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UnlinkedMetadataTable: hold only the offset table while no CodeBlock is linked #496

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UnlinkedMetadataTable: hold only the offset table while no CodeBlock is linked #496

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16 changes: 5 additions & 11 deletions Source/JavaScriptCore/bytecode/UnlinkedMetadataTable.cpp
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Expand Up @@ -148,23 +148,17 @@ void UnlinkedMetadataTable::finalize()
});
#endif

unsigned valueProfileSize = m_numValueProfiles * sizeof(ValueProfile);
ASSERT(!m_isLinked);
if (m_is32Bit) {
// offset already accounts for s_offset16TableSize
uint8_t* newBuffer = reinterpret_cast_ptr<uint8_t*>(MetadataTableMalloc::malloc(valueProfileSize + sizeof(LinkingData) + s_offset32TableSize + offset));
memset(newBuffer, 0, valueProfileSize + sizeof(LinkingData) + s_offset16TableSize);
memset(newBuffer + valueProfileSize + sizeof(LinkingData) + s_offset16TableSize + s_offset32TableSize, 0, offset - s_offset16TableSize);
Offset32* buffer = std::bit_cast<Offset32*>(newBuffer + valueProfileSize + sizeof(LinkingData) + s_offset16TableSize);
uint8_t* newBuffer = reinterpret_cast_ptr<uint8_t*>(MetadataTableMalloc::zeroedMalloc(s_offset16TableSize + s_offset32TableSize));
Offset32* buffer = std::bit_cast<Offset32*>(newBuffer + s_offset16TableSize);
for (unsigned i = 0; i < s_offsetTableEntries; ++i)
buffer[i] = preprocessBuffer()[i] + s_offset32TableSize;
MetadataTableMalloc::free(m_rawBuffer);
m_rawBuffer = newBuffer;
} else {
// offset already accounts for s_offset16TableSize
uint8_t* newBuffer = reinterpret_cast_ptr<uint8_t*>(MetadataTableMalloc::malloc(valueProfileSize + sizeof(LinkingData) + offset));
memset(newBuffer, 0, valueProfileSize + sizeof(LinkingData));
memset(newBuffer + valueProfileSize + sizeof(LinkingData) + s_offset16TableSize, 0, offset - s_offset16TableSize);
Offset16* buffer = std::bit_cast<Offset16*>(newBuffer + valueProfileSize + sizeof(LinkingData));
uint8_t* newBuffer = reinterpret_cast_ptr<uint8_t*>(MetadataTableMalloc::malloc(s_offset16TableSize));
Offset16* buffer = std::bit_cast<Offset16*>(newBuffer);
for (unsigned i = 0; i < s_offsetTableEntries; ++i)
buffer[i] = preprocessBuffer()[i];
MetadataTableMalloc::free(m_rawBuffer);
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14 changes: 8 additions & 6 deletions Source/JavaScriptCore/bytecode/UnlinkedMetadataTable.h
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Expand Up @@ -105,12 +105,12 @@ class UnlinkedMetadataTable : public ThreadSafeRefCounted<UnlinkedMetadataTable>
enum EmptyTag { Empty };

UnlinkedMetadataTable();
UnlinkedMetadataTable(bool is32Bit, unsigned numValueProfiles, unsigned lastOffset);
UnlinkedMetadataTable(bool is32Bit, unsigned numValueProfiles);
UnlinkedMetadataTable(EmptyTag);

static Ref<UnlinkedMetadataTable> create(bool is32Bit, unsigned numValueProfiles, unsigned lastOffset)
static Ref<UnlinkedMetadataTable> create(bool is32Bit, unsigned numValueProfiles)
{
return adoptRef(*new UnlinkedMetadataTable(is32Bit, numValueProfiles, lastOffset));
return adoptRef(*new UnlinkedMetadataTable(is32Bit, numValueProfiles));
}

static Ref<UnlinkedMetadataTable> empty()
Expand Down Expand Up @@ -151,18 +151,20 @@ class UnlinkedMetadataTable : public ThreadSafeRefCounted<UnlinkedMetadataTable>
// Then, s_offset16TableSize and s_offset16TableSize + s_offset32TableSize offer the same alignment characteristics for subsequent Metadata.
static constexpr unsigned s_offset32TableSize = roundUpToMultipleOf<s_maxMetadataAlignment>(s_offsetTableEntries * sizeof(Offset32));

void* buffer() const { return m_rawBuffer + m_numValueProfiles * sizeof(ValueProfile) + sizeof(LinkingData); }
// While no MetadataTable shares m_rawBuffer (!m_isLinked), the buffer holds only the offset table.
unsigned prefixSize() const { return m_isLinked ? m_numValueProfiles * sizeof(ValueProfile) + sizeof(LinkingData) : 0; }
void* buffer() const { return m_rawBuffer + prefixSize(); }
Offset32* preprocessBuffer() const { return std::bit_cast<Offset32*>(m_rawBuffer); }

Offset16* offsetTable16() const
{
ASSERT(!m_is32Bit);
return std::bit_cast<Offset16*>(m_rawBuffer + m_numValueProfiles * sizeof(ValueProfile) + sizeof(LinkingData));
return std::bit_cast<Offset16*>(m_rawBuffer + prefixSize());
}
Offset32* offsetTable32() const
{
ASSERT(m_is32Bit);
return std::bit_cast<Offset32*>(m_rawBuffer + m_numValueProfiles * sizeof(ValueProfile) + sizeof(LinkingData) + s_offset16TableSize);
return std::bit_cast<Offset32*>(m_rawBuffer + prefixSize() + s_offset16TableSize);
}

bool m_hasMetadata : 1;
Expand Down
22 changes: 13 additions & 9 deletions Source/JavaScriptCore/bytecode/UnlinkedMetadataTableInlines.h
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Expand Up @@ -42,13 +42,15 @@ ALWAYS_INLINE UnlinkedMetadataTable::UnlinkedMetadataTable()
{
}

ALWAYS_INLINE UnlinkedMetadataTable::UnlinkedMetadataTable(bool is32Bit, unsigned numValueProfiles, unsigned lastOffset)
// A finalized table as it comes out of the bytecode cache: the caller fills in the offset table; the value-profile /
// metadata buffer is allocated at link().
ALWAYS_INLINE UnlinkedMetadataTable::UnlinkedMetadataTable(bool is32Bit, unsigned numValueProfiles)
: m_hasMetadata(true)
, m_isFinalized(false)
, m_isLinked(false)
, m_is32Bit(is32Bit)
, m_numValueProfiles(numValueProfiles)
, m_rawBuffer(static_cast<uint8_t*>(MetadataTableMalloc::zeroedMalloc((sizeof(ValueProfile) * numValueProfiles) + sizeof(LinkingData) + lastOffset)))
, m_rawBuffer(static_cast<uint8_t*>(MetadataTableMalloc::zeroedMalloc(is32Bit ? s_offset16TableSize + s_offset32TableSize : s_offset16TableSize)))
{
}

Expand Down Expand Up @@ -123,21 +125,18 @@ ALWAYS_INLINE RefPtr<MetadataTable> UnlinkedMetadataTable::link()
unsigned totalSize = this->totalSize();
unsigned offsetTableSize = this->offsetTableSize();
unsigned valueProfileSize = m_numValueProfiles * sizeof(ValueProfile);
uint8_t* buffer;
uint8_t* buffer = static_cast<uint8_t*>(MetadataTableMalloc::zeroedMalloc(sizeof(LinkingData) + totalSize));
memcpy(buffer + valueProfileSize + sizeof(LinkingData), this->buffer(), offsetTableSize);
if (!m_isLinked) {
MetadataTableMalloc::free(m_rawBuffer);
m_rawBuffer = buffer;
m_isLinked = true;
buffer = m_rawBuffer;
} else {
#if ENABLE(METADATA_STATISTICS)
MetadataStatistics::numberOfCopiesFromLinking++;
MetadataStatistics::linkingCopyMemory += sizeof(LinkingData) + totalSize;
#endif
buffer = static_cast<uint8_t*>(MetadataTableMalloc::malloc(sizeof(LinkingData) + totalSize));
memcpy(buffer + valueProfileSize + sizeof(LinkingData), m_rawBuffer + valueProfileSize + sizeof(LinkingData), offsetTableSize);
}
// FIXME: Is this needed since we'll clear the data in the CodeBlock Constructor... Plus I could see caching value profiles being profitable.
memset(buffer, 0, valueProfileSize);
memset(buffer + valueProfileSize + sizeof(LinkingData) + offsetTableSize, 0, totalSize - offsetTableSize - valueProfileSize);
return adoptRef(*new (buffer + valueProfileSize + sizeof(LinkingData)) MetadataTable(*this));
}

Expand All @@ -149,6 +148,11 @@ ALWAYS_INLINE void UnlinkedMetadataTable::unlink(MetadataTable& metadataTable)

if (metadataTable.buffer() == buffer()) {
ASSERT(m_isLinked);
unsigned offsetTableSize = this->offsetTableSize();
uint8_t* compact = static_cast<uint8_t*>(MetadataTableMalloc::malloc(offsetTableSize));
memcpy(compact, buffer(), offsetTableSize);
MetadataTableMalloc::free(m_rawBuffer);
m_rawBuffer = compact;
m_isLinked = false;
return;
}
Expand Down
2 changes: 1 addition & 1 deletion Source/JavaScriptCore/runtime/CachedTypes.cpp
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Expand Up @@ -1614,7 +1614,7 @@ class CachedMetadataTable : public CachedObject<UnlinkedMetadataTable> {
if (!m_hasMetadata)
return UnlinkedMetadataTable::empty();

Ref<UnlinkedMetadataTable> metadataTable = UnlinkedMetadataTable::create(m_is32Bit, m_numValueProfiles, m_metadata[UnlinkedMetadataTable::s_offsetTableEntries - 1]);
Ref<UnlinkedMetadataTable> metadataTable = UnlinkedMetadataTable::create(m_is32Bit, m_numValueProfiles);
metadataTable->m_isFinalized = true;
metadataTable->m_isLinked = false;
metadataTable->m_hasMetadata = m_hasMetadata;
Expand Down
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