[Bug target/87832] AMD pipeline models are very costly size-wise

cvs-commit at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Mon Jan 2 16:39:08 GMT 2023


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87832

--- Comment #13 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Alexander Monakov <amonakov@gcc.gnu.org>:

https://gcc.gnu.org/g:ec1db9017939bb8289c9bd63aace66c0f3957ecd

commit r13-4956-gec1db9017939bb8289c9bd63aace66c0f3957ecd
Author: Alexander Monakov <amonakov@ispras.ru>
Date:   Fri Dec 9 20:47:55 2022 +0300

    i386: correct division modeling in lujiazui.md

    Model the divider in Lujiazui processors as a separate automaton to
    significantly reduce the overall model size. This should also result
    in improved accuracy, as pipe 0 should be able to accept new
    instructions while the divider is occupied.

    It is unclear why integer divisions are modeled as if pipes 0-3 are all
    occupied. I've opted to keep a single-cycle reservation of all four
    pipes together, so GCC should continue trying to pack instructions
    around a division accordingly.

    Currently top three symbols in insn-automata.o are:

    106102 r lujiazui_core_check
    106102 r lujiazui_core_transitions
    196123 r lujiazui_core_min_issue_delay

    This patch shrinks all lujiazui tables to:

    3 r lujiazui_decoder_min_issue_delay
    20 r lujiazui_decoder_transitions
    32 r lujiazui_agu_min_issue_delay
    126 r lujiazui_agu_transitions
    304 r lujiazui_div_base
    352 r lujiazui_div_check
    352 r lujiazui_div_transitions
    1152 r lujiazui_core_min_issue_delay
    1592 r lujiazui_agu_translate
    1592 r lujiazui_core_translate
    1592 r lujiazui_decoder_translate
    1592 r lujiazui_div_translate
    3952 r lujiazui_div_min_issue_delay
    9216 r lujiazui_core_transitions

    This continues the work on reducing i386 insn-automata.o size started
    with similar fixes for division and multiplication instructions in
    znver.md.

    gcc/ChangeLog:

            PR target/87832
            * config/i386/lujiazui.md (lujiazui_div): New automaton.
            (lua_div): New unit.
            (lua_idiv_qi): Correct unit in the reservation.
            (lua_idiv_qi_load): Ditto.
            (lua_idiv_hi): Ditto.
            (lua_idiv_hi_load): Ditto.
            (lua_idiv_si): Ditto.
            (lua_idiv_si_load): Ditto.
            (lua_idiv_di): Ditto.
            (lua_idiv_di_load): Ditto.
            (lua_fdiv_SF): Ditto.
            (lua_fdiv_SF_load): Ditto.
            (lua_fdiv_DF): Ditto.
            (lua_fdiv_DF_load): Ditto.
            (lua_fdiv_XF): Ditto.
            (lua_fdiv_XF_load): Ditto.
            (lua_ssediv_SF): Ditto.
            (lua_ssediv_load_SF): Ditto.
            (lua_ssediv_V4SF): Ditto.
            (lua_ssediv_load_V4SF): Ditto.
            (lua_ssediv_V8SF): Ditto.
            (lua_ssediv_load_V8SF): Ditto.
            (lua_ssediv_SD): Ditto.
            (lua_ssediv_load_SD): Ditto.
            (lua_ssediv_V2DF): Ditto.
            (lua_ssediv_load_V2DF): Ditto.
            (lua_ssediv_V4DF): Ditto.
            (lua_ssediv_load_V4DF): Ditto.


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