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/*
* Copyright (C) 2015-2018 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.
*/
#pragma once
#include <wtf/Assertions.h>
#include <wtf/FastMalloc.h>
namespace JSC { namespace DFG {
class StructureAbstractValue;
} } // namespace JSC::DFG
namespace WTF {
// FIXME: This currently only works for types that are pointer-like: they should have the size
// of a pointer and like a pointer they should not have assignment operators, copy constructors,
// non-trivial default constructors, and non-trivial destructors. It may be possible to lift all
// of these restrictions. If we succeeded then this should be renamed to just TinySet.
// https://bugs.webkit.org/show_bug.cgi?id=145741
template<typename T>
class TinyPtrSet {
static_assert(sizeof(T) == sizeof(void*), "It's in the title of the class.");
public:
TinyPtrSet()
: m_pointer(0)
{
setEmpty();
}
TinyPtrSet(T element)
: m_pointer(0)
{
set(element);
}
ALWAYS_INLINE TinyPtrSet(const TinyPtrSet& other)
: m_pointer(0)
{
copyFrom(other);
}
ALWAYS_INLINE TinyPtrSet& operator=(const TinyPtrSet& other)
{
if (this == &other)
return *this;
deleteListIfNecessary();
copyFrom(other);
return *this;
}
~TinyPtrSet()
{
deleteListIfNecessary();
}
void clear()
{
deleteListIfNecessary();
setEmpty();
}
// Returns the only entry if the array has exactly one entry.
T onlyEntry() const
{
if (isThin())
return singleEntry();
OutOfLineList* list = this->list();
if (list->m_length != 1)
return T();
return list->list()[0];
}
bool isEmpty() const
{
bool result = isThin() && !singleEntry();
if (result)
ASSERT(m_pointer != reservedValue);
return result;
}
// Returns true if the value was added, or false if the value was already there.
ALWAYS_INLINE bool add(T value)
{
ASSERT(value);
if (isThin()) {
if (singleEntry() == value)
return false;
if (!singleEntry()) {
set(value);
return true;
}
OutOfLineList* list = OutOfLineList::create(defaultStartingSize);
list->m_length = 2;
list->list()[0] = singleEntry();
list->list()[1] = value;
set(list);
return true;
}
return addOutOfLine(value);
}
bool remove(T value)
{
if (isThin()) {
if (singleEntry() == value) {
setEmpty();
return true;
}
return false;
}
OutOfLineList* list = this->list();
for (unsigned i = 0; i < list->m_length; ++i) {
if (list->list()[i] != value)
continue;
list->list()[i] = list->list()[--list->m_length];
if (!list->m_length) {
OutOfLineList::destroy(list);
setEmpty();
}
return true;
}
return false;
}
bool contains(T value) const
{
if (isThin())
return singleEntry() == value;
return containsOutOfLine(value);
}
ALWAYS_INLINE bool merge(const TinyPtrSet& other)
{
if (other.isThin()) {
if (other.singleEntry())
return add(other.singleEntry());
return false;
}
return mergeOtherOutOfLine(other);
}
template<typename Functor>
void forEach(const Functor& functor) const
{
if (isThin()) {
if (!singleEntry())
return;
functor(singleEntry());
return;
}
OutOfLineList* list = this->list();
for (unsigned i = 0; i < list->m_length; ++i)
functor(list->list()[i]);
}
template<typename Functor>
void genericFilter(const Functor& functor)
{
if (isThin()) {
if (!singleEntry())
return;
if (functor(singleEntry()))
return;
clear();
return;
}
OutOfLineList* list = this->list();
for (unsigned i = 0; i < list->m_length; ++i) {
if (functor(list->list()[i]))
continue;
list->list()[i--] = list->list()[--list->m_length];
}
if (!list->m_length)
clear();
}
void filter(const TinyPtrSet& other)
{
if (other.isThin()) {
if (!other.singleEntry() || !contains(other.singleEntry()))
clear();
else {
clear();
set(other.singleEntry());
}
return;
}
genericFilter([&] (T value) { return other.containsOutOfLine(value); });
}
void exclude(const TinyPtrSet& other)
{
if (other.isThin()) {
if (other.singleEntry())
remove(other.singleEntry());
return;
}
genericFilter([&] (T value) { return !other.containsOutOfLine(value); });
}
bool isSubsetOf(const TinyPtrSet& other) const
{
if (isThin()) {
if (!singleEntry())
return true;
return other.contains(singleEntry());
}
if (other.isThin()) {
if (!other.singleEntry())
return false;
OutOfLineList* list = this->list();
if (list->m_length >= 2)
return false;
if (list->list()[0] == other.singleEntry())
return true;
return false;
}
OutOfLineList* list = this->list();
for (unsigned i = 0; i < list->m_length; ++i) {
if (!other.containsOutOfLine(list->list()[i]))
return false;
}
return true;
}
bool isSupersetOf(const TinyPtrSet& other) const
{
return other.isSubsetOf(*this);
}
bool overlaps(const TinyPtrSet& other) const
{
if (isThin()) {
if (!singleEntry())
return false;
return other.contains(singleEntry());
}
if (other.isThin()) {
if (!other.singleEntry())
return false;
return containsOutOfLine(other.singleEntry());
}
OutOfLineList* list = this->list();
for (unsigned i = 0; i < list->m_length; ++i) {
if (other.containsOutOfLine(list->list()[i]))
return true;
}
return false;
}
size_t size() const
{
if (isThin())
return !!singleEntry();
return list()->m_length;
}
T at(size_t i) const
{
if (isThin()) {
ASSERT(!i);
ASSERT(singleEntry());
return singleEntry();
}
ASSERT(i < list()->m_length);
return list()->list()[i];
}
T operator[](size_t i) const { return at(i); }
T last() const
{
if (isThin()) {
ASSERT(singleEntry());
return singleEntry();
}
return list()->list()[list()->m_length - 1];
}
class iterator {
public:
iterator()
: m_set(nullptr)
, m_index(0)
{
}
iterator(const TinyPtrSet* set, size_t index)
: m_set(set)
, m_index(index)
{
}
T operator*() const { return m_set->at(m_index); }
iterator& operator++()
{
m_index++;
return *this;
}
bool operator==(const iterator& other) const { return m_index == other.m_index; }
bool operator!=(const iterator& other) const { return !(*this == other); }
private:
const TinyPtrSet* m_set;
size_t m_index;
};
iterator begin() const { return iterator(this, 0); }
iterator end() const { return iterator(this, size()); }
bool operator==(const TinyPtrSet& other) const
{
if (size() != other.size())
return false;
return isSubsetOf(other);
}
bool operator!=(const TinyPtrSet& other) const
{
return !(*this == other);
}
private:
friend class JSC::DFG::StructureAbstractValue;
static const uintptr_t fatFlag = 1;
static const uintptr_t reservedFlag = 2;
static const uintptr_t flags = fatFlag | reservedFlag;
static const uintptr_t reservedValue = 4;
static const unsigned defaultStartingSize = 4;
NEVER_INLINE bool addOutOfLine(T value)
{
OutOfLineList* list = this->list();
for (unsigned i = 0; i < list->m_length; ++i) {
if (list->list()[i] == value)
return false;
}
if (list->m_length < list->m_capacity) {
list->list()[list->m_length++] = value;
return true;
}
OutOfLineList* newList = OutOfLineList::create(list->m_capacity * 2);
newList->m_length = list->m_length + 1;
for (unsigned i = list->m_length; i--;)
newList->list()[i] = list->list()[i];
newList->list()[list->m_length] = value;
OutOfLineList::destroy(list);
set(newList);
return true;
}
NEVER_INLINE bool mergeOtherOutOfLine(const TinyPtrSet& other)
{
OutOfLineList* list = other.list();
if (list->m_length >= 2) {
if (isThin()) {
OutOfLineList* myNewList = OutOfLineList::create(
list->m_length + !!singleEntry());
if (singleEntry()) {
myNewList->m_length = 1;
myNewList->list()[0] = singleEntry();
}
set(myNewList);
}
bool changed = false;
for (unsigned i = 0; i < list->m_length; ++i)
changed |= addOutOfLine(list->list()[i]);
return changed;
}
ASSERT(list->m_length);
return add(list->list()[0]);
}
bool containsOutOfLine(T value) const
{
OutOfLineList* list = this->list();
for (unsigned i = 0; i < list->m_length; ++i) {
if (list->list()[i] == value)
return true;
}
return false;
}
ALWAYS_INLINE void copyFrom(const TinyPtrSet& other)
{
if (other.isThin() || other.m_pointer == reservedValue) {
bool value = getReservedFlag();
m_pointer = other.m_pointer;
setReservedFlag(value);
return;
}
copyFromOutOfLine(other);
}
NEVER_INLINE void copyFromOutOfLine(const TinyPtrSet& other)
{
ASSERT(!other.isThin() && other.m_pointer != reservedValue);
OutOfLineList* otherList = other.list();
OutOfLineList* myList = OutOfLineList::create(otherList->m_length);
myList->m_length = otherList->m_length;
for (unsigned i = otherList->m_length; i--;)
myList->list()[i] = otherList->list()[i];
set(myList);
}
class OutOfLineList {
public:
static OutOfLineList* create(unsigned capacity)
{
return new (NotNull, fastMalloc(sizeof(OutOfLineList) + capacity * sizeof(T))) OutOfLineList(0, capacity);
}
static void destroy(OutOfLineList* list)
{
fastFree(list);
}
T* list() { return bitwise_cast<T*>(this + 1); }
OutOfLineList(unsigned length, unsigned capacity)
: m_length(length)
, m_capacity(capacity)
{
}
unsigned m_length;
unsigned m_capacity;
};
ALWAYS_INLINE void deleteListIfNecessary()
{
if (!isThin()) {
ASSERT(m_pointer != reservedValue);
OutOfLineList::destroy(list());
}
}
bool isThin() const { return !(m_pointer & fatFlag); }
void* pointer() const
{
return bitwise_cast<void*>(m_pointer & ~flags);
}
T singleEntry() const
{
ASSERT(isThin());
return bitwise_cast<T>(pointer());
}
OutOfLineList* list() const
{
ASSERT(!isThin());
return static_cast<OutOfLineList*>(pointer());
}
void set(T value)
{
set(bitwise_cast<uintptr_t>(value), true);
}
void set(OutOfLineList* list)
{
set(bitwise_cast<uintptr_t>(list), false);
}
void setEmpty()
{
set(0, true);
}
void set(uintptr_t pointer, bool singleEntry)
{
m_pointer = pointer | (singleEntry ? 0 : fatFlag) | (m_pointer & reservedFlag);
}
bool getReservedFlag() const { return m_pointer & reservedFlag; }
void setReservedFlag(bool value)
{
if (value)
m_pointer |= reservedFlag;
else
m_pointer &= ~reservedFlag;
}
uintptr_t m_pointer;
};
} // namespace WTF
using WTF::TinyPtrSet;