Failed assert when lowering UOP_MAX_TRACE_LENGTH to 200

[gvanrossum]

Crash report

See faster-cpython/ideas#669 (comment)

By lowering UOP_MAX_TRACE_LENGTH to 200 I managed to cause a failing assert in this line in translate_bytecode_to_trace() in optimizer.c:

    if (trace[trace_length-1].opcode != _JUMP_TO_TOP) {
        ADD_TO_TRACE(_EXIT_TRACE, 0, 0, target);
    }

I suspect a missing RESERVE() or RESERVE_RAW() call somewhere.

While I didn't see this with higher max trace length, I suspect that the bug is universal, just harder to tickle (there aren't that many long traces).

[markshannon]

May have been fixed by #118106, but I haven't checked it.