[tree-ssa] Loop analysis

Jan Hubicka jh@suse.cz
Wed Apr 16 21:03:00 GMT 2003

> On Tue, 2003-04-15 at 09:56, Pop SĂŠbastian wrote:
> > I don't know whether it is worth to handle differences between representations
> > in a cfg_hook structure, or simply guard the code with a boolean: cfg_at_rtl_level.
> >
> 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.
> > What is difficult is to register static functions in the hook structure. 
> > 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)


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