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//==- llvm/Support/Recycler.h - Recycling Allocator --------------*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the Recycler class template. See the doxygen comment for
// Recycler for more details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_RECYCLER_H
#define LLVM_SUPPORT_RECYCLER_H
#include "llvm/ADT/ilist.h"
#include "llvm/Support/AlignOf.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/ErrorHandling.h"
#include <cassert>
namespace llvm {
/// PrintRecyclingAllocatorStats - Helper for RecyclingAllocator for
/// printing statistics.
///
void PrintRecyclerStats(size_t Size, size_t Align, size_t FreeListSize);
/// RecyclerStruct - Implementation detail for Recycler. This is a
/// class that the recycler imposes on free'd memory to carve out
/// next/prev pointers.
struct RecyclerStruct {
RecyclerStruct *Prev, *Next;
};
template<>
struct ilist_traits<RecyclerStruct> :
public ilist_default_traits<RecyclerStruct> {
static RecyclerStruct *getPrev(const RecyclerStruct *t) { return t->Prev; }
static RecyclerStruct *getNext(const RecyclerStruct *t) { return t->Next; }
static void setPrev(RecyclerStruct *t, RecyclerStruct *p) { t->Prev = p; }
static void setNext(RecyclerStruct *t, RecyclerStruct *n) { t->Next = n; }
mutable RecyclerStruct Sentinel;
RecyclerStruct *createSentinel() const {
return &Sentinel;
}
static void destroySentinel(RecyclerStruct *) {}
RecyclerStruct *provideInitialHead() const { return createSentinel(); }
RecyclerStruct *ensureHead(RecyclerStruct*) const { return createSentinel(); }
static void noteHead(RecyclerStruct*, RecyclerStruct*) {}
static void deleteNode(RecyclerStruct *) {
llvm_unreachable("Recycler's ilist_traits shouldn't see a deleteNode call!");
}
};
/// Recycler - This class manages a linked-list of deallocated nodes
/// and facilitates reusing deallocated memory in place of allocating
/// new memory.
///
template<class T, size_t Size = sizeof(T), size_t Align = AlignOf<T>::Alignment>
class Recycler {
/// FreeList - Doubly-linked list of nodes that have deleted contents and
/// are not in active use.
///
iplist<RecyclerStruct> FreeList;
public:
~Recycler() {
// If this fails, either the callee has lost track of some allocation,
// or the callee isn't tracking allocations and should just call
// clear() before deleting the Recycler.
assert(FreeList.empty() && "Non-empty recycler deleted!");
}
/// clear - Release all the tracked allocations to the allocator. The
/// recycler must be free of any tracked allocations before being
/// deleted; calling clear is one way to ensure this.
template<class AllocatorType>
void clear(AllocatorType &Allocator) {
while (!FreeList.empty()) {
T *t = reinterpret_cast<T *>(FreeList.remove(FreeList.begin()));
Allocator.Deallocate(t);
}
}
/// Special case for BumpPtrAllocator which has an empty Deallocate()
/// function.
///
/// There is no need to traverse the free list, pulling all the objects into
/// cache.
void clear(BumpPtrAllocator&) {
FreeList.clearAndLeakNodesUnsafely();
}
template<class SubClass, class AllocatorType>
SubClass *Allocate(AllocatorType &Allocator) {
static_assert(AlignOf<SubClass>::Alignment <= Align,
"Recycler allocation alignment is less than object align!");
static_assert(sizeof(SubClass) <= Size,
"Recycler allocation size is less than object size!");
return !FreeList.empty() ?
reinterpret_cast<SubClass *>(FreeList.remove(FreeList.begin())) :
static_cast<SubClass *>(Allocator.Allocate(Size, Align));
}
template<class AllocatorType>
T *Allocate(AllocatorType &Allocator) {
return Allocate<T>(Allocator);
}
template<class SubClass, class AllocatorType>
void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) {
FreeList.push_front(reinterpret_cast<RecyclerStruct *>(Element));
}
void PrintStats() {
PrintRecyclerStats(Size, Align, FreeList.size());
}
};
}
#endif
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