From: kilgallen@eisner.decus.org (Larry Kilgallen)
Subject: Re: Fortran's Equivalence
Date: 1997/03/26
Date: 1997-03-26T00:00:00+00:00 [thread overview]
Message-ID: <1997Mar26.113448.1@eisner> (raw)
In-Reply-To: 5hbcdn$i1h@top.mitre.org
In article <5hbcdn$i1h@top.mitre.org>, mfb@mbunix.mitre.org (Michael F Brenner) writes:
> manner. Had it done so, then about half of all bit field applications
> would have been portable using address overlays. As it is, true
> portability (without a changing global flag telling where bit one is), is
> difficult to accomplish without using specific operations (like SHIFT),
> which have effects on performance (both speed and logically overspecified
> algorithms).
But each compiler knows which end is up and has enough information
to optimize away shifts done only for the sake of addressing this
issue. For instance, many machines have a more efficient set of
instructions for testing bit 3 (from whichever end) without actually
shifting it to the end of a register.
Larry Kilgallen
next prev parent reply other threads:[~1997-03-26 0:00 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-03-25 0:00 Fortran's Equivalence Viqar Abbasi
1997-03-26 0:00 ` Robert Dewar
1997-03-26 0:00 ` Robert A Duff
1997-03-29 0:00 ` Matthew Heaney
1997-03-29 0:00 ` Robert Dewar
1997-04-02 0:00 ` JP Thornley
1997-03-26 0:00 ` FORTRAN's Equivalence Nick Roberts
1997-03-26 0:00 ` Fortran's Equivalence Tom Moran
1997-03-26 0:00 ` Michael F Brenner
1997-03-26 0:00 ` Larry Kilgallen [this message]
1997-03-28 0:00 ` Oliver Kellogg
1997-03-29 0:00 ` Matthew Heaney
1997-03-29 0:00 ` Robert Dewar
1997-03-29 0:00 ` Robert Dewar
1997-04-01 0:00 ` Keith Thompson
1997-04-01 0:00 ` Robert Dewar
1997-04-01 0:00 ` Robert A Duff
1997-04-01 0:00 ` Robert Dewar
1997-04-04 0:00 ` Keith Thompson
1997-04-04 0:00 ` Robert Dewar
1997-04-07 0:00 ` Viqar Abbasi
1997-04-08 0:00 ` Charles H. Sampson
1997-04-08 0:00 ` Matthew Heaney
1997-04-09 0:00 ` Stephen Leake
1997-04-09 0:00 ` Robert Dewar
1997-04-10 0:00 ` Simon Wright
1997-04-10 0:00 ` Robert Dewar
1997-04-08 0:00 ` Robert Dewar
[not found] ` <1997Apr15.163103.27481@nosc.mil>
1997-04-16 0:00 ` Robert Dewar
1997-04-07 0:00 ` Keith Thompson
1997-04-07 0:00 ` Charles H. Sampson
1997-04-04 0:00 ` Keith Thompson
1997-04-04 0:00 ` Robert Dewar
1997-04-08 0:00 ` Keith Thompson
1997-04-07 0:00 ` Charles H. Sampson
1997-03-28 0:00 ` Charles H. Sampson
1997-03-29 0:00 ` Matthew Heaney
1997-04-01 0:00 ` Charles H. Sampson
1997-03-29 0:00 ` Matthew Heaney
1997-03-29 0:00 ` Robert Dewar
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox