Ok. Looks like the warnings are there with and without my hack(s), and the
minimal set of edits needed to get Eigen to build on Mac with nvcc consists
of:

Half.h. Change this:
#if !defined(EIGEN_HAS_NATIVE_FP16) || EIGEN_COMP_CLANG // Emulate support
for half floats
to this:
#if !defined(EIGEN_HAS_NATIVE_FP16) || (EIGEN_COMP_CLANG &&
!EIGEN_COMP_NVCC) // Emulate support for half floats

And in PacketMath.h, change this:
#if defined(EIGEN_CUDA_ARCH) || defined(EIGEN_HIP_DEVICE_COMPILE) ||
(defined(EIGEN_CUDACC) && EIGEN_COMP_CLANG)
to this:
#if defined(EIGEN_CUDA_ARCH) || defined(EIGEN_HIP_DEVICE_COMPILE) ||
(defined(EIGEN_CUDACC) && EIGEN_COMP_CLANG && !EIGEN_COMP_NVCC)

Obviously that's excluding any enlightening comments about why that's being
done.

Would you like me to prepare a patch file, or is this something that would
be better handled by one of the regular contributors?

Thank you!
---
Eric Klein
[email protected]


On Thu, Jun 20, 2019 at 12:01 AM Eric Klein <[email protected]> wrote:

> That appears to work, although there are 2-3 other places that need
> similar modifications in order to work. I'll try to get you a more complete
> list tomorrow.
>
> I'm paying more attention tonight to warnings coming from Eigen than I had
> been previously ignoring, and both with my old Macros.h based hack and the
> newer modifications, I'm seeing some of these: "warning: calling a __host__
> function from a __host__ __device__ function is not allowed". A
> representative one is:
>
> external/eigen_archive/unsupported/Eigen/CXX11/src/Tensor/TensorReduction.h(735):
> warning: calling a __host__ function from a __host__ __device__ function is
> not allowed
>           detected during:
>             instantiation of "__nv_bool Eigen::TensorEvaluator<const
> Eigen::TensorReductionOp<Op, Dims, ArgType, MakePointer_>,
> Device>::evalSubExprsIfNeeded(MakePointer_<Eigen::TensorEvaluator<const
> Eigen::TensorReductionOp<Op, Dims, ArgType, MakePointer_>,
> Device>::CoeffReturnType>::Type) [with
> Op=Eigen::internal::AvgPoolMeanReducer<double>, Dims=const
> Eigen::IndexList<Eigen::type2index<1L>, Eigen::type2index<2L>>,
> ArgType=const Eigen::TensorImagePatchOp<-1L, -1L, const
> Eigen::TensorLayoutSwapOp<const Eigen::TensorMap<Eigen::Tensor<const
> double, 4, 1, Eigen::DenseIndex>, 16, Eigen::MakePointer>>>,
> MakePointer_=Eigen::MakePointer, Device=Eigen::GpuDevice]"
> external/eigen_archive/unsupported/Eigen/CXX11/src/Tensor/TensorMorphing.h(172):
> here
>             instantiation of "__nv_bool Eigen::TensorEvaluator<const
> Eigen::TensorReshapingOp<NewDimensions, ArgType>,
> Device>::evalSubExprsIfNeeded(Eigen::TensorEvaluator<const
> Eigen::TensorReshapingOp<NewDimensions, ArgType>, Device>::CoeffReturnType
> *) [with NewDimensions=const Eigen::DSizes<Eigen::DenseIndex, 4>,
> ArgType=const
> Eigen::TensorReductionOp<Eigen::internal::AvgPoolMeanReducer<double>, const
> Eigen::IndexList<Eigen::type2index<1L>, Eigen::type2index<2L>>, const
> Eigen::TensorImagePatchOp<-1L, -1L, const Eigen::TensorLayoutSwapOp<const
> Eigen::TensorMap<Eigen::Tensor<const double, 4, 1, Eigen::DenseIndex>, 16,
> Eigen::MakePointer>>>, Eigen::MakePointer>, Device=Eigen::GpuDevice]"
> external/eigen_archive/unsupported/Eigen/CXX11/src/Tensor/TensorAssign.h(146):
> here
>             instantiation of "__nv_bool Eigen::TensorEvaluator<const
> Eigen::TensorAssignOp<LeftArgType, RightArgType>,
> Device>::evalSubExprsIfNeeded(Eigen::TensorEvaluator<const
> Eigen::TensorAssignOp<LeftArgType, RightArgType>, Device>::Scalar *) [with
> LeftArgType=Eigen::TensorLayoutSwapOp<Eigen::TensorMap<Eigen::Tensor<double,
> 4, 1, Eigen::DenseIndex>, 16, Eigen::MakePointer>>, RightArgType=const
> Eigen::TensorReshapingOp<const Eigen::DSizes<Eigen::DenseIndex, 4>, const
> Eigen::TensorReductionOp<Eigen::internal::AvgPoolMeanReducer<double>, const
> Eigen::IndexList<Eigen::type2index<1L>, Eigen::type2index<2L>>, const
> Eigen::TensorImagePatchOp<-1L, -1L, const Eigen::TensorLayoutSwapOp<const
> Eigen::TensorMap<Eigen::Tensor<const double, 4, 1, Eigen::DenseIndex>, 16,
> Eigen::MakePointer>>>, Eigen::MakePointer>>, Device=Eigen::GpuDevice]"
> external/eigen_archive/unsupported/Eigen/CXX11/src/Tensor/TensorExecutor.h(422):
> here
>             instantiation of "void
> Eigen::internal::TensorExecutor<Expression, Eigen::GpuDevice, Vectorizable,
> Tileable>::run(const Expression &, const Eigen::GpuDevice &) [with
> Expression=const
> Eigen::TensorAssignOp<Eigen::TensorLayoutSwapOp<Eigen::TensorMap<Eigen::Tensor<double,
> 4, 1, Eigen::DenseIndex>, 16, Eigen::MakePointer>>, const
> Eigen::TensorReshapingOp<const Eigen::DSizes<Eigen::DenseIndex, 4>, const
> Eigen::TensorReductionOp<Eigen::internal::AvgPoolMeanReducer<double>, const
> Eigen::IndexList<Eigen::type2index<1L>, Eigen::type2index<2L>>, const
> Eigen::TensorImagePatchOp<-1L, -1L, const Eigen::TensorLayoutSwapOp<const
> Eigen::TensorMap<Eigen::Tensor<const double, 4, 1, Eigen::DenseIndex>, 16,
> Eigen::MakePointer>>>, Eigen::MakePointer>>>, Vectorizable=false,
> Tileable=false]"
> external/eigen_archive/unsupported/Eigen/CXX11/src/Tensor/TensorDevice.h(35):
> here
>             instantiation of "Eigen::TensorDevice<ExpressionType,
> DeviceType> &Eigen::TensorDevice<ExpressionType,
> DeviceType>::operator=(const OtherDerived &) [with
> ExpressionType=Eigen::TensorLayoutSwapOp<Eigen::TensorMap<Eigen::Tensor<double,
> 4, 1, Eigen::DenseIndex>, 16, Eigen::MakePointer>>,
> DeviceType=tensorflow::GPUDevice,
> OtherDerived=Eigen::TensorReshapingOp<const
> Eigen::DSizes<Eigen::DenseIndex, 4>, const
> Eigen::TensorReductionOp<Eigen::internal::AvgPoolMeanReducer<double>, const
> Eigen::IndexList<Eigen::type2index<1L>, Eigen::type2index<2L>>, const
> Eigen::TensorImagePatchOp<-1L, -1L, const Eigen::TensorLayoutSwapOp<const
> Eigen::TensorMap<Eigen::Tensor<const double, 4, 1, Eigen::DenseIndex>, 16,
> Eigen::MakePointer>>>, Eigen::MakePointer>>]"
> ./tensorflow/core/kernels/avgpooling_op.h(42): here
>             instantiation of "void
> tensorflow::functor::SpatialAvgPooling<Device, T>::operator()(const Device
> &, tensorflow::TTypes<T, 4, Eigen::DenseIndex>::Tensor,
> tensorflow::TTypes<T, 4, Eigen::DenseIndex>::ConstTensor, int, int, int,
> int, const Eigen::PaddingType &) [with Device=tensorflow::GPUDevice,
> T=double]"
> tensorflow/core/kernels/avgpooling_op_gpu.cu.cc(38): here
>
>
> I'm not sure how concerned I should be about these. The build will
> succeed, but... I wouldn't be at all surprised to get weird results
> eventually.
>
> In this particular case, it looks like it's complaining because
> Eigen::GpuDevice::allocate_temp appears to be __host__ rather than __host__
> __device__ (i.e. missing EIGEN_DEVICE_FUNC). I fully admit that I could be
> misinterpreting that or otherwise misunderstanding something basic.
>
> Should I be concerned about these?
>
> Thanks!
> ---
> Eric Klein
> [email protected]
>
>
> On Wed, Jun 19, 2019 at 5:21 PM Rasmus Munk Larsen <[email protected]>
> wrote:
>
>> Erik, does Artem's suggestion work for you?
>>
>> On Wed, Jun 19, 2019 at 2:52 PM Artem Belevich <[email protected]> wrote:
>>
>>>
>>>
>>> On Wed, Jun 19, 2019 at 1:47 PM Rasmus Munk Larsen <[email protected]>
>>> wrote:
>>>
>>>> It looks like we broke the Eigen Cuda build on Mac. What do you think
>>>> about his workaround?
>>>>
>>>> ---------- Forwarded message ---------
>>>> From: Eric Klein <[email protected]>
>>>> Date: Wed, Jun 19, 2019 at 1:39 PM
>>>> Subject: [eigen] Mac CUDA build failure question
>>>> To: <[email protected]>
>>>>
>>>>
>>>> Hello all,
>>>>
>>>> I posted a question on the forums several days back, but suspect that
>>>> might not be the right place to be asking what I'm asking, so I'm trying
>>>> the mailing list as well.
>>>>
>>>> I'll just repost here what I put in the forums, but the link to that is
>>>> here: https://forum.kde.org/viewtopic.php?f=74&t=161199
>>>>
>>>> I'm trying to build Eigen on Mac for CUDA (using the nvcc compiler),
>>>> and getting build errors. I understand the errors, and I have a change that
>>>> lets me dodge the build failures, but I suspect it's not the right change
>>>> for checkin, and so I'm looking for feedback.
>>>>
>>>> So the issue I have is in Half.h. I wind up getting errors about a
>>>> bunch of operators being already defined. The core issue is that on Mac,
>>>> nvcc (the CUDA compliler) is using gcc as the host compiler, but gcc on Mac
>>>> is built on top of clang. Eigen seems to be implicitly assuming that the
>>>> presence of clang implies that absence of CUDA (or at least the absence of
>>>> nvcc CUDA support).
>>>>
>>>> In my build I'm hitting this block:
>>>>
>>>> #if (defined(EIGEN_HAS_CUDA_FP16) && defined(EIGEN_CUDA_ARCH) && \
>>>>      EIGEN_CUDA_ARCH >= 530) ||                                  \
>>>>     (defined(EIGEN_HAS_HIP_FP16) && defined(HIP_DEVICE_COMPILE))
>>>> #define EIGEN_HAS_NATIVE_FP16
>>>> #endif
>>>>
>>>> which results in EIGEN_HAS_NATIVE_FP16 being set, and so we wind up
>>>> compiling in all the operators from Half.h:253-313. That's fine so far.
>>>>
>>>
>>> This assumes device-side compilation.
>>>
>>>
>>>>
>>>> What happens next is we hit this line:
>>>>
>>>> #if !defined(EIGEN_HAS_NATIVE_FP16) || EIGEN_COMP_CLANG // Emulate
>>>> support for half floats
>>>>
>>>> which is followed shortly after by (roughly) the same operator
>>>> functions (but... emulated), and I get errors because those operator
>>>> functions were defined above.
>>>>
>>>
>>> If Clang were CUDA compiler, that would not be a problem. This implies
>>> that it's a CUDA compilation with NVCC. What puzzles me is how did we end
>>> up with EIGEN_COMP_CLANG defined for the *device* side of the
>>> compilation. I suspect it's the side effect of NVCC doing device-side
>>> preprocessing with clang, but actually compiling with cicc, which is
>>> obviously not clang.
>>>
>>> I guess what we need to do here is something like this:
>>> #if !defined(EIGEN_HAS_NATIVE_FP16) || (EIGEN_COMP_CLANG && !
>>> EIGEN_COMP_NVCC)
>>>
>>> That, and a comment explaining what's going on.
>>>
>>> If that does not help, it would be great to compile with '-keep
>>> -verbose' and check which compilation phase is failing and what exactly is
>>> it trying to compile.
>>>
>>> --Artem
>>>
>>>
>>>> So. My hack to work around this is to ensure that EIGEN_COMP_CLANG gets
>>>> set to 0 in Macros.h if __NVCC__ is defined. That works fine for me
>>>> locally, and gets Eigen building fine (and thus unblocks me on getting
>>>> TensorFlow building for Mac, or at least unblocks this issue).
>>>>
>>>> I'm willing to bet however that this is the wrong thing to do in
>>>> general. I don't understand enough of what this second code block is doing
>>>> to really understand why clang is being treated differently than nvcc here
>>>> (and specifically why half support needs to be emulated in the presence of
>>>> clang). I believe there is a version of clang that supports CUDA (at least
>>>> on some platforms?). Presumably this is for that, but I don't know enough
>>>> about how that differs from nvcc to fully grok this.
>>>>
>>>> Can anyone help enlighten me about the best way to fix this?
>>>>
>>>> Thanks!
>>>> ---
>>>> Eric Klein
>>>> [email protected]
>>>>
>>>
>>>
>>> --
>>> --Artem Belevich
>>>
>>

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