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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
// 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_
#include "jspubtd.h"
#include "js/Utility.h"
namespace js {
namespace irregexp {
class RegExpStack;
// Maintains a per-thread 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 RegExpStackScope
{
public:
// Create and delete an instance to control the life-time of a growing stack.
// Initializes the stack memory area if necessary.
explicit RegExpStackScope(JSRuntime* rt);
// Releases the stack if it has grown.
~RegExpStackScope();
private:
RegExpStack* regexp_stack;
};
class RegExpStack
{
public:
// Number of allocated locations on the stack above the limit.
// No sequence of pushes must be longer that this without doing a stack-limit
// check.
static const int kStackLimitSlack = 32;
RegExpStack();
~RegExpStack();
bool init();
// Resets the buffer if it has grown beyond the default/minimum size.
void reset();
// Attempts to grow the stack by at least kStackLimitSlack entries.
bool grow();
// Address of allocated memory.
const void* addressOfBase() { return &base_; }
const void* addressOfLimit() { return &limit_; }
void* base() { return base_; }
void* limit() { return limit_; }
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, in bytes.
static const size_t kMinimumStackSize = 1 * 1024;
// Maximal size of allocated stack area, in bytes.
static const size_t kMaximumStackSize = 64 * 1024 * 1024;
// If size > 0 then base must be non-nullptr.
void* base_;
// Length in bytes of base.
size_t size;
// If the stack pointer gets above 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 above the stack limit,
// so users of the stack should check the stack limit during any
// sequence of pushes longer than this.
void* limit_;
void updateLimit() {
MOZ_ASSERT(size >= kStackLimitSlack * sizeof(void*));
limit_ = static_cast<uint8_t*>(base()) + size - (kStackLimitSlack * sizeof(void*));
}
};
bool
GrowBacktrackStack(JSRuntime* rt);
}} // namespace js::irregexp
#endif // V8_REGEXP_STACK_H_
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