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

[Jan Hubicka]

> On Sat, 2002-08-10 at 17:31, Richard Henderson wrote:
> 
> > > You have to tell the optimizers that they cannot look *into* those
> > > trees.  MD builtins have this problem as well, we can't really
> > > simplify those trees as we don't know what the backend might expect.
> > 
> > You won't be incorrect if you treat them like a regular
> > function call.
> > 
> That's exactly what we're doing now.  Trees that cannot be simplified
> are flagged TF_NOT_SIMPLE.  This causes the reference finder to create
> definitions for all the symbols referenced by the expression.  Safe and
> easy.
Is this necesary?  The builtins behave like real C functions, so they
don't modify their arguments.
I would believe that it is wortwhile to invest energy into simplifying
everything around to avoid creating of tons of special cases like we
have in RTL.

Honza