Topic refactor cuda hip atomics #1768
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| // | ||
| // Atomics can be used in the hierarchy level grids, blocks and threads. | ||
| // Atomics are not guaranteed to be save between devices. | ||
| class AtomicUniformCudaHipBuiltIn |
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Does it also works, if the CUDA and the HIP are enabled at the same time?
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As I know. You can not enable CUDA and HIP at the same time.
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Really, I thought Andrea implemented it? Or is it permitted by the CMake?
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As I know he is compiling a library for CUDA and a library for HIP and linking both together.
Both libs will use a different compiler.
@fwyzard Could you check if this PR is working for you. I do not exactly know your workflows.
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I think I remember that we introduced the device API struct to avoid naming conflicts. Nevertheless, these changes are fully on the device side and should not create symbols on the host side which can conflict.
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Sorry, I have been doing night shifts this week, and had little time for the rest :-/
I'll try to have a look ASAP.
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- check for builtin atomics and use these if available - emulate atomics which are not provided as builtin via atomicCas - emulate atomicCas for floating point data
Unify CPU and HIP/CUDA atomic tests. For CUDA run tests only for 32bit and 64bit data types.
``` alpaka/atomic/AtomicOaccExtended.hpp:209:36: error: comparing floating-point with '==' or '!=' is unsafe [-Werror=float-equal] ```
For architectures where __hip_atomic_compare_exchange_strong is false HIP is emulating atomics with `atomicCAS` but with a broken implementation.
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In #1767 I already enabled the usage of building atomicAdd for double precision.
Nevertheless, we are emulating in alpaka often atomics because it is a nightmare to maintain the list of supported atomic functions for HIP and CUDA. The list of supported types for different atomics differs between both models.
This PR introduces a "simple" way to let the compiler decide if a built-in function is available and use these. If not we will emulate the required atomics by using
atomicCas.hierarchy::Threads-> mapped toatomicXXX_block()