perf(router): remove NYI to be more JIT-friendly

[ADD-SP]

Please SQUASH AND MERGE

Summary

---- TRACE 1772 start fields.lua:457
0001  UGET     4   0      ; FIELDS_FUNCS       (fields.lua:458)
0002  TGETV    4   4   1       (fields.lua:458)
0003  IST          4       (fields.lua:458)
0004  JMP      5 => 0009
0005  UGET     4   1      ; get_field_accessor       (fields.lua:459)
0006  TGETS    6   0   0  ; "funcs"       (fields.lua:459)
0007  MOV      7   1       (fields.lua:459)
0008  CALL     4   2   3       (fields.lua:459)
0000  . FUNCF    9          ; fields.lua:266
0001  . TGETV    2   0   1       (fields.lua:267)
0002  . ISF          2       (fields.lua:268)
0003  . JMP      3 => 0005
0004  . UCLO     0 => 0055       (fields.lua:269)
---- TRACE 1772 abort fields.lua:269 -- NYI: bytecode 50

Generating a field accessor in place in the get_field_accessor() is not JIT friendly, so let' generate accessor from the other function.

---

And tail call is not JIT-friendly in some cases, so rewrote it.

Checklist

• [N/A] The Pull Request has tests
• [N/A] A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• [N/A] There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Issue reference

KAG-3653

[bungle]

Not sure if CI is flaky, but seems like this may have caused issue. Restarting CI 3rd time.

[bungle]

Not sure if CI is flaky, but seems like this may have caused issue. Restarting CI 3rd time.

Seems to gone green now.

[bungle]

Today is code freeze, so I am not sure do we want this in still? Seems like a stretch. How much this improves anything?

[bungle]

@ADD-SP are we going to merge this? Ping @chronolaw, can you review and approve?

[chronolaw]

@ADD-SP are we going to merge this? Ping @chronolaw, can you review and approve?

I already approved this PR and did some work on it, I think that we can merge it.

[ADD-SP]

Merge on CI green

[team-gateway-bot]

Successfully created cherry-pick PR for master:

• https://github.com/kong/kong-ee/pull/8498