src/objects.h - Issue 2101002: Cardmarking writebarrier.

Unified Diff: src/objects.h

Issue 2101002: Cardmarking writebarrier. (Closed)

Patch Set: fixed review comments Created 10 years, 7 months ago

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Index: src/objects.h

diff --git a/src/objects.h b/src/objects.h

index 8b114a64ffd11fce213b353a3b23547d1628f65c..3d37e721d7de67b8b0dbf87b6b172022154a5a2a 100644

--- a/src/objects.h

+++ b/src/objects.h

@@ -54,29 +54,28 @@

// - JSGlobalObject

// - JSBuiltinsObject

// - JSGlobalProxy

-// - JSValue

-// - Array

-// - ByteArray

-// - PixelArray

-// - ExternalArray

-// - ExternalByteArray

-// - ExternalUnsignedByteArray

-// - ExternalShortArray

-// - ExternalUnsignedShortArray

-// - ExternalIntArray

-// - ExternalUnsignedIntArray

-// - ExternalFloatArray

-// - FixedArray

-// - DescriptorArray

-// - HashTable

-// - Dictionary

-// - SymbolTable

-// - CompilationCacheTable

-// - CodeCacheHashTable

-// - MapCache

-// - Context

-// - GlobalContext

-// - JSFunctionResultCache

+// - JSValue

+// - ByteArray

+// - PixelArray

+// - ExternalArray

+// - ExternalByteArray

+// - ExternalUnsignedByteArray

+// - ExternalShortArray

+// - ExternalUnsignedShortArray

+// - ExternalIntArray

+// - ExternalUnsignedIntArray

+// - ExternalFloatArray

+// - FixedArray

+// - DescriptorArray

+// - HashTable

+// - Dictionary

+// - SymbolTable

+// - CompilationCacheTable

+// - CodeCacheHashTable

+// - MapCache

+// - Context

+// - GlobalContext

+// - JSFunctionResultCache

// - String

// - SeqString

// - SeqAsciiString

@@ -676,6 +675,10 @@ class Object BASE_EMBEDDED {

// Return the object's prototype (might be Heap::null_value()).

Object* GetPrototype();

+ // Tries to convert an object to an array index. Returns true and sets

+ // the output parameter if it succeeds.

+ inline bool ToArrayIndex(uint32_t* index);

// Returns true if this is a JSValue containing a string and the index is

// < the length of the string. Used to implement [] on strings.

inline bool IsStringObjectWithCharacterAt(uint32_t index);

@@ -1026,7 +1029,7 @@ class HeapObject: public Object {

// Returns the field at offset in obj, as a read/write Object* reference.

// Does no checking, and is safe to use during GC, while maps are invalid.

- // Does not update remembered sets, so should only be assigned to

+ // Does not invoke write barrier, so should only be assigned to

// during marking GC.

static inline Object** RawField(HeapObject* obj, int offset);

@@ -1046,6 +1049,7 @@ class HeapObject: public Object {

void HeapObjectPrint();

void HeapObjectVerify();

inline void VerifyObjectField(int offset);

+ inline void VerifySmiField(int offset);

void PrintHeader(const char* id);

@@ -1150,7 +1154,7 @@ class JSObject: public HeapObject {

};

// [properties]: Backing storage for properties.

- // properties is a FixedArray in the fast case, and a Dictionary in the

+ // properties is a FixedArray in the fast case and a Dictionary in the

// slow case.

DECL_ACCESSORS(properties, FixedArray) // Get and set fast properties.

inline void initialize_properties();

@@ -1158,9 +1162,9 @@ class JSObject: public HeapObject {

inline StringDictionary* property_dictionary(); // Gets slow properties.

// [elements]: The elements (properties with names that are integers).

- // elements is a FixedArray in the fast case, and a Dictionary in the slow

- // case or a PixelArray in a special case.

- DECL_ACCESSORS(elements, Array) // Get and set fast elements.

+ // elements is a FixedArray in the fast case, a Dictionary in the slow

+ // case, and a PixelArray or ExternalArray in special cases.

+ DECL_ACCESSORS(elements, HeapObject)

inline void initialize_elements();

inline ElementsKind GetElementsKind();

inline bool HasFastElements();

@@ -1577,37 +1581,13 @@ class JSObject: public HeapObject {

};

-// Abstract super class arrays. It provides length behavior.

-class Array: public HeapObject {

+// FixedArray describes fixed-sized arrays with element type Object*.

+class FixedArray: public HeapObject {

public:

// [length]: length of the array.

inline int length();

inline void set_length(int value);

- // Convert an object to an array index.

- // Returns true if the conversion succeeded.

- static inline bool IndexFromObject(Object* object, uint32_t* index);

- // Layout descriptor.

- static const int kLengthOffset = HeapObject::kHeaderSize;

- protected:

- // No code should use the Array class directly, only its subclasses.

- // Use the kHeaderSize of the appropriate subclass, which may be aligned.

- static const int kHeaderSize = kLengthOffset + kIntSize;

- static const int kAlignedSize = POINTER_SIZE_ALIGN(kHeaderSize);

- private:

- DISALLOW_IMPLICIT_CONSTRUCTORS(Array);

-};

-// FixedArray describes fixed sized arrays where element

-// type is Object*.

-class FixedArray: public Array {

- public:

// Setter and getter for elements.

inline Object* get(int index);

// Setter that uses write barrier.

@@ -1648,7 +1628,10 @@ class FixedArray: public Array {

// Casting.

static inline FixedArray* cast(Object* obj);

- static const int kHeaderSize = Array::kAlignedSize;

+ // Layout description.

+ // Length is smi tagged when it is stored.

+ static const int kLengthOffset = HeapObject::kHeaderSize;

+ static const int kHeaderSize = kLengthOffset + kPointerSize;

// Maximal allowed size, in bytes, of a single FixedArray.

// Prevents overflowing size computations, as well as extreme memory

@@ -2347,8 +2330,12 @@ class JSFunctionResultCache: public FixedArray {

// ByteArray represents fixed sized byte arrays. Used by the outside world,

// such as PCRE, and also by the memory allocator and garbage collector to

// fill in free blocks in the heap.

-class ByteArray: public Array {

+class ByteArray: public HeapObject {

public:

+ // [length]: length of the array.

+ inline int length();

+ inline void set_length(int value);

// Setter and getter.

inline byte get(int index);

inline void set(int index, byte value);

@@ -2357,7 +2344,7 @@ class ByteArray: public Array {

inline int get_int(int index);

static int SizeFor(int length) {

- return OBJECT_SIZE_ALIGN(kHeaderSize + length);

+ return OBJECT_POINTER_ALIGN(kHeaderSize + length);

}

// We use byte arrays for free blocks in the heap. Given a desired size in

// bytes that is a multiple of the word size and big enough to hold a byte

@@ -2385,9 +2372,12 @@ class ByteArray: public Array {

void ByteArrayVerify();

#endif

- // ByteArray headers are not quadword aligned.

- static const int kHeaderSize = Array::kHeaderSize;

- static const int kAlignedSize = Array::kAlignedSize;

+ // Layout description.

+ // Length is smi tagged when it is stored.

+ static const int kLengthOffset = HeapObject::kHeaderSize;

+ static const int kHeaderSize = kLengthOffset + kPointerSize;

+ static const int kAlignedSize = OBJECT_POINTER_ALIGN(kHeaderSize);

// Maximal memory consumption for a single ByteArray.

static const int kMaxSize = 512 * MB;

@@ -2406,8 +2396,12 @@ class ByteArray: public Array {

// multipage/the-canvas-element.html#canvaspixelarray

// In particular, write access clamps the value written to 0 or 255 if the

// value written is outside this range.

-class PixelArray: public Array {

+class PixelArray: public HeapObject {

public:

+ // [length]: length of the array.

+ inline int length();

+ inline void set_length(int value);

// [external_pointer]: The pointer to the external memory area backing this

// pixel array.

DECL_ACCESSORS(external_pointer, uint8_t) // Pointer to the data store.

@@ -2432,9 +2426,11 @@ class PixelArray: public Array {

static const int kMaxLength = 0x3fffffff;

// PixelArray headers are not quadword aligned.

- static const int kExternalPointerOffset = Array::kAlignedSize;

+ static const int kLengthOffset = HeapObject::kHeaderSize;

+ static const int kExternalPointerOffset =

+ POINTER_SIZE_ALIGN(kLengthOffset + kIntSize);

static const int kHeaderSize = kExternalPointerOffset + kPointerSize;

- static const int kAlignedSize = OBJECT_SIZE_ALIGN(kHeaderSize);

+ static const int kAlignedSize = OBJECT_POINTER_ALIGN(kHeaderSize);

private:

DISALLOW_IMPLICIT_CONSTRUCTORS(PixelArray);

@@ -2452,8 +2448,12 @@ class PixelArray: public Array {

// Out-of-range values passed to the setter are converted via a C

// cast, not clamping. Out-of-range indices cause exceptions to be

// raised rather than being silently ignored.

-class ExternalArray: public Array {

+class ExternalArray: public HeapObject {

public:

+ // [length]: length of the array.

+ inline int length();

+ inline void set_length(int value);

// [external_pointer]: The pointer to the external memory area backing this

// external array.

DECL_ACCESSORS(external_pointer, void) // Pointer to the data store.

@@ -2465,9 +2465,11 @@ class ExternalArray: public Array {

static const int kMaxLength = 0x3fffffff;

// ExternalArray headers are not quadword aligned.

- static const int kExternalPointerOffset = Array::kAlignedSize;

+ static const int kLengthOffset = HeapObject::kHeaderSize;

+ static const int kExternalPointerOffset =

+ POINTER_SIZE_ALIGN(kLengthOffset + kIntSize);

static const int kHeaderSize = kExternalPointerOffset + kPointerSize;

- static const int kAlignedSize = OBJECT_SIZE_ALIGN(kHeaderSize);

+ static const int kAlignedSize = OBJECT_POINTER_ALIGN(kHeaderSize);

private:

DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalArray);

@@ -3021,7 +3023,13 @@ class Map: public HeapObject {

kConstructorOffset + kPointerSize;

static const int kCodeCacheOffset = kInstanceDescriptorsOffset + kPointerSize;

static const int kPadStart = kCodeCacheOffset + kPointerSize;

- static const int kSize = MAP_SIZE_ALIGN(kPadStart);

+ static const int kSize = MAP_POINTER_ALIGN(kPadStart);

+ // Layout of pointer fields. Heap iteration code relies on them

+ // being continiously allocated.

+ static const int kPointerFieldsBeginOffset = Map::kPrototypeOffset;

+ static const int kPointerFieldsEndOffset =

+ Map::kCodeCacheOffset + kPointerSize;

// Byte offsets within kInstanceSizesOffset.

static const int kInstanceSizeOffset = kInstanceSizesOffset + 0;

@@ -3333,23 +3341,64 @@ class SharedFunctionInfo: public HeapObject {

static const int kInferredNameOffset = kDebugInfoOffset + kPointerSize;

static const int kThisPropertyAssignmentsOffset =

kInferredNameOffset + kPointerSize;

- // Integer fields.

+#if V8_HOST_ARCH_32_BIT

+ // Smi fields.

static const int kLengthOffset =

kThisPropertyAssignmentsOffset + kPointerSize;

- static const int kFormalParameterCountOffset = kLengthOffset + kIntSize;

+ static const int kFormalParameterCountOffset = kLengthOffset + kPointerSize;

static const int kExpectedNofPropertiesOffset =

- kFormalParameterCountOffset + kIntSize;

- static const int kNumLiteralsOffset = kExpectedNofPropertiesOffset + kIntSize;

+ kFormalParameterCountOffset + kPointerSize;

+ static const int kNumLiteralsOffset =

+ kExpectedNofPropertiesOffset + kPointerSize;

static const int kStartPositionAndTypeOffset =

+ kNumLiteralsOffset + kPointerSize;

+ static const int kEndPositionOffset =

+ kStartPositionAndTypeOffset + kPointerSize;

+ static const int kFunctionTokenPositionOffset =

+ kEndPositionOffset + kPointerSize;

+ static const int kCompilerHintsOffset =

+ kFunctionTokenPositionOffset + kPointerSize;

+ static const int kThisPropertyAssignmentsCountOffset =

+ kCompilerHintsOffset + kPointerSize;

+ // Total size.

+ static const int kSize = kThisPropertyAssignmentsCountOffset + kPointerSize;

+#else

+ // The only reason to use smi fields instead of int fields

+ // is to allow interation without maps decoding during

+ // garbage collections.

+ // To avoid wasting space on 64-bit architectures we use

+ // the following trick: we group integer fields into pairs

+ // First integer in each pair is shifted left by 1.

+ // By doing this we guarantee that LSB of each kPointerSize aligned

+ // word is not set and thus this word cannot be treated as pointer

+ // to HeapObject during old space traversal.

+ static const int kLengthOffset =

+ kThisPropertyAssignmentsOffset + kPointerSize;

+ static const int kFormalParameterCountOffset =

+ kLengthOffset + kIntSize;

+ static const int kExpectedNofPropertiesOffset =

+ kFormalParameterCountOffset + kIntSize;

+ static const int kNumLiteralsOffset =

+ kExpectedNofPropertiesOffset + kIntSize;

+ static const int kEndPositionOffset =

kNumLiteralsOffset + kIntSize;

- static const int kEndPositionOffset = kStartPositionAndTypeOffset + kIntSize;

- static const int kFunctionTokenPositionOffset = kEndPositionOffset + kIntSize;

+ static const int kStartPositionAndTypeOffset =

+ kEndPositionOffset + kIntSize;

+ static const int kFunctionTokenPositionOffset =

+ kStartPositionAndTypeOffset + kIntSize;

static const int kCompilerHintsOffset =

kFunctionTokenPositionOffset + kIntSize;

static const int kThisPropertyAssignmentsCountOffset =

kCompilerHintsOffset + kIntSize;

// Total size.

static const int kSize = kThisPropertyAssignmentsCountOffset + kIntSize;

+#endif

static const int kAlignedSize = POINTER_SIZE_ALIGN(kSize);

private:

@@ -4094,8 +4143,7 @@ class String: public HeapObject {

// Layout description.

static const int kLengthOffset = HeapObject::kHeaderSize;

static const int kHashFieldOffset = kLengthOffset + kPointerSize;

- static const int kSize = kHashFieldOffset + kIntSize;

- // Notice: kSize is not pointer-size aligned if pointers are 64-bit.

+ static const int kSize = kHashFieldOffset + kPointerSize;

// Maximum number of characters to consider when trying to convert a string

// value into an array index.

@@ -4114,7 +4162,7 @@ class String: public HeapObject {

// whether a hash code has been computed. If the hash code has been

// computed the 2nd bit tells whether the string can be used as an

// array index.

- static const int kHashComputedMask = 1;

+ static const int kHashNotComputedMask = 1;

static const int kIsArrayIndexMask = 1 << 1;

static const int kNofLengthBitFields = 2;

@@ -4132,9 +4180,14 @@ class String: public HeapObject {

static const int kArrayIndexHashMask = (1 << kArrayIndexHashLengthShift) - 1;

static const int kArrayIndexValueBits =

kArrayIndexHashLengthShift - kHashShift;

+ static const int kArrayIndexValueMask =

+ ((1 << kArrayIndexValueBits) - 1) << kHashShift;

// Value of empty hash field indicating that the hash is not computed.

- static const int kEmptyHashField = 0;

+ static const int kEmptyHashField = kHashNotComputedMask;

+ // Value of hash field containing computed hash equal to zero.

+ static const int kZeroHash = 0;

// Maximal string length.

static const int kMaxLength = (1 << (32 - 2)) - 1;

@@ -4197,6 +4250,8 @@ class String: public HeapObject {

unsigned max_chars);

private:

+ static inline bool IsHashFieldComputed(uint32_t field);

// Slow case of String::Equals. This implementation works on any strings

// but it is most efficient on strings that are almost flat.

bool SlowEquals(String* other);

@@ -4246,7 +4301,7 @@ class SeqAsciiString: public SeqString {

// Computes the size for an AsciiString instance of a given length.

static int SizeFor(int length) {

- return OBJECT_SIZE_ALIGN(kHeaderSize + length * kCharSize);

+ return OBJECT_POINTER_ALIGN(kHeaderSize + length * kCharSize);

}

// Layout description.

@@ -4298,7 +4353,7 @@ class SeqTwoByteString: public SeqString {

// Computes the size for a TwoByteString instance of a given length.

static int SizeFor(int length) {

- return OBJECT_SIZE_ALIGN(kHeaderSize + length * kShortSize);

+ return OBJECT_POINTER_ALIGN(kHeaderSize + length * kShortSize);

}

// Layout description.

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