From: Warner Losh <imp@bsdimp.com>
To: Doug McIlroy <doug@cs.dartmouth.edu>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] History of popularity of C
Date: Sat, 6 Jun 2020 15:55:07 -0600 [thread overview]
Message-ID: <CANCZdfrnNhU4wLv=3gBfFBxaXBOg1yyaa6G_++LyzOOfWNxy+Q@mail.gmail.com> (raw)
In-Reply-To: <202006062149.056LnNsb074899@tahoe.cs.Dartmouth.EDU>
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On Sat, Jun 6, 2020 at 3:50 PM Doug McIlroy <doug@cs.dartmouth.edu> wrote:
> > Steve Johnson's position paper on optimising compilers may amuse you:
> > https://dl.acm.org/doi/abs/10.1145/567532.567542
>
> Indeed. This passage struck a particular chord:
>
> "I contend that the class of applications that depend on, for example, loop
> optimization and dead code elimination for their efficient solution is of
> modest size, growing smaller, and often very susceptible to expression in
> applicative languages where the optimization is built into the individual
> applicative operators."
>
> I don't know whether I saw that note at the time, but since then I've
> come to believe, particularly in regard to C, that one case of dead-code
> elmination should be guaranteed. That case is if(0), where 0 is the
> value of a constant expression.
>
> This guarantee would take the place of many--possibly even
> most--ifdefs. Every ifdef is an ugly intrusion and a pain to read.
> Syntactically it occurs at top level completely out of sync with the
> indentation and flow of text. Conversion to if would be a big win.
>
I'd love something like this to work, but the semantic interpretation would
need to also somehow be omitted, otherwise how do you replace
#ifdef AIX
ioct(fd, AIX_SPECIFIC_IOCTL, ...)
#endif
on a HUPX system that doesn't define AIX_SPECIFIC_IOCTL...
I remember hearing that BLISS could cope because it deferred the semantic
interpretation of the identifiers until after a round of dead code
elimination so it didn't need a pre-processor...
Warner
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next prev parent reply other threads:[~2020-06-06 21:55 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-06 21:49 Doug McIlroy
2020-06-06 21:55 ` Warner Losh [this message]
2020-06-08 13:56 ` Derek Fawcus
2020-06-08 15:20 ` Richard Salz
2020-06-08 15:30 ` Dan Cross
2020-06-08 16:32 ` Tony Finch
-- strict thread matches above, loose matches on Subject: below --
2020-05-21 18:28 Noel Chiappa
2020-05-21 18:44 ` Thomas Paulsen
2020-05-21 19:06 ` Paul Winalski
2020-05-21 20:27 ` Thomas Paulsen
2020-05-22 8:52 ` Tom Ivar Helbekkmo via TUHS
2020-05-22 9:51 ` Tyler Adams
2020-05-22 11:09 ` arnold
2020-05-22 11:15 ` Tyler Adams
2020-05-22 18:40 ` John Gilmore
2020-05-22 19:01 ` Toby Thain
2020-05-22 19:35 ` Larry McVoy
2020-05-22 19:31 ` Larry McVoy
2020-05-22 20:19 ` Michael Kjörling
2020-05-22 14:59 ` Toby Thain
2020-05-22 11:58 ` A. P. Garcia
2020-05-21 15:27 Tyler Adams
2020-05-21 16:10 ` Toby Thain
2020-05-21 16:30 ` Larry McVoy
2020-05-21 17:22 ` John Foust
2020-05-21 20:17 ` Toby Thain
2020-05-21 16:43 ` Tony Finch
2020-05-21 17:35 ` arnold
2020-05-21 19:16 ` CHARLES KESTER
2020-05-21 20:33 ` Thomas Paulsen
2020-05-21 20:09 ` Toby Thain
2020-05-21 20:12 ` Tony Finch
2020-05-22 8:28 ` David Arnold
2020-05-21 20:07 ` Toby Thain
2020-05-21 20:56 ` Clem Cole
2020-05-21 23:45 ` Toby Thain
2020-05-21 23:57 ` Richard Salz
2020-05-22 0:17 ` Toby Thain
2020-05-22 4:10 ` John Gilmore
2020-05-22 14:11 ` Larry McVoy
2020-05-22 14:34 ` Richard Salz
2020-05-22 14:17 ` Larry McVoy
2020-05-22 7:42 ` arnold
2020-05-22 23:50 ` Greg A. Woods
2020-05-23 7:28 ` Andy Kosela
2020-05-23 17:08 ` Clem Cole
2020-05-23 17:22 ` Richard Salz
2020-05-23 18:42 ` Derek Fawcus
2020-05-23 19:28 ` Michael Kjörling
2020-05-26 4:21 ` Dave Horsfall
2020-05-26 4:32 ` Ed Carp
2020-05-26 8:21 ` Rob Pike
2020-05-26 14:44 ` Clem Cole
2020-05-26 14:32 ` Clem Cole
2020-05-26 19:50 ` Greg A. Woods
2020-05-26 21:48 ` Thomas Paulsen
2020-05-26 22:36 ` Greg A. Woods
2020-05-27 14:37 ` Ronald Natalie
2020-05-27 15:09 ` Clem Cole
2020-05-27 16:11 ` Thomas Paulsen
2020-05-27 19:49 ` Greg A. Woods
2020-05-27 20:13 ` Larry McVoy
2020-05-27 20:23 ` Richard Salz
2020-05-27 21:00 ` Nevin Liber
2020-05-27 23:17 ` Greg A. Woods
2020-06-05 20:57 ` Dave Horsfall
2020-06-05 21:40 ` Nemo Nusquam
2020-06-05 21:47 ` Richard Salz
2020-06-05 22:01 ` Bakul Shah
2020-06-06 20:49 ` Ed Carp
2020-06-06 21:08 ` Thomas Paulsen
2020-06-06 21:13 ` Larry McVoy
2020-06-06 22:27 ` Ed Carp
2020-06-06 23:14 ` Tyler Adams
2020-06-07 5:57 ` arnold
2020-06-07 9:22 ` Andy Kosela
2020-06-07 9:39 ` Ed Carp
2020-06-07 10:02 ` Brantley Coile
2020-06-07 11:30 ` Thomas Paulsen
2020-06-07 15:26 ` Clem Cole
2020-06-07 15:52 ` Larry McVoy
2020-06-08 1:02 ` Adam Thornton
2020-06-08 8:04 ` Thomas Paulsen
2020-06-07 17:26 ` Bakul Shah
2020-06-07 17:35 ` Bakul Shah
2020-06-07 18:50 ` Nemo Nusquam
2020-06-07 21:15 ` Chris Torek
2020-06-07 22:16 ` Dan Cross
2020-06-07 22:56 ` Chris Torek
2020-06-08 0:24 ` Bram Wyllie
2020-06-08 5:48 ` Lars Brinkhoff
2020-06-06 23:31 ` Bakul Shah
2020-06-07 0:12 ` Greg A. Woods
2020-06-07 11:04 ` emanuel stiebler
2020-06-07 11:33 ` Thomas Paulsen
2020-05-26 15:19 ` Toby Thain
2020-05-26 16:00 ` Thomas Paulsen
2020-05-26 16:21 ` Christopher Browne
2020-05-26 19:29 ` Thomas Paulsen
2020-05-26 19:55 ` Dan Cross
2020-05-26 20:00 ` Jon Steinhart
2020-05-21 16:18 ` Jim Capp
2020-05-21 18:58 ` A. P. Garcia
2020-05-21 19:02 ` Clem Cole
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