[llvm] [AArch64][GlobalISel] Add support for pre-indexed loads/stores. (PR #70185)

[Amara Emerson via llvm-commits]

aemerson wrote:

> You added new asserts without the common && "something bad happened". I am wondering why they are not just if() return false?

It's something we're not that consistent with. In selection of instructions where we should be confident in the completeness of the legalization rules, we can use asserts. However if the legalizer rules may have gaps, it's probably better to be safe and fall back instead of asserting.

https://github.com/llvm/llvm-project/pull/70185