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// Copyright 2009 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_REGEXP_STACK_H_
#define V8_REGEXP_STACK_H_
namespace v8 {
namespace internal {
// Maintains a per-v8thread stack area that can be used by irregexp
// implementation for its backtracking stack.
// Since there is only one stack area, the Irregexp implementation is not
// re-entrant. I.e., no regular expressions may be executed in the same thread
// during a preempted Irregexp execution.
class RegExpStack {
public:
// Number of allocated locations on the stack below the limit.
// No sequence of pushes must be longer that this without doing a stack-limit
// check.
static const int kStackLimitSlack = 32;
// Create and delete an instance to control the life-time of a growing stack.
RegExpStack(); // Initializes the stack memory area if necessary.
~RegExpStack(); // Releases the stack if it has grown.
// Gives the top of the memory used as stack.
static Address stack_base() {
ASSERT(thread_local_.memory_size_ != 0);
return thread_local_.memory_ + thread_local_.memory_size_;
}
// The total size of the memory allocated for the stack.
static size_t stack_capacity() { return thread_local_.memory_size_; }
// If the stack pointer gets below the limit, we should react and
// either grow the stack or report an out-of-stack exception.
// There is only a limited number of locations below the stack limit,
// so users of the stack should check the stack limit during any
// sequence of pushes longer that this.
static Address* limit_address() { return &(thread_local_.limit_); }
// Ensures that there is a memory area with at least the specified size.
// If passing zero, the default/minimum size buffer is allocated.
static Address EnsureCapacity(size_t size);
// Thread local archiving.
static size_t ArchiveSpacePerThread() { return sizeof(thread_local_); }
static char* ArchiveStack(char* to);
static char* RestoreStack(char* from);
private:
// Artificial limit used when no memory has been allocated.
static const uintptr_t kMemoryTop = static_cast<uintptr_t>(-1);
// Minimal size of allocated stack area.
static const size_t kMinimumStackSize = 1 * KB;
// Maximal size of allocated stack area.
static const size_t kMaximumStackSize = 64 * MB;
// Structure holding the allocated memory, size and limit.
struct ThreadLocal {
ThreadLocal()
: memory_(NULL),
memory_size_(0),
limit_(reinterpret_cast<Address>(kMemoryTop)) {}
// If memory_size_ > 0 then memory_ must be non-NULL.
Address memory_;
size_t memory_size_;
Address limit_;
};
// Resets the buffer if it has grown beyond the default/minimum size.
// After this, the buffer is either the default size, or it is empty, so
// you have to call EnsureCapacity before using it again.
static void Reset();
static ThreadLocal thread_local_;
};
}} // namespace v8::internal
#endif // V8_REGEXP_STACK_H_
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