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/*
* Copyright (C) 2013 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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.
*/
#include "config.h"
#include "VMEntryScope.h"
#include "Debugger.h"
#include "VM.h"
#include <wtf/StackBounds.h>
namespace JSC {
VMEntryScope::VMEntryScope(VM& vm, JSGlobalObject* globalObject)
: m_vm(vm)
, m_stack(wtfThreadData().stack())
, m_globalObject(globalObject)
, m_prev(vm.entryScope)
, m_prevStackLimit(vm.stackLimit())
, m_recompilationNeeded(false)
{
if (!vm.entryScope) {
#if ENABLE(ASSEMBLER)
if (ExecutableAllocator::underMemoryPressure())
vm.heap.deleteAllCompiledCode();
#endif
vm.entryScope = this;
// Reset the date cache between JS invocations to force the VM to
// observe time xone changes.
vm.resetDateCache();
}
// Clear the exception stack between entries
vm.clearExceptionStack();
void* limit = m_stack.recursionLimit(requiredCapacity());
vm.setStackLimit(limit);
}
VMEntryScope::~VMEntryScope()
{
m_vm.entryScope = m_prev;
m_vm.setStackLimit(m_prevStackLimit);
if (m_recompilationNeeded) {
if (m_vm.entryScope)
m_vm.entryScope->setRecompilationNeeded(true);
else {
if (Debugger* debugger = m_globalObject->debugger())
debugger->recompileAllJSFunctions(&m_vm);
}
}
}
size_t VMEntryScope::requiredCapacity() const
{
Interpreter* interpreter = m_vm.interpreter;
// We require a smaller stack budget for the error stack. This is to allow
// some minimal JS execution to proceed and do the work of throwing a stack
// overflow error if needed. In contrast, arbitrary JS code will require the
// more generous stack budget in order to proceed.
//
// These sizes were derived from the stack usage of a number of sites when
// layout occurs when we've already consumed most of the C stack.
const size_t requiredStack = 128 * KB;
const size_t errorModeRequiredStack = 64 * KB;
size_t requiredCapacity = interpreter->isInErrorHandlingMode() ? errorModeRequiredStack : requiredStack;
RELEASE_ASSERT(m_stack.size() >= requiredCapacity);
return requiredCapacity;
}
} // namespace JSC
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