mirror of
https://github.com/KhronosGroup/SPIRV-Tools
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b25b330069
Create class to encapsulate control flow analysis and share across validator and optimizer. A WIP. Start with DepthFirstTraversal. Next pull in CalculateDominators.
136 lines
4.6 KiB
C++
136 lines
4.6 KiB
C++
// Copyright (c) 2015-2016 The Khronos Group Inc.
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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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#ifndef SPVTOOLS_CFA_H_
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#define SPVTOOLS_CFA_H_
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#include <algorithm>
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#include <cassert>
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#include <functional>
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#include <map>
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#include <unordered_map>
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#include <unordered_set>
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#include <utility>
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#include <vector>
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using std::find;
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using std::function;
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using std::get;
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using std::pair;
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using std::unordered_map;
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using std::unordered_set;
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using std::vector;
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namespace spvtools {
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// Control Flow Analysis of control flow graphs of basic block nodes |BB|.
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template<class BB> class CFA {
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using bb_ptr = BB*;
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using cbb_ptr = const BB*;
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using bb_iter = typename std::vector<BB*>::const_iterator;
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using get_blocks_func =
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std::function<const std::vector<BB*>*(const BB*)>;
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struct block_info {
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cbb_ptr block; ///< pointer to the block
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bb_iter iter; ///< Iterator to the current child node being processed
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};
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/// Returns true if a block with @p id is found in the @p work_list vector
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///
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/// @param[in] work_list Set of blocks visited in the the depth first traversal
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/// of the CFG
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/// @param[in] id The ID of the block being checked
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///
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/// @return true if the edge work_list.back().block->id() => id is a back-edge
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static bool FindInWorkList(
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const std::vector<block_info>& work_list, uint32_t id);
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public:
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/// @brief Depth first traversal starting from the \p entry BasicBlock
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///
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/// This function performs a depth first traversal from the \p entry
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/// BasicBlock and calls the pre/postorder functions when it needs to process
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/// the node in pre order, post order. It also calls the backedge function
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/// when a back edge is encountered.
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///
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/// @param[in] entry The root BasicBlock of a CFG
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/// @param[in] successor_func A function which will return a pointer to the
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/// successor nodes
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/// @param[in] preorder A function that will be called for every block in a
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/// CFG following preorder traversal semantics
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/// @param[in] postorder A function that will be called for every block in a
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/// CFG following postorder traversal semantics
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/// @param[in] backedge A function that will be called when a backedge is
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/// encountered during a traversal
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/// NOTE: The @p successor_func and predecessor_func each return a pointer to a
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/// collection such that iterators to that collection remain valid for the
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/// lifetime of the algorithm.
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static void DepthFirstTraversal(const BB* entry,
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get_blocks_func successor_func,
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std::function<void(cbb_ptr)> preorder,
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std::function<void(cbb_ptr)> postorder,
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std::function<void(cbb_ptr, cbb_ptr)> backedge);
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};
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template<class BB> bool CFA<BB>::FindInWorkList(const vector<block_info>& work_list,
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uint32_t id) {
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for (const auto b : work_list) {
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if (b.block->id() == id) return true;
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}
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return false;
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}
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template<class BB> void CFA<BB>::DepthFirstTraversal(const BB* entry,
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get_blocks_func successor_func,
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function<void(cbb_ptr)> preorder,
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function<void(cbb_ptr)> postorder,
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function<void(cbb_ptr, cbb_ptr)> backedge) {
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unordered_set<uint32_t> processed;
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/// NOTE: work_list is the sequence of nodes from the root node to the node
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/// being processed in the traversal
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vector<block_info> work_list;
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work_list.reserve(10);
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work_list.push_back({ entry, begin(*successor_func(entry)) });
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preorder(entry);
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processed.insert(entry->id());
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while (!work_list.empty()) {
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block_info& top = work_list.back();
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if (top.iter == end(*successor_func(top.block))) {
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postorder(top.block);
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work_list.pop_back();
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}
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else {
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BB* child = *top.iter;
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top.iter++;
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if (FindInWorkList(work_list, child->id())) {
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backedge(top.block, child);
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}
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if (processed.count(child->id()) == 0) {
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preorder(child);
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work_list.emplace_back(
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block_info{ child, begin(*successor_func(child)) });
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processed.insert(child->id());
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}
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}
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}
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}
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} // namespace spvtools
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#endif // SPVTOOLS_CFA_H_
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