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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_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_
#define V8_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_
#include "src/ast/ast-value-factory.h"
#include "src/globals.h"
#include "src/identity-map.h"
#include "src/interpreter/bytecodes.h"
#include "src/objects/smi.h"
#include "src/zone/zone-containers.h"
namespace v8 {
namespace internal {
class Isolate;
class AstRawString;
class AstValue;
namespace interpreter {
// Constant array entries that represent singletons.
#define SINGLETON_CONSTANT_ENTRY_TYPES(V) \
V(AsyncIteratorSymbol, async_iterator_symbol) \
V(ClassFieldsSymbol, class_fields_symbol) \
V(EmptyObjectBoilerplateDescription, empty_object_boilerplate_description) \
V(EmptyArrayBoilerplateDescription, empty_array_boilerplate_description) \
V(EmptyFixedArray, empty_fixed_array) \
V(HomeObjectSymbol, home_object_symbol) \
V(IteratorSymbol, iterator_symbol) \
V(InterpreterTrampolineSymbol, interpreter_trampoline_symbol) \
V(NaN, nan_value)
// A helper class for constructing constant arrays for the
// interpreter. Each instance of this class is intended to be used to
// generate exactly one FixedArray of constants via the ToFixedArray
// method.
class V8_EXPORT_PRIVATE ConstantArrayBuilder final {
public:
// Capacity of the 8-bit operand slice.
static const size_t k8BitCapacity = 1u << kBitsPerByte;
// Capacity of the 16-bit operand slice.
static const size_t k16BitCapacity = (1u << 2 * kBitsPerByte) - k8BitCapacity;
// Capacity of the 32-bit operand slice.
static const size_t k32BitCapacity =
kMaxUInt32 - k16BitCapacity - k8BitCapacity + 1;
explicit ConstantArrayBuilder(Zone* zone);
// Generate a fixed array of constant handles based on inserted objects.
Handle<FixedArray> ToFixedArray(Isolate* isolate);
// Returns the object, as a handle in |isolate|, that is in the constant pool
// array at index |index|. Returns null if there is no handle at this index.
// Only expected to be used in tests.
MaybeHandle<Object> At(size_t index, Isolate* isolate) const;
// Returns the number of elements in the array.
size_t size() const;
// Insert an object into the constants array if it is not already present.
// Returns the array index associated with the object.
size_t Insert(Smi smi);
size_t Insert(double number);
size_t Insert(const AstRawString* raw_string);
size_t Insert(AstBigInt bigint);
size_t Insert(const Scope* scope);
#define INSERT_ENTRY(NAME, ...) size_t Insert##NAME();
SINGLETON_CONSTANT_ENTRY_TYPES(INSERT_ENTRY)
#undef INSERT_ENTRY
// Inserts an empty entry and returns the array index associated with the
// reservation. The entry's handle value can be inserted by calling
// SetDeferredAt().
size_t InsertDeferred();
// Inserts |size| consecutive empty entries and returns the array index
// associated with the first reservation. Each entry's Smi value can be
// inserted by calling SetJumpTableSmi().
size_t InsertJumpTable(size_t size);
// Sets the deferred value at |index| to |object|.
void SetDeferredAt(size_t index, Handle<Object> object);
// Sets the jump table entry at |index| to |smi|. Note that |index| is the
// constant pool index, not the switch case value.
void SetJumpTableSmi(size_t index, Smi smi);
// Creates a reserved entry in the constant pool and returns
// the size of the operand that'll be required to hold the entry
// when committed.
OperandSize CreateReservedEntry();
// Commit reserved entry and returns the constant pool index for the
// SMI value.
size_t CommitReservedEntry(OperandSize operand_size, Smi value);
// Discards constant pool reservation.
void DiscardReservedEntry(OperandSize operand_size);
private:
using index_t = uint32_t;
struct ConstantArraySlice;
class Entry {
private:
enum class Tag : uint8_t;
public:
explicit Entry(Smi smi) : smi_(smi), tag_(Tag::kSmi) {}
explicit Entry(double heap_number)
: heap_number_(heap_number), tag_(Tag::kHeapNumber) {}
explicit Entry(const AstRawString* raw_string)
: raw_string_(raw_string), tag_(Tag::kRawString) {}
explicit Entry(AstBigInt bigint) : bigint_(bigint), tag_(Tag::kBigInt) {}
explicit Entry(const Scope* scope) : scope_(scope), tag_(Tag::kScope) {}
#define CONSTRUCT_ENTRY(NAME, LOWER_NAME) \
static Entry NAME() { return Entry(Tag::k##NAME); }
SINGLETON_CONSTANT_ENTRY_TYPES(CONSTRUCT_ENTRY)
#undef CONSTRUCT_ENTRY
static Entry Deferred() { return Entry(Tag::kDeferred); }
static Entry UninitializedJumpTableSmi() {
return Entry(Tag::kUninitializedJumpTableSmi);
}
bool IsDeferred() const { return tag_ == Tag::kDeferred; }
bool IsJumpTableEntry() const {
return tag_ == Tag::kUninitializedJumpTableSmi ||
tag_ == Tag::kJumpTableSmi;
}
void SetDeferred(Handle<Object> handle) {
DCHECK_EQ(tag_, Tag::kDeferred);
tag_ = Tag::kHandle;
handle_ = handle;
}
void SetJumpTableSmi(Smi smi) {
DCHECK_EQ(tag_, Tag::kUninitializedJumpTableSmi);
tag_ = Tag::kJumpTableSmi;
smi_ = smi;
}
Handle<Object> ToHandle(Isolate* isolate) const;
private:
explicit Entry(Tag tag) : tag_(tag) {}
union {
Handle<Object> handle_;
Smi smi_;
double heap_number_;
const AstRawString* raw_string_;
AstBigInt bigint_;
const Scope* scope_;
};
enum class Tag : uint8_t {
kDeferred,
kHandle,
kSmi,
kRawString,
kHeapNumber,
kBigInt,
kScope,
kUninitializedJumpTableSmi,
kJumpTableSmi,
#define ENTRY_TAG(NAME, ...) k##NAME,
SINGLETON_CONSTANT_ENTRY_TYPES(ENTRY_TAG)
#undef ENTRY_TAG
} tag_;
#if DEBUG
// Required by CheckAllElementsAreUnique().
friend struct ConstantArraySlice;
#endif
};
index_t AllocateIndex(Entry constant_entry);
index_t AllocateIndexArray(Entry constant_entry, size_t size);
index_t AllocateReservedEntry(Smi value);
struct ConstantArraySlice final : public ZoneObject {
ConstantArraySlice(Zone* zone, size_t start_index, size_t capacity,
OperandSize operand_size);
void Reserve();
void Unreserve();
size_t Allocate(Entry entry, size_t count = 1);
Entry& At(size_t index);
const Entry& At(size_t index) const;
#if DEBUG
void CheckAllElementsAreUnique(Isolate* isolate) const;
#endif
inline size_t available() const { return capacity() - reserved() - size(); }
inline size_t reserved() const { return reserved_; }
inline size_t capacity() const { return capacity_; }
inline size_t size() const { return constants_.size(); }
inline size_t start_index() const { return start_index_; }
inline size_t max_index() const { return start_index_ + capacity() - 1; }
inline OperandSize operand_size() const { return operand_size_; }
private:
const size_t start_index_;
const size_t capacity_;
size_t reserved_;
OperandSize operand_size_;
ZoneVector<Entry> constants_;
DISALLOW_COPY_AND_ASSIGN(ConstantArraySlice);
};
ConstantArraySlice* IndexToSlice(size_t index) const;
ConstantArraySlice* OperandSizeToSlice(OperandSize operand_size) const;
ConstantArraySlice* idx_slice_[3];
base::TemplateHashMapImpl<intptr_t, index_t,
base::KeyEqualityMatcher<intptr_t>,
ZoneAllocationPolicy>
constants_map_;
ZoneMap<Smi, index_t> smi_map_;
ZoneVector<std::pair<Smi, index_t>> smi_pairs_;
ZoneMap<double, index_t> heap_number_map_;
#define SINGLETON_ENTRY_FIELD(NAME, LOWER_NAME) int LOWER_NAME##_;
SINGLETON_CONSTANT_ENTRY_TYPES(SINGLETON_ENTRY_FIELD)
#undef SINGLETON_ENTRY_FIELD
Zone* zone_;
};
} // namespace interpreter
} // namespace internal
} // namespace v8
#endif // V8_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_