Allocator.h revision 85b0ea5f3cf581036e37fc610567281af2d65038 
1//===--- Allocator.h - Simple memory allocation abstraction -----*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines the MallocAllocator and BumpPtrAllocator interfaces.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_SUPPORT_ALLOCATOR_H
15#define LLVM_SUPPORT_ALLOCATOR_H
16
17#include "llvm/Support/AlignOf.h"
18#include <cstdlib>
19
20namespace llvm {
21
22class MallocAllocator {
23public:
24  MallocAllocator() {}
25  ~MallocAllocator() {}
26
27  void Reset() {}
28
29  void *Allocate(size_t Size, size_t /*Alignment*/) { return malloc(Size); }
30
31  template <typename T>
32  T *Allocate() { return static_cast<T*>(malloc(sizeof(T))); }
33
34  template <typename T>
35  T *Allocate(size_t Num) {
36    return static_cast<T*>(malloc(sizeof(T)*Num));
37  }
38
39  void Deallocate(const void *Ptr) { free(const_cast<void*>(Ptr)); }
40
41  void PrintStats() const {}
42};
43
44/// BumpPtrAllocator - This allocator is useful for containers that need very
45/// simple memory allocation strategies.  In particular, this just keeps
46/// allocating memory, and never deletes it until the entire block is dead. This
47/// makes allocation speedy, but must only be used when the trade-off is ok.
48class BumpPtrAllocator {
49  BumpPtrAllocator(const BumpPtrAllocator &); // do not implement
50  void operator=(const BumpPtrAllocator &);   // do not implement
51
52  void *TheMemory;
53public:
54  BumpPtrAllocator();
55  ~BumpPtrAllocator();
56
57  void Reset();
58
59  void *Allocate(size_t Size, size_t Alignment);
60
61  /// Allocate space, but do not construct, one object.
62  ///
63  template <typename T>
64  T *Allocate() {
65    return static_cast<T*>(Allocate(sizeof(T),AlignOf<T>::Alignment));
66  }
67
68  /// Allocate space for an array of objects.  This does not construct the
69  /// objects though.
70  template <typename T>
71  T *Allocate(size_t Num) {
72    return static_cast<T*>(Allocate(Num * sizeof(T), AlignOf<T>::Alignment));
73  }
74
75  /// Allocate space for a specific count of elements and with a specified
76  /// alignment.
77  template <typename T>
78  T *Allocate(size_t Num, unsigned Alignment) {
79    // Round EltSize up to the specified alignment.
80    unsigned EltSize = (sizeof(T)+Alignment-1)&(-Alignment);
81    return static_cast<T*>(Allocate(Num * EltSize, Alignment));
82  }
83
84  void Deallocate(const void * /*Ptr*/) {}
85
86  void PrintStats() const;
87};
88
89}  // end namespace llvm
90
91#endif
92