mesa/src/amd/compiler/aco_dead_code_analysis.cpp
Rhys Perry 156fd58cda aco: reserve 2 sgprs for each branch
We'll need two sgprs for the possibility of a long jump.

fossil-db (Navi):
Totals from 10197 (7.50% of 135946) affected shaders:
SGPRs: 946268 -> 946468 (+0.02%)
VGPRs: 705884 -> 707956 (+0.29%); split: -0.00%, +0.30%
SpillSGPRs: 31485 -> 36212 (+15.01%); split: -0.04%, +15.05%
CodeSize: 88296484 -> 88384604 (+0.10%); split: -0.01%, +0.11%
MaxWaves: 81379 -> 81171 (-0.26%)
Instrs: 17219111 -> 17231682 (+0.07%); split: -0.03%, +0.10%
Cycles: 1594875900 -> 1596450136 (+0.10%); split: -0.05%, +0.15%
VMEM: 1687263 -> 1689080 (+0.11%); split: +0.14%, -0.03%
SMEM: 657726 -> 660262 (+0.39%); split: +0.61%, -0.22%
VClause: 294806 -> 294638 (-0.06%); split: -0.08%, +0.02%
SClause: 556702 -> 556210 (-0.09%); split: -0.12%, +0.03%
Copies: 1466323 -> 1469349 (+0.21%); split: -0.57%, +0.78%
Branches: 619793 -> 618556 (-0.20%); split: -0.28%, +0.08%
PreSGPRs: 806364 -> 811477 (+0.63%); split: -0.14%, +0.77%
PreVGPRs: 655845 -> 657174 (+0.20%)

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Cc: 20.2 <mesa-stable>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6212>
2020-08-26 13:26:58 +00:00

108 lines
3.4 KiB
C++

/*
* Copyright © 2019 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 "aco_ir.h"
#include <algorithm>
/*
* Implements an analysis pass to determine the number of uses
* for each SSA-definition.
*/
namespace aco {
namespace {
struct dce_ctx {
int current_block;
std::vector<uint16_t> uses;
std::vector<std::vector<bool>> live;
dce_ctx(Program* program) : current_block(program->blocks.size() - 1), uses(program->peekAllocationId())
{
live.reserve(program->blocks.size());
for (Block& block : program->blocks)
live.emplace_back(block.instructions.size());
}
};
void process_block(dce_ctx& ctx, Block& block)
{
std::vector<bool>& live = ctx.live[block.index];
assert(live.size() == block.instructions.size());
bool process_predecessors = false;
for (int idx = block.instructions.size() - 1; idx >= 0; idx--) {
if (live[idx])
continue;
aco_ptr<Instruction>& instr = block.instructions[idx];
if (!is_dead(ctx.uses, instr.get())) {
for (const Operand& op : instr->operands) {
if (op.isTemp()) {
if (ctx.uses[op.tempId()] == 0)
process_predecessors = true;
ctx.uses[op.tempId()]++;
}
}
live[idx] = true;
}
}
if (process_predecessors) {
for (unsigned pred_idx : block.linear_preds)
ctx.current_block = std::max(ctx.current_block, (int) pred_idx);
}
}
} /* end namespace */
bool is_dead(const std::vector<uint16_t>& uses, Instruction *instr)
{
if (instr->definitions.empty() || instr->format == Format::PSEUDO_BRANCH)
return false;
if (std::any_of(instr->definitions.begin(), instr->definitions.end(),
[&uses] (const Definition& def) { return uses[def.tempId()];}))
return false;
return !(get_sync_info(instr).semantics & (semantic_volatile | semantic_acqrel));
}
std::vector<uint16_t> dead_code_analysis(Program *program) {
dce_ctx ctx(program);
while (ctx.current_block >= 0) {
unsigned next_block = ctx.current_block--;
process_block(ctx, program->blocks[next_block]);
}
/* add one use to exec to prevent startpgm from being removed */
aco_ptr<Instruction>& startpgm = program->blocks[0].instructions[0];
assert(startpgm->opcode == aco_opcode::p_startpgm);
ctx.uses[startpgm->definitions.back().tempId()]++;
return ctx.uses;
}
}