Section 3.10.1 describes the __critical attribute to apply to functions or blocks to disable interrupts, and does not mention anything about it working only on certain targets. On the PIC16 target, it appears to have no effect. This is with "SDCC : mcs51/gbz80/z80/avr/ds390/pic16/pic14/TININative/xa51/ds400/hc08 2.9.0 #5416 (Oct 8 2010) (UNIX)"
Hopefully and finally fixed in r7307.