[Mesa-dev] [PATCH 1/2] nir: add nir_opt_move_load_ubo() optimization pass
Timothy Arceri
tarceri at itsqueeze.com
Fri Mar 16 00:38:40 UTC 2018
On 09/03/18 01:50, Samuel Pitoiset wrote:
> This pass moves load UBO operations just before their first use,
> loosely based on nir_opt_move_comparisons.
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
> src/compiler/Makefile.sources | 1 +
> src/compiler/nir/meson.build | 1 +
> src/compiler/nir/nir.h | 2 +
> src/compiler/nir/nir_opt_move_load_ubo.c | 116 +++++++++++++++++++++++++++++++
> 4 files changed, 120 insertions(+)
> create mode 100644 src/compiler/nir/nir_opt_move_load_ubo.c
>
> diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
> index 37340ba809..55143dbc66 100644
> --- a/src/compiler/Makefile.sources
> +++ b/src/compiler/Makefile.sources
> @@ -266,6 +266,7 @@ NIR_FILES = \
> nir/nir_opt_intrinsics.c \
> nir/nir_opt_loop_unroll.c \
> nir/nir_opt_move_comparisons.c \
> + nir/nir_opt_move_load_ubo.c \
> nir/nir_opt_peephole_select.c \
> nir/nir_opt_remove_phis.c \
> nir/nir_opt_shrink_load.c \
> diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build
> index a70c236b95..289bb9ea78 100644
> --- a/src/compiler/nir/meson.build
> +++ b/src/compiler/nir/meson.build
> @@ -160,6 +160,7 @@ files_libnir = files(
> 'nir_opt_intrinsics.c',
> 'nir_opt_loop_unroll.c',
> 'nir_opt_move_comparisons.c',
> + 'nir_opt_move_load_ubo.c',
> 'nir_opt_peephole_select.c',
> 'nir_opt_remove_phis.c',
> 'nir_opt_shrink_load.c',
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index 5b28c727c8..4224da5f82 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -2786,6 +2786,8 @@ bool nir_opt_loop_unroll(nir_shader *shader, nir_variable_mode indirect_mask);
>
> bool nir_opt_move_comparisons(nir_shader *shader);
>
> +bool nir_opt_move_load_ubo(nir_shader *shader);
> +
> bool nir_opt_peephole_select(nir_shader *shader, unsigned limit);
>
> bool nir_opt_remove_phis(nir_shader *shader);
> diff --git a/src/compiler/nir/nir_opt_move_load_ubo.c b/src/compiler/nir/nir_opt_move_load_ubo.c
> new file mode 100644
> index 0000000000..642651152b
> --- /dev/null
> +++ b/src/compiler/nir/nir_opt_move_load_ubo.c
> @@ -0,0 +1,116 @@
> +/*
> + * Copyright © 2016 Intel Corporation
> + * Copyright © 2018 Valve Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include "nir.h"
> +
> +/**
> + * \file nir_opt_move_load_ubo.c
> + *
> + * This pass moves load UBO operations just before their first use.
> + */
> +static bool
> +move_load_ubo_source(nir_src *src, nir_block *block, nir_instr *before)
> +{
> + if (!src->is_ssa)
> + return false;
> +
> + nir_instr *src_instr = src->ssa->parent_instr;
> +
> + if (src_instr->block == block &&
> + src_instr->type == nir_instr_type_intrinsic &&
> + nir_instr_as_intrinsic(src_instr)->intrinsic == nir_intrinsic_load_ubo) {
> +
> + exec_node_remove(&src_instr->node);
> +
> + if (before)
> + exec_node_insert_node_before(&before->node, &src_instr->node);
> + else
> + exec_list_push_tail(&block->instr_list, &src_instr->node);
I'm not sure this is completely safe. It assumes we will never see a
case were the load_ubo src is used inside both branches of an if:
vec1 32 ssa_6 = load_const (0x00000010 /* 0.000000 */)
vec1 32 ssa_7 = intrinsic load_ubo (ssa_0, ssa_0) () ()
vec1 32 ssa_8 = ieq ssa_7, ssa_0
/* succs: block_1 block_2 */
if ssa_8 {
block block_1:
/* preds: block_0 */
vec1 32 ssa_11 = imov ssa_7.x
vec1 32 ssa_12 = fadd ssa_1.y, ssa_10.y
vec1 32 ssa_13 = imov ssa_7.z
vec1 32 ssa_14 = imov ssa_7.w
/* succs: block_3 */
} else {
block block_2:
/* preds: block_0 */
vec1 32 ssa_17 = fadd ssa_2.z, ssa_16.z
vec1 32 ssa_18 = ieq ssa_7, ssa_3
vec1 32 ssa_19 = load_const (0x40000000 /* 2.000000 */)
vec1 32 ssa_20 = fadd ssa_19, ssa_16.z
vec1 32 ssa_21 = imov ssa_7.x
vec1 32 ssa_22 = imov ssa_7.y
vec1 32 ssa_23 = bcsel ssa_18, ssa_20, ssa_17
vec1 32 ssa_24 = imov ssa_7.w
vec1 32 ssa_25 = iadd ssa_5, ssa_4
vec1 32 ssa_26 = bcsel ssa_18, ssa_25, ssa_7
/* succs: block_3 */
}
block block_3:
I tried (and failed) to make a piglit test to trip this up but the GLSL
IR ops kept moving the load inside each of the if branches. I'm not so
sure that will always be the case.
> +
> + return true;
> + }
> + return false;
> +}
> +
> +static bool
> +move_load_ubo_source_cb(nir_src *src, void *data)
> +{
> + bool *progress = data;
> +
> + nir_instr *instr = src->parent_instr;
> + if (move_load_ubo_source(src, instr->block, instr))
> + *progress = true;
> +
> + return true; /* nir_foreach_src should keep going */
> +}
> +
> +static bool
> +move_load_ubo(nir_block *block)
> +{
> + bool progress = false;
> +
> + nir_if *iff = nir_block_get_following_if(block);
> + if (iff) {
> + progress |= move_load_ubo_source(&iff->condition, block, NULL);
> + }
> +
> + nir_foreach_instr_reverse(instr, block) {
> +
> + if (instr->type == nir_instr_type_phi) {
> + /* We're going backwards so everything else is a phi too */
> + } else if (instr->type == nir_instr_type_alu) {
> + nir_alu_instr *alu = nir_instr_as_alu(instr);
> +
> + for (int i = nir_op_infos[alu->op].num_inputs - 1; i >= 0; i--) {
> + progress |= move_load_ubo_source(&alu->src[i].src, block, instr);
> + }
> + } else {
> + nir_foreach_src(instr, move_load_ubo_source_cb, &progress);
> + }
> + }
> +
> + return false;
> +}
> +
> +bool
> +nir_opt_move_load_ubo(nir_shader *shader)
> +{
> + bool progress = false;
> +
> + nir_foreach_function(func, shader) {
> + if (!func->impl)
> + continue;
> +
> + nir_foreach_block(block, func->impl) {
> + if (move_load_ubo(block)) {
> + nir_metadata_preserve(func->impl, nir_metadata_block_index |
> + nir_metadata_dominance |
> + nir_metadata_live_ssa_defs);
> + progress = true;
> + }
> + }
> + }
> +
> + return progress;
> +}
>
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