X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=qemu%2Fdisas%2Flibvixl%2Fvixl%2Finvalset.h;fp=qemu%2Fdisas%2Flibvixl%2Fvixl%2Finvalset.h;h=ffdc0237b47ca7d915858ecd0408b1f5d9e85d50;hb=437fd90c0250dee670290f9b714253671a990160;hp=0000000000000000000000000000000000000000;hpb=5bbd6fe9b8bab2a93e548c5a53b032d1939eec05;p=kvmfornfv.git diff --git a/qemu/disas/libvixl/vixl/invalset.h b/qemu/disas/libvixl/vixl/invalset.h new file mode 100644 index 000000000..ffdc0237b --- /dev/null +++ b/qemu/disas/libvixl/vixl/invalset.h @@ -0,0 +1,775 @@ +// Copyright 2015, ARM Limited +// 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 ARM Limited 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 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 VIXL_INVALSET_H_ +#define VIXL_INVALSET_H_ + +#include + +#include +#include + +#include "vixl/globals.h" + +namespace vixl { + +// We define a custom data structure template and its iterator as `std` +// containers do not fit the performance requirements for some of our use cases. +// +// The structure behaves like an iterable unordered set with special properties +// and restrictions. "InvalSet" stands for "Invalidatable Set". +// +// Restrictions and requirements: +// - Adding an element already present in the set is illegal. In debug mode, +// this is checked at insertion time. +// - The templated class `ElementType` must provide comparison operators so that +// `std::sort()` can be used. +// - A key must be available to represent invalid elements. +// - Elements with an invalid key must compare higher or equal to any other +// element. +// +// Use cases and performance considerations: +// Our use cases present two specificities that allow us to design this +// structure to provide fast insertion *and* fast search and deletion +// operations: +// - Elements are (generally) inserted in order (sorted according to their key). +// - A key is available to mark elements as invalid (deleted). +// The backing `std::vector` allows for fast insertions. When +// searching for an element we ensure the elements are sorted (this is generally +// the case) and perform a binary search. When deleting an element we do not +// free the associated memory immediately. Instead, an element to be deleted is +// marked with the 'invalid' key. Other methods of the container take care of +// ignoring entries marked as invalid. +// To avoid the overhead of the `std::vector` container when only few entries +// are used, a number of elements are preallocated. + +// 'ElementType' and 'KeyType' are respectively the types of the elements and +// their key. The structure only reclaims memory when safe to do so, if the +// number of elements that can be reclaimed is greater than `RECLAIM_FROM` and +// greater than ` / RECLAIM_FACTOR. +#define TEMPLATE_INVALSET_P_DECL \ + class ElementType, \ + unsigned N_PREALLOCATED_ELEMENTS, \ + class KeyType, \ + KeyType INVALID_KEY, \ + size_t RECLAIM_FROM, \ + unsigned RECLAIM_FACTOR + +#define TEMPLATE_INVALSET_P_DEF \ +ElementType, N_PREALLOCATED_ELEMENTS, \ +KeyType, INVALID_KEY, RECLAIM_FROM, RECLAIM_FACTOR + +template class InvalSetIterator; // Forward declaration. + +template class InvalSet { + public: + InvalSet(); + ~InvalSet(); + + static const size_t kNPreallocatedElements = N_PREALLOCATED_ELEMENTS; + static const KeyType kInvalidKey = INVALID_KEY; + + // It is illegal to insert an element already present in the set. + void insert(const ElementType& element); + + // Looks for the specified element in the set and - if found - deletes it. + void erase(const ElementType& element); + + // This indicates the number of (valid) elements stored in this set. + size_t size() const; + + // Returns true if no elements are stored in the set. + // Note that this does not mean the the backing storage is empty: it can still + // contain invalid elements. + bool empty() const; + + void clear(); + + const ElementType min_element(); + + // This returns the key of the minimum element in the set. + KeyType min_element_key(); + + static bool IsValid(const ElementType& element); + static KeyType Key(const ElementType& element); + static void SetKey(ElementType* element, KeyType key); + + protected: + // Returns a pointer to the element in vector_ if it was found, or NULL + // otherwise. + ElementType* Search(const ElementType& element); + + // The argument *must* point to an element stored in *this* set. + // This function is not allowed to move elements in the backing vector + // storage. + void EraseInternal(ElementType* element); + + // The elements in the range searched must be sorted. + ElementType* BinarySearch(const ElementType& element, + ElementType* start, + ElementType* end) const; + + // Sort the elements. + enum SortType { + // The 'hard' version guarantees that invalid elements are moved to the end + // of the container. + kHardSort, + // The 'soft' version only guarantees that the elements will be sorted. + // Invalid elements may still be present anywhere in the set. + kSoftSort + }; + void Sort(SortType sort_type); + + // Delete the elements that have an invalid key. The complexity is linear + // with the size of the vector. + void Clean(); + + const ElementType Front() const; + const ElementType Back() const; + + // Delete invalid trailing elements and return the last valid element in the + // set. + const ElementType CleanBack(); + + // Returns a pointer to the start or end of the backing storage. + const ElementType* StorageBegin() const; + const ElementType* StorageEnd() const; + ElementType* StorageBegin(); + ElementType* StorageEnd(); + + // Returns the index of the element within the backing storage. The element + // must belong to the backing storage. + size_t ElementIndex(const ElementType* element) const; + + // Returns the element at the specified index in the backing storage. + const ElementType* ElementAt(size_t index) const; + ElementType* ElementAt(size_t index); + + static const ElementType* FirstValidElement(const ElementType* from, + const ElementType* end); + + void CacheMinElement(); + const ElementType CachedMinElement() const; + + bool ShouldReclaimMemory() const; + void ReclaimMemory(); + + bool IsUsingVector() const { return vector_ != NULL; } + void set_sorted(bool sorted) { sorted_ = sorted; } + + // We cache some data commonly required by users to improve performance. + // We cannot cache pointers to elements as we do not control the backing + // storage. + bool valid_cached_min_; + size_t cached_min_index_; // Valid iff `valid_cached_min_` is true. + KeyType cached_min_key_; // Valid iff `valid_cached_min_` is true. + + // Indicates whether the elements are sorted. + bool sorted_; + + // This represents the number of (valid) elements in this set. + size_t size_; + + // The backing storage is either the array of preallocated elements or the + // vector. The structure starts by using the preallocated elements, and + // transitions (permanently) to using the vector once more than + // kNPreallocatedElements are used. + // Elements are only invalidated when using the vector. The preallocated + // storage always only contains valid elements. + ElementType preallocated_[kNPreallocatedElements]; + std::vector* vector_; + +#ifdef VIXL_DEBUG + // Iterators acquire and release this monitor. While a set is acquired, + // certain operations are illegal to ensure that the iterator will + // correctly iterate over the elements in the set. + int monitor_; + int monitor() const { return monitor_; } + void Acquire() { monitor_++; } + void Release() { + monitor_--; + VIXL_ASSERT(monitor_ >= 0); + } +#endif + + friend class InvalSetIterator >; + typedef ElementType _ElementType; + typedef KeyType _KeyType; +}; + + +template class InvalSetIterator { + private: + // Redefine types to mirror the associated set types. + typedef typename S::_ElementType ElementType; + typedef typename S::_KeyType KeyType; + + public: + explicit InvalSetIterator(S* inval_set); + ~InvalSetIterator(); + + ElementType* Current() const; + void Advance(); + bool Done() const; + + // Mark this iterator as 'done'. + void Finish(); + + // Delete the current element and advance the iterator to point to the next + // element. + void DeleteCurrentAndAdvance(); + + static bool IsValid(const ElementType& element); + static KeyType Key(const ElementType& element); + + protected: + void MoveToValidElement(); + + // Indicates if the iterator is looking at the vector or at the preallocated + // elements. + const bool using_vector_; + // Used when looking at the preallocated elements, or in debug mode when using + // the vector to track how many times the iterator has advanced. + size_t index_; + typename std::vector::iterator iterator_; + S* inval_set_; +}; + + +template +InvalSet::InvalSet() + : valid_cached_min_(false), + sorted_(true), size_(0), vector_(NULL) { +#ifdef VIXL_DEBUG + monitor_ = 0; +#endif +} + + +template +InvalSet::~InvalSet() { + VIXL_ASSERT(monitor_ == 0); + delete vector_; +} + + +template +void InvalSet::insert(const ElementType& element) { + VIXL_ASSERT(monitor() == 0); + VIXL_ASSERT(IsValid(element)); + VIXL_ASSERT(Search(element) == NULL); + set_sorted(empty() || (sorted_ && (element > CleanBack()))); + if (IsUsingVector()) { + vector_->push_back(element); + } else { + if (size_ < kNPreallocatedElements) { + preallocated_[size_] = element; + } else { + // Transition to using the vector. + vector_ = new std::vector(preallocated_, + preallocated_ + size_); + vector_->push_back(element); + } + } + size_++; + + if (valid_cached_min_ && (element < min_element())) { + cached_min_index_ = IsUsingVector() ? vector_->size() - 1 : size_ - 1; + cached_min_key_ = Key(element); + valid_cached_min_ = true; + } + + if (ShouldReclaimMemory()) { + ReclaimMemory(); + } +} + + +template +void InvalSet::erase(const ElementType& element) { + VIXL_ASSERT(monitor() == 0); + VIXL_ASSERT(IsValid(element)); + ElementType* local_element = Search(element); + if (local_element != NULL) { + EraseInternal(local_element); + } +} + + +template +ElementType* InvalSet::Search( + const ElementType& element) { + VIXL_ASSERT(monitor() == 0); + if (empty()) { + return NULL; + } + if (ShouldReclaimMemory()) { + ReclaimMemory(); + } + if (!sorted_) { + Sort(kHardSort); + } + if (!valid_cached_min_) { + CacheMinElement(); + } + return BinarySearch(element, ElementAt(cached_min_index_), StorageEnd()); +} + + +template +size_t InvalSet::size() const { + return size_; +} + + +template +bool InvalSet::empty() const { + return size_ == 0; +} + + +template +void InvalSet::clear() { + VIXL_ASSERT(monitor() == 0); + size_ = 0; + if (IsUsingVector()) { + vector_->clear(); + } + set_sorted(true); + valid_cached_min_ = false; +} + + +template +const ElementType InvalSet::min_element() { + VIXL_ASSERT(monitor() == 0); + VIXL_ASSERT(!empty()); + CacheMinElement(); + return *ElementAt(cached_min_index_); +} + + +template +KeyType InvalSet::min_element_key() { + VIXL_ASSERT(monitor() == 0); + if (valid_cached_min_) { + return cached_min_key_; + } else { + return Key(min_element()); + } +} + + +template +bool InvalSet::IsValid(const ElementType& element) { + return Key(element) != kInvalidKey; +} + + +template +void InvalSet::EraseInternal(ElementType* element) { + // Note that this function must be safe even while an iterator has acquired + // this set. + VIXL_ASSERT(element != NULL); + size_t deleted_index = ElementIndex(element); + if (IsUsingVector()) { + VIXL_ASSERT((&(vector_->front()) <= element) && + (element <= &(vector_->back()))); + SetKey(element, kInvalidKey); + } else { + VIXL_ASSERT((preallocated_ <= element) && + (element < (preallocated_ + kNPreallocatedElements))); + ElementType* end = preallocated_ + kNPreallocatedElements; + size_t copy_size = sizeof(*element) * (end - element - 1); + memmove(element, element + 1, copy_size); + } + size_--; + + if (valid_cached_min_ && + (deleted_index == cached_min_index_)) { + if (sorted_ && !empty()) { + const ElementType* min = FirstValidElement(element, StorageEnd()); + cached_min_index_ = ElementIndex(min); + cached_min_key_ = Key(*min); + valid_cached_min_ = true; + } else { + valid_cached_min_ = false; + } + } +} + + +template +ElementType* InvalSet::BinarySearch( + const ElementType& element, ElementType* start, ElementType* end) const { + if (start == end) { + return NULL; + } + VIXL_ASSERT(sorted_); + VIXL_ASSERT(start < end); + VIXL_ASSERT(!empty()); + + // Perform a binary search through the elements while ignoring invalid + // elements. + ElementType* elements = start; + size_t low = 0; + size_t high = (end - start) - 1; + while (low < high) { + // Find valid bounds. + while (!IsValid(elements[low]) && (low < high)) ++low; + while (!IsValid(elements[high]) && (low < high)) --high; + VIXL_ASSERT(low <= high); + // Avoid overflow when computing the middle index. + size_t middle = low / 2 + high / 2 + (low & high & 1); + if ((middle == low) || (middle == high)) { + break; + } + while (!IsValid(elements[middle]) && (middle < high - 1)) ++middle; + while (!IsValid(elements[middle]) && (low + 1 < middle)) --middle; + if (!IsValid(elements[middle])) { + break; + } + if (elements[middle] < element) { + low = middle; + } else { + high = middle; + } + } + + if (elements[low] == element) return &elements[low]; + if (elements[high] == element) return &elements[high]; + return NULL; +} + + +template +void InvalSet::Sort(SortType sort_type) { + VIXL_ASSERT(monitor() == 0); + if (sort_type == kSoftSort) { + if (sorted_) { + return; + } + } + if (empty()) { + return; + } + + Clean(); + std::sort(StorageBegin(), StorageEnd()); + + set_sorted(true); + cached_min_index_ = 0; + cached_min_key_ = Key(Front()); + valid_cached_min_ = true; +} + + +template +void InvalSet::Clean() { + VIXL_ASSERT(monitor() == 0); + if (empty() || !IsUsingVector()) { + return; + } + // Manually iterate through the vector storage to discard invalid elements. + ElementType* start = &(vector_->front()); + ElementType* end = start + vector_->size(); + ElementType* c = start; + ElementType* first_invalid; + ElementType* first_valid; + ElementType* next_invalid; + + while (c < end && IsValid(*c)) { c++; } + first_invalid = c; + + while (c < end) { + while (c < end && !IsValid(*c)) { c++; } + first_valid = c; + while (c < end && IsValid(*c)) { c++; } + next_invalid = c; + + ptrdiff_t n_moved_elements = (next_invalid - first_valid); + memmove(first_invalid, first_valid, n_moved_elements * sizeof(*c)); + first_invalid = first_invalid + n_moved_elements; + c = next_invalid; + } + + // Delete the trailing invalid elements. + vector_->erase(vector_->begin() + (first_invalid - start), vector_->end()); + VIXL_ASSERT(vector_->size() == size_); + + if (sorted_) { + valid_cached_min_ = true; + cached_min_index_ = 0; + cached_min_key_ = Key(*ElementAt(0)); + } else { + valid_cached_min_ = false; + } +} + + +template +const ElementType InvalSet::Front() const { + VIXL_ASSERT(!empty()); + return IsUsingVector() ? vector_->front() : preallocated_[0]; +} + + +template +const ElementType InvalSet::Back() const { + VIXL_ASSERT(!empty()); + return IsUsingVector() ? vector_->back() : preallocated_[size_ - 1]; +} + + +template +const ElementType InvalSet::CleanBack() { + VIXL_ASSERT(monitor() == 0); + if (IsUsingVector()) { + // Delete the invalid trailing elements. + typename std::vector::reverse_iterator it = vector_->rbegin(); + while (!IsValid(*it)) { + it++; + } + vector_->erase(it.base(), vector_->end()); + } + return Back(); +} + + +template +const ElementType* InvalSet::StorageBegin() const { + return IsUsingVector() ? &(vector_->front()) : preallocated_; +} + + +template +const ElementType* InvalSet::StorageEnd() const { + return IsUsingVector() ? &(vector_->back()) + 1 : preallocated_ + size_; +} + + +template +ElementType* InvalSet::StorageBegin() { + return IsUsingVector() ? &(vector_->front()) : preallocated_; +} + + +template +ElementType* InvalSet::StorageEnd() { + return IsUsingVector() ? &(vector_->back()) + 1 : preallocated_ + size_; +} + + +template +size_t InvalSet::ElementIndex( + const ElementType* element) const { + VIXL_ASSERT((StorageBegin() <= element) && (element < StorageEnd())); + return element - StorageBegin(); +} + + +template +const ElementType* InvalSet::ElementAt( + size_t index) const { + VIXL_ASSERT( + (IsUsingVector() && (index < vector_->size())) || (index < size_)); + return StorageBegin() + index; +} + +template +ElementType* InvalSet::ElementAt(size_t index) { + VIXL_ASSERT( + (IsUsingVector() && (index < vector_->size())) || (index < size_)); + return StorageBegin() + index; +} + +template +const ElementType* InvalSet::FirstValidElement( + const ElementType* from, const ElementType* end) { + while ((from < end) && !IsValid(*from)) { + from++; + } + return from; +} + + +template +void InvalSet::CacheMinElement() { + VIXL_ASSERT(monitor() == 0); + VIXL_ASSERT(!empty()); + + if (valid_cached_min_) { + return; + } + + if (sorted_) { + const ElementType* min = FirstValidElement(StorageBegin(), StorageEnd()); + cached_min_index_ = ElementIndex(min); + cached_min_key_ = Key(*min); + valid_cached_min_ = true; + } else { + Sort(kHardSort); + } + VIXL_ASSERT(valid_cached_min_); +} + + +template +bool InvalSet::ShouldReclaimMemory() const { + if (!IsUsingVector()) { + return false; + } + size_t n_invalid_elements = vector_->size() - size_; + return (n_invalid_elements > RECLAIM_FROM) && + (n_invalid_elements > vector_->size() / RECLAIM_FACTOR); +} + + +template +void InvalSet::ReclaimMemory() { + VIXL_ASSERT(monitor() == 0); + Clean(); +} + + +template +InvalSetIterator::InvalSetIterator(S* inval_set) + : using_vector_((inval_set != NULL) && inval_set->IsUsingVector()), + index_(0), + inval_set_(inval_set) { + if (inval_set != NULL) { + inval_set->Sort(S::kSoftSort); +#ifdef VIXL_DEBUG + inval_set->Acquire(); +#endif + if (using_vector_) { + iterator_ = typename std::vector::iterator( + inval_set_->vector_->begin()); + } + MoveToValidElement(); + } +} + + +template +InvalSetIterator::~InvalSetIterator() { +#ifdef VIXL_DEBUG + if (inval_set_ != NULL) { + inval_set_->Release(); + } +#endif +} + + +template +typename S::_ElementType* InvalSetIterator::Current() const { + VIXL_ASSERT(!Done()); + if (using_vector_) { + return &(*iterator_); + } else { + return &(inval_set_->preallocated_[index_]); + } +} + + +template +void InvalSetIterator::Advance() { + VIXL_ASSERT(!Done()); + if (using_vector_) { + iterator_++; +#ifdef VIXL_DEBUG + index_++; +#endif + MoveToValidElement(); + } else { + index_++; + } +} + + +template +bool InvalSetIterator::Done() const { + if (using_vector_) { + bool done = (iterator_ == inval_set_->vector_->end()); + VIXL_ASSERT(done == (index_ == inval_set_->size())); + return done; + } else { + return index_ == inval_set_->size(); + } +} + + +template +void InvalSetIterator::Finish() { + VIXL_ASSERT(inval_set_->sorted_); + if (using_vector_) { + iterator_ = inval_set_->vector_->end(); + } + index_ = inval_set_->size(); +} + + +template +void InvalSetIterator::DeleteCurrentAndAdvance() { + if (using_vector_) { + inval_set_->EraseInternal(&(*iterator_)); + MoveToValidElement(); + } else { + inval_set_->EraseInternal(inval_set_->preallocated_ + index_); + } +} + + +template +bool InvalSetIterator::IsValid(const ElementType& element) { + return S::IsValid(element); +} + + +template +typename S::_KeyType InvalSetIterator::Key(const ElementType& element) { + return S::Key(element); +} + + +template +void InvalSetIterator::MoveToValidElement() { + if (using_vector_) { + while ((iterator_ != inval_set_->vector_->end()) && !IsValid(*iterator_)) { + iterator_++; + } + } else { + VIXL_ASSERT(inval_set_->empty() || IsValid(inval_set_->preallocated_[0])); + // Nothing to do. + } +} + +#undef TEMPLATE_INVALSET_P_DECL +#undef TEMPLATE_INVALSET_P_DEF + +} // namespace vixl + +#endif // VIXL_INVALSET_H_