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Update CDP support macros for if-target compatibility #486
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The definition of CUB_RUNTIME_FUNCTION is modified to be
consistently defined across all NVCC compilation passes. Rather
than depending on __CUDA_ARCH__, its definition now only depends
on whether or not RDC is enabled.
A new CUB_RDC_ENABLED macro has been added as a replacement for
CUB_RUNTIME_ENABLED. CUB_RUNTIME_ENABLED also depends on the
definition of __CUDA_ARCH__ and should no longer be used
in CUB code. It is provided for legacy purposes only. Usages should
be replaced by NV_IF_TARGET and the new CUB_RDC_ENABLED macro.
To summarize the differences between the old and new macros:
- `CUB_RUNTIME_FUNCTION`
- Old:
- RDC enabled: Defined to `__host__ __device__`.
- RDC not enabled:
- NVCC host pass: Defined to `__host__ __device__`.
- NVCC device pass: Defined to `__host__`.
- New:
- RDC enabled: Defined to `__host__ __device__`.
- RDC not enabled: Defined to `__host__`.
- `CUB_*_ENABLED`
- `RUNTIME` (old)
- RDC enabled: Macro is defined.
- RDC not enabled:
- NVCC host pass: Macro is defined.
- NVCC device pass: Macro is not defined.
- `RDC` (new)
- RDC enabled: Macro is defined.
- RDC not enabled: Macro is not defined.
The most common pattern used with the old macros looked like this:
```
CUB_RUNTIME_FUNCTION
cudaError_t SomeFunction()
{
return cudaErrorNotSupported;
// Actual implementation here
return cudaSuccess;
}
```
This pattern can now be simplified to:
```
CUB_RUNTIME_FUNCTION
cudaError_t SomeFunction()
{
// Actual implementation here
return cudaSuccess;
}
```
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Some test already had some support for CDP testing, this commit uses the %PARAM% system to enable these. The radix sort tests saw some addition changes that remove some excessive testing. More work could be done here.
`SyncStream` should continue to be used for required synchronizations. `DebugSyncStream` should only be used for sync that are non-essential and only used to handle the `debug_synchronous` flag of the device algorithms.
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Goes with NVIDIA/thrust#1661. Updates the CDP/CUDART macros to be consistent across host/device passes and thus compatible with NV_IF_TARGET.
All device algorithm tests with existing CDP tests have been updated to exercise this functionality. Some device algorithm tests do not have CDP tests and will need to be updated in a future PR.
Pre-written Release Notes
Breaking Changes
NV_IF_TARGET. They are now defined consistently across all host/device compilation passes. This should not affect most usages of these macros, but may require changes for some edge cases.CUB_RUNTIME_FUNCTION: Execution space annotations for functions that invoke CUDA Runtime APIs.__host__ __device____host__ __device____host____host__ __device____host__CUB_RUNTIME_ENABLED: No change in behavior, but no longer used in CUB. Provided for legacy support only. Legacy behavior:CUB_RDC_ENABLED: New macro, may be combined withNV_IF_TARGETto replace most usages ofCUB_RUNTIME_ENABLED. Behavior:Other Enhancements
debug_synchronousflag in the device algorithm layer now print a log message.