Re: How to clean up i386 machine description?

[Jan Hubicka <hubicka at horac dot ta dot jcu dot cz>]

> Thanks.  I haven't had a chance to look at it in any detail yet.

I've run into problems with recent snapshots and this patch.
It also contains the wrong fix for FP conversion bug, so I will have to
prepare updated version soon. (In fact I have it, but it runs into some
kind of weird reload problem. I will delay it for the moment.)
>   > I've already split some patterns in way you describe, but I was unsure if
>   > it is good idea. .info says it isn't, because reload can change register
>   > to constant but keep the register version. So it says it is generally
>   > better  to use general addition pattern instead of inc pattern.
>   > Is this still relevant? 
> Most of the time tightening the predicates to more closely match the machine
> is going to win.  That's become a rule of thumb for most new ports.  There
> are sometimes exceptions, but they're becoming rare.
>   > Can you explain me the problem in some detail?
> It's difficult to explain.  Again, the general rule of thumb is to make the
> predicate match the hardware more closely.  Exceptions exist, but they are
> analyzed on a case by case basis.

OK, so I will just believe you.
> 
> If you have a more specific pattern, then you should put it first.  Your
> general pattern may (or may not) still need to handle the case that is
> in the specific pattern -- it depends on a variety of factors.

OK, we should discuss this later once other problems are settled down.
> 
> jeff

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