mirror of
https://github.com/KytyPS5/KytyPS5.git
synced 2026-10-20 02:47:02 +02:00
nmzik
92 lines
3.3 KiB
C++
92 lines
3.3 KiB
C++
#include "graphics/shader/recompiler/ir/passes/DeadCodeElimination.h"
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#include "graphics/shader/recompiler/ir/ShaderIR.h"
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#include <algorithm>
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namespace Libs::Graphics::ShaderRecompiler::IR {
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void RemoveIdentities(Program& program) {
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// Resolve metadata before deleting its identity nodes; retain only folded native constants.
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for (auto& write: program.scalar_writes) {
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const auto value = write.value.Resolve();
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write.value = value.IsImmediate() && value.GetType() == Type::U32 ? value : Value {};
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}
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for (auto* block: program.blocks) {
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block->condition = block->condition.Resolve();
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block->indirect_target = block->indirect_target.Resolve();
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}
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for (auto* block: program.blocks) {
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auto& instructions = block->Instructions();
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for (auto inst = instructions.begin(); inst != instructions.end();) {
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if (inst->GetOpcode() != ValueOpcode::Identity) {
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inst++;
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continue;
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}
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const auto replacement = inst->Arg(0);
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inst->ReplaceUsesWith(replacement, false);
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inst = instructions.erase(inst);
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}
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}
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}
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void EliminateDeadCode(const BlockList& blocks) {
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bool changed;
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do {
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std::vector<Inst*> pending;
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for (auto* block: blocks) {
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for (auto& inst: *block) {
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// Retained resource-planning instructions live outside the block list.
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inst.live = inst.MayHaveSideEffects() || std::ranges::any_of(inst.Uses(),
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[](const Use& use) { return use.user->Parent() == nullptr; });
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if (inst.live) pending.push_back(&inst);
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}
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}
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while (!pending.empty()) {
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const auto* inst = pending.back();
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pending.pop_back();
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for (size_t arg = 0; arg < inst->NumArgs(); ++arg) {
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auto* input = inst->Arg(arg).TryInstruction();
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if (input != nullptr && input->Parent() != nullptr && !input->live) {
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input->live = true;
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pending.push_back(input);
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}
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}
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}
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// Unlink every dead operand before freeing nodes in a dead Phi cycle.
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for (auto* block: blocks)
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for (auto& inst: *block)
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if (!inst.live) inst.Invalidate();
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for (auto* block: blocks)
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std::erase_if(block->Instructions(), [](const Inst& inst) { return !inst.live; });
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changed = false;
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for (auto* block: blocks) {
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const auto& term = block->terminator;
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if (term.kind != CFG::TerminatorKind::ConditionalBranch || term.loop_header ||
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block->condition.IsImmediate()) continue;
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for (const bool take_true: {false, true}) {
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const auto* empty = take_true ? term.false_block : term.true_block;
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const auto* merge = take_true ? term.true_block : term.false_block;
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if (empty == nullptr || merge == nullptr || !empty->empty() ||
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empty->terminator.loop_header || merge->terminator.loop_header ||
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empty->terminator.kind != CFG::TerminatorKind::Branch ||
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empty->terminator.true_block != merge ||
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std::ranges::any_of(*merge, [](const Inst& inst) {
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return inst.GetOpcode() == ValueOpcode::Phi;
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})) continue;
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// Keep the CFG and SSA edges intact; only the empty detour's predicate is dead.
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for (auto& inst: *block) {
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if (inst.GetOpcode() == ValueOpcode::Reference &&
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inst.Arg(0).Resolve() == block->condition.Resolve())
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inst.SetArg(0, Value(take_true));
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}
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block->condition = Value(take_true);
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changed = true;
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break;
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}
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}
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} while (changed);
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}
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} // namespace Libs::Graphics::ShaderRecompiler::IR
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