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dead_code_elimination_pass: Remove unreachable Phi arguments

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This commit is contained in:
ameerj 2022-03-22 18:34:31 -04:00
parent f10d40a0a2
commit 67159e3be7
3 changed files with 36 additions and 0 deletions
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27
src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp
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@ -2,6 +2,10 @@
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <algorithm>
#include <boost/container/small_vector.hpp>
#include "shader_recompiler/frontend/ir/basic_block.h"
#include "shader_recompiler/frontend/ir/value.h"
#include "shader_recompiler/ir_opt/passes.h"
@ -25,7 +29,26 @@ void DeadInstElimination(IR::Block* const block) {
}
}
void DeletedPhiArgElimination(IR::Program& program, std::span<const IR::Block*> dead_blocks) {
for (IR::Block* const block : program.blocks) {
for (IR::Inst& phi : *block) {
if (!IR::IsPhi(phi)) {
continue;
}
for (size_t i = 0; i < phi.NumArgs(); ++i) {
if (std::ranges::find(dead_blocks, phi.PhiBlock(i)) == dead_blocks.end()) {
continue;
}
// Phi operand at this index is an unreachable block
phi.ErasePhiOperand(i);
--i;
}
}
}
}
void DeadBranchElimination(IR::Program& program) {
boost::container::small_vector<const IR::Block*, 3> dead_blocks;
const auto begin_it{program.syntax_list.begin()};
for (auto node_it = begin_it; node_it != program.syntax_list.end(); ++node_it) {
if (node_it->type != IR::AbstractSyntaxNode::Type::If) {
@ -55,6 +78,7 @@ void DeadBranchElimination(IR::Program& program) {
case IR::AbstractSyntaxNode::Type::Block: {
IR::Block* const block{node_it->data.block};
DeadInstElimination<false>(block);
dead_blocks.push_back(block);
break;
}
default:
@ -66,6 +90,9 @@ void DeadBranchElimination(IR::Program& program) {
// Account for loop increment
--node_it;
}
if (!dead_blocks.empty()) {
DeletedPhiArgElimination(program, std::span(dead_blocks.data(), dead_blocks.size()));
}
}
} // namespace