[llvm] [GlobalIsel][AArch64] legalize ptr add (PR #89218)

[David Green via llvm-commits]

davemgreen wrote:

Can you add a .ll test to make sure we test the entire process? .mir tests are good for specific cases, but don't test the whole pipeline. I think I would also vote for just clamping the first index (and it only needs to clamp the max), but either way that sounds OK to me so long as you can add the test.

https://github.com/llvm/llvm-project/pull/89218