jdoerfert added inline comments.
================
Comment at: lib/Headers/__clang_cuda_cmath.h:55-56
+#if defined(_OPENMP) && defined(__cplusplus)
+__DEVICE__ const float abs(const float __x) { return ::fabsf((float)__x); }
+__DEVICE__ const double abs(const double __x) { return ::fabs((double)__x); }
+#endif
----------------
efriedma wrote:
> gtbercea wrote:
> > tra wrote:
> > > Where do these functions come from?
> > > https://en.cppreference.com/w/cpp/numeric/math/fabs does not seem to show
> > > any `abs` functions with const args.
> > What's happening is that when including the random header file, this header
> > file uses abs with const arguments:
> >
> >
> > ```
> > const double __n = _M_nd(__urng);
> > const double __y = -std::abs(__n) * __param._M_sm - 1;
> > ```
> >
> > And without there functions here the error I get is:
> >
> >
> > ```
> > In file included from test.c:8:
> > In file included from
> > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/random:52:
> > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/bits/random.tcc:1476:27:
> > error: call to 'abs' is ambiguous
> > const double __y = -std::abs(__n) * __param._M_sm - 1;
> > ^~~~~~~~
> > /usr/include/stdlib.h:770:12: note: candidate function
> > extern int abs (int __x) __THROW __attribute__ ((__const__)) __wur;
> > ^
> > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/cstdlib:166:3:
> > note: candidate function
> > abs(long __i) { return __builtin_labs(__i); }
> > ^
> > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/cstdlib:174:3:
> > note: candidate function
> > abs(long long __x) { return __builtin_llabs (__x); }
> > ^
> > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/cstdlib:179:3:
> > note: candidate function
> > abs(__int128 __x) { return __x >= 0 ? __x : -__x; }
> > ^
> > ```
> Overloading ignores the "const"; `float abs(float)` is the same thing. So
> probably clearer to declare it without the extra "const" modifiers, and then
> clean up the redundant definitions.
>
> That said, I'm not sure how you managed to pick up the declarations from
> cstdlib, but not cmath. What files are getting included when this fails?
>
> (Actually, in C++17, both cmath and cstdlib are supposed to declare all the
> float and integer overloads of abs, but that's only implemented in newer
> versions of libstdc++.)
> That said, I'm not sure how you managed to pick up the declarations from
> cstdlib, but not cmath. What files are getting included when this fails?
Until we get support for OpenMP `omp declare variant begin/end` support in
clang (X), we will only provide the CUDA declarations & definitions for math
functions, not the host ones. It is one of these problems that arises when the
single source language needs both, device and host definitions. (In CUDA the
`__device__` overload is the way out, in OpenMP it will be `variant` with an
appropriate device context.)
(X) I'm right now working on integrating this into OpenMP 5.1 but we can
implement it as soon as the design is decided on.
Repository:
rC Clang
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D62046/new/
https://reviews.llvm.org/D62046
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