[Bug target/36503] x86 can use x >> -y for x >> 32-y

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36503

--- Comment #15 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Uros Bizjak <u...@gcc.gnu.org>:

https://gcc.gnu.org/g:093584abb854559393e36cd4cdcf9dc4862dd046

commit r15-5731-g093584abb854559393e36cd4cdcf9dc4862dd046
Author: Uros Bizjak <ubiz...@gmail.com>
Date:   Wed Nov 27 20:45:25 2024 +0100

    i386: x86 can use x >> y for x >> 32+y [PR36503]

    x86 targets mask 32-bit shifts with a 5-bit mask (and 64-bit with 6-bit
mask),
    so they can use x >> y instead of x >> 32+y.

    The optimization converts:

            leal    32(%rsi), %ecx
            sall    %cl, %eax

    to:
            sall    %cl, %eax

            PR target/36503

    gcc/ChangeLog:

            * config/i386/i386.md (*ashl<mode>3_add):
            New define_insn_and_split pattern.
            (*ashl<mode>3_add_1): Ditto.
            (*<insn><mode>3_add): Ditto.
            (*<insn><mode>3_add_1): Ditto.
            (*ashl<mode>3_sub): Rename from *ashl<mode>3_negcnt.
            (*ashl<mode>3_sub_1): Rename from *ashl<mode>3_negcnt_1.
            (*<insn><mode>3_sub): Rename from *<insn><mode>3_negcnt.
            (*<insn><mode>3_sub_1): Rename from *<insn><mode>3_negcnt_1.

    gcc/testsuite/ChangeLog:

            * gcc.target/i386/pr36503-3.c: New test.
            * gcc.target/i386/pr36503-4.c: New test.