Mesa (master): aco: improve live variable analysis
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Wed Oct 30 19:48:52 UTC 2019
Module: Mesa
Branch: master
Commit: 78bca0d0ce5aab154b95ddbaeb659035996d3f8b
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=78bca0d0ce5aab154b95ddbaeb659035996d3f8b
Author: Daniel Schürmann <daniel at schuermann.dev>
Date: Tue Oct 29 11:56:09 2019 +0100
aco: improve live variable analysis
This patch makes the live variable analysis more precise
w.r.t. killed phi operands and the block's register pressure.
Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
---
src/amd/compiler/aco_live_var_analysis.cpp | 89 +++++++++++++++++++++---------
1 file changed, 64 insertions(+), 25 deletions(-)
diff --git a/src/amd/compiler/aco_live_var_analysis.cpp b/src/amd/compiler/aco_live_var_analysis.cpp
index a4a2e5c49bb..05ddb7bc68a 100644
--- a/src/amd/compiler/aco_live_var_analysis.cpp
+++ b/src/amd/compiler/aco_live_var_analysis.cpp
@@ -71,14 +71,17 @@ void process_live_temps_per_block(Program *program, live& lives, Block* block,
new_demand.sgpr -= phi_sgpr_ops[block->index];
/* traverse the instructions backwards */
- for (int idx = block->instructions.size() -1; idx >= 0; idx--)
- {
+ int idx;
+ for (idx = block->instructions.size() -1; idx >= 0; idx--) {
+ Instruction *insn = block->instructions[idx].get();
+ if (is_phi(insn))
+ break;
+
/* substract the 2 sgprs from exec */
if (exec_live)
assert(new_demand.sgpr >= 2);
register_demand[idx] = RegisterDemand(new_demand.vgpr, new_demand.sgpr - (exec_live ? 2 : 0));
- Instruction *insn = block->instructions[idx].get();
/* KILL */
for (Definition& definition : insn->definitions) {
if (!definition.isTemp()) {
@@ -105,28 +108,7 @@ void process_live_temps_per_block(Program *program, live& lives, Block* block,
}
/* GEN */
- if (insn->opcode == aco_opcode::p_phi ||
- insn->opcode == aco_opcode::p_linear_phi) {
- /* directly insert into the predecessors live-out set */
- std::vector<unsigned>& preds = insn->opcode == aco_opcode::p_phi
- ? block->logical_preds
- : block->linear_preds;
- for (unsigned i = 0; i < preds.size(); ++i)
- {
- Operand &operand = insn->operands[i];
- if (!operand.isTemp()) {
- continue;
- }
- /* check if we changed an already processed block */
- const bool inserted = live_temps[preds[i]].insert(operand.getTemp()).second;
- if (inserted) {
- operand.setFirstKill(true);
- worklist.insert(preds[i]);
- if (insn->opcode == aco_opcode::p_phi && operand.getTemp().type() == RegType::sgpr)
- phi_sgpr_ops[preds[i]] += operand.size();
- }
- }
- } else if (insn->opcode == aco_opcode::p_logical_end) {
+ if (insn->opcode == aco_opcode::p_logical_end) {
new_demand.sgpr += phi_sgpr_ops[block->index];
} else {
for (unsigned i = 0; i < insn->operands.size(); ++i)
@@ -160,6 +142,37 @@ void process_live_temps_per_block(Program *program, live& lives, Block* block,
block->register_demand.update(register_demand[idx]);
}
+ /* update block's register demand for a last time */
+ if (exec_live)
+ assert(new_demand.sgpr >= 2);
+ new_demand.sgpr -= exec_live ? 2 : 0;
+ block->register_demand.update(new_demand);
+
+ /* handle phi definitions */
+ int phi_idx = idx;
+ while (phi_idx >= 0) {
+ register_demand[phi_idx] = new_demand;
+ Instruction *insn = block->instructions[phi_idx].get();
+
+ assert(is_phi(insn));
+ assert(insn->definitions.size() == 1 && insn->definitions[0].isTemp());
+ Definition& definition = insn->definitions[0];
+ const Temp temp = definition.getTemp();
+ size_t n = 0;
+
+ if (temp.is_linear())
+ n = live_sgprs.erase(temp);
+ else
+ n = live_vgprs.erase(temp);
+
+ if (n)
+ definition.setKill(false);
+ else
+ definition.setKill(true);
+
+ phi_idx--;
+ }
+
/* now, we have the live-in sets and need to merge them into the live-out sets */
for (unsigned pred_idx : block->logical_preds) {
for (Temp vgpr : live_vgprs) {
@@ -177,6 +190,32 @@ void process_live_temps_per_block(Program *program, live& lives, Block* block,
}
}
+ /* handle phi operands */
+ phi_idx = idx;
+ while (phi_idx >= 0) {
+ Instruction *insn = block->instructions[phi_idx].get();
+ assert(is_phi(insn));
+ /* directly insert into the predecessors live-out set */
+ std::vector<unsigned>& preds = insn->opcode == aco_opcode::p_phi
+ ? block->logical_preds
+ : block->linear_preds;
+ for (unsigned i = 0; i < preds.size(); ++i) {
+ Operand &operand = insn->operands[i];
+ if (!operand.isTemp()) {
+ continue;
+ }
+ /* check if we changed an already processed block */
+ const bool inserted = live_temps[preds[i]].insert(operand.getTemp()).second;
+ if (inserted) {
+ operand.setKill(true);
+ worklist.insert(preds[i]);
+ if (insn->opcode == aco_opcode::p_phi && operand.getTemp().type() == RegType::sgpr)
+ phi_sgpr_ops[preds[i]] += operand.size();
+ }
+ }
+ phi_idx--;
+ }
+
if (!(block->index != 0 || (live_vgprs.empty() && live_sgprs.empty()))) {
aco_print_program(program, stderr);
fprintf(stderr, "These temporaries are never defined or are defined after use:\n");
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