Re: Something general (beginner related)

[Joe Buck <Joe dot Buck at synopsys dot COM>]

On Wed, Aug 20, 2008 at 12:21:42AM +0200, Nils Pipenbrinck wrote:
> Well - I had a lot of time to kill during the last weeks, and I had a 
> lot of timeto read into the source. Business trips without internet 
> access are a perfect opportunity to read such stuf...
> 
> Anyway, after all this passive read-work, I've been able to add the 
> humble beginnings of my pass. I'm now able to  and I've been able to run 
> a code that does a printf as soon as I find an structure in the SSA tree 
> that is a potential candidate for my optimization.
> 
> However, approaching this point has been very painfull and I'm far away 
> from chainging anything in the SSA.
> 
> Let's get to the point: The documentation sucks. If you want to learn 
> how things work the wiki and the documentation is of little help. You 
> have to read other code, step through other optimizations  and do a lot 
> of reverse-engineering and code-reading to understand how all the 
> different things fit and relate to each other.

You may be in a unique position to do something about this problem,
as someone who has just had to painfully learn how to write a pass.
You could write up what you've learned on a wiki page, and we might
be able to convince some more experienced people to help correct anything
you got wrong.

> I think a well commented pseudo-pass (well document as: talk to someone 
> who know C but has no idea about the GCC magic..) that does something 
> stupid but valid like re-inventing the neg-operator by using not and 
> subtraction could act as be a very nice boilerplate code for people like me.

Alternatively you could contribute that.

> For someone who is into the SSA structures and the gcc internals should 
> be able to write up something within a day or an half.

Right, but in many cases the people that know this stuff cold don't have
a day and a half, so it will happen when someone contributes it.