58 lines
1.8 KiB
C++
58 lines
1.8 KiB
C++
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// Copyright 2021 yuzu Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#pragma once
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#include <optional>
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#include <type_traits>
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#include <queue>
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#include <boost/container/small_vector.hpp>
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#include "shader_recompiler/frontend/ir/microinstruction.h"
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#include "shader_recompiler/frontend/ir/value.h"
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namespace Shader::IR {
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template <typename Pred>
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auto BreadthFirstSearch(const Value& value, Pred&& pred)
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-> std::invoke_result_t<Pred, const Inst*> {
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if (value.IsImmediate()) {
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// Nothing to do with immediates
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return std::nullopt;
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}
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// Breadth-first search visiting the right most arguments first
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// Small vector has been determined from shaders in Super Smash Bros. Ultimate
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boost::container::small_vector<const Inst*, 2> visited;
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std::queue<const Inst*> queue;
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queue.push(value.InstRecursive());
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while (!queue.empty()) {
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// Pop one instruction from the queue
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const Inst* const inst{queue.front()};
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queue.pop();
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if (const std::optional result = pred(inst)) {
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// This is the instruction we were looking for
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return result;
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}
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// Visit the right most arguments first
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for (size_t arg = inst->NumArgs(); arg--;) {
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const Value arg_value{inst->Arg(arg)};
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if (arg_value.IsImmediate()) {
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continue;
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}
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// Queue instruction if it hasn't been visited
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const Inst* const arg_inst{arg_value.InstRecursive()};
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if (std::ranges::find(visited, arg_inst) == visited.end()) {
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visited.push_back(arg_inst);
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queue.push(arg_inst);
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}
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}
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}
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// SSA tree has been traversed and the result hasn't been found
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return std::nullopt;
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}
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} // namespace Shader::IR
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