This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [tree-ssa] Loop analysis


> On Fri, May 09, 2003 at 12:41:36PM -0400, David Edelsohn wrote:
> > 	Why is the loop optimizer inserted before the SSA transformation?
> > 
> The loop detector is independent of SSA framework.  It uses the CFG representation
> for the initializer, and thus loops should be initialized after the cfg builder.
> 
> The destructor could be moved after the SSA optimizers allowing these to use the 
> loop information.  However, for the moment, the loop analysis is not used.

While the loop detection is easy, maintaining the infromation up-to-date
is dificult (it is superset of maintaining the dominance tree
information that is still a research topic).
I think it makes more sense to first get SSA, do the
simple (non-loop) optimizations like DCE, cprop, CSE, GVM and then start
to worry about the loops.

Honza
> 
> 	Sebastian


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]