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/*
* Copyright (C) 2008-2019 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.
* 3. Neither the name of Apple Inc. ("Apple") 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 APPLE AND ITS 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 APPLE OR ITS 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.
*/
#pragma once
#include <wtf/Assertions.h>
#include <wtf/Vector.h>
#include <limits.h>
namespace JSC {
template<typename Traits>
class BytecodeGeneratorBase;
struct JSGeneratorTraits;
template<typename Traits>
class GenericLabel;
template<typename Traits>
class GenericBoundLabel {
using BytecodeGenerator = BytecodeGeneratorBase<Traits>;
using Label = GenericLabel<Traits>;
public:
GenericBoundLabel()
: m_type(Offset)
, m_generator(nullptr)
, m_target(0)
{ }
explicit GenericBoundLabel(int offset)
: m_type(Offset)
, m_generator(nullptr)
, m_target(offset)
{ }
GenericBoundLabel(BytecodeGenerator* generator, Label* label)
: m_type(GeneratorForward)
, m_generator(generator)
, m_label(label)
{ }
GenericBoundLabel(BytecodeGenerator* generator, int offset)
: m_type(GeneratorBackward)
, m_generator(generator)
, m_target(offset)
{ }
int target()
{
switch (m_type) {
case Offset:
return m_target;
case GeneratorBackward:
return m_target - m_generator->m_writer.position();
case GeneratorForward:
return 0;
default:
RELEASE_ASSERT_NOT_REACHED();
}
}
int saveTarget()
{
if (m_type == GeneratorForward) {
m_savedTarget = m_generator->m_writer.position();
return 0;
}
m_savedTarget = target();
return m_savedTarget;
}
int commitTarget()
{
if (m_type == GeneratorForward) {
m_label->m_unresolvedJumps.append(m_savedTarget);
return 0;
}
return m_savedTarget;
}
operator int() { return target(); }
private:
enum Type : uint8_t {
Offset,
GeneratorForward,
GeneratorBackward,
};
Type m_type;
int m_savedTarget { 0 };
BytecodeGenerator* m_generator;
union {
Label* m_label;
int m_target;
};
};
template<typename Traits>
class GenericLabel {
WTF_MAKE_NONCOPYABLE(GenericLabel);
using BytecodeGenerator = BytecodeGeneratorBase<Traits>;
using BoundLabel = GenericBoundLabel<Traits>;
using JumpVector = Vector<int, 8>;
public:
GenericLabel() = default;
void setLocation(BytecodeGenerator&, unsigned location);
BoundLabel bind(BytecodeGenerator* generator)
{
m_bound = true;
if (!isForward())
return BoundLabel(generator, m_location);
return BoundLabel(generator, this);
}
BoundLabel bind(unsigned offset)
{
m_bound = true;
if (!isForward())
return BoundLabel(m_location - offset);
m_unresolvedJumps.append(offset);
return BoundLabel();
}
BoundLabel bind()
{
ASSERT(!isForward());
return bind(0u);
}
void ref() { ++m_refCount; }
void deref()
{
--m_refCount;
ASSERT(m_refCount >= 0);
}
int refCount() const { return m_refCount; }
bool hasOneRef() const { return m_refCount == 1; }
bool isForward() const { return m_location == invalidLocation; }
bool isBound() const { return m_bound; }
unsigned location() const
{
ASSERT(!isForward());
m_bound = true;
return m_location;
};
const JumpVector& unresolvedJumps() const { return m_unresolvedJumps; }
private:
friend BoundLabel;
static constexpr unsigned invalidLocation = UINT_MAX;
int m_refCount { 0 };
unsigned m_location { invalidLocation };
mutable bool m_bound { false };
mutable JumpVector m_unresolvedJumps;
};
using Label = GenericLabel<JSGeneratorTraits>;
using BoundLabel = GenericBoundLabel<JSGeneratorTraits>;
namespace Wasm {
struct GeneratorTraits;
using Label = GenericLabel<Wasm::GeneratorTraits>;
}
// This cannot be declared in the Wasm namespace as it conflicts with the
// ruby Wasm namespace when referencing it from BytecodeList.rb
using WasmBoundLabel = GenericBoundLabel<Wasm::GeneratorTraits>;
} // namespace JSC
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