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// Copyright 2011 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/heap/store-buffer.h"
#include <algorithm>
#include "src/counters.h"
#include "src/heap/incremental-marking.h"
#include "src/isolate.h"
#include "src/objects-inl.h"
#include "src/v8.h"
namespace v8 {
namespace internal {
StoreBuffer::StoreBuffer(Heap* heap)
: heap_(heap), top_(nullptr), current_(0), virtual_memory_(nullptr) {
for (int i = 0; i < kStoreBuffers; i++) {
start_[i] = nullptr;
limit_[i] = nullptr;
lazy_top_[i] = nullptr;
}
task_running_ = false;
}
void StoreBuffer::SetUp() {
// Allocate 3x the buffer size, so that we can start the new store buffer
// aligned to 2x the size. This lets us use a bit test to detect the end of
// the area.
virtual_memory_ = new base::VirtualMemory(kStoreBufferSize * 3);
uintptr_t start_as_int =
reinterpret_cast<uintptr_t>(virtual_memory_->address());
start_[0] =
reinterpret_cast<Address*>(RoundUp(start_as_int, kStoreBufferSize));
limit_[0] = start_[0] + (kStoreBufferSize / kPointerSize);
start_[1] = limit_[0];
limit_[1] = start_[1] + (kStoreBufferSize / kPointerSize);
Address* vm_limit = reinterpret_cast<Address*>(
reinterpret_cast<char*>(virtual_memory_->address()) +
virtual_memory_->size());
USE(vm_limit);
for (int i = 0; i < kStoreBuffers; i++) {
DCHECK(reinterpret_cast<Address>(start_[i]) >= virtual_memory_->address());
DCHECK(reinterpret_cast<Address>(limit_[i]) >= virtual_memory_->address());
DCHECK(start_[i] <= vm_limit);
DCHECK(limit_[i] <= vm_limit);
DCHECK((reinterpret_cast<uintptr_t>(limit_[i]) & kStoreBufferMask) == 0);
}
if (!virtual_memory_->Commit(reinterpret_cast<Address>(start_[0]),
kStoreBufferSize * kStoreBuffers,
false)) { // Not executable.
V8::FatalProcessOutOfMemory("StoreBuffer::SetUp");
}
current_ = 0;
top_ = start_[current_];
}
void StoreBuffer::TearDown() {
delete virtual_memory_;
top_ = nullptr;
for (int i = 0; i < kStoreBuffers; i++) {
start_[i] = nullptr;
limit_[i] = nullptr;
lazy_top_[i] = nullptr;
}
}
void StoreBuffer::StoreBufferOverflow(Isolate* isolate) {
isolate->heap()->store_buffer()->FlipStoreBuffers();
isolate->counters()->store_buffer_overflows()->Increment();
}
void StoreBuffer::FlipStoreBuffers() {
base::LockGuard<base::Mutex> guard(&mutex_);
int other = (current_ + 1) % kStoreBuffers;
MoveEntriesToRememberedSet(other);
lazy_top_[current_] = top_;
current_ = other;
top_ = start_[current_];
if (!task_running_) {
task_running_ = true;
Task* task = new Task(heap_->isolate(), this);
V8::GetCurrentPlatform()->CallOnBackgroundThread(
task, v8::Platform::kShortRunningTask);
}
}
void StoreBuffer::MoveEntriesToRememberedSet(int index) {
if (!lazy_top_[index]) return;
DCHECK_GE(index, 0);
DCHECK_LT(index, kStoreBuffers);
for (Address* current = start_[index]; current < lazy_top_[index];
current++) {
DCHECK(!heap_->code_space()->Contains(*current));
Address addr = *current;
Page* page = Page::FromAnyPointerAddress(heap_, addr);
if (IsDeletionAddress(addr)) {
current++;
Address end = *current;
DCHECK(!IsDeletionAddress(end));
addr = UnmarkDeletionAddress(addr);
if (end) {
RememberedSet<OLD_TO_NEW>::RemoveRange(page, addr, end,
SlotSet::PREFREE_EMPTY_BUCKETS);
} else {
RememberedSet<OLD_TO_NEW>::Remove(page, addr);
}
} else {
DCHECK(!IsDeletionAddress(addr));
RememberedSet<OLD_TO_NEW>::Insert(page, addr);
}
}
lazy_top_[index] = nullptr;
}
void StoreBuffer::MoveAllEntriesToRememberedSet() {
base::LockGuard<base::Mutex> guard(&mutex_);
int other = (current_ + 1) % kStoreBuffers;
MoveEntriesToRememberedSet(other);
lazy_top_[current_] = top_;
MoveEntriesToRememberedSet(current_);
top_ = start_[current_];
}
void StoreBuffer::ConcurrentlyProcessStoreBuffer() {
base::LockGuard<base::Mutex> guard(&mutex_);
int other = (current_ + 1) % kStoreBuffers;
MoveEntriesToRememberedSet(other);
task_running_ = false;
}
void StoreBuffer::DeleteEntry(Address start, Address end) {
// Deletions coming from the GC are directly deleted from the remembered
// set. Deletions coming from the runtime are added to the store buffer
// to allow concurrent processing.
if (heap_->gc_state() == Heap::NOT_IN_GC) {
if (top_ + sizeof(Address) * 2 > limit_[current_]) {
StoreBufferOverflow(heap_->isolate());
}
*top_ = MarkDeletionAddress(start);
top_++;
*top_ = end;
top_++;
} else {
// In GC the store buffer has to be empty at any time.
DCHECK(Empty());
Page* page = Page::FromAddress(start);
if (end) {
RememberedSet<OLD_TO_NEW>::RemoveRange(page, start, end,
SlotSet::PREFREE_EMPTY_BUCKETS);
} else {
RememberedSet<OLD_TO_NEW>::Remove(page, start);
}
}
}
} // namespace internal
} // namespace v8
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