src/type-info.h

// Copyright 2011 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_TYPE_INFO_H_
#define V8_TYPE_INFO_H_

#include "globals.h"
#include "zone.h"
#include "zone-inl.h"

namespace v8 {
namespace internal {

//         Unknown
//           |   |
//           |   \--------------|
//      Primitive             Non-primitive
//           |   \--------|     |
//         Number      String   |
//         /    |         |     |
//    Double  Integer32   |    /
//        |      |       /    /
//        |     Smi     /    /
//        |      |     /    /
//        |      |    /    /
//        Uninitialized.--/

class TypeInfo {
 public:
  TypeInfo() : type_(kUninitialized) { }

  static TypeInfo Unknown() { return TypeInfo(kUnknown); }
  // We know it's a primitive type.
  static TypeInfo Primitive() { return TypeInfo(kPrimitive); }
  // We know it's a number of some sort.
  static TypeInfo Number() { return TypeInfo(kNumber); }
  // We know it's a signed 32 bit integer.
  static TypeInfo Integer32() { return TypeInfo(kInteger32); }
  // We know it's a Smi.
  static TypeInfo Smi() { return TypeInfo(kSmi); }
  // We know it's a heap number.
  static TypeInfo Double() { return TypeInfo(kDouble); }
  // We know it's a string.
  static TypeInfo String() { return TypeInfo(kString); }
  // We know it's a non-primitive (object) type.
  static TypeInfo NonPrimitive() { return TypeInfo(kNonPrimitive); }
  // We haven't started collecting info yet.
  static TypeInfo Uninitialized() { return TypeInfo(kUninitialized); }

  // Return compact representation.  Very sensitive to enum values below!
  // Compacting drops information about primitive types and strings types.
  // We use the compact representation when we only care about number types.
  int ThreeBitRepresentation() {
    ASSERT(type_ != kUninitialized);
    int answer = type_ & 0xf;
    answer = answer > 6 ? answer - 2 : answer;
    ASSERT(answer >= 0);
    ASSERT(answer <= 7);
    return answer;
  }

  // Decode compact representation.  Very sensitive to enum values below!
  static TypeInfo ExpandedRepresentation(int three_bit_representation) {
    Type t = static_cast<Type>(three_bit_representation > 4 ?
                               three_bit_representation + 2 :
                               three_bit_representation);
    t = (t == kUnknown) ? t : static_cast<Type>(t | kPrimitive);
    ASSERT(t == kUnknown ||
           t == kNumber ||
           t == kInteger32 ||
           t == kSmi ||
           t == kDouble);
    return TypeInfo(t);
  }

  int ToInt() {
    return type_;
  }

  static TypeInfo FromInt(int bit_representation) {
    Type t = static_cast<Type>(bit_representation);
    ASSERT(t == kUnknown ||
           t == kPrimitive ||
           t == kNumber ||
           t == kInteger32 ||
           t == kSmi ||
           t == kDouble ||
           t == kString ||
           t == kNonPrimitive);
    return TypeInfo(t);
  }

  // Return the weakest (least precise) common type.
  static TypeInfo Combine(TypeInfo a, TypeInfo b) {
    return TypeInfo(static_cast<Type>(a.type_ & b.type_));
  }


  // Integer32 is an integer that can be represented as a signed
  // 32-bit integer. It has to be
  // in the range [-2^31, 2^31 - 1]. We also have to check for negative 0
  // as it is not an Integer32.
  static inline bool IsInt32Double(double value) {
    const DoubleRepresentation minus_zero(-0.0);
    DoubleRepresentation rep(value);
    if (rep.bits == minus_zero.bits) return false;
    if (value >= kMinInt && value <= kMaxInt &&
        value == static_cast<int32_t>(value)) {
      return true;
    }
    return false;
  }

  static TypeInfo TypeFromValue(Handle<Object> value);

  bool Equals(const TypeInfo& other) {
    return type_ == other.type_;
  }

  inline bool IsUnknown() {
    ASSERT(type_ != kUninitialized);
    return type_ == kUnknown;
  }

  inline bool IsPrimitive() {
    ASSERT(type_ != kUninitialized);
    return ((type_ & kPrimitive) == kPrimitive);
  }

  inline bool IsNumber() {
    ASSERT(type_ != kUninitialized);
    return ((type_ & kNumber) == kNumber);
  }

  inline bool IsSmi() {
    ASSERT(type_ != kUninitialized);
    return ((type_ & kSmi) == kSmi);
  }

  inline bool IsInteger32() {
    ASSERT(type_ != kUninitialized);
    return ((type_ & kInteger32) == kInteger32);
  }

  inline bool IsDouble() {
    ASSERT(type_ != kUninitialized);
    return ((type_ & kDouble) == kDouble);
  }

  inline bool IsString() {
    ASSERT(type_ != kUninitialized);
    return ((type_ & kString) == kString);
  }

  inline bool IsNonPrimitive() {
    ASSERT(type_ != kUninitialized);
    return ((type_ & kNonPrimitive) == kNonPrimitive);
  }

  inline bool IsUninitialized() {
    return type_ == kUninitialized;
  }

  const char* ToString() {
    switch (type_) {
      case kUnknown: return "Unknown";
      case kPrimitive: return "Primitive";
      case kNumber: return "Number";
      case kInteger32: return "Integer32";
      case kSmi: return "Smi";
      case kDouble: return "Double";
      case kString: return "String";
      case kNonPrimitive: return "Object";
      case kUninitialized: return "Uninitialized";
    }
    UNREACHABLE();
    return "Unreachable code";
  }

 private:
  enum Type {
    kUnknown = 0,          // 0000000
    kPrimitive = 0x10,     // 0010000
    kNumber = 0x11,        // 0010001
    kInteger32 = 0x13,     // 0010011
    kSmi = 0x17,           // 0010111
    kDouble = 0x19,        // 0011001
    kString = 0x30,        // 0110000
    kNonPrimitive = 0x40,  // 1000000
    kUninitialized = 0x7f  // 1111111
  };
  explicit inline TypeInfo(Type t) : type_(t) { }

  Type type_;
};


enum StringStubFeedback {
  DEFAULT_STRING_STUB = 0,
  STRING_INDEX_OUT_OF_BOUNDS = 1
};


// Forward declarations.
class Assignment;
class BinaryOperation;
class Call;
class CompareOperation;
class CompilationInfo;
class Property;
class CaseClause;

class TypeFeedbackOracle BASE_EMBEDDED {
 public:
  TypeFeedbackOracle(Handle<Code> code, Handle<Context> global_context);

  bool LoadIsMonomorphic(Property* expr);
  bool StoreIsMonomorphic(Expression* expr);
  bool CallIsMonomorphic(Call* expr);

  Handle<Map> LoadMonomorphicReceiverType(Property* expr);
  Handle<Map> StoreMonomorphicReceiverType(Expression* expr);

  ZoneMapList* LoadReceiverTypes(Property* expr, Handle<String> name);
  ZoneMapList* StoreReceiverTypes(Assignment* expr, Handle<String> name);
  ZoneMapList* CallReceiverTypes(Call* expr, Handle<String> name);

  ExternalArrayType GetKeyedLoadExternalArrayType(Property* expr);
  ExternalArrayType GetKeyedStoreExternalArrayType(Expression* expr);

  CheckType GetCallCheckType(Call* expr);
  Handle<JSObject> GetPrototypeForPrimitiveCheck(CheckType check);

  bool LoadIsBuiltin(Property* expr, Builtins::Name id);

  // Get type information for arithmetic operations and compares.
  TypeInfo BinaryType(BinaryOperation* expr);
  TypeInfo CompareType(CompareOperation* expr);
  TypeInfo SwitchType(CaseClause* clause);

 private:
  ZoneMapList* CollectReceiverTypes(int position,
                                    Handle<String> name,
                                    Code::Flags flags);

  void SetInfo(int position, Object* target);

  void PopulateMap(Handle<Code> code);

  void CollectPositions(Code* code,
                        List<int>* code_positions,
                        List<int>* source_positions);

  // Returns an element from the backing store. Returns undefined if
  // there is no information.
  Handle<Object> GetInfo(int pos);

  Handle<Context> global_context_;
  Handle<NumberDictionary> dictionary_;

  DISALLOW_COPY_AND_ASSIGN(TypeFeedbackOracle);
};

} }  // namespace v8::internal

#endif  // V8_TYPE_INFO_H_