Mesa (staging/21.0): aco: remove divergent branches which only jump over very few instructions
GitLab Mirror
gitlab-mirror at kemper.freedesktop.org
Wed Jan 13 19:31:07 UTC 2021
Module: Mesa
Branch: staging/21.0
Commit: 3aaf5188fe0741776bb8218aee9c7507518cb0b8
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=3aaf5188fe0741776bb8218aee9c7507518cb0b8
Author: Daniel Schürmann <daniel at schuermann.dev>
Date: Thu Nov 26 17:36:47 2020 +0100
aco: remove divergent branches which only jump over very few instructions
Totals from 18436 (13.23% of 139391) affected shaders (NAVI10):
CodeSize: 138428504 -> 138172588 (-0.18%)
Instrs: 26605127 -> 26541176 (-0.24%)
Cycles: 1624994088 -> 1622461620 (-0.16%)
VMEM: 3689892 -> 3689102 (-0.02%)
SMEM: 1131767 -> 1131761 (-0.00%)
Branches: 851796 -> 787852 (-7.51%)
Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7814>
(cherry picked from commit 288032a87316f8542d1d5de8b8e1d3a20359ceab)
---
.pick_status.json | 2 +-
src/amd/compiler/aco_lower_to_hw_instr.cpp | 56 +++++++++++++++++++++++-------
2 files changed, 44 insertions(+), 14 deletions(-)
diff --git a/.pick_status.json b/.pick_status.json
index ee6bc6c3f46..eae4a01e3e8 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -274,7 +274,7 @@
"description": "aco: remove divergent branches which only jump over very few instructions",
"nominated": false,
"nomination_type": null,
- "resolution": 4,
+ "resolution": 1,
"master_sha": null,
"because_sha": null
},
diff --git a/src/amd/compiler/aco_lower_to_hw_instr.cpp b/src/amd/compiler/aco_lower_to_hw_instr.cpp
index a5b939e905b..a4e2d5b6404 100644
--- a/src/amd/compiler/aco_lower_to_hw_instr.cpp
+++ b/src/amd/compiler/aco_lower_to_hw_instr.cpp
@@ -1792,7 +1792,7 @@ void lower_to_hw_instr(Program* program)
{
Block *discard_block = NULL;
- for (size_t block_idx = 0; block_idx < program->blocks.size(); block_idx++)
+ for (int block_idx = program->blocks.size() - 1; block_idx >= 0; block_idx--)
{
Block *block = &program->blocks[block_idx];
lower_context ctx;
@@ -1980,40 +1980,70 @@ void lower_to_hw_instr(Program* program)
}
} else if (instr->format == Format::PSEUDO_BRANCH) {
Pseudo_branch_instruction* branch = static_cast<Pseudo_branch_instruction*>(instr.get());
+ uint32_t target = branch->target[0];
+
/* check if all blocks from current to target are empty */
- bool can_remove = block->index < branch->target[0];
+ /* In case there are <= 4 SALU or <= 2 VALU instructions, remove the branch */
+ bool can_remove = block->index < target;
+ unsigned num_scalar = 0;
+ unsigned num_vector = 0;
for (unsigned i = block->index + 1; can_remove && i < branch->target[0]; i++) {
- if (program->blocks[i].instructions.size())
+ /* uniform branches must not be ignored if they
+ * are about to jump over actual instructions */
+ if (!program->blocks[i].instructions.empty() &&
+ (branch->opcode != aco_opcode::p_cbranch_z ||
+ branch->operands[0].physReg() != exec)) {
can_remove = false;
+ break;
+ }
+
+ for (aco_ptr<Instruction>& inst : program->blocks[i].instructions) {
+ if (inst->format == Format::SOPP) {
+ can_remove = false;
+ } else if (inst->isSALU()) {
+ num_scalar++;
+ } else if (inst->isVALU()) {
+ num_vector++;
+ } else {
+ can_remove = false;
+ }
+
+ if (num_scalar + num_vector * 2 > 4)
+ can_remove = false;
+
+ if (!can_remove)
+ break;
+ }
}
+
if (can_remove)
continue;
switch (instr->opcode) {
case aco_opcode::p_branch:
- assert(block->linear_succs[0] == branch->target[0]);
- bld.sopp(aco_opcode::s_branch, branch->definitions[0], branch->target[0]);
+ assert(block->linear_succs[0] == target);
+ bld.sopp(aco_opcode::s_branch, branch->definitions[0], target);
break;
case aco_opcode::p_cbranch_nz:
- assert(block->linear_succs[1] == branch->target[0]);
+ assert(block->linear_succs[1] == target);
if (branch->operands[0].physReg() == exec)
- bld.sopp(aco_opcode::s_cbranch_execnz, branch->definitions[0], branch->target[0]);
+ bld.sopp(aco_opcode::s_cbranch_execnz, branch->definitions[0], target);
else if (branch->operands[0].physReg() == vcc)
- bld.sopp(aco_opcode::s_cbranch_vccnz, branch->definitions[0], branch->target[0]);
+ bld.sopp(aco_opcode::s_cbranch_vccnz, branch->definitions[0], target);
else {
assert(branch->operands[0].physReg() == scc);
- bld.sopp(aco_opcode::s_cbranch_scc1, branch->definitions[0], branch->target[0]);
+ bld.sopp(aco_opcode::s_cbranch_scc1, branch->definitions[0], target);
}
break;
case aco_opcode::p_cbranch_z:
- assert(block->linear_succs[1] == branch->target[0]);
+ assert(block->linear_succs[1] == target);
if (branch->operands[0].physReg() == exec)
- bld.sopp(aco_opcode::s_cbranch_execz, branch->definitions[0], branch->target[0]);
+ bld.sopp(aco_opcode::s_cbranch_execz, branch->definitions[0], target);
else if (branch->operands[0].physReg() == vcc)
- bld.sopp(aco_opcode::s_cbranch_vccz, branch->definitions[0], branch->target[0]);
+ bld.sopp(aco_opcode::s_cbranch_vccz, branch->definitions[0], target);
else {
assert(branch->operands[0].physReg() == scc);
- bld.sopp(aco_opcode::s_cbranch_scc0, branch->definitions[0], branch->target[0]);
+ bld.sopp(aco_opcode::s_cbranch_scc0, branch->definitions[0], target);
}
break;
default:
More information about the mesa-commit
mailing list