Re: Detailed algorithms on inline optimization

Chris Dodd <cdodd@acm.org>
23 Jan 2010 02:15:04 +0100

          From comp.compilers

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[5 earlier articles]
Re: Detailed algorithms on inline optimization miles@gnu.org (Miles Bader) (2010-01-20)
Re: Detailed algorithms on inline optimization rangsynth@gmail.com (Robin Holmes) (2010-01-20)
Re: Detailed algorithms on inline optimization jeremy.wright@microfocus.com (Jeremy Wright) (2010-01-20)
Re: Detailed algorithms on inline optimization dot@dotat.at (Tony Finch) (2010-01-21)
Re: Detailed algorithms on inline optimization bear@sonic.net (Ray) (2010-01-21)
Re: Detailed algorithms on inline optimization bobduff@shell01.TheWorld.com (Robert A Duff) (2010-01-21)
Re: Detailed algorithms on inline optimization cdodd@acm.org (Chris Dodd) (2010-01-23)
Re: Detailed algorithms on inline optimization mcrodgers@gmail.com (Martin Rodgers) (2010-01-24)
Re: Detailed algorithms on inline optimization anton@mips.complang.tuwien.ac.at (2010-01-25)
Re: Detailed algorithms on inline optimization monnier@iro.umontreal.ca (Stefan Monnier) (2010-01-25)
Re: Detailed algorithms on inline optimization kkylheku@gmail.com (Kaz Kylheku) (2010-01-28)
Re: Detailed algorithms on inline optimization martin@gkc.org.uk (Martin Ward) (2010-01-28)
Re: Detailed algorithms on inline optimization anton@mips.complang.tuwien.ac.at (2010-01-31)
[2 later articles]
| List of all articles for this month |

From: Chris Dodd <cdodd@acm.org>
Newsgroups: comp.compilers
Date: 23 Jan 2010 02:15:04 +0100
Organization: Compilers Central
References: 10-01-058 10-01-061
Keywords: optimize

Robert A Duff <bobduff@shell01.TheWorld.com> wrote in
> You can inline recursive calls if you limit the depth.
>
> [True. Does anyone do that, inline the first few times though and then
> punt to the normal routine? -John]


Recent versions of gcc do pretty well. Its instructive to look at what it
does for a naive fibonacci function:


unsigned fib(unsigned n) { return n < 2 ? n : fib(n-2) + fib(n-1); }


Gcc 4.3 with -O3 will turn this into a loop via tail-recursion elimination of
one of the recursive calls, and then inline the other call several times,
ending up with 8 nested loops...


         -chris



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