KOS_OP_CALL_FAST_ATTR

• Style: EXTRA. Schema: FASTVAR (slot index for obj), CONST (attr name), COUNT (npos), NOARG.

• Stack: [..., arg_0, ..., arg_{N-1}] → [..., result]. Same resolution and invocation rules as KOS_OP_CALL_ATTR, but obj is not on the stack: it is read from the current frame’s fast slot a0, so the frame must have fast locals. An unbound function found on the class receives obj as its first argument; any other callable receives the N arguments alone.

• Compiler form: Not emitted by the compiler; available for manual bytecode construction.