Re: [tree-ssa] What would be interesting SPEC2000 tests flags?

[Andrew MacLeod <amacleod at redhat dot com>]

On Sat, 2003-05-31 at 23:04, Daniel Berlin wrote:
> 
> 
> > PTA.  I believe we have switches for both.
> PTA, as of a month ago, shaved a few percent off the bootstrap
> time.
> Feel free to turn it on, it bootstraps fine.
> Well, actually, wait a day, i've got to commit the fix for the problem
> Diego introduced with memory tags (querying about fake variables).
> 
> 
> SSAPRE's effects are not worth measure right now without a flag
> to disable the into-ssa optimizations.
> It only makes  189 reloads (as of this afternoon) during a compile of gcc
> (IE a single stage of bootstrap with only the c compiler enabled) with
> the into-ssa optimizations enabled.
> Thus, you'd need a flag to disable into-ssa optimizations to see how much
> better it does, because the into-ssa optimizations block redundancy
> eliminations.
> As an example, in yyparse of gengtype-yacc.c, the into-ssa optimizations
> eliminate 19 redundant expressions.  PRE then eliminates 1 more.
> 
> However, if you turn off the redundancy elimination in tree-ssa.c,
> PRE will eliminate 24 redundancies.
> 
> Thus, you won't get a sense how well PRE does unless you have numbers
> with and without into-ssa optimizations to compare it to.
> 

Yes, we should have aflag to turn off any/all the into-ssa optimizations
for other reasons too.

And we definately want to see the effect of PRE without any of them...
It may be that having PRE turned on might automatically disable some/all
the into-ssa optimizations...

Andrew