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d8ee44349c
* Update to latest LLVM code. * Add LLVM's raw_ostream. * MathExtras.h: Include cmath for log2.
95 lines
3.1 KiB
C++
95 lines
3.1 KiB
C++
//===- llvm/Support/PointerLikeTypeTraits.h - Pointer Traits ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the PointerLikeTypeTraits class. This allows data
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// structures to reason about pointers and other things that are pointer sized.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_POINTERLIKETYPETRAITS_H
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#define LLVM_SUPPORT_POINTERLIKETYPETRAITS_H
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#include "llvm/AlignOf.h"
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#include <cstdint>
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namespace llvm {
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/// A traits type that is used to handle pointer types and things that are just
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/// wrappers for pointers as a uniform entity.
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template <typename T> class PointerLikeTypeTraits {
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// getAsVoidPointer
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// getFromVoidPointer
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// getNumLowBitsAvailable
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};
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namespace detail {
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/// A tiny meta function to compute the log2 of a compile time constant.
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template <size_t N>
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struct ConstantLog2
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: std::integral_constant<size_t, ConstantLog2<N / 2>::value + 1> {};
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template <> struct ConstantLog2<1> : std::integral_constant<size_t, 0> {};
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}
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// Provide PointerLikeTypeTraits for non-cvr pointers.
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template <typename T> class PointerLikeTypeTraits<T *> {
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public:
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static inline void *getAsVoidPointer(T *P) { return P; }
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static inline T *getFromVoidPointer(void *P) { return static_cast<T *>(P); }
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enum {
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NumLowBitsAvailable = detail::ConstantLog2<AlignOf<T>::Alignment>::value
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};
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};
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template <> class PointerLikeTypeTraits<void *> {
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public:
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static inline void *getAsVoidPointer(void *P) { return P; }
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static inline void *getFromVoidPointer(void *P) { return P; }
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/// Note, we assume here that void* is related to raw malloc'ed memory and
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/// that malloc returns objects at least 4-byte aligned. However, this may be
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/// wrong, or pointers may be from something other than malloc. In this case,
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/// you should specify a real typed pointer or avoid this template.
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///
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/// All clients should use assertions to do a run-time check to ensure that
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/// this is actually true.
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enum { NumLowBitsAvailable = 2 };
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};
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// Provide PointerLikeTypeTraits for const pointers.
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template <typename T> class PointerLikeTypeTraits<const T *> {
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typedef PointerLikeTypeTraits<T *> NonConst;
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public:
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static inline const void *getAsVoidPointer(const T *P) {
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return NonConst::getAsVoidPointer(const_cast<T *>(P));
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}
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static inline const T *getFromVoidPointer(const void *P) {
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return NonConst::getFromVoidPointer(const_cast<void *>(P));
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}
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enum { NumLowBitsAvailable = NonConst::NumLowBitsAvailable };
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};
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// Provide PointerLikeTypeTraits for uintptr_t.
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template <> class PointerLikeTypeTraits<uintptr_t> {
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public:
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static inline void *getAsVoidPointer(uintptr_t P) {
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return reinterpret_cast<void *>(P);
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}
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static inline uintptr_t getFromVoidPointer(void *P) {
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return reinterpret_cast<uintptr_t>(P);
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}
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// No bits are available!
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enum { NumLowBitsAvailable = 0 };
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};
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} // end namespace llvm
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#endif
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