Re: Pessimization from reduce-all-givs and move-all-movables

[Toon Moene <toon at moene dot indiv dot nluug dot nl>]

Jerry Quinn wrote:

> Without -fmove-all-movables -freduce-all-givs, performance improves to
> 1048 Kpos/sec, a 7% difference.
This wouldn't surprise me.  Between when I introduced those flags (in 
1997) and now we gathered quite some information on them.  It turns out 
they're mostly useful for Fortran code (subroutines) with rank-n dummy 
arguments where n>1.  Because this situation is so common in Fortran 
code, these options are enabled by default when invoking g77.

For all other types of code it's a loss, especially on targets with very 
few integer registers, like the Intel x86 line and derivatives.

Hope this helps [I can make the above reasoning more precise if you're 
interested],

--
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
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