From: kilgallen@eisner.decus.org (Larry Kilgallen)
Subject: Re: Apex vs GNAT on solaris
Date: 1999/12/07
Date: 1999-12-07T00:00:00+00:00 [thread overview]
Message-ID: <1999Dec7.084947.1@eisner> (raw)
In-Reply-To: 384cfdb3.691883075@newsnew.draper.com
In article <384cfdb3.691883075@newsnew.draper.com>, rracine@myremarq.com (Roger Racine) writes:
> On Tue, 07 Dec 1999 01:25:13 GMT, Robert Dewar <dewar@gnat.com> wrote:
>
>>In article <82hiuj$74o$1@nnrp1.deja.com>,
>> reason67@my-deja.com wrote:
>>
>>
>>You need to say what options you are using for both compilers.
>>We have sometimes found people making the *amazing* mistake
>>of compiling GNAT with -O0. Generally the appropriate options
>>for benchmarking are -O2 -gnatn.
>>
>>The options are critical, because otherwise you may simply
>>be measuring differences in choices of default options. For
>>example if one compiler inlines by default, the other one
>>does not, then the comparison may be meaningless.
> I have been hit many times by optimizer bugs, and generally assume
> that the compiler vendors knows what they are doing when the defaults
> are created. They are giving what they think should be the most
> common values for the options.
For you to say the vendor's default is always your favorite is certainly
within your power. But then to say that your favorite settings for
compiler #1 produce a faster (or smaller, or smoother, or more gender-
neutral) executable than your favorite settings for compiler #2 is quite
meaningless if your basis for choosing favorite settings is unrelated to
the comparison metric.
A compiler vendor may choose their defaults as being "best for those who
don't care about settings", which to me pretty much translates into those
for whom performance is not a big deal.
Larry Kilgallen
next prev parent reply other threads:[~1999-12-07 0:00 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-12-07 0:00 Apex vs GNAT on solaris reason67
1999-12-07 0:00 ` reason67
1999-12-07 0:00 ` reason67
1999-12-07 0:00 ` Robert Dewar
1999-12-07 0:00 ` Roger Racine
1999-12-07 0:00 ` David Starner
1999-12-08 0:00 ` Robert Dewar
1999-12-07 0:00 ` Jean-Pierre Rosen
1999-12-07 0:00 ` Samuel T. Harris
1999-12-07 0:00 ` Larry Kilgallen [this message]
1999-12-08 0:00 ` Ted Dennison
1999-12-08 0:00 ` Robert Dewar
1999-12-08 0:00 ` Robert A Duff
1999-12-08 0:00 ` Roger Racine
1999-12-08 0:00 ` Larry Kilgallen
1999-12-08 0:00 ` Roger Racine
1999-12-08 0:00 ` Larry Kilgallen
1999-12-08 0:00 ` tmoran
1999-12-09 0:00 ` Robert Dewar
1999-12-09 0:00 ` Roger Racine
1999-12-09 0:00 ` Larry Kilgallen
1999-12-10 0:00 ` Robert Dewar
1999-12-09 0:00 ` Mike Silva
1999-12-10 0:00 ` Robert Dewar
1999-12-16 0:00 ` Stefan Skoglund
1999-12-07 0:00 ` reason67
1999-12-08 0:00 ` Robert Dewar
1999-12-08 0:00 ` reason67
1999-12-08 0:00 ` Larry Kilgallen
1999-12-08 0:00 ` Robert Dewar
1999-12-08 0:00 ` Robert A Duff
1999-12-07 0:00 ` reason67
1999-12-07 0:00 ` reason67
1999-12-07 0:00 ` reason67
1999-12-07 0:00 ` Robert Dewar
1999-12-07 0:00 ` reason67
1999-12-07 0:00 ` reason67
1999-12-07 0:00 ` reason67
1999-12-07 0:00 ` Robert Dewar
1999-12-07 0:00 ` Vladimir Olensky
1999-12-07 0:00 ` Vladimir Olensky
1999-12-09 0:00 ` Geoff Bull
1999-12-09 0:00 ` Vladimir Olensky
1999-12-10 0:00 ` Vladimir Olensky
1999-12-09 0:00 ` Vladimir Olensky
1999-12-07 0:00 ` reason67
1999-12-08 0:00 ` Robert Dewar
1999-12-08 0:00 ` reason67
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