#ifndef LLVM_SUPPORT_POINTERLIKETYPETRAITS_H
#define LLVM_SUPPORT_POINTERLIKETYPETRAITS_H
+#include "llvm/Support/AlignOf.h"
#include "llvm/Support/DataTypes.h"
namespace llvm {
-
-/// PointerLikeTypeTraits - This is a traits object that is used to handle
-/// pointer types and things that are just wrappers for pointers as a uniform
-/// entity.
-template <typename T>
-class PointerLikeTypeTraits {
+
+/// A traits type that is used to handle pointer types and things that are just
+/// wrappers for pointers as a uniform entity.
+template <typename T> class PointerLikeTypeTraits {
// getAsVoidPointer
// getFromVoidPointer
// getNumLowBitsAvailable
};
+namespace detail {
+/// A tiny meta function to compute the log2 of a compile time constant.
+template <size_t N>
+struct ConstantLog2
+ : std::integral_constant<size_t, ConstantLog2<N / 2>::value + 1> {};
+template <> struct ConstantLog2<1> : std::integral_constant<size_t, 0> {};
+}
+
// Provide PointerLikeTypeTraits for non-cvr pointers.
-template<typename T>
-class PointerLikeTypeTraits<T*> {
-public:
- static inline void *getAsVoidPointer(T* P) { return P; }
- static inline T *getFromVoidPointer(void *P) {
- return static_cast<T*>(P);
- }
-
- /// Note, we assume here that malloc returns objects at least 8-byte aligned.
- /// However, this may be wrong, or pointers may be from something other than
- /// malloc. In this case, you should specialize this template to reduce this.
+template <typename T> struct PointerLikeTypeTraits<T *> {
+ static inline void *getAsVoidPointer(T *P) { return P; }
+ static inline T *getFromVoidPointer(void *P) { return static_cast<T *>(P); }
+
+ enum {
+ NumLowBitsAvailable = detail::ConstantLog2<AlignOf<T>::Alignment>::value
+ };
+};
+
+template <> struct PointerLikeTypeTraits<void *> {
+ static inline void *getAsVoidPointer(void *P) { return P; }
+ static inline void *getFromVoidPointer(void *P) { return P; }
+
+ /// Note, we assume here that void* is related to raw malloc'ed memory and
+ /// that malloc returns objects at least 4-byte aligned. However, this may be
+ /// wrong, or pointers may be from something other than malloc. In this case,
+ /// you should specify a real typed pointer or avoid this template.
///
/// All clients should use assertions to do a run-time check to ensure that
/// this is actually true.
enum { NumLowBitsAvailable = 2 };
};
-
+
// Provide PointerLikeTypeTraits for const pointers.
-template<typename T>
-class PointerLikeTypeTraits<const T*> {
+template <typename T> class PointerLikeTypeTraits<const T *> {
+ typedef PointerLikeTypeTraits<T *> NonConst;
+
public:
- static inline const void *getAsVoidPointer(const T* P) { return P; }
+ static inline const void *getAsVoidPointer(const T *P) {
+ return NonConst::getAsVoidPointer(const_cast<T *>(P));
+ }
static inline const T *getFromVoidPointer(const void *P) {
- return static_cast<const T*>(P);
+ return NonConst::getFromVoidPointer(const_cast<void *>(P));
}
- enum { NumLowBitsAvailable = 2 };
+ enum { NumLowBitsAvailable = NonConst::NumLowBitsAvailable };
};
// Provide PointerLikeTypeTraits for uintptr_t.
-template<>
-class PointerLikeTypeTraits<uintptr_t> {
+template <> class PointerLikeTypeTraits<uintptr_t> {
public:
static inline void *getAsVoidPointer(uintptr_t P) {
- return reinterpret_cast<void*>(P);
+ return reinterpret_cast<void *>(P);
}
static inline uintptr_t getFromVoidPointer(void *P) {
return reinterpret_cast<uintptr_t>(P);
// No bits are available!
enum { NumLowBitsAvailable = 0 };
};
-
+
} // end namespace llvm
#endif