gh-128563: Move labels in ceval.c to bytecodes.c

[Fidget-Spinner]

• Issue: A new tail-calling interpreter for significantly better interpreter performance #128563

[markshannon]

I don't think adding another code generator is the way to go.
The code in labels is part of the interpreter, so they should be handled similarly to instructions.

For code in labels we will, in the future, want to:

• Spill the stack around escaping calls
• Use the same dispatching mechanism as for instructions
• Potentially access stack variables without cumbersome explicit pops and pushes.

I'm not suggesting that we do any of the above in this PR. The simple code you generate is fine for now, but it needs to be a bit more closely integrated into the interpreter/JIT generators.

Since labels exist outside the dispatch loop, we'll need to generate the dispatch loop as well. We can simply copy the few lines of code surrounding #include "generated_cases.c.h" into the tier1 code generator.

The tier 1 code generator would then generate:

• The dispatch preamble (from /* Start instructions */ onwards)
• The cases
• The dispatch loop end including EXTRA_CASES up to Py_UNREACHABLE();
• All the labels

[Fidget-Spinner]

Alright. I've moved the labels generator back into the tier 1 generator. We need to port over tier 2 in a separate PR as well.

I've combined the switch-case generator into the cases generator as well.

[markshannon]

Mostly looks good. One thing doesn't look right

[markshannon]

Adding the markers to the generated code for testing looks good, but the parsing in the test is a bit cumbersome.

[markshannon]

You can replace this line by line processing, including the start and end comment stripping, by splitting the whole file on INSTRUCTION_START_MARKER and INSTRUCTION_START_MARKER, discarding the first and last parts.

text = temp_output.read()
_, rest = text.split(INSTRUCTION_START_MARKER)
actual, _ = rest.split(LABEL_START_MARKER)

[Fidget-Spinner]

Good observation. Thanks!

[bedevere-app]

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