The Unix Heritage Society mailing list
 help / color / mirror / Atom feed
From: Anthony Martin <ality@pbrane.org>
To: Dan Cross <crossd@gmail.com>
Cc: tuhs@tuhs.org
Subject: [TUHS] Re: I can't drive 55: "GOTO considered harmful" 55th anniversary
Date: Sat, 11 Mar 2023 23:39:25 -0800	[thread overview]
Message-ID: <ZA2BraoOmogS/cWY@alice> (raw)
In-Reply-To: <CAEoi9W6=F=0Lod1jBkY5bmygAh4u5t_XT7qSVq2aBCzCSqz66w@mail.gmail.com>

Dan Cross <crossd@gmail.com> once said:
> I'm told that the plan9 C compilers were callee-save in part to keep
> these state labels svelte.

The Plan 9 compilers are caller-save. That means the labels only have
to contain pc and sp. Waserror works well except for one small issue
involving whether or not the compiler decides to store a value to a
non-volatile, non-pointer variable when the value would not be used
after a function call. As in:

	int a;
	a = 1;
	if(waserror()){ /* ... */ }
	a = 2;
	a = foo(a);

The waserror branch may see a == 1 if foo errors.

Ken's compilers are great, though. They don't engage in antisocial
optimizations based on dubious notions of undefined behavior. I'd
prefer my compiler to not elide explicit null checks or loads and
stores from a pointer.

Cheers,
  Anthony

  reply	other threads:[~2023-03-12  7:40 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-10 11:37 Noel Chiappa
2023-03-10 11:51 ` [TUHS] Conditions, AKA exceptions. (Was: I can't drive 55: "GOTO considered harmful" 55th anniversary) Ralph Corderoy
2023-03-10 15:54 ` [TUHS] Re: I can't drive 55: "GOTO considered harmful" 55th anniversary Dan Cross
2023-03-12  7:39   ` Anthony Martin [this message]
2023-03-12 11:40     ` Dan Cross
2023-03-12 16:40       ` Paul Winalski
2023-03-13  3:25       ` John Cowan
2023-03-13 10:40         ` Alejandro Colomar (man-pages)
2023-03-13 12:19           ` Dan Cross
2023-03-13 12:43             ` [TUHS] [TUHS]: C dialects (was: I can't drive 55: "GOTO considered harmful" 55th anniversary) Alejandro Colomar
2023-03-13 12:46               ` [TUHS] " Dan Cross
2023-03-13 16:00               ` Paul Winalski
2023-03-13 19:00                 ` Clem Cole
2023-03-13 19:09                   ` Larry McVoy
2023-03-13 19:17                   ` Steve Nickolas
2023-03-13 20:26                     ` Dan Cross
2023-03-13 22:25                       ` Alejandro Colomar (man-pages)
2023-03-13 19:24                   ` [TUHS] Re: [TUHS]: C dialects Luther Johnson
2023-03-13 19:38                     ` Luther Johnson
2023-03-14 19:48                     ` John Cowan
2023-03-14 19:56                       ` Joseph Holsten
2023-03-14 20:01                       ` Luther Johnson
2023-03-13 20:48                   ` [TUHS] Re: [TUHS]: C dialects (was: I can't drive 55: "GOTO considered harmful" 55th anniversary) Paul Winalski
2023-03-13 20:56                     ` Bakul Shah
2023-03-14  1:06                     ` Larry McVoy
2023-03-13 21:00                   ` Paul Winalski
2023-03-13 21:07                     ` Bakul Shah
2023-03-13 21:14                       ` Dan Cross
2023-03-13 22:15                         ` Dave Horsfall
2023-03-13 22:47                           ` Dave Horsfall
2023-03-14  0:23                             ` Dan Cross
2023-03-14  0:21                           ` Dan Cross
2023-03-14 13:52                             ` Chet Ramey
2023-03-14  1:27                         ` Bakul Shah
2023-03-13 21:28                       ` Paul Winalski
2023-03-14 10:04                       ` [TUHS] C dialects Ralph Corderoy
2023-03-14 20:02                         ` [TUHS] " John Cowan
2023-03-14 21:34                           ` Thomas Paulsen
2023-03-14  0:38                     ` [TUHS] Re: [TUHS]: C dialects (was: I can't drive 55: "GOTO considered harmful" 55th anniversary) John Cowan
2023-03-14  2:49                 ` Theodore Ts'o
2023-03-14  3:06                   ` G. Branden Robinson
  -- strict thread matches above, loose matches on Subject: below --
2023-03-10 15:37 [TUHS] Re: I can't drive 55: "GOTO considered harmful" 55th anniversary Noel Chiappa
2023-03-10 15:46 ` Larry McVoy
2023-03-10 16:04 ` Dan Cross
2023-03-10 18:55 ` Ron Natalie
2023-03-10 19:04   ` Dan Cross
2023-03-10 19:35     ` segaloco via TUHS
2023-03-10 11:51 Noel Chiappa
2023-03-10 14:16 ` Ronald Natalie
2023-03-10 14:39   ` John Cowan
2023-03-10 16:30   ` Phil Budne
2023-03-10 17:50     ` Steffen Nurpmeso
2023-03-10 17:57       ` Paul Winalski
2023-03-10 18:12         ` Lawrence Stewart
2023-03-10 17:28   ` Clem Cole
2023-03-10 17:54     ` Paul Winalski
2023-03-09 23:01 [TUHS] " Steffen Nurpmeso
2023-03-09 23:18 ` [TUHS] " segaloco via TUHS
2023-03-09 23:21   ` Warner Losh
2023-03-09 23:31     ` Luther Johnson
2023-03-09 23:44       ` josh
2023-03-09 23:54       ` Warner Losh
2023-03-10  0:54         ` segaloco via TUHS
2023-03-10  1:08           ` Warner Losh
2023-03-10 10:08             ` Ralph Corderoy
2023-03-10 11:37               ` arnold
2023-03-10 11:56                 ` Ralph Corderoy
2023-03-10 11:59                   ` arnold
2023-03-10 12:11                     ` Ralph Corderoy
2023-03-10  6:15     ` Dave Horsfall
2023-03-10 16:55       ` Steffen Nurpmeso
2023-03-10 17:02         ` Bakul Shah
2023-03-12 20:47         ` Dave Horsfall
2023-03-12 21:50           ` Warner Losh
2023-03-12 22:27             ` Steffen Nurpmeso
2023-03-10  1:31   ` Rich Morin

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=ZA2BraoOmogS/cWY@alice \
    --to=ality@pbrane.org \
    --cc=crossd@gmail.com \
    --cc=tuhs@tuhs.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).