[llvm] [LLVM][CodeGen][AArch64] Increase opportunities to fold shift-of-extend into sshll/ushll. (PR #213989)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

> Is it worth having tests where both A and B are extended? To avoid potential regressions if multiply-long nodes are ever removed or formed later.

It cannot hurt.  It has no effect today but I've also added code to block the transformation for this scenario as well.


https://github.com/llvm/llvm-project/pull/213989