| //===--- 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 |