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Re: [PATCH] Splitting of virtual definitions (aka. V_MUST_DEF)
On Mon, 2004-06-07 at 11:29, Geert Bosch wrote:
> On Jun 7, 2004, at 09:45, Brian Booth wrote:
> > WITH_PATCH WITHOUT_PATCH
> >
> > real 48m24.896s 48m18.499s
> > user 37m57.030s 37m37.460s
> > sys 6m10.790s 6m5.690s
> >
> > There is a slow down of about six seconds but I feel that this can be
> > overcome with future tuning of the optimization passes to take
> > advantage
> > of the V_MUST_DEF construct (dse for example).
>
> It is 25 seconds, 20 seconds in user time and 5 for the system.
> That seems like a very large increase, which would need some
> more justification.
Having a V_MUST_DEF allows us to do some interest things as it
indicates a more precise level of aliasing information. ie, it
allows us to say that a highly specific area of memory is going
to be changed. With that information we can improve redundant
load/store elimination in addition to improving alias analysis.
jeff