Re: Algorithm Optimization

From	"Johann 'Myrkraverk' Oskarsson" <johann@myrkraverk.com>
Newsgroups	comp.compilers
Subject	Re: Algorithm Optimization
Date	2021-04-21 16:29 +0000
Organization	Compilers Central
Message-ID	<21-04-011@comp.compilers> (permalink)
References	<20-09-032@comp.compilers> <20-09-035@comp.compilers> <20-09-036@comp.compilers>

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On 16/09/2020 5:25 am, gah4 wrote:

> I think I remember this being discussed many years ago.

> One thought was that someone codes bubblesort, and the compiler
> generates quicksort. Small complication that bubblesort is stable, and
> quicksort isn't. (Add an array with the original position to break
> ties.)

Here are even more dragons.

What if you're sorting exactly three elements?  In that situation, I'll
be very surprised if bubblesort doesn't outperform all other algorithms.

How does the /compiler/ decide that an algorithm is better, based
on data it never sees?  Even if we account for profile guided optimi-
zations, we shouldn't allow the compiler to adjust for /what if this is
run with more data in production?/ kind of questions.

If you want to go down this rabbit hole, I'd much prefer warnings than
outright algorithm changes.

--
Johann

 I'm not from the internet, I just work there.

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Algorithm Optimization "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2020-09-13 13:00 -0400
  Re: Algorithm Optimization Elijah Stone <elronnd@elronnd.net> - 2020-09-14 20:47 -0700
    Re: Algorithm Optimization "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2020-09-15 00:42 -0400
  Re: Algorithm Optimization "Derek M. Jones" <derek@_NOSPAM_knosof.co.uk> - 2020-09-15 14:29 +0100
    Re: Algorithm Optimization gah4 <gah4@u.washington.edu> - 2020-09-15 22:25 -0700
      Re: Algorithm Optimization "Derek M. Jones" <derek@_NOSPAM_knosof.co.uk> - 2020-09-16 20:11 +0100
      Re: Algorithm Optimization Richard Harnden <richard.nospam@gmail.com> - 2020-09-16 22:45 +0100
      Re: Algorithm Optimization Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2020-09-17 06:35 +0200
        Re: Algorithm Optimization "A. K." <minforth@arcor.de> - 2020-09-21 02:12 -0700
      Re: Algorithm Optimization "Johann 'Myrkraverk' Oskarsson" <johann@myrkraverk.com> - 2021-04-21 16:29 +0000
  Re: Algorithm Optimization "mwmarkland@gmail.com" <mwmarkland@gmail.com> - 2020-09-16 07:57 -0700
    Re: Algorithm Optimization "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2020-09-16 11:44 -0400
    Re: Algorithm Optimization gah4 <gah4@u.washington.edu> - 2020-09-16 13:59 -0700
      Re: Algorithm Optimization Thomas Koenig <tkoenig@netcologne.de> - 2020-09-17 06:39 +0000
  Re: Algorithm Optimization Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2020-12-13 23:13 +0100
    Re: Algorithm Optimization gah4 <gah4@u.washington.edu> - 2020-12-20 22:45 -0800

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