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Re: [rfc] Moving bbs back to pools


On 6/7/07, Zdenek Dvorak <rakdver@kam.mff.cuni.cz> wrote:
Hello,

> Ian Lance Taylor <iant@google.com> writes:
>
> > Zdenek Dvorak <rakdver@kam.mff.cuni.cz> writes:
> >
> > > The problem is, that it does not give any speedups (it is almost
> > > completely compile-time neutral for compilation of preprocessed
> > > gcc sources).  I will check whether moving also edges to pools
> > > changes anything, but so far it does not seem very promising :-(
> >
> > Does it make any difference for gcc.c-torture/compile/20001226-1.c?
> > And of course it won't make any difference if you have enough memory
> > that you never need to garbage collect without your patch.
>
> I was wrong to say that.  It could make a difference even if you don't
> garbage collect, since the allocation will be cheaper.  But that is
> likely to be a relatively small effect.

actually, the expected speedup was mostly supposed to come from better
locality.  The speed of garbage collection should be about unchanged.
Regarding the speed of allocation, pool_alloc might be slightly faster,
but probably not significantly.

Uh, structures as big as basic_block won't get better locality by placing them near each other. But maybe I'm missing something ;)

Richard.


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