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Re: gcc-4.4 optimizations question



On Sun, Apr 26, 2009 at 12:52:00PM -0400, Neal Becker wrote:
> I saw this on gcc devel ML:
> 
> ------------
> On Thu, 23 Apr 2009, David Ronis wrote:
> 
> > >From the info pages it seems that the new optimizations,
> > -floop-interchange, -floop-strip-mine, and -floop-block, are NOT turned
> > on when -O3 is specified.  Is this correct and if so, why aren't they?
> 
> Because the behavior of -O3 must not depend on whether optional libraries 
> are linked into GCC, and we did not decide to make PPL and CLooG required 
> to build GCC, so -O3 cannot enable any optimizations using optional 
> libraries.
> 
> Joseph S. Myers
> joseph codesourcery com
> -------------
> 
> Does our gcc-4.4 have these optional libs?

Yes, it does (though, I've patched it a little bit, so that cc1/cc1plus/f951
etc. aren't unconditionally linked against -lcloog -lppl -lppl_c -lm -lstdc++ -lgmpxx
libs cloog/ppl depend on, but instead dlopens libcloog.so.0 when the
graphite optimizations are used (-floop-block, -floop-interchange,
-floop-strip-mine, -fgraphite-identity or -fgraphite)).

	Jakub


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