Remove +PTX from CUDA 12.8 builds and small refactor in build_cuda.sh.
Removing +PTX reduces binary size required to be able to upload binaries to pypi

Pull Request resolved: #157516
Approved by: https://github.com/malfet, https://github.com/ptrblck, https://github.com/tinglvv

(cherry picked from commit 8408522)

Remove +PTX from CUDA 12.8 builds (#157516)

Remove +PTX from CUDA 12.8 builds and small refactor in build_cuda.sh.
Removing +PTX reduces binary size required to be able to upload binaries to pypi

Pull Request resolved: #157516
Approved by: https://github.com/malfet, https://github.com/ptrblck, https://github.com/tinglvv

(cherry picked from commit 8408522)

Co-authored-by: atalman <atalman@fb.com>

…pytorch#157516)

…57791)

NVCC apparently has a [compression-mode flag](https://docs.nvidia.com/cuda/cuda-compiler-driver-nvcc/#compress-mode-default-size-speed-balance-none-compress-mode) to tell it how you want to compress the fatbinary since 12.4. This mode defaults to speed (pick a low compression mode that loads the file quickly). Since we are running into PyPi size issues, this will allow us to upload smaller wheel files.

From: https://docs.nvidia.com/cuda/cuda-compiler-driver-nvcc/index.html#compress-mode-default-size-speed-balance-none-compress-mode
```
size
Uses a compression mode more focused on reduced binary size, at the cost of compression and decompression time.
```

Up to 37.2%  reduction in binary size with virtually no drawback (except potentially a little slower loading of the .so at PyTorch startup).

694 MB for CUDA 12.9 builds with 6.0;7.0;7.5;8.0;8.6;9.0;10.0;12.0+PTX
vs
1.08GB for CUDA 12.9 builds with 7.5;8.0;8.6;9.0;10.0;12.0+PTX

CUDA 12.9 ***694MB*** vs ***1.08GB***

CUDA 12.8 ***604MB*** vs ***845MB***

This ends up saving PyPi.org approximately 19.6 PiB of bandwidth per month for the CUDA 12.9 case.

This will also allow us to add back CUDA 12.8 12.0+PTX which will make the package forward compatible on newer GPUs. Undoing the need for PR #157516 and #157634

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More details can be found in Nvidia's technical blog for CUDA 12.4: https://developer.nvidia.com/blog/runtime-fatbin-creation-using-the-nvidia-cuda-toolkit-12-4-compiler/

Pull Request resolved: #157791
Approved by: https://github.com/malfet, https://github.com/atalman