[Bug target/121096] [16 Regression] ICE: in store_by_pieces, at expr.cc:1847 with -Os -mtune=... -mstringop-strategy=vector_loop

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121096

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

https://gcc.gnu.org/g:881df7a0b1e8e8c1454309fe23c0edd026296b8b

commit r16-3460-g881df7a0b1e8e8c1454309fe23c0edd026296b8b
Author: H.J. Lu <hjl.to...@gmail.com>
Date:   Thu Aug 28 17:55:46 2025 -0700

    x86: Allow by_pieces op when expanding memcpy/memset epilogue

    Since

    commit 401199377c50045ede560daf3f6e8b51749c2a87
    Author: H.J. Lu <hjl.to...@gmail.com>
    Date:   Tue Jun 17 10:17:17 2025 +0800

        x86: Improve vector_loop/unrolled_loop for memset/memcpy

    uses move_by_pieces and store_by_pieces to expand memcpy/memset epilogue
    with vector_loop even when targetm.use_by_pieces_infrastructure_p returns
    false, which triggers

      gcc_assert (targetm.use_by_pieces_infrastructure_p
                    (len, align,
                     memsetp ? SET_BY_PIECES : STORE_BY_PIECES,
                     optimize_insn_for_speed_p ()));

    in store_by_pieces.  Fix it by:

    1. Add by_pieces_in_use to machine_function to indicate that by_pieces op
    is currently in use.
    2. Set and clear by_pieces_in_use when expanding memcpy/memset epilogue
    with move_by_pieces and store_by_pieces.
    3. Define TARGET_USE_BY_PIECES_INFRASTRUCTURE_P to return true if
    by_pieces_in_use is true.

    gcc/

            PR target/121096
            * config/i386/i386-expand.cc (expand_cpymem_epilogue): Set and
            clear by_pieces_in_use when using by_pieces op.
            (expand_setmem_epilogue): Likewise.
            * config/i386/i386.cc (ix86_use_by_pieces_infrastructure_p): New.
            (TARGET_USE_BY_PIECES_INFRASTRUCTURE_P): Likewise.
            * config/i386/i386.h (machine_function): Add by_pieces_in_use.

    gcc/testsuite/

            PR target/121096
            * gcc.target/i386/memcpy-strategy-14.c: New test.
            * gcc.target/i386/memcpy-strategy-15.c: Likewise.
            * gcc.target/i386/memset-strategy-10.c: Likewise.
            * gcc.target/i386/memset-strategy-11.c: Likewise.
            * gcc.target/i386/memset-strategy-12.c: Likewise.
            * gcc.target/i386/memset-strategy-13.c: Likewise.
            * gcc.target/i386/memset-strategy-14.c: Likewise.
            * gcc.target/i386/memset-strategy-15.c: Likewise.

    Signed-off-by: H.J. Lu <hjl.to...@gmail.com>