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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Compiling CUDA does not predefine macros according to doc"
href="https://bugs.llvm.org/show_bug.cgi?id=43706">43706</a>
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<th>Summary</th>
<td>Compiling CUDA does not predefine macros according to doc
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>9.0
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>eldlistmailingz@tropicsoft.com
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>According to the documentation regarding clang and CUDA at
<a href="https://llvm.org/docs/CompileCudaWithLLVM.html#detecting-clang-vs-nvcc-from-code">https://llvm.org/docs/CompileCudaWithLLVM.html#detecting-clang-vs-nvcc-from-code</a>,
when compiling a CUDA file with clang, the macros __clang__, __CUDA__, and
__CUDACC__ are predefined. Yet given this source as 'clang_cuda_example.cu':
#if !defined(__clang__)
#if !defined(__CUDACC__)
#if !defined(__CUDA__)
#error The predefined macros __clang__ and __CUDACC__ and __CUDA__ are not
defined
#else
#error The predefined macros __clang__ and __CUDACC__ are not defined
#endif
#elif !defined(__CUDA__)
#error The predefined macros __clang__ and __CUDA__ are not defined
#else
#error The predefined macro __clang__ is not defined
#endif
#elif !defined(__CUDACC__)
#if !defined(__CUDA__)
#error The predefined macros __CUDACC__ and __CUDA__ are not defined
#else
#error The predefined macro __CUDACC__ is not defined
#endif
#elif !defined(__CUDA__)
#error The predefined macro __CUDA__ is not defined
#endif
int main(void) { return 0; }
If I compile this with:
clang++ -c -m64 -nocudainc -nocudalib -x cuda clang_cuda_example.cu
the output is:
"clang_cuda_example.cu:17:2: error: The predefined macro __CUDACC__ is not
defined
#error The predefined macro __CUDACC__ is not defined
^
1 error generated when compiling for sm_20."
So either the documentation regarding clang and CUDA is incorrect or there is a
bug in clang when compiling CUDA files. If something else must be present when
compiling a CUDA file so that the __CUDAACC__ macro is predefined the
documentation should specify what that is.
I realize that my test does not actually compile any CUDA code despite the
source file ending with .cu and also telling the clang compiler, through the
'-x cuda' compiler option, that I am compiling a CUDA file. I am trying to test
clang compilation of CUDA code for a change I made in the Boost preprocessor
library, of which I am the maintainer, and I need a minimum test which shows
that clang compiling a CUDA file does indeed define the predefined macros which
the documentation says it does.</pre>
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