Re: Re : Tr : [redundency elimination, code motion, commun expression elimination] GCC optimizations

[Jeff Law <law at redhat dot com>]

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On 09/26/11 03:06, charfi asma wrote:
> Hello every body,
> 
> First of all, thank you for all your responses ;)
> 
> 
> this situation is frequent in real time and embedded system
> development (developper use switch cas statements to express the
> behavior of the system).
> 
> I think that GCC purpose is to help developper to produce an
> optimized code for their application. developper are not obliged to
> optimize the code, we have to be happy if they manage to write the
> correct code (that runs just like developper want it to run).
> Otherwise, optimization is the GCC stuff... @ David: if (x=1) was a
> typo, I meant if (x==1).
> 
> you said that The "tail merging" and "block merging" mentioned by
> Jeff Law sounds like optimisations to suit such cases.
> 
> I tested with gcc 4.6 (the current gcc version) I compiled the code
> using -Os and GCC did not optimize the code. did block merging and
> tail merging are not included in -Os ?
> 
Tom's changes aren't in GCC 4.6, you'd have to test the current sources.

jeff
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