src/compiler/node-matchers.h

// 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_NODE_MATCHERS_H_
#define V8_COMPILER_NODE_MATCHERS_H_

#include "src/compiler/node.h"
#include "src/compiler/operator.h"

namespace v8 {
namespace internal {
namespace compiler {

// A pattern matcher for nodes.
struct NodeMatcher {
  explicit NodeMatcher(Node* node) : node_(node) {}

  Node* node() const { return node_; }
  const Operator* op() const { return node()->op(); }
  IrOpcode::Value opcode() const { return node()->opcode(); }

  bool HasProperty(Operator::Property property) const {
    return op()->HasProperty(property);
  }
  Node* InputAt(int index) const { return node()->InputAt(index); }

#define DEFINE_IS_OPCODE(Opcode) \
  bool Is##Opcode() const { return opcode() == IrOpcode::k##Opcode; }
  ALL_OP_LIST(DEFINE_IS_OPCODE)
#undef DEFINE_IS_OPCODE

 private:
  Node* node_;
};


// A pattern matcher for abitrary value constants.
template <typename T, IrOpcode::Value kOpcode>
struct ValueMatcher : public NodeMatcher {
  explicit ValueMatcher(Node* node)
      : NodeMatcher(node), value_(), has_value_(opcode() == kOpcode) {
    if (has_value_) {
      value_ = OpParameter<T>(node);
    }
  }

  bool HasValue() const { return has_value_; }
  const T& Value() const {
    DCHECK(HasValue());
    return value_;
  }

  bool Is(const T& value) const {
    return this->HasValue() && this->Value() == value;
  }

  bool IsInRange(const T& low, const T& high) const {
    return this->HasValue() && low <= this->Value() && this->Value() <= high;
  }

 private:
  T value_;
  bool has_value_;
};


// A pattern matcher for integer constants.
template <typename T, IrOpcode::Value kOpcode>
struct IntMatcher FINAL : public ValueMatcher<T, kOpcode> {
  explicit IntMatcher(Node* node) : ValueMatcher<T, kOpcode>(node) {}

  bool IsPowerOf2() const {
    return this->HasValue() && this->Value() > 0 &&
           (this->Value() & (this->Value() - 1)) == 0;
  }
};

typedef IntMatcher<int32_t, IrOpcode::kInt32Constant> Int32Matcher;
typedef IntMatcher<uint32_t, IrOpcode::kInt32Constant> Uint32Matcher;
typedef IntMatcher<int64_t, IrOpcode::kInt64Constant> Int64Matcher;
typedef IntMatcher<uint64_t, IrOpcode::kInt64Constant> Uint64Matcher;


// A pattern matcher for floating point constants.
template <typename T, IrOpcode::Value kOpcode>
struct FloatMatcher FINAL : public ValueMatcher<T, kOpcode> {
  explicit FloatMatcher(Node* node) : ValueMatcher<T, kOpcode>(node) {}

  bool IsNaN() const { return this->HasValue() && std::isnan(this->Value()); }
};

typedef FloatMatcher<float, IrOpcode::kFloat32Constant> Float32Matcher;
typedef FloatMatcher<double, IrOpcode::kFloat64Constant> Float64Matcher;
typedef FloatMatcher<double, IrOpcode::kNumberConstant> NumberMatcher;


// A pattern matcher for heap object constants.
template <typename T>
struct HeapObjectMatcher FINAL
    : public ValueMatcher<Unique<T>, IrOpcode::kHeapConstant> {
  explicit HeapObjectMatcher(Node* node)
      : ValueMatcher<Unique<T>, IrOpcode::kHeapConstant>(node) {}
};


// For shorter pattern matching code, this struct matches both the left and
// right hand sides of a binary operation and can put constants on the right
// if they appear on the left hand side of a commutative operation.
template <typename Left, typename Right>
struct BinopMatcher FINAL : public NodeMatcher {
  explicit BinopMatcher(Node* node)
      : NodeMatcher(node), left_(InputAt(0)), right_(InputAt(1)) {
    if (HasProperty(Operator::kCommutative)) PutConstantOnRight();
  }

  const Left& left() const { return left_; }
  const Right& right() const { return right_; }

  bool IsFoldable() const { return left().HasValue() && right().HasValue(); }
  bool LeftEqualsRight() const { return left().node() == right().node(); }

 private:
  void PutConstantOnRight() {
    if (left().HasValue() && !right().HasValue()) {
      std::swap(left_, right_);
      node()->ReplaceInput(0, left().node());
      node()->ReplaceInput(1, right().node());
    }
  }

  Left left_;
  Right right_;
};

typedef BinopMatcher<Int32Matcher, Int32Matcher> Int32BinopMatcher;
typedef BinopMatcher<Uint32Matcher, Uint32Matcher> Uint32BinopMatcher;
typedef BinopMatcher<Int64Matcher, Int64Matcher> Int64BinopMatcher;
typedef BinopMatcher<Uint64Matcher, Uint64Matcher> Uint64BinopMatcher;
typedef BinopMatcher<Float64Matcher, Float64Matcher> Float64BinopMatcher;


// Fairly intel-specify node matcher used for matching scale factors in
// addressing modes.
// Matches nodes of form [x * N] for N in {1,2,4,8}
class ScaleFactorMatcher : public NodeMatcher {
 public:
  explicit ScaleFactorMatcher(Node* node)
      : NodeMatcher(node), left_(NULL), power_(0) {
    Match();
  }

  bool Matches() { return left_ != NULL; }
  int Power() {
    DCHECK(Matches());
    return power_;
  }
  Node* Left() {
    DCHECK(Matches());
    return left_;
  }

 private:
  void Match() {
    if (opcode() != IrOpcode::kInt32Mul) return;
    Int32BinopMatcher m(node());
    if (!m.right().HasValue()) return;
    int32_t value = m.right().Value();
    switch (value) {
      case 8:
        power_++;  // Fall through.
      case 4:
        power_++;  // Fall through.
      case 2:
        power_++;  // Fall through.
      case 1:
        break;
      default:
        return;
    }
    left_ = m.left().node();
  }

  Node* left_;
  int power_;
};


// Fairly intel-specify node matcher used for matching index and displacement
// operands in addressing modes.
// Matches nodes of form:
//  [x * N]
//  [x * N + K]
//  [x + K]
//  [x] -- fallback case
// for N in {1,2,4,8} and K int32_t
class IndexAndDisplacementMatcher : public NodeMatcher {
 public:
  explicit IndexAndDisplacementMatcher(Node* node)
      : NodeMatcher(node), index_node_(node), displacement_(0), power_(0) {
    Match();
  }

  Node* index_node() { return index_node_; }
  int displacement() { return displacement_; }
  int power() { return power_; }

 private:
  void Match() {
    if (opcode() == IrOpcode::kInt32Add) {
      // Assume reduction has put constant on the right.
      Int32BinopMatcher m(node());
      if (m.right().HasValue()) {
        displacement_ = m.right().Value();
        index_node_ = m.left().node();
      }
    }
    // Test scale factor.
    ScaleFactorMatcher scale_matcher(index_node_);
    if (scale_matcher.Matches()) {
      index_node_ = scale_matcher.Left();
      power_ = scale_matcher.Power();
    }
  }

  Node* index_node_;
  int displacement_;
  int power_;
};


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

#endif  // V8_COMPILER_NODE_MATCHERS_H_