[Bug target/113715] RISC-V: If the Zcmp is enabled, the a0 register operates abnormally when the program returns

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113715

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-14 branch has been updated by Fei Gao <feigao@gcc.gnu.org>:

https://gcc.gnu.org/g:efa30f619361b043616e624e57366a50982e11df

commit r14-10403-gefa30f619361b043616e624e57366a50982e11df
Author: Fei Gao <gaofei@eswincomputing.com>
Date:   Tue Jul 9 10:00:29 2024 +0000

    RISC-V: backport fix zcmp popretz [PR113715]

    Root cause:
   
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b27d323a368033f0b37e93c57a57a35fd9997864
    Commit above tries in targetm.gen_epilogue () to detect if
    there's li a0,0 insn at the end of insn chain, if so, cm.popret
    is replaced by cm.popretz and li a0,0 insn is deleted.

    Insertion of the generated epilogue sequence
    into the insn chain doesn't happen at this moment.
    If later shrink-wrap decides NOT to insert the epilogue sequence at the end
    of insn chain, then the li a0,0 insn has already been mistakeny removed.

    Fix this issue by removing generation of cm.popretz in epilogue,
    leaving the assignment to a0 and use insn with cm.popret.

    That's likely going to result in some kind of code size regression,
    but not a correctness regression.

    Optimization can be done in future.

    Signed-off-by: Fei Gao <gaofei@eswincomputing.com>

    gcc/ChangeLog:
            PR target/113715

            * config/riscv/riscv.cc (riscv_zcmp_can_use_popretz): Removed.
            (riscv_gen_multi_pop_insn): Remove generation of cm.popretz.

    gcc/testsuite/ChangeLog:

            * gcc.target/riscv/rv32e_zcmp.c: Adapt TC.
            * gcc.target/riscv/rv32i_zcmp.c: Likewise.