tracing + specialization + EXTENDED_ARG = assertion failure

[sweeneyde]

I found this while working on #91713

def f(x):
    ( # EXTENDED_ARG + UNPACK_SEQUENCE
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,

        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
        y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y, y,y,y,y,y,
    ) = x

for _ in range(20):
    f(range(300))  # warmup

import sys
sys.settrace(print)
f(range(300))  # assertion failure

This results in Assertion failed: cframe.use_tracing == 0, from here, in the UNPACK_SEQUENCE_ADAPTIVE instruction. Presumably, other specialized opcodes are similar.

@markshannon @brandtbucher

[sweeneyde]

I won't have time to work on it this week, but(looks like I found time)

One potential solution could be to make EXTENDED_ARG always check for tracing and add an EXTEDED_ARG_QUICK that doesn't check for tracing.