Re: Apex vs GNAT on solaris

[rracine@myremarq.com (Roger Racine)]

On Thu, 09 Dec 1999 06:21:49 GMT, Robert Dewar
<robert_dewar@my-deja.com> wrote:

>In article <384e52db.779218947@newsnew.draper.com>,
>  rracine@myremarq.com (Roger Racine) wrote:
>If we really felt the default were wrong, we would consider
>changing it, but in fact we agree with gcc's choice of defaults
>anyway. There is certainly no disadvantage in practice (we don't
>see any problem of users shying away from optimization merely
>because it is not the default -- why, even you, who are SO
>inclined to use the default, end up following normal practice
>and using -O2 :-)
>

I am only trying to tell you that there are many people with my
experience.  I am trying to help ACT.  You do not need to convince
-me- to use a higher level of optimization.  I happen to have built
the GNU tools, and have enough sense to use the same options as are
used building those tools.  That, however, is not going to be the case
for many other people (they have not built the GNU tools).  I truly
believe you that all optimization levels are tested.  There are,
unfortunately, many people who are not subscribed to this newslist,
and there are many who would not believe the CEO of a compiler company
making this claim. :-)

>The one disadvantage of the no optimization default seems to
>be the problem of naive benchmarking, which in fact is the
>scenario that started this thread.
>

Exactly.  Which also could lead to selection of a compiler vendor for
the wrong reason (See.  I am really only concerned with ACT's
interests).  Or it could lead to programs losing time fixing
performance problems that would be unnecessary if they simply used a
higher optimization level (OK, so it is not -just- ACT's interests).

And the disadvantage of having -O1 or -O2 the default is what?  I have
not seen any difficulty debugging -O2 code yet.  Compilation speed is
probably at least one order of magnitude faster than what I was used
to 6 or 7 years ago.

>But I don't think it is right to change the default just because
>of this concern. Indeed, anyone doing benchmarks who does not
>understand the need for carefully studying what options should
>be used is going to get meaningless results in any case.

Again, I only am trying to make you understand that there are many
people who have experiences similar to mine.  I spoke to some
colleagues yesterday about this thread, and they were truly surprised
and shocked to learn that the default was picked -not- based on "best
optimization that is well-tested".

I think we can end this thread.  The decision is certainly the
compiler vendors' to make.  I think I have made my point that I
believe there are people (like my colleagues I talked to), large in
number, who will use the default, or less, with confidence, but will
not use higher without a good reason.

There are compiler vendors who pick their defaults based on the
criterion I mentioned.

Roger Racine