// Copyright 2015 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_COMPILER_BRANCH_ELIMINATION_H_
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#define V8_COMPILER_BRANCH_ELIMINATION_H_
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#include "src/base/compiler-specific.h"
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#include "src/compiler/functional-list.h"
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#include "src/compiler/graph-reducer.h"
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#include "src/compiler/node-aux-data.h"
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#include "src/globals.h"
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namespace v8 {
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namespace internal {
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namespace compiler {
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// Forward declarations.
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class CommonOperatorBuilder;
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class JSGraph;
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class V8_EXPORT_PRIVATE BranchElimination final
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: public NON_EXPORTED_BASE(AdvancedReducer) {
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public:
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BranchElimination(Editor* editor, JSGraph* js_graph, Zone* zone);
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~BranchElimination() final;
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const char* reducer_name() const override { return "BranchElimination"; }
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Reduction Reduce(Node* node) final;
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private:
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struct BranchCondition {
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Node* condition;
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Node* branch;
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bool is_true;
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bool operator==(BranchCondition other) const {
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return condition == other.condition && branch == other.branch &&
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is_true == other.is_true;
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}
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bool operator!=(BranchCondition other) const { return !(*this == other); }
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};
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// Class for tracking information about branch conditions.
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// At the moment it is a linked list of conditions and their values
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// (true or false).
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class ControlPathConditions : public FunctionalList<BranchCondition> {
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public:
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bool LookupCondition(Node* condition, Node** branch, bool* is_true) const;
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void AddCondition(Zone* zone, Node* condition, Node* branch, bool is_true,
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ControlPathConditions hint);
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private:
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using FunctionalList<BranchCondition>::PushFront;
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};
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Reduction ReduceBranch(Node* node);
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Reduction ReduceDeoptimizeConditional(Node* node);
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Reduction ReduceIf(Node* node, bool is_true_branch);
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Reduction ReduceLoop(Node* node);
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Reduction ReduceMerge(Node* node);
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Reduction ReduceStart(Node* node);
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Reduction ReduceOtherControl(Node* node);
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Reduction TakeConditionsFromFirstControl(Node* node);
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Reduction UpdateConditions(Node* node, ControlPathConditions conditions);
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Reduction UpdateConditions(Node* node, ControlPathConditions prev_conditions,
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Node* current_condition, Node* current_branch,
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bool is_true_branch);
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Node* dead() const { return dead_; }
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Graph* graph() const;
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JSGraph* jsgraph() const { return jsgraph_; }
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Isolate* isolate() const;
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CommonOperatorBuilder* common() const;
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JSGraph* const jsgraph_;
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// Maps each control node to the condition information known about the node.
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// If the information is nullptr, then we have not calculated the information
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// yet.
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NodeAuxData<ControlPathConditions> node_conditions_;
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NodeAuxData<bool> reduced_;
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Zone* zone_;
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Node* dead_;
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};
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} // namespace compiler
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} // namespace internal
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} // namespace v8
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#endif // V8_COMPILER_BRANCH_ELIMINATION_H_
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