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intel/nir: Vectorize all IO

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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: 4434591bf5 "intel/nir: Call nir_lower_io_to_scalar_early"
Fixes: 8d8222461f "intel/nir: Enable nir_opt_find_array_copies"
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
This commit is contained in:
Jason Ekstrand 2019-03-07 15:01:37 -06:00 • committed by Jason Ekstrand
parent 5ef2b8f1f2
commit 6d5d89d25a
1 changed files with 17 additions and 0 deletions
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17
src/intel/compiler/brw_nir.c
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@ -788,6 +788,23 @@ brw_nir_link_shaders(const struct brw_compiler *compiler,
*producer = brw_nir_optimize(*producer, compiler, p_is_scalar, false);
*consumer = brw_nir_optimize(*consumer, compiler, c_is_scalar, false);
}
NIR_PASS_V(*producer, nir_lower_io_to_vector, nir_var_shader_out);
NIR_PASS_V(*consumer, nir_lower_io_to_vector, nir_var_shader_in);
if ((*producer)->info.stage != MESA_SHADER_TESS_CTRL) {
/* Calling lower_io_to_vector creates output variable writes with
* write-masks. On non-TCS outputs, the back-end can't handle it and we
* need to call nir_lower_io_to_temporaries to get rid of them. This,
* in turn, creates temporary variables and extra copy_deref intrinsics
* that we need to clean up.
*/
NIR_PASS_V(*producer, nir_lower_io_to_temporaries,
nir_shader_get_entrypoint(*producer), true, false);
NIR_PASS_V(*producer, nir_lower_global_vars_to_local);
NIR_PASS_V(*producer, nir_split_var_copies);
NIR_PASS_V(*producer, nir_lower_var_copies);
}
}
/* Prepare the given shader for codegen