VTK
vtkAssume.h
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1/*=========================================================================
2
3 Program: Visualization Toolkit
4 Module: vtkAssume.h
5
6 Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
7 All rights reserved.
8 See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
9
10 This software is distributed WITHOUT ANY WARRANTY; without even
11 the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
12 PURPOSE. See the above copyright notice for more information.
13
14=========================================================================*/
20#ifndef vtkAssume_h
21#define vtkAssume_h
22
23#include "vtkConfigure.h"
24
25#include <cassert>
26
42#define VTK_ASSUME(cond) \
43 do { \
44 const bool c = cond; \
45 assert("Bad assumption in VTK_ASSUME: " #cond && c); \
46 VTK_ASSUME_IMPL(c); \
47 (void)c; /* Prevents unused var warnings */ \
48 } while (false) /* do-while prevents extra semicolon warnings */
49
50// VTK_ASSUME_IMPL is compiler-specific:
51#if defined(VTK_COMPILER_MSVC) || defined(VTK_COMPILER_ICC)
52# define VTK_ASSUME_IMPL(cond) __assume(cond)
53#elif defined(VTK_COMPILER_GCC) && VTK_COMPILER_GCC_VERSION >= 40500
54// Added in 4.5.0:
55# define VTK_ASSUME_IMPL(cond) if (!(cond)) __builtin_unreachable()
56#elif defined(VTK_COMPILER_CLANG)
57# define VTK_ASSUME_IMPL(cond) if (!(cond)) __builtin_unreachable()
58#else
59# define VTK_ASSUME_IMPL(cond) do {} while (false) /* no-op */
60#endif
61
62#endif // vtkAssume_h
63// VTK-HeaderTest-Exclude: vtkAssume.h