70 lines
2.1 KiB
C++
70 lines
2.1 KiB
C++
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// Copyright (c) 2017 Google 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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#include "local_redundancy_elimination.h"
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#include "value_number_table.h"
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namespace spvtools {
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namespace opt {
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Pass::Status LocalRedundancyEliminationPass::Process(ir::IRContext* c) {
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InitializeProcessing(c);
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bool modified = false;
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ValueNumberTable vnTable(context());
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for (auto& func : *get_module()) {
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for (auto& bb : func) {
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// Keeps track of all ids that contain a given value number. We keep
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// track of multiple values because they could have the same value, but
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// different decorations.
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std::map<uint32_t, uint32_t> value_to_ids;
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if (EliminateRedundanciesInBB(&bb, vnTable, &value_to_ids))
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modified = true;
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}
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}
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return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
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}
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bool LocalRedundancyEliminationPass::EliminateRedundanciesInBB(
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ir::BasicBlock* block, const ValueNumberTable& vnTable,
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std::map<uint32_t, uint32_t>* value_to_ids) {
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bool modified = false;
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auto func = [this, &vnTable, &modified, value_to_ids](ir::Instruction* inst) {
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if (inst->result_id() == 0) {
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return;
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}
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uint32_t value = vnTable.GetValueNumber(inst);
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if (value == 0) {
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return;
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}
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auto candidate = value_to_ids->insert({value, inst->result_id()});
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if (!candidate.second) {
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context()->KillNamesAndDecorates(inst);
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context()->ReplaceAllUsesWith(inst->result_id(), candidate.first->second);
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context()->KillInst(inst);
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modified = true;
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}
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};
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block->ForEachInst(func);
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return modified;
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}
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} // namespace opt
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} // namespace spvtools
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