// Copyright 2014 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_INT64_LOWERING_H_
#define V8_COMPILER_INT64_LOWERING_H_

#include "src/common/globals.h"
#include "src/compiler/common-operator.h"
#include "src/compiler/graph.h"
#include "src/compiler/machine-operator.h"
#include "src/compiler/node-marker.h"
#include "src/zone/zone-containers.h"

namespace v8 {
namespace internal {

template <typename T>
class Signature;

namespace compiler {

// Struct for CallDescriptors that need special lowering.
struct V8_EXPORT_PRIVATE Int64LoweringSpecialCase {
  Int64LoweringSpecialCase()
      : bigint_to_i64_call_descriptor(nullptr),
        i64_to_bigint_call_descriptor(nullptr),
        bigint_to_i32_pair_call_descriptor(nullptr),
        i32_pair_to_bigint_call_descriptor(nullptr) {}

  // CallDescriptors that need special lowering.
  CallDescriptor* bigint_to_i64_call_descriptor;
  CallDescriptor* i64_to_bigint_call_descriptor;

  // The replacement CallDescriptors.
  CallDescriptor* bigint_to_i32_pair_call_descriptor;
  CallDescriptor* i32_pair_to_bigint_call_descriptor;
};

class V8_EXPORT_PRIVATE Int64Lowering {
 public:
  Int64Lowering(
      Graph* graph, MachineOperatorBuilder* machine,
      CommonOperatorBuilder* common, Zone* zone,
      Signature<MachineRepresentation>* signature,
      std::unique_ptr<Int64LoweringSpecialCase> special_case = nullptr);

  void LowerGraph();

  static int GetParameterCountAfterLowering(
      Signature<MachineRepresentation>* signature);

 private:
  enum class State : uint8_t { kUnvisited, kOnStack, kVisited };

  struct Replacement {
    Node* low;
    Node* high;
  };

  Zone* zone() const { return zone_; }
  Graph* graph() const { return graph_; }
  MachineOperatorBuilder* machine() const { return machine_; }
  CommonOperatorBuilder* common() const { return common_; }
  Signature<MachineRepresentation>* signature() const { return signature_; }

  void PushNode(Node* node);
  void LowerNode(Node* node);
  bool DefaultLowering(Node* node, bool low_word_only = false);
  void LowerComparison(Node* node, const Operator* signed_op,
                       const Operator* unsigned_op);
  void LowerWord64AtomicBinop(Node* node, const Operator* op);
  void LowerWord64AtomicNarrowOp(Node* node, const Operator* op);

  CallDescriptor* LowerCallDescriptor(const CallDescriptor* call_descriptor);

  void ReplaceNode(Node* old, Node* new_low, Node* new_high);
  bool HasReplacementLow(Node* node);
  Node* GetReplacementLow(Node* node);
  bool HasReplacementHigh(Node* node);
  Node* GetReplacementHigh(Node* node);
  void PreparePhiReplacement(Node* phi);
  void GetIndexNodes(Node* index, Node** index_low, Node** index_high);
  void ReplaceNodeWithProjections(Node* node);
  void LowerMemoryBaseAndIndex(Node* node);

  struct NodeState {
    Node* node;
    int input_index;
  };

  Zone* zone_;
  Graph* const graph_;
  MachineOperatorBuilder* machine_;
  CommonOperatorBuilder* common_;
  NodeMarker<State> state_;
  ZoneDeque<NodeState> stack_;
  Replacement* replacements_;
  Signature<MachineRepresentation>* signature_;
  Node* placeholder_;
  std::unique_ptr<Int64LoweringSpecialCase> special_case_;
};

}  // namespace compiler
}  // namespace internal
}  // namespace v8

#endif  // V8_COMPILER_INT64_LOWERING_H_