llvm-6502/include/llvm/Support/AlignOf.h
2007-10-17 22:12:14 +00:00

49 lines
1.7 KiB
C++

//===--- AlignOf.h - Portable calculation of type alignment -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Ted Kremenek and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the AlignOf function that computes alignments for
// arbitrary types.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_ALIGNOF_H
#define LLVM_SUPPORT_ALIGNOF_H
namespace llvm {
template <typename T>
struct AlignmentCalcImpl {
char x;
T t;
private:
AlignmentCalcImpl() {} // Never instantiate.
};
/// AlignOf - A templated class that contains an enum value representing
/// the alignment of the template argument. For example,
/// AlignOf<int>::Alignment represents the alignment of type "int". The
/// alignment calculated is the minimum alignment, and not necessarily
/// the "desired" alignment returned by GCC's __alignof__ (for example). Note
/// that because the alignment is an enum value, it can be used as a
/// compile-time constant (e.g., for template instantiation).
template <typename T>
struct AlignOf {
enum { Alignment = sizeof(AlignmentCalcImpl<T>) - sizeof(T) };
};
/// alignof - A templated function that returns the mininum alignment of
/// of a type. This provides no extra functionality beyond the AlignOf
/// class besides some cosmetic cleanliness. Example usage:
/// alignof<int>() returns the alignment of an int.
template <typename T>
static inline unsigned alignof() { return AlignOf<T>::Alignment; }
} // end namespace llvm
#endif