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// Copyright (c) 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "source/opt/redundancy_elimination.h"
#include "source/opt/value_number_table.h"
namespace spvtools {
namespace opt {
Pass::Status RedundancyEliminationPass::Process() {
bool modified = false;
ValueNumberTable vnTable(context());
for (auto& func : *get_module()) {
if (func.IsDeclaration()) {
continue;
}
// Build the dominator tree for this function. It is how the code is
// traversed.
DominatorTree& dom_tree =
context()->GetDominatorAnalysis(&func)->GetDomTree();
if (EliminateRedundanciesFrom(dom_tree.GetRoot(), vnTable)) {
modified = true;
}
}
return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
}
bool RedundancyEliminationPass::EliminateRedundanciesFrom(
DominatorTreeNode* bb, const ValueNumberTable& vnTable) {
struct State {
DominatorTreeNode* node;
std::map<uint32_t, uint32_t> value_to_id_map;
};
std::vector<State> todo;
todo.push_back({bb, std::map<uint32_t, uint32_t>()});
bool modified = false;
for (size_t next_node = 0; next_node < todo.size(); next_node++) {
modified |= EliminateRedundanciesInBB(todo[next_node].node->bb_, vnTable,
&todo[next_node].value_to_id_map);
for (DominatorTreeNode* child : todo[next_node].node->children_) {
todo.push_back({child, todo[next_node].value_to_id_map});
}
}
return modified;
}
} // namespace opt
} // namespace spvtools
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