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82 lines
1.9 KiB
82 lines
1.9 KiB
// Copyright (c) 2018 Google LLC
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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 "source/opt/dominator_analysis.h"
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#include <unordered_set>
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#include "source/opt/ir_context.h"
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namespace spvtools {
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namespace opt {
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BasicBlock* DominatorAnalysisBase::CommonDominator(BasicBlock* b1,
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BasicBlock* b2) const {
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if (!b1 || !b2) return nullptr;
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std::unordered_set<BasicBlock*> seen;
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BasicBlock* block = b1;
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while (block && seen.insert(block).second) {
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block = ImmediateDominator(block);
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}
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block = b2;
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while (block && !seen.count(block)) {
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block = ImmediateDominator(block);
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}
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return block;
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}
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bool DominatorAnalysisBase::Dominates(Instruction* a, Instruction* b) const {
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if (!a || !b) {
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return false;
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}
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if (a == b) {
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return true;
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}
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BasicBlock* bb_a = a->context()->get_instr_block(a);
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BasicBlock* bb_b = b->context()->get_instr_block(b);
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if (bb_a != bb_b) {
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return tree_.Dominates(bb_a, bb_b);
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}
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const Instruction* current = a;
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const Instruction* other = b;
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if (tree_.IsPostDominator()) {
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std::swap(current, other);
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}
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// We handle OpLabel instructions explicitly since they are not stored in the
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// instruction list.
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if (current->opcode() == SpvOpLabel) {
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return true;
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}
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while ((current = current->NextNode())) {
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if (current == other) {
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return true;
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}
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}
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return false;
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}
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} // namespace opt
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} // namespace spvtools
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