| // Copyright 2013 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef V8_HYDROGEN_UNIQUE_H_ |
| #define V8_HYDROGEN_UNIQUE_H_ |
| |
| #include "src/handles.h" |
| #include "src/objects.h" |
| #include "src/utils.h" |
| #include "src/zone.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| |
| template <typename T> |
| class UniqueSet; |
| |
| |
| // Represents a handle to an object on the heap, but with the additional |
| // ability of checking for equality and hashing without accessing the heap. |
| // |
| // Creating a Unique<T> requires first dereferencing the handle to obtain |
| // the address of the object, which is used as the hashcode and the basis for |
| // comparison. The object can be moved later by the GC, but comparison |
| // and hashing use the old address of the object, without dereferencing it. |
| // |
| // Careful! Comparison of two Uniques is only correct if both were created |
| // in the same "era" of GC or if at least one is a non-movable object. |
| template <typename T> |
| class Unique V8_FINAL { |
| public: |
| // TODO(titzer): make private and introduce a uniqueness scope. |
| explicit Unique(Handle<T> handle) { |
| if (handle.is_null()) { |
| raw_address_ = NULL; |
| } else { |
| // This is a best-effort check to prevent comparing Unique<T>'s created |
| // in different GC eras; we require heap allocation to be disallowed at |
| // creation time. |
| // NOTE: we currently consider maps to be non-movable, so no special |
| // assurance is required for creating a Unique<Map>. |
| // TODO(titzer): other immortable immovable objects are also fine. |
| ASSERT(!AllowHeapAllocation::IsAllowed() || handle->IsMap()); |
| raw_address_ = reinterpret_cast<Address>(*handle); |
| ASSERT_NE(raw_address_, NULL); // Non-null should imply non-zero address. |
| } |
| handle_ = handle; |
| } |
| |
| // TODO(titzer): this is a hack to migrate to Unique<T> incrementally. |
| Unique(Address raw_address, Handle<T> handle) |
| : raw_address_(raw_address), handle_(handle) { } |
| |
| // Constructor for handling automatic up casting. |
| // Eg. Unique<JSFunction> can be passed when Unique<Object> is expected. |
| template <class S> Unique(Unique<S> uniq) { |
| #ifdef DEBUG |
| T* a = NULL; |
| S* b = NULL; |
| a = b; // Fake assignment to enforce type checks. |
| USE(a); |
| #endif |
| raw_address_ = uniq.raw_address_; |
| handle_ = uniq.handle_; |
| } |
| |
| template <typename U> |
| inline bool operator==(const Unique<U>& other) const { |
| ASSERT(IsInitialized() && other.IsInitialized()); |
| return raw_address_ == other.raw_address_; |
| } |
| |
| template <typename U> |
| inline bool operator!=(const Unique<U>& other) const { |
| ASSERT(IsInitialized() && other.IsInitialized()); |
| return raw_address_ != other.raw_address_; |
| } |
| |
| inline intptr_t Hashcode() const { |
| ASSERT(IsInitialized()); |
| return reinterpret_cast<intptr_t>(raw_address_); |
| } |
| |
| inline bool IsNull() const { |
| ASSERT(IsInitialized()); |
| return raw_address_ == NULL; |
| } |
| |
| inline bool IsKnownGlobal(void* global) const { |
| ASSERT(IsInitialized()); |
| return raw_address_ == reinterpret_cast<Address>(global); |
| } |
| |
| inline Handle<T> handle() const { |
| return handle_; |
| } |
| |
| template <class S> static Unique<T> cast(Unique<S> that) { |
| return Unique<T>(that.raw_address_, Handle<T>::cast(that.handle_)); |
| } |
| |
| inline bool IsInitialized() const { |
| return raw_address_ != NULL || handle_.is_null(); |
| } |
| |
| // TODO(titzer): this is a hack to migrate to Unique<T> incrementally. |
| static Unique<T> CreateUninitialized(Handle<T> handle) { |
| return Unique<T>(reinterpret_cast<Address>(NULL), handle); |
| } |
| |
| static Unique<T> CreateImmovable(Handle<T> handle) { |
| return Unique<T>(reinterpret_cast<Address>(*handle), handle); |
| } |
| |
| friend class UniqueSet<T>; // Uses internal details for speed. |
| template <class U> |
| friend class Unique; // For comparing raw_address values. |
| |
| private: |
| Unique<T>() : raw_address_(NULL) { } |
| |
| Address raw_address_; |
| Handle<T> handle_; |
| |
| friend class SideEffectsTracker; |
| }; |
| |
| |
| template <typename T> |
| class UniqueSet V8_FINAL : public ZoneObject { |
| public: |
| // Constructor. A new set will be empty. |
| UniqueSet() : size_(0), capacity_(0), array_(NULL) { } |
| |
| // Capacity constructor. A new set will be empty. |
| UniqueSet(int capacity, Zone* zone) |
| : size_(0), capacity_(capacity), |
| array_(zone->NewArray<Unique<T> >(capacity)) { |
| ASSERT(capacity <= kMaxCapacity); |
| } |
| |
| // Singleton constructor. |
| UniqueSet(Unique<T> uniq, Zone* zone) |
| : size_(1), capacity_(1), array_(zone->NewArray<Unique<T> >(1)) { |
| array_[0] = uniq; |
| } |
| |
| // Add a new element to this unique set. Mutates this set. O(|this|). |
| void Add(Unique<T> uniq, Zone* zone) { |
| ASSERT(uniq.IsInitialized()); |
| // Keep the set sorted by the {raw_address} of the unique elements. |
| for (int i = 0; i < size_; i++) { |
| if (array_[i] == uniq) return; |
| if (array_[i].raw_address_ > uniq.raw_address_) { |
| // Insert in the middle. |
| Grow(size_ + 1, zone); |
| for (int j = size_ - 1; j >= i; j--) array_[j + 1] = array_[j]; |
| array_[i] = uniq; |
| size_++; |
| return; |
| } |
| } |
| // Append the element to the the end. |
| Grow(size_ + 1, zone); |
| array_[size_++] = uniq; |
| } |
| |
| // Remove an element from this set. Mutates this set. O(|this|) |
| void Remove(Unique<T> uniq) { |
| for (int i = 0; i < size_; i++) { |
| if (array_[i] == uniq) { |
| while (++i < size_) array_[i - 1] = array_[i]; |
| size_--; |
| return; |
| } |
| } |
| } |
| |
| // Compare this set against another set. O(|this|). |
| bool Equals(const UniqueSet<T>* that) const { |
| if (that->size_ != this->size_) return false; |
| for (int i = 0; i < this->size_; i++) { |
| if (this->array_[i] != that->array_[i]) return false; |
| } |
| return true; |
| } |
| |
| // Check whether this set contains the given element. O(|this|) |
| // TODO(titzer): use binary search for large sets to make this O(log|this|) |
| template <typename U> |
| bool Contains(const Unique<U> elem) const { |
| for (int i = 0; i < this->size_; ++i) { |
| Unique<T> cand = this->array_[i]; |
| if (cand.raw_address_ >= elem.raw_address_) { |
| return cand.raw_address_ == elem.raw_address_; |
| } |
| } |
| return false; |
| } |
| |
| // Check if this set is a subset of the given set. O(|this| + |that|). |
| bool IsSubset(const UniqueSet<T>* that) const { |
| if (that->size_ < this->size_) return false; |
| int j = 0; |
| for (int i = 0; i < this->size_; i++) { |
| Unique<T> sought = this->array_[i]; |
| while (true) { |
| if (sought == that->array_[j++]) break; |
| // Fail whenever there are more elements in {this} than {that}. |
| if ((this->size_ - i) > (that->size_ - j)) return false; |
| } |
| } |
| return true; |
| } |
| |
| // Returns a new set representing the intersection of this set and the other. |
| // O(|this| + |that|). |
| UniqueSet<T>* Intersect(const UniqueSet<T>* that, Zone* zone) const { |
| if (that->size_ == 0 || this->size_ == 0) return new(zone) UniqueSet<T>(); |
| |
| UniqueSet<T>* out = new(zone) UniqueSet<T>( |
| Min(this->size_, that->size_), zone); |
| |
| int i = 0, j = 0, k = 0; |
| while (i < this->size_ && j < that->size_) { |
| Unique<T> a = this->array_[i]; |
| Unique<T> b = that->array_[j]; |
| if (a == b) { |
| out->array_[k++] = a; |
| i++; |
| j++; |
| } else if (a.raw_address_ < b.raw_address_) { |
| i++; |
| } else { |
| j++; |
| } |
| } |
| |
| out->size_ = k; |
| return out; |
| } |
| |
| // Returns a new set representing the union of this set and the other. |
| // O(|this| + |that|). |
| UniqueSet<T>* Union(const UniqueSet<T>* that, Zone* zone) const { |
| if (that->size_ == 0) return this->Copy(zone); |
| if (this->size_ == 0) return that->Copy(zone); |
| |
| UniqueSet<T>* out = new(zone) UniqueSet<T>( |
| this->size_ + that->size_, zone); |
| |
| int i = 0, j = 0, k = 0; |
| while (i < this->size_ && j < that->size_) { |
| Unique<T> a = this->array_[i]; |
| Unique<T> b = that->array_[j]; |
| if (a == b) { |
| out->array_[k++] = a; |
| i++; |
| j++; |
| } else if (a.raw_address_ < b.raw_address_) { |
| out->array_[k++] = a; |
| i++; |
| } else { |
| out->array_[k++] = b; |
| j++; |
| } |
| } |
| |
| while (i < this->size_) out->array_[k++] = this->array_[i++]; |
| while (j < that->size_) out->array_[k++] = that->array_[j++]; |
| |
| out->size_ = k; |
| return out; |
| } |
| |
| // Returns a new set representing all elements from this set which are not in |
| // that set. O(|this| * |that|). |
| UniqueSet<T>* Subtract(const UniqueSet<T>* that, Zone* zone) const { |
| if (that->size_ == 0) return this->Copy(zone); |
| |
| UniqueSet<T>* out = new(zone) UniqueSet<T>(this->size_, zone); |
| |
| int i = 0, j = 0; |
| while (i < this->size_) { |
| Unique<T> cand = this->array_[i]; |
| if (!that->Contains(cand)) { |
| out->array_[j++] = cand; |
| } |
| i++; |
| } |
| |
| out->size_ = j; |
| return out; |
| } |
| |
| // Makes an exact copy of this set. O(|this|). |
| UniqueSet<T>* Copy(Zone* zone) const { |
| UniqueSet<T>* copy = new(zone) UniqueSet<T>(this->size_, zone); |
| copy->size_ = this->size_; |
| memcpy(copy->array_, this->array_, this->size_ * sizeof(Unique<T>)); |
| return copy; |
| } |
| |
| void Clear() { |
| size_ = 0; |
| } |
| |
| inline int size() const { |
| return size_; |
| } |
| |
| inline Unique<T> at(int index) const { |
| ASSERT(index >= 0 && index < size_); |
| return array_[index]; |
| } |
| |
| private: |
| // These sets should be small, since operations are implemented with simple |
| // linear algorithms. Enforce a maximum size. |
| static const int kMaxCapacity = 65535; |
| |
| uint16_t size_; |
| uint16_t capacity_; |
| Unique<T>* array_; |
| |
| // Grow the size of internal storage to be at least {size} elements. |
| void Grow(int size, Zone* zone) { |
| CHECK(size < kMaxCapacity); // Enforce maximum size. |
| if (capacity_ < size) { |
| int new_capacity = 2 * capacity_ + size; |
| if (new_capacity > kMaxCapacity) new_capacity = kMaxCapacity; |
| Unique<T>* new_array = zone->NewArray<Unique<T> >(new_capacity); |
| if (size_ > 0) { |
| memcpy(new_array, array_, size_ * sizeof(Unique<T>)); |
| } |
| capacity_ = new_capacity; |
| array_ = new_array; |
| } |
| } |
| }; |
| |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_HYDROGEN_UNIQUE_H_ |