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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/103743] PPC: Inefficient equality compare for large
 64-bit constants having only 16-bit relevant bits in high part
Date: Tue, 20 Dec 2022 03:59:43 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103743

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jiu Fu Guo <guojiufu@gcc.gnu.org>:

https://gcc.gnu.org/g:1060cd2ad00b5174f4f8ef8ca3d8c283e321ffca

commit r13-4803-g1060cd2ad00b5174f4f8ef8ca3d8c283e321ffca
Author: Jiufu Guo <guojiufu@linux.ibm.com>
Date:   Tue Dec 20 11:43:57 2022 +0800

    rs6000: Optimize cmp on rotated 16bits constant

    Hi,

    When checking eq/ne with a constant which has only 16bits, it can be
    optimized to check the rotated data.  By this, the constant building
    is optimized.

    As the example in PR103743:
    For "in =3D=3D 0x8000000000000000LL", this patch generates:
            rotldi 3,3,1 ; cmpldi 0,3,1
    instead of:
            li 9,-1 ; rldicr 9,9,0,0 ; cmpd 0,3,9

    Compare with previous version:
    https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600475.html.
    This patch refactor the code according to review comments.
    e.g. updating function names/comments/code.

    This patch pass bootstrap and regtest on ppc64 and ppc64le.
    Is it ok for trunk?  Thanks for comments!

    BR,
    Jeff(Jiufu)

            PR target/103743

    gcc/ChangeLog:

            * config/rs6000/rs6000-protos.h (can_be_rotated_to_lowbits): Ne=
w.
            (can_be_rotated_to_positive_16bits): New.
            (can_be_rotated_to_negative_15bits): New.
            * config/rs6000/rs6000.cc (can_be_rotated_to_lowbits): New
definition.
            (can_be_rotated_to_positive_16bits): New definition.
            (can_be_rotated_to_negative_15bits): New definition.
            * config/rs6000/rs6000.md (*rotate_on_cmpdi): New
define_insn_and_split.
            (eqne): Move earlier.

    gcc/testsuite/ChangeLog:

            * gcc.target/powerpc/pr103743.c: New test.
            * gcc.target/powerpc/pr103743_1.c: New test.=