[tree-ssa] alias analysis

[Diego Novillo]

On Fri, 2003-02-14 at 19:12, law@redhat.com wrote:

>  >Faster than what we have now?  At this point I will need to see the
>  >patch :)  Right now we are so fast mainly because we bag most
>  >addressables and dereferences together.
> Yup.  My scheme is faster than what we have now.  
> 
Faster to compute aliasing, or faster when combined with the SSA
builder?  If you are trying to improve times that are in the fractions
of a second for a multi-second compile, I think you're wasting your
time.  We have much bigger performance problems in the branch, don't you
think?

> FWIW, after my various improvements to CCP, alias analysis has become the
> clear CPU hog again as far as the tree optimizers are concerned
> (with gimplification running a close second).  And I know how to make
> mine even faster and probably use less memory as well :-)
> 
Now you lost me again.  Why are you so interested in making alias
analysis a CPU hog?  We were trying to do the opposite!

>  >What I would like to avoid is getting into the situation where we start
>  >to implement various additional heuristics to the type-based analyzer
>  >instead of relying on the PTA code.  I think I'd rather have a good PTA
>  >implementation.  The type-based analyzer was something to get by in the
>  >meantime, really.
> Conceptually you should think of PTA as a way to prune the aliases 
> found by type analysis.  In all likelihood they're going to have to
> work together.
> 
I always thought that TBA was a way of pruning PTA.  You first do a
quick TBA query, if that fails, you do PTA.


Diego.