[Bug target/126959] -march=znver4 prefers load from memory for mask register

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126959

--- Comment #9 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by H.J. Lu <[email protected]>:

https://gcc.gnu.org/g:086b41669e64fda333cd91144070314912ae4ae9

commit r17-3496-g086b41669e64fda333cd91144070314912ae4ae9
Author: H.J. Lu <[email protected]>
Date:   Thu Aug 20 12:17:41 2026 +0800

    x86: Allow minus ones for Kn and standard constants for XMMn

    Since we can load minus ones into a MASK register and standard SSE
    constants into a SSE register, allow them for MASK and SSE registers
    so that

            kxnor   %k0, %k0, %k0

    is used to load -1 into mask register, instead of loading from memory.

    gcc/

            PR target/126959
            * config/i386/i386.cc (ix86_preferred_reload_class): Allow
            minus ones for MASK register and standard SSE constants for
            SSE register.

    gcc/testsuite/

            PR target/126959
            * gcc.target/i386/pr126959-1a.c: New test.
            * gcc.target/i386/pr126959-1b.c: Likewise.
            * gcc.target/i386/pr126959-2a.c: Likewise.
            * gcc.target/i386/pr126959-2b.c: Likewise.

    Signed-off-by: H.J. Lu <[email protected]>