gtbercea marked an inline comment as done.
gtbercea added inline comments.
================
Comment at: lib/Headers/__clang_cuda_math_forward_declares.h:30-38
+#ifndef _OPENMP
+__DEVICE__ long abs(long);
+__DEVICE__ long long abs(long long);
+#else
+#ifndef __cplusplus
__DEVICE__ long abs(long);
__DEVICE__ long long abs(long long);
----------------
tra wrote:
> tra wrote:
> > gtbercea wrote:
> > > jdoerfert wrote:
> > > > gtbercea wrote:
> > > > > tra wrote:
> > > > > > I'm not quite sure what's the idea here. It may be worth adding a
> > > > > > comment.
> > > > > >
> > > > > > It could also be expressed somewhat simpler:
> > > > > >
> > > > > > ```
> > > > > > #if !(defined(_OPENMP) && defined(__cplusplus))
> > > > > > ...
> > > > > > #endif
> > > > > > ```
> > > > > >
> > > > > When these two functions definitions are here or in the
> > > > > __clang_cuda_cmath.h header then I get the following error (adapted
> > > > > for the __clang_cuda_cmath.h case):
> > > > >
> > > > >
> > > > > ```
> > > > > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/cstdlib:166:3:
> > > > > error: declaration conflicts with target of using declaration
> > > > > already in scope
> > > > > abs(long __i) { return __builtin_labs(__i); }
> > > > > ^
> > > > > /autofs/home/gbercea/patch-compiler/obj-release/lib/clang/9.0.0/include/__clang_cuda_cmath.h:40:17:
> > > > > note: target of using declaration
> > > > > __DEVICE__ long abs(long __n) { return ::labs(__n); }
> > > > > ^
> > > > > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/cstdlib:122:11:
> > > > > note: using declaration
> > > > > using ::abs;
> > > > > ^
> > > > > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/cstdlib:174:3:
> > > > > error: declaration conflicts with target of using declaration
> > > > > already in scope
> > > > > abs(long long __x) { return __builtin_llabs (__x); }
> > > > > ^
> > > > > /autofs/home/gbercea/patch-compiler/obj-release/lib/clang/9.0.0/include/__clang_cuda_cmath.h:39:22:
> > > > > note: target of using declaration
> > > > > __DEVICE__ long long abs(long long __n) { return ::llabs(__n); }
> > > > > ^
> > > > > /usr/lib/gcc/ppc64le-redhat-linux/4.8.5/../../../../include/c++/4.8.5/cstdlib:122:11:
> > > > > note: using declaration
> > > > > using ::abs;
> > > > > ```
> > > > >
> > > > >
> > > > Long story short, we currently cannot use the overload trick through
> > > > `__device__` and therefore *replace* (not augment) host math headers
> > > > with the cuda versions which unfortunately mix std math functions with
> > > > other functions that we don't want/need.
> > > This doesn't seem to be happening in the CUDA case. My suspicion is it's
> > > because of the __device__ attribute.
> > It looks like until OpenMP supports some sort of target-based overloading
> > this will not play nicely with libstdc++.
> > Did you, by any chance, check if the header works with libc++ ? I wonder if
> > we may encounter more conflicts like these.
> Correct. `__device__` functions overload whatever `(implicitly)__host__`
> functions declared by the standard library, so they coexist w/o problems.
> Usually. host/device implementation nuances are still observable.
>
Just did a few quick tests with libstdc++ and it was all good.
Repository:
rC Clang
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https://reviews.llvm.org/D61765/new/
https://reviews.llvm.org/D61765
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