Keil has quite an unusual take on optimising this bit of code:

----- FUNCTION main (BEGIN) -----
FILE: 'junk.c'
26: void main(void)
27: {
28: unsigned char q;
29:
30: q = 0x00;
;---- Variable 'q' assigned to Register 'R7' ----
0000A9 E4 CLR A
0000AA FF MOV R7,A
0000AB ?C0002?JUNK:
31: while (q == 0x00);
0000AB EF MOV A,R7
0000AC 60FD JZ ?C0002?JUNK
32: }
0000AE 22 RET
----- FUNCTION main (END) -------