Re: [tree-ssa-branch] Optimizing non-SIMPLE trees

[Jan Hubicka <jh at suse dot cz>]

> On Sun, Aug 11, 2002 at 11:06:49AM +0200, Jan Hubicka wrote:
> > I guess it is a must to constant propagate just before
> > RTL generation, that should fix the problem.
> 
> Well, just before builtin expansion anyway.  In many cases we
> would be better off expanding to trees instead of rtl.  Some 
> of them don't make sense to do that but...
> 
> > Similary I think it is neccesary to put in the memories when used
> > exactly once, that should solve builtin_stdarg.
> 
> Making the last parameter of stdarg a reference parameter might
> solve it.  Alternately, is the last parameter even used other 
> than for checking that it is in fact the last parameter?  If not,
> then the front end could do the error check and expand that
> builtin right away.

Yes. At least with current RTL generation scheme probably propagating
memoryies is bad idea.  Our current RTL generator hides memories as well
to help CSE when optimizing.  I remember seeing few cases in i386
backend where knowing whether the operand is memory or not would help
but these are rare. Definitly much more rare than the builtin expansion
case.

Honza
> 
> 
> 
> r~