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: [RTL] Canonicalize commutative operations more


On Apr 2, 2013, at 1:55 AM, Eric Botcazou <ebotcazou@adacore.com> wrote:
> The question is: do we really need to canonicalize everything?

> The fear (at least mine) is that, by canonicalizing everything, you will make 
> changes behind the back of back-ends that could disable some of their patterns 
> silently.

My take, yes, we really need to.  My take, during construction, the canonicalization code should kick in and build it canonically.  If you had a total ordering predicate, and defined an ordering for any two rtls, then the builder could use it and then there would be no case in which things are not canonicalized.  If one tries to do this after the fact, we'll, let's just say, no good come from that.

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