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https://gitlab.kitware.com/vtk/vtk-m
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65 lines
2.5 KiB
C
65 lines
2.5 KiB
C
//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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//
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//============================================================================
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#ifndef vtk_m_internal_Assume_h
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#define vtk_m_internal_Assume_h
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#include <vtkm/Assert.h>
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// Description:
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// VTKM_ASSUME instructs the compiler that a certain non-obvious condition will
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// *always* be true. Beware that if cond is false at runtime, the results are
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// unpredictable (and likely catastrophic). A runtime assertion is added so
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// that debugging builds may easily catch violations of the condition.
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//
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// A useful application of this macro is when a method is passed in a
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// vtkm::Vec that is uninitialized and conditional fills the vtkm::Vec
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// based on other runtime information such as cell type. This allows you to
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// assert that only valid cell types will be used, producing more efficient
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// code.
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//
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#define VTKM_ASSUME(cond) \
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VTKM_SWALLOW_SEMICOLON_PRE_BLOCK \
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{ \
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const bool c = cond; \
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VTKM_ASSERT("Bad assumption in VTKM_ASSUME: " #cond&& c); \
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VTKM_ASSUME_IMPL(c); \
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(void)c; /* Prevents unused var warnings */ \
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} \
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VTKM_SWALLOW_SEMICOLON_POST_BLOCK
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// VTKM_ASSUME_IMPL is compiler-specific:
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#if defined(VTKM_CUDA_DEVICE_PASS)
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//For all versions of CUDA this is a no-op while we look
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//for a CUDA asm snippet that replicates this kind of behavior
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#define VTKM_ASSUME_IMPL(cond) (void)0 /* no-op */
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#else
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#if defined(VTKM_MSVC)
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#define VTKM_ASSUME_IMPL(cond) __assume(cond)
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#elif defined(VTKM_ICC) && !defined(__GNUC__)
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#define VTKM_ASSUME_IMPL(cond) __assume(cond)
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#elif (defined(VTKM_GCC) || defined(VTKM_ICC)) && \
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(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5))
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// Added in 4.5.0:
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#define VTKM_ASSUME_IMPL(cond) \
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if (!(cond)) \
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__builtin_unreachable()
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#elif defined(VTKM_CLANG)
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#define VTKM_ASSUME_IMPL(cond) \
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if (!(cond)) \
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__builtin_unreachable()
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#else
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#define VTKM_ASSUME_IMPL(cond) (void)0 /* no-op */
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#endif
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#endif
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#endif // vtk_m_internal_Assume_h
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