pan/bi: Add dual texture fusing pass

Bifrost supports a special "dual texture" instruction, sampling from two
textures at once at the same coordinate. Each subinstruction is highly
restricted (a subset of TEXS_2D); together, they are represented by TEXC
with a special dual texture operation descriptor. Add an optimization
pass to fuse these instructions.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13723>
This commit is contained in:
Alyssa Rosenzweig 2021-11-08 14:49:53 -05:00 committed by Marge Bot
parent e6c6a1afb4
commit 9146bafbb4
3 changed files with 156 additions and 0 deletions

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@ -0,0 +1,154 @@
/*
* Copyright (C) 2021 Collabora, Ltd.
*
* 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 "compiler.h"
#include "bi_builder.h"
#define XXH_INLINE_ALL
#include "xxhash.h"
/* Fuse pairs of TEXS_2D instructions into a single dual texture TEXC, if both
* sample at the same coordinate with the default LOD mode for the shader stage
* (computed LOD in fragment shaders, else zero LOD) and immediate
* texture/sampler indices 0...3.
*
* Fusing across basic block boundaries is not expected to be useful, as it
* increases register pressure and causes redundant memory traffic. As such, we
* use a local optimization pass.
*
* To pair ops efficiently, we maintain a set (backed by a hash table) using
* only the coordinate sources for hashing and equality. Hence the pass runs in
* O(n) worst case expected time for n insturctions in a block. We reject
* invalid texture instructions quickly to reduce the constant factor.
*
* Dual texture instructions have skip flags, like normal texture instructions.
* Adding a skip flag to an instruction that doesn't have it is illegal, but
* removing a skip flag from one that has it is legal. Accordingly, set the
* fused TEXC's skip to the logical AND of the unfused TEXS flags. We run the
* optimization pass to run after bi_analyze_helper_requirements.
*/
static inline bool
bi_can_fuse_dual_tex(bi_instr *I, bool fuse_zero_lod)
{
return (I->op == BI_OPCODE_TEXS_2D_F32 || I->op == BI_OPCODE_TEXS_2D_F16) &&
(I->texture_index < 4 && I->sampler_index < 4) &&
(I->lod_mode == fuse_zero_lod);
}
static enum bifrost_texture_format
bi_format_for_texs_2d(enum bi_opcode op)
{
switch (op) {
case BI_OPCODE_TEXS_2D_F32: return BIFROST_TEXTURE_FORMAT_F32;
case BI_OPCODE_TEXS_2D_F16: return BIFROST_TEXTURE_FORMAT_F16;
default: unreachable("Invalid TEXS_2D instruction");
}
}
static void
bi_fuse_dual(bi_context *ctx, bi_instr *I1, bi_instr *I2)
{
/* Construct a texture operation descriptor for the dual texture */
struct bifrost_dual_texture_operation desc = {
.mode = BIFROST_TEXTURE_OPERATION_DUAL,
.primary_texture_index = I1->texture_index,
.primary_sampler_index = I1->sampler_index,
.primary_format = bi_format_for_texs_2d(I1->op),
.primary_mask = 0xF,
.secondary_texture_index = I2->texture_index,
.secondary_sampler_index = I2->sampler_index,
.secondary_format = bi_format_for_texs_2d(I2->op),
.secondary_mask = 0xF,
};
/* LOD mode is implied in a shader stage */
assert(I1->lod_mode == I2->lod_mode);
/* Insert before the earlier instruction in case its result is consumed
* before the later instruction
*/
bi_builder b = bi_init_builder(ctx, bi_before_instr(I1));
bi_instr *I = bi_texc_to(&b,
I1->dest[0], I2->dest[0], bi_null(), /* staging */
I1->src[0], I1->src[1], /* coordinates */
bi_imm_u32(bi_dual_tex_as_u32(desc)), I1->lod_mode,
bi_count_write_registers(I1, 0),
bi_count_write_registers(I2, 0));
I->skip = I1->skip && I2->skip;
bi_remove_instruction(I1);
bi_remove_instruction(I2);
}
#define HASH(hash, data) XXH32(&(data), sizeof(data), hash)
static uint32_t
coord_hash(const void *key)
{
const bi_instr *I = key;
return XXH32(&I->src[0], sizeof(I->src[0]) + sizeof(I->src[1]), 0);
}
static bool
coord_equal(const void *key1, const void *key2)
{
const bi_instr *I = key1;
const bi_instr *J = key2;
return memcmp(&I->src[0], &J->src[0],
sizeof(I->src[0]) + sizeof(I->src[1])) == 0;
}
static void
bi_opt_fuse_dual_texture_block(bi_context *ctx, bi_block *block)
{
struct set *set = _mesa_set_create(ctx, coord_hash, coord_equal);
bool fuse_zero_lod = (ctx->stage != MESA_SHADER_FRAGMENT);
bool found = false;
bi_foreach_instr_in_block_safe(block, I) {
if (!bi_can_fuse_dual_tex(I, fuse_zero_lod)) continue;
struct set_entry *ent = _mesa_set_search_or_add(set, I, &found);
if (found) {
bi_fuse_dual(ctx, (bi_instr *) ent->key, I);
_mesa_set_remove(set, ent);
}
}
}
void
bi_opt_fuse_dual_texture(bi_context *ctx)
{
bi_foreach_block(ctx, block) {
bi_opt_fuse_dual_texture_block(ctx, block);
}
}

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@ -905,6 +905,7 @@ void bi_opt_cse(bi_context *ctx);
void bi_opt_mod_prop_forward(bi_context *ctx);
void bi_opt_mod_prop_backward(bi_context *ctx);
void bi_opt_dead_code_eliminate(bi_context *ctx);
void bi_opt_fuse_dual_texture(bi_context *ctx);
void bi_opt_dce_post_ra(bi_context *ctx);
void bi_opt_push_ubo(bi_context *ctx);
void bi_lower_swizzle(bi_context *ctx);

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@ -34,6 +34,7 @@ libpanfrost_bifrost_files = files(
'bi_opt_cse.c',
'bi_opt_push_ubo.c',
'bi_opt_mod_props.c',
'bi_opt_dual_tex.c',
'bi_pack.c',
'bi_ra.c',
'bi_schedule.c',