Generalize Arm64 ldr/str to ldp/stp optimization #81278
Description
#77540 introduced a JIT peephole optimization to convert consecutive ldr/str instructions to ldp/stp. It was limited to avoiding this optimization when either of the two ldr/str represented lclvar, which requires more work to properly handle the GC effects.
See #77540 (review) for more discussion.
This issue tracks generalizing the optimization to handle the lclvar cases.
Also, the optimization was restricted to not work in prologs or epilogs, to avoid affecting unwind codes. There are two potential improvements here:
- Make sure the unwind codes work with the optimization.
- Allow the optimization in the non-OS (not unwindable) part of the prolog/epilog.