Re: [PATCH] Value profile based optimizations, part 1

[Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>]

Hello,

> >there are several optimizations that may benefit from some knowledge
> >about values of expressions in the program, e.g specialization of
> >operations/standard functions, prefetching, decision heuristics for
> >some optimizations, etc.  We have implemented and tested some of them
> >on hammer-3_3-branch; I think they are ready to be merged to mainline
> >now.
> >
> >This patch brings in the means to instrument the program to obtain
> >data about values of expressions.
> 
> 
> 
> Does this improve the performance of SPEC?

yes. I have just numbers for c part of specs for prefetching I have
done recently at hand:

   164.gzip          1400   193       726    *     1400   193       725    *
   175.vpr           1400   197       710    *     1400   197       711    *
   176.gcc           1100   114       964    *     1100   114       968    *
   181.mcf           1800   398       452    *     1800   337       535    *
   186.crafty        1000    81.7    1224    *     1000    82.0    1220    *
   197.parser        1800   301       599    *     1800   300       600    *
   253.perlbmk       1800   195       921    *     1800   195       923    *
   254.gap           1100   160       685    *     1100   161       684    *
   255.vortex        1900   186      1019    *     1900   186      1021    *
   256.bzip2         1500   208       722    *     1500   208       721    *
   300.twolf         3000   390       768    *     3000   392       766    *

but there are other significant improvements.

> Also does this improve the compile time of gcc when compiled
> with profiledbootstrap?

I will try.

Zdenek