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// Copyright 2009 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 "regexp/regexp-stack.h"
namespace v8 {
namespace internal {
RegExpStackScope::RegExpStackScope(Isolate* isolate)
: regexp_stack_(isolate->regexp_stack()) {
// Initialize, if not already initialized.
regexp_stack_->EnsureCapacity(0);
}
RegExpStackScope::~RegExpStackScope() {
// Reset the buffer if it has grown.
regexp_stack_->Reset();
}
RegExpStack::RegExpStack() : thread_local_(this), isolate_(nullptr) {}
RegExpStack::~RegExpStack() { thread_local_.FreeAndInvalidate(); }
char* RegExpStack::ArchiveStack(char* to) {
if (!thread_local_.owns_memory_) {
// Force dynamic stacks prior to archiving. Any growth will do. A dynamic
// stack is needed because stack archival & restoration rely on `memory_`
// pointing at a fixed-location backing store, whereas the static stack is
// tied to a RegExpStack instance.
EnsureCapacity(thread_local_.memory_size_ + 1);
DCHECK(thread_local_.owns_memory_);
}
size_t size = sizeof(thread_local_);
MemCopy(reinterpret_cast<void*>(to), &thread_local_, size);
thread_local_ = ThreadLocal(this);
return to + size;
}
char* RegExpStack::RestoreStack(char* from) {
size_t size = sizeof(thread_local_);
MemCopy(&thread_local_, reinterpret_cast<void*>(from), size);
return from + size;
}
void RegExpStack::Reset() { thread_local_.ResetToStaticStack(this); }
void RegExpStack::ThreadLocal::ResetToStaticStack(RegExpStack* regexp_stack) {
if (owns_memory_) DeleteArray(memory_);
memory_ = regexp_stack->static_stack_;
memory_top_ = regexp_stack->static_stack_ + kStaticStackSize;
memory_size_ = kStaticStackSize;
limit_ = reinterpret_cast<Address>(regexp_stack->static_stack_) +
kStackLimitSlack * kSystemPointerSize;
owns_memory_ = false;
}
void RegExpStack::ThreadLocal::FreeAndInvalidate() {
if (owns_memory_) DeleteArray(memory_);
// This stack may not be used after being freed. Just reset to invalid values
// to ensure we don't accidentally use old memory areas.
memory_ = nullptr;
memory_top_ = nullptr;
memory_size_ = 0;
limit_ = kMemoryTop;
}
Address RegExpStack::EnsureCapacity(size_t size) {
if (size > kMaximumStackSize) return kNullAddress;
if (size < kMinimumDynamicStackSize) size = kMinimumDynamicStackSize;
if (thread_local_.memory_size_ < size) {
byte* new_memory = NewArray<byte>(size);
if (thread_local_.memory_size_ > 0) {
// Copy original memory into top of new memory.
MemCopy(new_memory + size - thread_local_.memory_size_,
thread_local_.memory_, thread_local_.memory_size_);
if (thread_local_.owns_memory_) DeleteArray(thread_local_.memory_);
}
thread_local_.memory_ = new_memory;
thread_local_.memory_top_ = new_memory + size;
thread_local_.memory_size_ = size;
thread_local_.limit_ = reinterpret_cast<Address>(new_memory) +
kStackLimitSlack * kSystemPointerSize;
thread_local_.owns_memory_ = true;
}
return reinterpret_cast<Address>(thread_local_.memory_top_);
}
} // namespace internal
} // namespace v8
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