1 //===- llvm/Support/PointerLikeTypeTraits.h - Pointer Traits ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the PointerLikeTypeTraits class. This allows data
11 // structures to reason about pointers and other things that are pointer sized.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_SUPPORT_POINTERLIKETYPETRAITS_H
16 #define LLVM_SUPPORT_POINTERLIKETYPETRAITS_H
18 #include "llvm/Support/DataTypes.h"
22 /// PointerLikeTypeTraits - This is a traits object that is used to handle
23 /// pointer types and things that are just wrappers for pointers as a uniform
26 class PointerLikeTypeTraits {
29 // getNumLowBitsAvailable
32 // Provide PointerLikeTypeTraits for non-cvr pointers.
34 class PointerLikeTypeTraits<T*> {
36 static inline void *getAsVoidPointer(T *P) { return P; }
37 static inline T *getFromVoidPointer(void *P) { return static_cast<T *>(P); }
39 /// Note, we assume here that malloc returns objects at least 4-byte aligned.
40 /// However, this may be wrong, or pointers may be from something other than
41 /// malloc. In this case, you should specialize this template to reduce this.
43 /// All clients should use assertions to do a run-time check to ensure that
44 /// this is actually true.
45 enum { NumLowBitsAvailable = 2 };
48 // Provide PointerLikeTypeTraits for const pointers.
50 class PointerLikeTypeTraits<const T*> {
51 typedef PointerLikeTypeTraits<T*> NonConst;
54 static inline const void *getAsVoidPointer(const T* P) {
55 return NonConst::getAsVoidPointer(const_cast<T*>(P));
57 static inline const T *getFromVoidPointer(const void *P) {
58 return NonConst::getFromVoidPointer(const_cast<void*>(P));
60 enum { NumLowBitsAvailable = NonConst::NumLowBitsAvailable };
63 // Provide PointerLikeTypeTraits for uintptr_t.
65 class PointerLikeTypeTraits<uintptr_t> {
67 static inline void *getAsVoidPointer(uintptr_t P) {
68 return reinterpret_cast<void*>(P);
70 static inline uintptr_t getFromVoidPointer(void *P) {
71 return reinterpret_cast<uintptr_t>(P);
73 // No bits are available!
74 enum { NumLowBitsAvailable = 0 };
77 } // end namespace llvm