gh-105481: refactor instr flag related code into a new InstructionFlags class

[iritkatriel]

1. save the complete flags data on the instruction (not just the bitmap)
2. refactor all the code into a new flag management class.

This will help later when we want to use the flags for things like generating hasarg, etc.

• Issue: Generate opcode metadata from bytecodes.c instead of opcode.py #105481

[gvanrossum]

I like refactoring this, but I'd like to go a little beyond just packaging up the old code in a class.

[gvanrossum]

At this point, in my optimizer work, I have a need to prevent one flag ("IS_UOP") from being propagated. How would you do that using the new API?

[iritkatriel]

We can add an arg to this function to tell it which flags to skip?

[gvanrossum]

Yeah, something like exclude: set[str] | None = None would work.

[iritkatriel]

Let's add it when we need it. I don't like adding code that is neither used nor tested.

[gvanrossum]

I can add it after I merge your code into gh-105924.

[gvanrossum]

LGTM!

[iritkatriel]

It's doing this now that I removed the hash and eq:

Traceback (most recent call last):
  File "/Users/iritkatriel/src/cpython-1/./Tools/cases_generator/generate_cases.py", line 1422, in <module>
    main()
  File "/Users/iritkatriel/src/cpython-1/./Tools/cases_generator/generate_cases.py", line 1414, in main
    a.analyze()  # Prints messages and sets a.errors on failure
    ^^^^^^^^^^^
  File "/Users/iritkatriel/src/cpython-1/./Tools/cases_generator/generate_cases.py", line 708, in analyze
    self.analyze_macros_and_pseudos()
  File "/Users/iritkatriel/src/cpython-1/./Tools/cases_generator/generate_cases.py", line 827, in analyze_macros_and_pseudos
    self.pseudo_instrs[name] = self.analyze_pseudo(pseudo)
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/iritkatriel/src/cpython-1/./Tools/cases_generator/generate_cases.py", line 865, in analyze_pseudo
    flags_list = list(set([t.instr_flags for t in targets]))
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: unhashable type: 'InstructionFlags'

[gvanrossum]

It's doing this now that I removed the hash and eq:

Traceback (most recent call last):
[...]
  File "/Users/iritkatriel/src/cpython-1/./Tools/cases_generator/generate_cases.py", line 865, in analyze_pseudo
    flags_list = list(set([t.instr_flags for t in targets]))
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: unhashable type: 'InstructionFlags'

Oh dang. Dataclasses don't generate a hash by default. You can either put the __hash__ back or write @dataclass(unsafe_hash=True). The "unsafe" part concerns me.

[gvanrossum]

That works too!

[iritkatriel]

I changed it to not hash the data class object but the bitmap representation. It's just for an assertion that all the flags of a pseudo-op's targets are the same.