julia

5e1bcdf9 - Remove references to non opaque pointers in codegen and LLVM passes (#54853)

Remove references to non opaque pointers in codegen and LLVM passes (#54853) This is in preparation for the bump to LLVM18 where some of these APIs are removed. This also removes uses of bitcasts between pointers since those were already noops and just complicated the code. This also changes a couple of the GEPs in the code to be int8 GEPs in preparation for whatever version of https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699 that eventually gets made. In any case LLVM already canonicalizes GEPs to i8 GEPs so this doesn't hurt.