Wrong oparg is passed to trace recorder when `JUMP_BACKWARD_JIT` is preceded by `EXTENDED_ARG`

[markshannon]

Bug report

Bug description:

This doesn't seem to cause any failure, AFAICT, but there could be a failure mode somewhere.
Found when experimenting with a new (small) optimization.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-152192: Fix JUMP_BACKWARD passing a truncated oparg to the jit tracer #152382

[markshannon]

To clarify what is happening:
The instruction made of this pair of code units: EXTENDED_ARG 1; JUMP_BACKWARD_JIT 1 has an oparg of 257, but the EXTENDED_ARG part is ignored and _PyJit_TryInitializeTracing gets passed oparg=1.

[markshannon]

Please don't dump AI output into the issue.
If you have a working fix, by all means open PR

[Codeer22]

Deleted that

[deadlovelll]

To clarify what is happening: The instruction made of this pair of code units: EXTENDED_ARG 1; JUMP_BACKWARD_JIT 1 has an oparg of 257, but the EXTENDED_ARG part is ignored and _PyJit_TryInitializeTracing gets passed oparg=1.

Hello! If you don't mind, can i try work on this?