minor followups on recent CodeInstance refactors

[aviatesk]

• simplifies the signature of transform_result_for_cache
• make jl_uncompress_ir take MethodInstance instead of CodeInstance
  and simplifies the inlining algorithm
• renames of codeinst::CodeInstace objects
• removal of dead code

[vtjnash]

The metadata argument is mandatory to be a CodeInstance, as it contains some of the required context for uncompressing and populating the CodeInfo correctly and efficiently

[vtjnash]

This is fine to change, but it had seemed inconvenient to cause breakage for external clients which are supposed to overload this method signature.

[aviatesk]

Well, that does happen frequently. The overload signature of transform_result_for_cache was changed in #53219, and this PR serves as a follow-up to that change. So I believe making modifications at this PR wouldn't be an issue. We need to add some updates to external abstract interpreter packages anyway.

[aviatesk]

The metadata argument is mandatory to be a CodeInstance, as it contains some of the required context for uncompressing and populating the CodeInfo correctly and efficiently

Is it not feasible to check the identity of codeinst.def and mi in the callers of _uncompress_ir(mi, src)? I'd prefer to avoid the current state of affair where external abstract interpreter needs to have two overloads of retrieve_ir_for_inlining.

[aviatesk]

Having looked over #52415, I've gotten why jl_uncompress_ir requires a metadata::CodeInstance. That said, the custom inlining pass interface of src_inlining_policy and retrieve_ir_for_inlining needs more work, but I'm thinking of tackling that in another PR. This one keeps things pretty much cosmetic changes here, without messing with the compiler's workings too much.

[aviatesk]

@nanosoldier runbenchmarks("inference", vs=":master")

[nanosoldier]

Your benchmark job has completed - no performance regressions were detected. A full report can be found here.

[aviatesk]

I'd like to move this forward. @vtjnash can you give another review on this?

[vtjnash]

I am on vacation this month, so proceed as you see fit. I will try to remove my "request changes" if any

Changes have been addressed.

[aviatesk]

I dismissed it from my side. Have a great vacation!