare.

    gcc/testsuite/ChangeLog:
            PR tree-optimization/98602
            * g++.dg/tree-ssa/pr98602.C: New test.
            * g++.target/aarch64/sve/max_1.C: Remove fixed XFAILs.
            * g++.target/aarch64/sve/min_1.C: Likewise.

    Signed-off-by: Naveen <naveen.siddegowda@oss.qualcomm.com>