[m-rev.] for review: impurity & higher-order

[Fergus Henderson]

On 25-Jan-2003, Simon Taylor <stayl at cs.mu.OZ.AU> wrote:
> On 25-Jan-2003, Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> > +++ compiler/simplify.m	22 Jan 2003 16:28:38 -0000
> > @@ -726,13 +726,17 @@
> >  		simplify_do_calls(Info0),
> >  		% XXX We should do duplicate call elimination for
> >  		% class method calls here.
> > -		GenericCall = higher_order(Closure, _, _)
> > +		GenericCall = higher_order(Closure, Purity, _, _),
> > +		% XXX Should we handle impure/semipure higher-order calls too?
> > +		Purity = (pure)
> 
> Surely not?

For impure, yes, we don't want to do duplicate call elimination.
But for semipure higher-order calls it would make sense to do
duplicate call elimination, provided that there is no impure
code between the two duplicate calls.  However, doing that is
a bit tricky, and not worth the bother right now, hence the XXX.

I'll change the comment to 

	% XXX Should we handle semipure higher-order calls too?

The diff posted passes tools/bootcheck in both grades hlc.gc and asm_fast.gc.
I'll fix the line wrapping issues and go ahead and commit this.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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