Re: fast computing with GNAT (?)

[gisle@apal.ii.uib.no (Gisle S�lensminde)]

In article <38EDAEC0.412E6CC7@nord-com.net>, Andreas Schulz wrote:
>Gautier responded to :
>> > The f77 version takes about 7.5 s and the Ada version takes
>> > about 38 s on my Linux/laptop.
>> > The actual build commands are:
>> > gnatmake -O4 test1.adb
>> Ok. Try gnatmake -O4 -ffast-math -gnatp test1.adb
>
>Maybe you'll be better off with -O3 ?? According to the manual,
>gnat accepts only 0..3 for -O, and I had the impression that
>4+ is read as 0.

Then you got the wrong impression. Anything higher than the highest
optimization level (-O3 for gnat) is read as the highest. Some
C programs around use -O99 to allways get the highest level of
optimization. 

The pentiumGCC project, which is an alternative experimental backend for
gcc, uses -O6 as highest level of optimization.

>
>> The -gnatp is essential (=pragma suppress(all_checks))
>> to compare with Fortran!
>
>Andreas


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Gisle S�lensminde ( gisle@ii.uib.no )   

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