[llvm] [llvm][AArch64] intrinsic to generate a ubfx instruction (PR #80103)

[David Green via llvm-commits]

davemgreen wrote:

For the record I have the same comment as https://github.com/llvm/llvm-project/pull/79672#issuecomment-1919524950.

(Additionally, if we were to add the intrinsics, it would probably be better to have a ubfm intrinsic and push the figuring out of the width and whatnot to the frontend. UBFM is the more basic instruction, and it might be better to have a SBFM too to keep them symmetrical. There are also the same issues with the tablegen vs c++ lowering as in #79672.

But it still seems better to me to use normal instructions and optimize the backend where we need to.)

https://github.com/llvm/llvm-project/pull/80103