[Bug middle-end/102202] Inefficent expansion of memset when range is [0,1]

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102202

--- Comment #7 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:a8072f31bc90000b3b8a2c0c7819710cf924727a

commit r17-2113-ga8072f31bc90000b3b8a2c0c7819710cf924727a
Author: Naveen <naveen.siddegowda@oss.qualcomm.com>
Date:   Fri Jul 3 05:24:04 2026 -0700

    tree-optimization: fold memset with length in [0, 1] to conditional store
[PR102202]

    The patch improves memset optimization when the length is known to be 0 or
1.
    It uses Ranger information to recognize such cases, shrink-wraps the call
on
    the zero-length case and replaces the one-byte case with a direct byte
store.
    It also extends gimple_fold_builtin_memset to handle Ranger-proven
singleton
    lengths not just integer constants.

    gcc/ChangeLog:
            PR tree-optimization/102202
            * tree-call-cdce.cc: Include "tree-ssanames.h", "gimple-fold.h".
            (len_has_boolean_range_p): New function.
            (can_shrink_wrap_len_p): New function.
            (gen_zero_len_conditions): New function.
            (shrink_wrap_len_call): New function.
            (shrink_wrap_conditional_dead_built_in_calls): Dispatch to
            shrink_wrap_one_memset_call for memset calls eligible for the [0,
1]
            length transform, ahead of the generic LHS and range-test paths.
            (pass_call_cdce::execute): Collect memset calls satisfying
            can_shrink_wrap_memset_p as shrink-wrap candidates.

    gcc/testsuite/ChangeLog:
            PR tree-optimization/102202
            * gcc.dg/pr102202-1.c: New test.
            * gcc.dg/pr102202.c: New test.
            * gcc.target/aarch64/pr100518.c: Modify to handle the warning.

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