[llvm] [NVPTX] support dynamic allocas with PTX alloca instruction (PR #84585)

[Alex MacLean via llvm-commits]

AlexMaclean wrote:

> I was about to work on this issue #62812, I think your patch will fix it.

I just gave compiling the provided IR a try and I can confirm that with this change it is now successfully compiled (provided a supported arch and PTX version is specified).

https://github.com/llvm/llvm-project/pull/84585