03d93abc1a
There is a risk that we try to preserve a loop variable through multiple iterations, even though the dominating block is inside a loop. Fix this by analyzing if a block starts off by writing to a variable. In that case, there cannot be any preservation going on. If we don't, pretend the loop header is reading the variable, which moves the variable to an appropriate scope.
152 lines
3.2 KiB
C++
152 lines
3.2 KiB
C++
/*
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* Copyright 2016-2019 Arm Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef SPIRV_CROSS_CFG_HPP
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#define SPIRV_CROSS_CFG_HPP
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#include "spirv_common.hpp"
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#include <assert.h>
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namespace SPIRV_CROSS_NAMESPACE
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{
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class Compiler;
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class CFG
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{
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public:
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CFG(Compiler &compiler, const SPIRFunction &function);
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Compiler &get_compiler()
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{
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return compiler;
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}
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const Compiler &get_compiler() const
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{
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return compiler;
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}
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const SPIRFunction &get_function() const
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{
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return func;
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}
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uint32_t get_immediate_dominator(uint32_t block) const
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{
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auto itr = immediate_dominators.find(block);
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if (itr != std::end(immediate_dominators))
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return itr->second;
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else
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return 0;
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}
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uint32_t get_visit_order(uint32_t block) const
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{
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auto itr = visit_order.find(block);
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assert(itr != std::end(visit_order));
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int v = itr->second.get();
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assert(v > 0);
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return uint32_t(v);
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}
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uint32_t find_common_dominator(uint32_t a, uint32_t b) const;
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const SmallVector<uint32_t> &get_preceding_edges(uint32_t block) const
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{
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auto itr = preceding_edges.find(block);
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if (itr != std::end(preceding_edges))
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return itr->second;
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else
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return empty_vector;
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}
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const SmallVector<uint32_t> &get_succeeding_edges(uint32_t block) const
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{
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auto itr = succeeding_edges.find(block);
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if (itr != std::end(succeeding_edges))
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return itr->second;
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else
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return empty_vector;
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}
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template <typename Op>
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void walk_from(std::unordered_set<uint32_t> &seen_blocks, uint32_t block, const Op &op) const
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{
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if (seen_blocks.count(block))
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return;
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seen_blocks.insert(block);
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op(block);
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for (auto b : get_succeeding_edges(block))
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walk_from(seen_blocks, b, op);
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}
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uint32_t find_loop_dominator(uint32_t block) const;
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private:
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struct VisitOrder
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{
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int &get()
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{
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return v;
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}
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const int &get() const
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{
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return v;
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}
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int v = -1;
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};
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Compiler &compiler;
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const SPIRFunction &func;
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std::unordered_map<uint32_t, SmallVector<uint32_t>> preceding_edges;
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std::unordered_map<uint32_t, SmallVector<uint32_t>> succeeding_edges;
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std::unordered_map<uint32_t, uint32_t> immediate_dominators;
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std::unordered_map<uint32_t, VisitOrder> visit_order;
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SmallVector<uint32_t> post_order;
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SmallVector<uint32_t> empty_vector;
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void add_branch(uint32_t from, uint32_t to);
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void build_post_order_visit_order();
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void build_immediate_dominators();
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bool post_order_visit(uint32_t block);
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uint32_t visit_count = 0;
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bool is_back_edge(uint32_t to) const;
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};
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class DominatorBuilder
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{
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public:
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DominatorBuilder(const CFG &cfg);
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void add_block(uint32_t block);
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uint32_t get_dominator() const
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{
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return dominator;
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}
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void lift_continue_block_dominator();
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private:
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const CFG &cfg;
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uint32_t dominator = 0;
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};
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} // namespace SPIRV_CROSS_NAMESPACE
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#endif
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