[llvm] [NVPTX] fixup support for unaligned parameters and returns (PR #82562)

[Alex MacLean via llvm-commits]

AlexMaclean wrote:


> That said, considering that we've survived for so long with nobody noticing the issue, and that the fix is nontrivial, perhaps it may be better to disallow or ignore unaligned arguments? Did you run into any real use cases where parameter/return alignment was an issue?

I think you were involved in originally reporting this issue in CUDA way back in 2017, right? Do you recall more about why it was needed at the time? It's been fixed in CUDA for a long time now and I think it would be good to add support for `__attribute__((packed))` to the open source version as well. I agree it doesn't seem like it is going to be used all that frequently but still nice to have and the fix is already complete.

https://github.com/llvm/llvm-project/pull/82562