On a related (optimization) theme,
https://research.swtch.com/hwmm


On Fri, Jul 2, 2021 at 12:58 PM Paul Winalski <paul.winalski@gmail.com>
wrote:

> I sent a reply to this message to the TUHS mailing list but gmail may
> have rejected it and flagged it as spam.
>
> Please email me privately to let me know if the message made it to the
> list.
>
> -Paul W..
>
> On 7/1/21, scj@yaccman.com <scj@yaccman.com> wrote:
> > I saw this post and it reminded me of a meeting that Dennis and I had
> > with Bill Wulf.  At one point, Dennis decided to write an optimizer but
> > gave up after a week or two because when he had coded the data
> > structures he needed he had filled up the PDP-11 memory!   It was a very
> > strong part of the Unix meme that Unix and C would run on small
> > computers since most of the universities couldn't afford bigger ones at
> > the time.
> >
> > When PCC came along and started running on 32-bit machines, I started
> > thinking about algorithms for optimization.  A problem that I had no
> > good solution for could be illustrated by a simple piece of code:
> >
> >          x = *p;
> >
> >          y = *q;
> >
> >          q gets changed
> >
> >          *q = z;
> >
> > The question is, do I need to reload x now because q might have been
> > changed to point to the same place as p?   At around this time, Al Aho
> > was invited to go to CMU and give a talk, and he invited me to come with
> > him.  We spent about an hour and a half one-on-one with Bill Wulf -- I
> > seem to remember a lot of mutual respect going on.  But when I asked him
> > about my problem, he really didn't have much to say about it.  I finally
> > got him to agree that his compiler had a bug.  But he said there was a
> > flag they could set on the compiler that would turn of optimization and
> > if your program had mysterious bugs, you should use the flag.
> >
> > I recall that Al, always in search of better algorithms, was a bit
> > disappointed -- I was a bit more pragmatic about it.  On the whole, it
> > was a good meeting, and the "Engineering ... Compiler" book was one of
> > my favorites when it came out.
> >
> > Steve
>