[Bug rtl-optimization/123308] Recent ifcvt's change causes RISC-V regressions

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123308

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Andrew Pinski <pinskia@gcc.gnu.org>:

https://gcc.gnu.org/g:92f2a86794ad88d773b102c753e13be1b6f05ff9

commit r16-6436-g92f2a86794ad88d773b102c753e13be1b6f05ff9
Author: Andrew Pinski <andrew.pinski@oss.qualcomm.com>
Date:   Fri Dec 26 12:07:26 2025 -0800

    ifcvt: Handle lowpart subregs if noce_emit_cmove fails in
noce_try_cond_zero_arith [PR123308]

    This fixes up a missed optimization regression for riscv in ifcvt after
r16-6350-g9e61a171244110.
    The problem is noce_emit_cmove will fail for QImode. This can show up when
dealing with shifts
    and the right hand side is `(subreg:QI (reg:DI) lowpart)`. Trying first for
the subreg mode
    fails so the need to try to unwrap the subreg and try for the full mode.

    This fixes test_ShiftLeft_eqz in gcc.target/riscv/zicond_ifcvt_opt.c.

    Bootstrapped and tested on x86_64-linux-gnu.

            PR rtl-optimization/123308
    gcc/ChangeLog:

            * ifcvt.cc (noce_try_cond_zero_arith): If noce_emit_cmove fails
            for a lowpart subreg case, then try the full reg cmove and
            take the lowpart subreg afterwards.

    Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>