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//==- llvm/Support/Recycler.h - Recycling Allocator --------------*- C++ -*-==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// 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/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);
/// 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)>
class Recycler {
struct FreeNode {
FreeNode *Next;
};
/// List of nodes that have deleted contents and are not in active use.
FreeNode *FreeList = nullptr;
FreeNode *pop_val() {
auto *Val = FreeList;
__asan_unpoison_memory_region(Val, Size);
FreeList = FreeList->Next;
__msan_allocated_memory(Val, Size);
return Val;
}
void push(FreeNode *N) {
N->Next = FreeList;
FreeList = N;
__asan_poison_memory_region(N, Size);
}
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 && "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) {
T *t = reinterpret_cast<T *>(pop_val());
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 = nullptr; }
template<class SubClass, class AllocatorType>
SubClass *Allocate(AllocatorType &Allocator) {
static_assert(alignof(SubClass) <= Align,
"Recycler allocation alignment is less than object align!");
static_assert(sizeof(SubClass) <= Size,
"Recycler allocation size is less than object size!");
return FreeList ? reinterpret_cast<SubClass *>(pop_val())
: 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) {
push(reinterpret_cast<FreeNode *>(Element));
}
void PrintStats();
};
template <class T, size_t Size, size_t Align>
void Recycler<T, Size, Align>::PrintStats() {
size_t S = 0;
for (auto *I = FreeList; I; I = I->Next)
++S;
PrintRecyclerStats(Size, Align, S);
}
}
#endif
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