[Bug target/124448] RISC-V: Extract from tuple vector with lmul<1 may cause poor code generation

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124448

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Robin Dapp <rd...@gcc.gnu.org>:

https://gcc.gnu.org/g:8add8bccdcdd40103c320648d00a07c54d97160d

commit r17-337-g8add8bccdcdd40103c320648d00a07c54d97160d
Author: wangzicong <wangzic...@masscore.cn>
Date:   Thu Apr 30 21:23:07 2026 +0800

    RISC-V: Make tuple vector not tieable to some modes.

    This patch makes riscv tuple modes not tieable to non-tuple modes. Without
    this patch some unnecessary type conversions may occur, especially when zvl
    is specified.
    E.g. RVVMF2x4HI and RVVM2DI are tieable in gcc trunk, and when extracting
    an inner vector mode RVVMF2HI from RVVMF2x4HI and zvl is specified, it will
    be converted to DI, which is not expected. But with same inner modes, e.g.
    RVVM1x4QI and RVVM1QI, they should be tieable.

            PR target/124448

    gcc/ChangeLog:

            * config/riscv/riscv.cc (riscv_modes_tieable_p): Make tuple modes
            not tieable to some modes.

    gcc/testsuite/ChangeLog:

            * gcc.target/riscv/rvv/autovec/pr124448.c: New test.

    Signed-off-by: wangzicong <wangzic...@masscore.cn>