In preparation for later fixes to the non-integral addrspace handling (D59661)
As far as I could tell, all later code paths are guarded by the full condition that I'm now also using here:
I thought it seemed odd to check only part of the condition early, while deferring the full check until later.
OTOH, this might not be strictly NFC, since, while not a semantic difference in IR, I thought it seemed like ConstantFoldLoadFromConstPtr may sometimes have difficultly looking through this BitCast.
Bump. I wanted to confirm you agree now that this part of the change is NFC. I think I've addressed your other comments, so the other commits in the stack should also be ready for re-review also. Thanks!