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-rw-r--r--src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp98
1 files changed, 9 insertions, 89 deletions
diff --git a/src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp b/src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp
index 9a7d47344..1bd8afd6f 100644
--- a/src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp
+++ b/src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp
@@ -1,104 +1,24 @@
// SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
-#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"
namespace Shader::Optimization {
-namespace {
-template <bool TEST_USES>
-void DeadInstElimination(IR::Block* const block) {
+
+void DeadCodeEliminationPass(IR::Program& program) {
// We iterate over the instructions in reverse order.
// This is because removing an instruction reduces the number of uses for earlier instructions.
- auto it{block->end()};
- while (it != block->begin()) {
- --it;
- if constexpr (TEST_USES) {
- if (it->HasUses() || it->MayHaveSideEffects()) {
- continue;
- }
- }
- it->Invalidate();
- it = block->Instructions().erase(it);
- }
-}
-
-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) {
- continue;
- }
- IR::Inst* const cond_ref{node_it->data.if_node.cond.Inst()};
- const IR::U1 cond{cond_ref->Arg(0)};
- if (!cond.IsImmediate()) {
- continue;
- }
- if (cond.U1()) {
- continue;
- }
- // False immediate condition. Remove condition ref, erase the entire branch.
- cond_ref->Invalidate();
- // Account for nested if-statements within the if(false) branch
- u32 nested_ifs{1u};
- while (node_it->type != IR::AbstractSyntaxNode::Type::EndIf || nested_ifs > 0) {
- node_it = program.syntax_list.erase(node_it);
- switch (node_it->type) {
- case IR::AbstractSyntaxNode::Type::If:
- ++nested_ifs;
- break;
- case IR::AbstractSyntaxNode::Type::EndIf:
- --nested_ifs;
- break;
- case IR::AbstractSyntaxNode::Type::Block: {
- IR::Block* const block{node_it->data.block};
- DeadInstElimination<false>(block);
- dead_blocks.push_back(block);
- break;
- }
- default:
- break;
+ for (IR::Block* const block : program.post_order_blocks) {
+ auto it{block->end()};
+ while (it != block->begin()) {
+ --it;
+ if (!it->HasUses() && !it->MayHaveSideEffects()) {
+ it->Invalidate();
+ it = block->Instructions().erase(it);
}
}
- // Erase EndIf node of the if(false) branch
- node_it = program.syntax_list.erase(node_it);
- // Account for loop increment
- --node_it;
- }
- if (!dead_blocks.empty()) {
- DeletedPhiArgElimination(program, std::span(dead_blocks.data(), dead_blocks.size()));
- }
-}
-} // namespace
-
-void DeadCodeEliminationPass(IR::Program& program) {
- DeadBranchElimination(program);
- for (IR::Block* const block : program.post_order_blocks) {
- DeadInstElimination<true>(block);
}
}