[Bug 107510] [GEN8+] up to 10% perf drop on several 3D benchmarks

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107510

Jason Ekstrand <jason at jlekstrand.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|REOPENED                    |RESOLVED

--- Comment #24 from Jason Ekstrand <jason at jlekstrand.net> ---
This is fixed by the following commit now in master:

commit 6d5d89d25a0a4299dbfcbfeca71b6c7e65ef3d45 (HEAD -> master, origin/master,
origin/HEAD)
Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date:   Thu Mar 7 15:01:37 2019 -0600

    intel/nir: Vectorize all IO

    The IO scalarization pass that we run to help with linking end up
    turning some shader I/O such as that for tessellation and geometry
    shaders into many scalar URB operations rather than one vector one.  To
    alleviate this, we now vectorize the I/O once again.  This fixes a 10%
    performance regression in the GfxBench tessellation test that was caused
    by scalarizing.

    Shader-db results on Kaby Lake:

        total instructions in shared programs: 15224023 -> 15220871 (-0.02%)
        instructions in affected programs: 342009 -> 338857 (-0.92%)
        helped: 1236
        HURT: 443

        total spills in shared programs: 23471 -> 23465 (-0.03%)
        spills in affected programs: 6 -> 0
        helped: 1
        HURT: 0

        total fills in shared programs: 31770 -> 31766 (-0.01%)
        fills in affected programs: 4 -> 0
        helped: 1
        HURT: 0

    Cycles was just a lot of churn do to moves being different places.  Most
    of the pure churn in instructions was +/- one or two instructions in
    fragment shaders.

    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107510
    Fixes: 4434591bf56a "intel/nir: Call nir_lower_io_to_scalar_early"
    Fixes: 8d8222461f9d "intel/nir: Enable nir_opt_find_array_copies"
    Reviewed-by: Connor Abbott <cwabbott0 at gmail.com>

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