Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!lamaster
From: lamaster@ames.arc.nasa.gov (Hugh LaMaster)
Newsgroups: comp.lang.fortran
Subject: Re: FORTRAN 88
Message-ID: <17276@ames.arc.nasa.gov>
Date: 28 Oct 88 21:12:48 GMT
References: <5833@vdsvax.steinmetz.ge.com> <7540@megaron.arizona.edu> <5838@vdsvax.steinmetz.ge.com> <1128@microsoft.UUCP>
Reply-To: lamaster@ames.arc.nasa.gov.UUCP (Hugh LaMaster)
Distribution: comp.lang.fortran
Organization: NASA Ames Research Center, Moffett Field, Calif.
Lines: 31

In article <1128@microsoft.UUCP> bobal@microsoft.UUCP (Bob Allison (uunet!microsoft!bobal)) writes:

>Well, you may not care about compile time, but what about execution time.
>I can personally guarantee that, if you use array expressions, running
>any reasonable 8X program will be at least 25% slower than an equivalent 
>program written in 77 (to avoid an often belabored point: if such a 

Well, I wasn't going to butt in on this, but, I don't follow this.  On the
Cyber 205 at least, when the compiler recognizes array constructs (I don't
mean Q8 calls for those in the know, but rather, implicit and explicit
vector constructs) it generates optimal code.  On many newer 
microprocessors, there will be a significant advantage to optimally
pipelined code, and it is easier to generate optimal code for array
constructs when the array operations are already defined. 

A previous poster gave an example that used vector temporaries.  No problem
that I know of.  You just allocate space on the runtime stack.  Depending
on what kind of machine it is you are talking about, you may use an
intermediate representation that preserves the explicit vectors, and
copies the vector temporaries on the stack.  Then again, if you have a
scalar machine, you may not.  I just don't see why it is going to be so
hard to generate code for scalar machines as some people have been saying.
My experience is that it works the other way...



-- 
  Hugh LaMaster, m/s 233-9,  UUCP ames!lamaster
  NASA Ames Research Center  ARPA lamaster@ames.arc.nasa.gov
  Moffett Field, CA 94035     
  Phone:  (415)694-6117