Hi,
On Tue, 15 May 2007, Andrew Pinski wrote:
> On 5/15/07, Michael Matz <matz@suse.de> wrote:
> > Hmm, wait, you say that making conditional stores unconditional is bad,
> > but doing the same for conditional loads is good? Wasn't the basis for
> > the former the fear for load-store hazards in one constructed example? A
> > similar example can be constructed for the moved load. So, what has
> > changed?
>
> Two different parts of the Cell have different behaviors :). The SPU
> wants way less branches while the PowerPC part you have to take into
> account the load hit store hazzard.
Oh I see, the SPU<->ppc difference :)
> Yes this they are different targets. This is why GCC have to
> becareful when implementing any kind of optimization, including this
> one.
Okay, to perhaps move forward with this, do you have any suggestion on a
sensible heuristic when to not do the transformation I want? Otherwise
I'm tempted to simply activate them by default on x86* (at least the SPEC
results support that), and leave other architectures alone.