Re: [tree-ssa] New type-based aliasing (was: More CFG improvements)

[Daniel Berlin <dberlin at dberlin dot org>]

On Thursday, February 6, 2003, at 07:38  PM, law@redhat.com wrote:

> In message <20030207001037.GB6993@tornado.toronto.redhat.com>, Diego 
> Novillo wr
> ites:
> > On Thu, 06 Feb 2003, Daniel Berlin wrote:
> >
> > > Fully pruned SSA form is probably not a good idea.
> > > 1. It requires global liveness analysis
> > > 2. There are plenty of examples of optimizations that are missed on
> > > fully pruned SSA that aren't missed on semi-pruned or minimal.
> > I want to have the option of switching between semi-pruned and
> > pruned.  Some heuristic that says something like "oh, hell, no
> > way we are inserting a gazillion PHI nodes in this graph".
> And that is precisely what I am working on.
> But I'll take that loss of optimization opportunity in exchange for a
> compiler that doesn't die when compiling big ugly code.
So would I, i just see no reason to pessimize the common case to do it.
My concern was us not using heuristics, and just using fully pruned all 
the time, which is what your original message sounded like you were 
talking about.

> jeff