Re: [tree-ssa] Loop analysis

[Pop Sébastian <pop at gauvain dot u-strasbg dot fr>]

On Wed, Apr 16, 2003 at 11:03:38PM +0200, Jan Hubicka wrote:

> > Let's use an enum instead of a boolean.  We have talked about
> > introducing mid-RTL or low-GIMPLE in the future.  They *may* need
> > different hooks.
> 
> I hope to elliminate the booleans by subsequent cleanups.  Loop
> optimization already works on two different representation of the CFG -
> the cfglayout and normal RTL CFG.  These are close but different and
> some conditionals are already in the code.  I like Pop's hooks idea and
> hope to elliminate these.

I'm bootstrapping with a version that uses an enum: 

----
enum cfg_level {
  AT_TREE_LEVEL,
  AT_RTL_LEVEL
};

/* A global variable that keeps track of the state of the cfg.  */
extern enum cfg_level cfg_level;
----

Should I stop the bootstrapping, or is it ok with this version?

> > 
> > > What is difficult is to register static functions in the hook structure. 

The solution is to register static functions only in the file where they are 
defined/declared.  They should be registered into the hooks structure before
their use.  This is doable, but not very clean. 

> > > I think that the guarded code is the better solution.
> > > 
> > Why is it difficult?
> 
> Because at the moment the API is not very well separated - we do a lot
> by touching RTL we can do by generic CFG routines.  It is partly because
> of some sick features of RTL (for instance split_edge could be
> completely RTL indepdent if there wasn't those sick LOOP notes)
> 
Yep, I like the tree interface :-)  It seems much more IR independent.