[PicForth] Possible 'if' code generation bug

[Alex Holden]

Picforth seems to generate incorrect code when you have an 'if' with no 
action following it. Is it not legal Forth to use a construct like that 
if you want to only perform an action when a test fails? It works when I 
try it in gforth and pforth but picforth doesn't seem to like it.

Here's a rather contrived example:

: sometest 0 ;
: doaction ;
main : sometest if else doaction then ;

Compiles to:

0x0000  018A    clrf    0x0A
0x0001  2807    goto    0x007   ; (init-picforth)
         ; name: sometest
         ; max return-stack depth: 0
0x0003  0384    decf    0x04,f
0x0004  0180    clrf    0x00
0x0005  0008    return
         ; name: doaction
         ; max return-stack depth: 0
0x0006  0008    return
         ; name: (init-picforth)
         ; max return-stack depth: 0
0x0007  3032    movlw   0x32
0x0008  0084    movwf   0x04
         ; name: sometest
         ; max return-stack depth: 0
0x0009  0800    movf    0x00,w
0x000A  0A84    incf    0x04,f
0x000B  3800    iorlw   0x00
0x000C  1D03    btfss   0x03,2
0x000D  2800    goto    0x000   ; sometest + 0x005
0x000E  280F    goto    0x00F   ; sometest + 0x006
0x000F  0008    return

Which seems to me to be badly messed up. I stumbled across this when I 
had a similar construct in my 'main' word and the goto 0x000 instruction 
was making it continually reset itself.

Here's what happens if I do something similar with gforth (which behaves 
as expected):
: sometest 0 ;  ok
: doaction ." Hello" ;  ok
: test sometest if else doaction then ;  ok
test Hello ok

-- 
------------ Alex Holden - http://www.linuxhacker.org ------------
If it doesn't work, you're not hitting it with a big enough hammer