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