You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
75 lines
3.8 KiB
C
75 lines
3.8 KiB
C
/*=========================================================================
|
|
|
|
Program: Visualization Toolkit
|
|
Module: vtkAssume.h
|
|
|
|
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
|
|
All rights reserved.
|
|
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
|
|
|
|
This software is distributed WITHOUT ANY WARRANTY; without even
|
|
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
|
|
PURPOSE. See the above copyright notice for more information.
|
|
|
|
=========================================================================*/
|
|
/**
|
|
* @class VTK_ASSUME
|
|
* @brief Provide compiler hints for non-obvious conditions.
|
|
*/
|
|
|
|
#ifndef vtkAssume_h
|
|
#define vtkAssume_h
|
|
|
|
#include "vtkConfigure.h"
|
|
|
|
#include <cassert>
|
|
|
|
/**
|
|
* VTK_ASSUME instructs the compiler that a certain non-obvious condition will
|
|
* *always* be true. Beware that if cond is false at runtime, the results are
|
|
* unpredictable (and likely catastrophic). A runtime assertion is added so
|
|
* that debugging builds may easily catch violations of the condition.
|
|
|
|
* A useful application of this macro is when a vtkGenericDataArray subclass has
|
|
* a known number of components at compile time. Adding, for example,
|
|
* VTK_ASSUME(array->GetNumberOfComponents() == 3); allows the compiler to
|
|
* provide faster access through the GetTypedComponent method, as the fixed data
|
|
* stride in AOS arrays allows advanced optimization of the accesses.
|
|
|
|
* A more detailed description of this class and related tools can be found
|
|
* \ref VTK-7-1-ArrayDispatch "here".
|
|
*/
|
|
#define VTK_ASSUME(cond) \
|
|
do \
|
|
{ \
|
|
const bool c = cond; \
|
|
assert("Bad assumption in VTK_ASSUME: " #cond&& c); \
|
|
VTK_ASSUME_IMPL(c); \
|
|
(void)c; /* Prevents unused var warnings */ \
|
|
} while (false) /* do-while prevents extra semicolon warnings */
|
|
|
|
#define VTK_ASSUME_NO_ASSERT(cond) \
|
|
do \
|
|
{ \
|
|
const bool c = cond; \
|
|
VTK_ASSUME_IMPL(c); \
|
|
(void)c; /* Prevents unused var warnings */ \
|
|
} while (false) /* do-while prevents extra semicolon warnings */
|
|
|
|
// VTK_ASSUME_IMPL is compiler-specific:
|
|
#if defined(VTK_COMPILER_MSVC) || defined(VTK_COMPILER_ICC)
|
|
#define VTK_ASSUME_IMPL(cond) __assume(cond)
|
|
#elif defined(VTK_COMPILER_GCC) || defined(VTK_COMPILER_CLANG)
|
|
#define VTK_ASSUME_IMPL(cond) \
|
|
if (!(cond)) \
|
|
__builtin_unreachable()
|
|
#else
|
|
#define VTK_ASSUME_IMPL(cond) \
|
|
do \
|
|
{ \
|
|
} while (false) /* no-op */
|
|
#endif
|
|
|
|
#endif // vtkAssume_h
|
|
// VTK-HeaderTest-Exclude: vtkAssume.h
|