Mesa (master): aco: value number instructions using the execution mask
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Thu Nov 14 17:12:07 UTC 2019
Module: Mesa
Branch: master
Commit: 9d3e0705240333d07c028cf0e682d1e393e63020
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=9d3e0705240333d07c028cf0e682d1e393e63020
Author: Daniel Schürmann <daniel at schuermann.dev>
Date: Mon Nov 11 11:41:31 2019 +0100
aco: value number instructions using the execution mask
This patch tries to give instructions with the same execution
mask also the same pass_flags and enables VN for SALU instructions
using exec as Operand.
This patch also adds back VN for VOPC instructions and removes VN for phis.
v2 (by Timur Kristóf):
- Fix some regressions.
v3 (by Daniel Schürmann):
- Fix additional issues
Reviewed-By: Timur Kristóf <timur.kristof at gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
---
src/amd/compiler/aco_opt_value_numbering.cpp | 79 ++++++++++++++++++----------
1 file changed, 51 insertions(+), 28 deletions(-)
diff --git a/src/amd/compiler/aco_opt_value_numbering.cpp b/src/amd/compiler/aco_opt_value_numbering.cpp
index fe094ebb219..803249637d5 100644
--- a/src/amd/compiler/aco_opt_value_numbering.cpp
+++ b/src/amd/compiler/aco_opt_value_numbering.cpp
@@ -81,17 +81,6 @@ struct InstrPred {
return false;
if (a->operands.size() != b->operands.size() || a->definitions.size() != b->definitions.size())
return false; /* possible with pseudo-instructions */
- /* We can't value number v_readlane_b32 across control flow or discards
- * because of the possibility of live-range splits.
- * We can't value number permutes for the same reason as
- * v_readlane_b32 and because discards affect the result */
- if (a->opcode == aco_opcode::v_readfirstlane_b32 || a->opcode == aco_opcode::v_readlane_b32 ||
- a->opcode == aco_opcode::ds_bpermute_b32 || a->opcode == aco_opcode::ds_permute_b32 ||
- a->opcode == aco_opcode::ds_swizzle_b32 || a->format == Format::PSEUDO_REDUCTION ||
- a->opcode == aco_opcode::p_phi || a->opcode == aco_opcode::p_linear_phi) {
- if (a->pass_flags != b->pass_flags)
- return false;
- }
for (unsigned i = 0; i < a->operands.size(); i++) {
if (a->operands[i].isConstant()) {
if (!b->operands[i].isConstant())
@@ -108,11 +97,11 @@ struct InstrPred {
else if (a->operands[i].isUndefined() ^ b->operands[i].isUndefined())
return false;
if (a->operands[i].isFixed()) {
- if (a->operands[i].physReg() == exec)
- return false;
if (!b->operands[i].isFixed())
return false;
- if (!(a->operands[i].physReg() == b->operands[i].physReg()))
+ if (a->operands[i].physReg() != b->operands[i].physReg())
+ return false;
+ if (a->operands[i].physReg() == exec && a->pass_flags != b->pass_flags)
return false;
}
}
@@ -126,10 +115,19 @@ struct InstrPred {
if (a->definitions[i].isFixed()) {
if (!b->definitions[i].isFixed())
return false;
- if (!(a->definitions[i].physReg() == b->definitions[i].physReg()))
+ if (a->definitions[i].physReg() != b->definitions[i].physReg())
+ return false;
+ if (a->definitions[i].physReg() == exec)
return false;
}
}
+
+ if (a->opcode == aco_opcode::v_readfirstlane_b32)
+ return a->pass_flags == b->pass_flags;
+
+ /* The results of VOPC depend on the exec mask if used for subgroup operations. */
+ if ((uint32_t) a->format & (uint32_t) Format::VOPC && a->pass_flags != b->pass_flags)
+ return false;
if (a->format == Format::PSEUDO_BRANCH)
return false;
if (a->isVOP3()) {
@@ -157,11 +155,6 @@ struct InstrPred {
aDPP->neg[1] == bDPP->neg[1];
}
switch (a->format) {
- case Format::VOPC: {
- /* Since the results depend on the exec mask, these shouldn't
- * be value numbered (this is especially useful for subgroupBallot()). */
- return false;
- }
case Format::SOPK: {
SOPK_instruction* aK = static_cast<SOPK_instruction*>(a);
SOPK_instruction* bK = static_cast<SOPK_instruction*>(b);
@@ -185,7 +178,9 @@ struct InstrPred {
case Format::PSEUDO_REDUCTION: {
Pseudo_reduction_instruction *aR = static_cast<Pseudo_reduction_instruction*>(a);
Pseudo_reduction_instruction *bR = static_cast<Pseudo_reduction_instruction*>(b);
- return aR->reduce_op == bR->reduce_op && aR->cluster_size == bR->cluster_size;
+ return aR->pass_flags == bR->pass_flags &&
+ aR->reduce_op == bR->reduce_op &&
+ aR->cluster_size == bR->cluster_size;
}
case Format::MTBUF: {
/* this is fine since they are only used for vertex input fetches */
@@ -210,14 +205,16 @@ struct InstrPred {
case Format::SCRATCH:
return false;
case Format::DS: {
- /* we already handle potential issue with permute/swizzle above */
- DS_instruction* aD = static_cast<DS_instruction *>(a);
- DS_instruction* bD = static_cast<DS_instruction *>(b);
if (a->opcode != aco_opcode::ds_bpermute_b32 &&
a->opcode != aco_opcode::ds_permute_b32 &&
a->opcode != aco_opcode::ds_swizzle_b32)
return false;
- return aD->gds == bD->gds && aD->offset0 == bD->offset0 && aD->offset1 == bD->offset1;
+ DS_instruction* aD = static_cast<DS_instruction *>(a);
+ DS_instruction* bD = static_cast<DS_instruction *>(b);
+ return aD->pass_flags == bD->pass_flags &&
+ aD->gds == bD->gds &&
+ aD->offset0 == bD->offset0 &&
+ aD->offset1 == bD->offset1;
}
case Format::MIMG: {
MIMG_instruction* aM = static_cast<MIMG_instruction*>(a);
@@ -248,7 +245,13 @@ struct vn_ctx {
Program* program;
expr_set expr_values;
std::map<uint32_t, Temp> renames;
- uint32_t exec_id = 0;
+
+ /* The exec id should be the same on the same level of control flow depth.
+ * Together with the check for dominator relations, it is safe to assume
+ * that the same exec_id also means the same execution mask.
+ * Discards increment the exec_id, so that it won't return to the previous value.
+ */
+ uint32_t exec_id = 1;
vn_ctx(Program* program) : program(program) {}
};
@@ -276,7 +279,7 @@ void process_block(vn_ctx& ctx, Block& block)
op.setTemp(it->second);
}
- if (instr->definitions.empty()) {
+ if (instr->definitions.empty() || instr->opcode == aco_opcode::p_phi || instr->opcode == aco_opcode::p_linear_phi) {
new_instructions.emplace_back(std::move(instr));
continue;
}
@@ -339,14 +342,34 @@ void rename_phi_operands(Block& block, std::map<uint32_t, Temp>& renames)
void value_numbering(Program* program)
{
vn_ctx ctx(program);
+ std::vector<unsigned> loop_headers;
for (Block& block : program->blocks) {
+ assert(ctx.exec_id > 0);
+ /* decrement exec_id when leaving nested control flow */
+ if (block.kind & block_kind_loop_header)
+ loop_headers.push_back(block.index);
+ if (block.kind & block_kind_merge) {
+ ctx.exec_id--;
+ } else if (block.kind & block_kind_loop_exit) {
+ ctx.exec_id -= program->blocks[loop_headers.back()].logical_preds.size();
+ ctx.exec_id -= block.logical_preds.size();
+ loop_headers.pop_back();
+ }
+
if (block.logical_idom != -1)
process_block(ctx, block);
else
rename_phi_operands(block, ctx.renames);
- ctx.exec_id++;
+ /* increment exec_id when entering nested control flow */
+ if (block.kind & block_kind_branch ||
+ block.kind & block_kind_loop_preheader ||
+ block.kind & block_kind_break ||
+ block.kind & block_kind_continue)
+ ctx.exec_id++;
+ else if (block.kind & block_kind_continue_or_break)
+ ctx.exec_id += 2;
}
/* rename loop header phi operands */
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