[llvm] feat: fix big endian shuffle vector miscompile (PR #68673)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Hi - sorry about the delay it took a while to look through the details. There might be a way to convert NVCAST to BITCAST under LE and adjust all the needed patterns to handle either, but it doesn't look simple and this seems like a good fix for now. It checked out OK in all the tests I tried. There are some comments about adjusting the new test case below, but otherwise this looks OK to me.

https://github.com/llvm/llvm-project/pull/68673