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/*
* 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"
/* This optimization pass, intended to run once after code emission but before
* copy propagation, analyzes direct word-aligned UBO reads and promotes a
* subset to moves from FAU. It is the sole populator of the UBO push data
* structure returned back to the command stream. */
static bool
bi_is_direct_aligned_ubo(bi_instr *ins)
{
return (bi_opcode_props[ins->op].message == BIFROST_MESSAGE_LOAD) &&
(ins->seg == BI_SEG_UBO) &&
(ins->src[0].type == BI_INDEX_CONSTANT) &&
(ins->src[1].type == BI_INDEX_CONSTANT) &&
((ins->src[0].value & 0x3) == 0);
}
/* Represents use data for a single UBO */
#define MAX_UBO_WORDS (65536 / 16)
struct bi_ubo_block {
BITSET_DECLARE(pushed, MAX_UBO_WORDS);
uint8_t range[MAX_UBO_WORDS];
};
struct bi_ubo_analysis {
/* Per block analysis */
unsigned nr_blocks;
struct bi_ubo_block *blocks;
};
static struct bi_ubo_analysis
bi_analyze_ranges(bi_context *ctx)
{
struct bi_ubo_analysis res = {
.nr_blocks = ctx->nir->info.num_ubos + 1,
};
res.blocks = calloc(res.nr_blocks, sizeof(struct bi_ubo_block));
bi_foreach_instr_global(ctx, ins) {
if (!bi_is_direct_aligned_ubo(ins)) continue;
unsigned ubo = ins->src[1].value;
unsigned word = ins->src[0].value / 4;
unsigned channels = bi_opcode_props[ins->op].sr_count;
assert(ubo < res.nr_blocks);
assert(channels > 0 && channels <= 4);
if (word < MAX_UBO_WORDS)
res.blocks[ubo].range[word] = channels;
}
return res;
}
/* Select UBO words to push. A sophisticated implementation would consider the
* number of uses and perhaps the control flow to estimate benefit. This is not
* sophisticated. Select from the last UBO first to prioritize sysvals. */
static void
bi_pick_ubo(struct panfrost_ubo_push *push, struct bi_ubo_analysis *analysis)
{
for (signed ubo = analysis->nr_blocks - 1; ubo >= 0; --ubo) {
struct bi_ubo_block *block = &analysis->blocks[ubo];
for (unsigned r = 0; r < MAX_UBO_WORDS; ++r) {
unsigned range = block->range[r];
/* Don't push something we don't access */
if (range == 0) continue;
/* Don't push more than possible */
if (push->count > PAN_MAX_PUSH - range)
return;
for (unsigned offs = 0; offs < range; ++offs) {
struct panfrost_ubo_word word = {
.ubo = ubo,
.offset = (r + offs) * 4
};
push->words[push->count++] = word;
}
/* Mark it as pushed so we can rewrite */
BITSET_SET(block->pushed, r);
}
}
}
void
bi_opt_push_ubo(bi_context *ctx)
{
if (ctx->inputs->no_ubo_to_push)
return;
/* This pass only runs once */
assert(ctx->info->push.count == 0);
struct bi_ubo_analysis analysis = bi_analyze_ranges(ctx);
bi_pick_ubo(&ctx->info->push, &analysis);
bi_foreach_instr_global_safe(ctx, ins) {
if (!bi_is_direct_aligned_ubo(ins)) continue;
unsigned ubo = ins->src[1].value;
unsigned offset = ins->src[0].value;
/* Check if we decided to push this */
assert(ubo < analysis.nr_blocks);
if (!BITSET_TEST(analysis.blocks[ubo].pushed, offset / 4)) continue;
/* Replace the UBO load with moves from FAU */
bi_builder b = bi_init_builder(ctx, bi_after_instr(ins));
unsigned channels = bi_opcode_props[ins->op].sr_count;
for (unsigned w = 0; w < channels; ++w) {
/* FAU is grouped in pairs (2 x 4-byte) */
unsigned base =
pan_lookup_pushed_ubo(&ctx->info->push, ubo,
(offset + 4 * w));
unsigned fau_idx = (base >> 1);
unsigned fau_hi = (base & 1);
bi_mov_i32_to(&b,
bi_word(ins->dest[0], w),
bi_fau(BIR_FAU_UNIFORM | fau_idx, fau_hi));
}
bi_remove_instruction(ins);
}
free(analysis.blocks);
}
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