[chbot] GCC / Codesourcery #pragma for ARM Cortex M3

[Volker Kuhlmann]

Hi Mark,

> I need tight optimization around a small code block (can be made into 
> a function if need be).
> 
> The main body (10k lines) has been tested without any optimization, 
> so, I am loathed to change optimization for the whole system and then 
> have to re-test.
> 
> Anyone know of an optimization pragma I can use just for this tight piece ?

The gcc manual is pretty comprehensive, I'd look there, but I haven't
heard of or seen any way of influencing compiler switches during the
compilation of a module.

You can however change compiler option per module. So if you move this 1
function (10k lines for a function does sound badly structured though)
into a separate module, you can use different switches.

Re-testing would be the better way though, after constructing some test
automation. You want to enter a bet that you don't ever want to make any
other changes later?

> I guess the other option is do-it-in-assembler, which isn't such a 
> bad idea now I come to think of it. The M3 is such a lovely target...

There is never a case for assembler unless you are under extreme code
space or extreme performance limits and that applies only to high-volume
products where the high expense of development time pays off. For a
few-off you drop another gold coin on a bigger CPU.

Or you like beautiful assembler and its asthetics, but then you're not
looking at cost/benefit, you're entertaining yourself... ;-)

Volker

-- 
Volker Kuhlmann
http://volker.dnsalias.net/	Please do not CC list postings to me.