Michael Rigby-Jones escreveu:
>> Michael Rigby-Jones escreveu:
>>     =

>>> Optimisation is pretty much non-existent with the Lite version.  It
>>> seems some people assume the free compiler has been designed to
>>> deliberately emit very poor code, but in fact it's just the same as
>>>       =

> the
>   =

>>> standard compiler with optimisation disabled.
>>>
>>> Regards
>>>
>>> Mike
>>>       =

>
>   =

>> -----Original Message-----
>> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
>>     =

> Behalf
>   =

>> Of Isaac Marino Bavaresco
>> Sent: 26 May 2009 15:02
>> To: Microcontroller discussion list - Public.
>> Subject: RE: [PIC] Source boost V HiTech compilers for C use
>>
>> Some time ago I posted here a quick analysis that show that the code
>> generated is weird, not just inneficient, the only possibility is it
>> being made on purpose.
>>
>>     =

>
> Have you actually compared it to the old standard (commercial) compiler
> with all optimisations disabled?  That also produces some extremely
> non-optimal code that would doubtless look weird to someone used to
> coding in assembly.
>   =


Yes, it is weird compared to the code generated by the standard version
without optimizations.

I found my old post, what do you think of this:

<quote>
PPS.: Some time ago somebody talked about Hi-Tech *PICC*-Lite versus PRO
generated code.
I found that the Lite generates purposely (very) inefficient code, so
the PRO version looks even better.

Look how they do 'Var =3D 0;' :

bcf    STATUS,C
movlw   0
btfsc   STATUS,C
movlw   1
movwf   Var

'Var =3D 1;'

clrf   Var
bsf   STATUS,C
rlf   Var,f

'Var =3D 2;'

clrw
iorlw   2
movwf   Temp
movf   Temp,w
movwf   Var

And so on... </quote>


> I suggest that you need to write a compiler for yourself to understand
> just how much work an optimiser actually does.
>   =


I did.

> Regards
>
> Mike
>   =

Regards,

Isaac

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