Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!usc!rutgers!cmcl2!lanl!jlg
From: jlg@lanl.gov (Jim Giles)
Newsgroups: comp.lang.misc
Subject: Re: Answers, Chapter 2: to point or not to point
Message-ID: <5220@lanl.gov>
Date: 7 Nov 90 21:56:15 GMT
References: <6243:Nov720:29:4090@kramden.acf.nyu.edu>
Organization: Los Alamos Natl Lab, Los Alamos, N.M.
Lines: 22

From article <6243:Nov720:29:4090@kramden.acf.nyu.edu>, by brnstnd@kramden.acf.nyu.edu (Dan Bernstein):
> In article <5088@lanl.gov> jlg@lanl.gov (Jim Giles) writes:
> [...]
>>    Modula 2                     C
>>       for i := 1 to N do           p = &x[1][0]; q = p+N;
>> 	 x[1,i] := x[2,i]          for (i=0; i<N; i++)
>>       end;                            *p++ = *q++;
> [...]
> I believe that if you stated it correctly, the Convex compiler would be
> able to optimize it (specifically, vectorize it) the way you want.

I never claimed that a smart compiler _couldn't_ optimize the above.
I gave it originally as an example of something which the compiler
would have to do _extra_ work to recover information if the array
code were preprocessed into pointers (which you _did_ suggest should
be done).  I specifically said that a smart compiler _could_ find
the information again.

With your stand against optimizers though, why do you claim that it's
acceptable to put the compiler through all that extra work?

J. Giles