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// Copyright 2017 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.
#include "src/snapshot/default-deserializer-allocator.h"
#include "src/heap/heap-inl.h"
#include "src/snapshot/builtin-deserializer.h"
#include "src/snapshot/deserializer.h"
#include "src/snapshot/startup-deserializer.h"
namespace v8 {
namespace internal {
DefaultDeserializerAllocator::DefaultDeserializerAllocator(
Deserializer<DefaultDeserializerAllocator>* deserializer)
: deserializer_(deserializer) {}
// We know the space requirements before deserialization and can
// pre-allocate that reserved space. During deserialization, all we need
// to do is to bump up the pointer for each space in the reserved
// space. This is also used for fixing back references.
// We may have to split up the pre-allocation into several chunks
// because it would not fit onto a single page. We do not have to keep
// track of when to move to the next chunk. An opcode will signal this.
// Since multiple large objects cannot be folded into one large object
// space allocation, we have to do an actual allocation when deserializing
// each large object. Instead of tracking offset for back references, we
// reference large objects by index.
Address DefaultDeserializerAllocator::AllocateRaw(AllocationSpace space,
int size) {
if (space == LO_SPACE) {
AlwaysAllocateScope scope(isolate());
LargeObjectSpace* lo_space = isolate()->heap()->lo_space();
// TODO(jgruber): May be cleaner to pass in executability as an argument.
Executability exec =
static_cast<Executability>(deserializer_->source()->Get());
AllocationResult result = lo_space->AllocateRaw(size, exec);
HeapObject* obj = result.ToObjectChecked();
deserialized_large_objects_.push_back(obj);
return obj->address();
} else if (space == MAP_SPACE) {
DCHECK_EQ(Map::kSize, size);
return allocated_maps_[next_map_index_++];
} else {
DCHECK_LT(space, kNumberOfPreallocatedSpaces);
Address address = high_water_[space];
DCHECK_NE(address, kNullAddress);
high_water_[space] += size;
#ifdef DEBUG
// Assert that the current reserved chunk is still big enough.
const Heap::Reservation& reservation = reservations_[space];
int chunk_index = current_chunk_[space];
DCHECK_LE(high_water_[space], reservation[chunk_index].end);
#endif
if (space == CODE_SPACE) SkipList::Update(address, size);
return address;
}
}
Address DefaultDeserializerAllocator::Allocate(AllocationSpace space,
int size) {
Address address;
HeapObject* obj;
if (next_alignment_ != kWordAligned) {
const int reserved = size + Heap::GetMaximumFillToAlign(next_alignment_);
address = AllocateRaw(space, reserved);
obj = HeapObject::FromAddress(address);
// If one of the following assertions fails, then we are deserializing an
// aligned object when the filler maps have not been deserialized yet.
// We require filler maps as padding to align the object.
Heap* heap = isolate()->heap();
DCHECK(ReadOnlyRoots(heap).free_space_map()->IsMap());
DCHECK(ReadOnlyRoots(heap).one_pointer_filler_map()->IsMap());
DCHECK(ReadOnlyRoots(heap).two_pointer_filler_map()->IsMap());
obj = heap->AlignWithFiller(obj, size, reserved, next_alignment_);
address = obj->address();
next_alignment_ = kWordAligned;
return address;
} else {
return AllocateRaw(space, size);
}
}
void DefaultDeserializerAllocator::MoveToNextChunk(AllocationSpace space) {
DCHECK_LT(space, kNumberOfPreallocatedSpaces);
uint32_t chunk_index = current_chunk_[space];
const Heap::Reservation& reservation = reservations_[space];
// Make sure the current chunk is indeed exhausted.
CHECK_EQ(reservation[chunk_index].end, high_water_[space]);
// Move to next reserved chunk.
chunk_index = ++current_chunk_[space];
CHECK_LT(chunk_index, reservation.size());
high_water_[space] = reservation[chunk_index].start;
}
HeapObject* DefaultDeserializerAllocator::GetMap(uint32_t index) {
DCHECK_LT(index, next_map_index_);
return HeapObject::FromAddress(allocated_maps_[index]);
}
HeapObject* DefaultDeserializerAllocator::GetLargeObject(uint32_t index) {
DCHECK_LT(index, deserialized_large_objects_.size());
return deserialized_large_objects_[index];
}
HeapObject* DefaultDeserializerAllocator::GetObject(AllocationSpace space,
uint32_t chunk_index,
uint32_t chunk_offset) {
DCHECK_LT(space, kNumberOfPreallocatedSpaces);
DCHECK_LE(chunk_index, current_chunk_[space]);
Address address = reservations_[space][chunk_index].start + chunk_offset;
if (next_alignment_ != kWordAligned) {
int padding = Heap::GetFillToAlign(address, next_alignment_);
next_alignment_ = kWordAligned;
DCHECK(padding == 0 || HeapObject::FromAddress(address)->IsFiller());
address += padding;
}
return HeapObject::FromAddress(address);
}
void DefaultDeserializerAllocator::DecodeReservation(
std::vector<SerializedData::Reservation> res) {
DCHECK_EQ(0, reservations_[FIRST_SPACE].size());
int current_space = FIRST_SPACE;
for (auto& r : res) {
reservations_[current_space].push_back(
{r.chunk_size(), kNullAddress, kNullAddress});
if (r.is_last()) current_space++;
}
DCHECK_EQ(kNumberOfSpaces, current_space);
for (int i = 0; i < kNumberOfPreallocatedSpaces; i++) current_chunk_[i] = 0;
}
bool DefaultDeserializerAllocator::ReserveSpace() {
#ifdef DEBUG
for (int i = FIRST_SPACE; i < kNumberOfSpaces; ++i) {
DCHECK_GT(reservations_[i].size(), 0);
}
#endif // DEBUG
DCHECK(allocated_maps_.empty());
if (!isolate()->heap()->ReserveSpace(reservations_, &allocated_maps_)) {
return false;
}
for (int i = 0; i < kNumberOfPreallocatedSpaces; i++) {
high_water_[i] = reservations_[i][0].start;
}
return true;
}
// static
bool DefaultDeserializerAllocator::ReserveSpace(
StartupDeserializer* startup_deserializer,
BuiltinDeserializer* builtin_deserializer) {
Isolate* isolate = startup_deserializer->isolate();
// Create a set of merged reservations to reserve space in one go.
// The BuiltinDeserializer's reservations are ignored, since our actual
// requirements vary based on whether lazy deserialization is enabled.
// Instead, we manually determine the required code-space.
Heap::Reservation merged_reservations[kNumberOfSpaces];
for (int i = FIRST_SPACE; i < kNumberOfSpaces; i++) {
merged_reservations[i] =
startup_deserializer->allocator()->reservations_[i];
}
Heap::Reservation builtin_reservations =
builtin_deserializer->allocator()
->CreateReservationsForEagerBuiltinsAndHandlers();
DCHECK(!builtin_reservations.empty());
for (const auto& c : builtin_reservations) {
merged_reservations[CODE_SPACE].push_back(c);
}
if (!isolate->heap()->ReserveSpace(
merged_reservations,
&startup_deserializer->allocator()->allocated_maps_)) {
return false;
}
DisallowHeapAllocation no_allocation;
// Distribute the successful allocations between both deserializers.
// There's nothing to be done here except for code space.
{
const int num_builtin_reservations =
static_cast<int>(builtin_reservations.size());
for (int i = num_builtin_reservations - 1; i >= 0; i--) {
const auto& c = merged_reservations[CODE_SPACE].back();
DCHECK_EQ(c.size, builtin_reservations[i].size);
DCHECK_EQ(c.size, c.end - c.start);
builtin_reservations[i].start = c.start;
builtin_reservations[i].end = c.end;
merged_reservations[CODE_SPACE].pop_back();
}
builtin_deserializer->allocator()->InitializeFromReservations(
builtin_reservations);
}
// Write back startup reservations.
for (int i = FIRST_SPACE; i < kNumberOfSpaces; i++) {
startup_deserializer->allocator()->reservations_[i].swap(
merged_reservations[i]);
}
for (int i = FIRST_SPACE; i < kNumberOfPreallocatedSpaces; i++) {
startup_deserializer->allocator()->high_water_[i] =
startup_deserializer->allocator()->reservations_[i][0].start;
}
return true;
}
bool DefaultDeserializerAllocator::ReservationsAreFullyUsed() const {
for (int space = 0; space < kNumberOfPreallocatedSpaces; space++) {
const uint32_t chunk_index = current_chunk_[space];
if (reservations_[space].size() != chunk_index + 1) {
return false;
}
if (reservations_[space][chunk_index].end != high_water_[space]) {
return false;
}
}
return (allocated_maps_.size() == next_map_index_);
}
void DefaultDeserializerAllocator::
RegisterDeserializedObjectsForBlackAllocation() {
isolate()->heap()->RegisterDeserializedObjectsForBlackAllocation(
reservations_, deserialized_large_objects_, allocated_maps_);
}
Isolate* DefaultDeserializerAllocator::isolate() const {
return deserializer_->isolate();
}
} // namespace internal
} // namespace v8