1 // Copyright 2015 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_ 6 #define V8_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_ 7 8 #include "src/identity-map.h" 9 #include "src/interpreter/bytecodes.h" 10 #include "src/zone-containers.h" 11 12 namespace v8 { 13 namespace internal { 14 15 class Factory; 16 class Isolate; 17 18 namespace interpreter { 19 20 // A helper class for constructing constant arrays for the interpreter. 21 class ConstantArrayBuilder final : public ZoneObject { 22 public: 23 // Capacity of the 8-bit operand slice. 24 static const size_t kLowCapacity = 1u << kBitsPerByte; 25 26 // Capacity of the combined 8-bit and 16-bit operand slices. 27 static const size_t kMaxCapacity = 1u << (2 * kBitsPerByte); 28 29 // Capacity of the 16-bit operand slice. 30 static const size_t kHighCapacity = kMaxCapacity - kLowCapacity; 31 32 ConstantArrayBuilder(Isolate* isolate, Zone* zone); 33 34 // Generate a fixed array of constants based on inserted objects. 35 Handle<FixedArray> ToFixedArray(Factory* factory) const; 36 37 // Returns the object in the constant pool array that at index 38 // |index|. 39 Handle<Object> At(size_t index) const; 40 41 // Returns the number of elements in the array. 42 size_t size() const; 43 44 // Insert an object into the constants array if it is not already 45 // present. Returns the array index associated with the object. 46 size_t Insert(Handle<Object> object); 47 48 // Creates a reserved entry in the constant pool and returns 49 // the size of the operand that'll be required to hold the entry 50 // when committed. 51 OperandSize CreateReservedEntry(); 52 53 // Commit reserved entry and returns the constant pool index for the 54 // object. 55 size_t CommitReservedEntry(OperandSize operand_size, Handle<Object> object); 56 57 // Discards constant pool reservation. 58 void DiscardReservedEntry(OperandSize operand_size); 59 60 private: 61 typedef uint16_t index_t; 62 63 index_t AllocateEntry(Handle<Object> object); 64 65 struct ConstantArraySlice final { 66 ConstantArraySlice(Zone* zone, size_t start_index, size_t capacity); 67 void Reserve(); 68 void Unreserve(); 69 size_t Allocate(Handle<Object> object); 70 Handle<Object> At(size_t index) const; 71 availablefinal72 inline size_t available() const { return capacity() - reserved() - size(); } reservedfinal73 inline size_t reserved() const { return reserved_; } capacityfinal74 inline size_t capacity() const { return capacity_; } sizefinal75 inline size_t size() const { return constants_.size(); } start_indexfinal76 inline size_t start_index() const { return start_index_; } 77 78 private: 79 const size_t start_index_; 80 const size_t capacity_; 81 size_t reserved_; 82 ZoneVector<Handle<Object>> constants_; 83 84 DISALLOW_COPY_AND_ASSIGN(ConstantArraySlice); 85 }; 86 87 Isolate* isolate_; 88 ConstantArraySlice idx8_slice_; 89 ConstantArraySlice idx16_slice_; 90 IdentityMap<index_t> constants_map_; 91 }; 92 93 } // namespace interpreter 94 } // namespace internal 95 } // namespace v8 96 97 #endif // V8_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_ 98