The cases_generator handles some instructions incorrectly

[brandtbucher]

I triggered this assert...

Traceback (most recent call last):
  File "/home/brandtbucher/cpython/./Tools/cases_generator/generate_cases.py", line 1609, in <module>
    main()
  File "/home/brandtbucher/cpython/./Tools/cases_generator/generate_cases.py", line 1604, in main
    a.write_metadata()
  File "/home/brandtbucher/cpython/./Tools/cases_generator/generate_cases.py", line 1260, in write_metadata
    assert not instr.active_caches, (instr.name, instr.cache_effects)
AssertionError: ('TO_BOOL_ALWAYS_TRUE', [CacheEffect(context=<Python/bytecodes.c: 1807-1810>, name='unused', size=1), CacheEffect(context=<Python/bytecodes.c: 1811-1814>, name='version', size=2)]

...while defining this new instruction...

        inst(TO_BOOL_ALWAYS_TRUE, (unused/1, version/2, value -- res)) {
            // This one is a bit weird, because we expect *some* failures:
            assert(version);
            DEOPT_IF(Py_TYPE(value)->tp_version_tag != version, TO_BOOL);
            STAT_INC(TO_BOOL, hit);
            DECREF_INPUTS();
            res = Py_True;
        }

@gvanrossum thinks that the assert is incorrect: it appears that the current code doesn't know how to handle an instruction that uses caches but doesn't have an oparg.

Linked PRs

• gh-106250: Support inst() using one cache entry and no oparg #106252