16 May 00:37
Re: -optc-O2 considered useful
From: Don Stewart <dons <at> galois.com>
Subject: Re: -optc-O2 considered useful
Newsgroups: gmane.comp.lang.haskell.glasgow.user
Date: 2008-05-15 22:37:26 GMT
Subject: Re: -optc-O2 considered useful
Newsgroups: gmane.comp.lang.haskell.glasgow.user
Date: 2008-05-15 22:37:26 GMT
duncan.coutts:
>
> On Thu, 2008-05-15 at 23:00 +0400, Bulat Ziganshin wrote:
> > Hello Don,
> >
> > Thursday, May 15, 2008, 10:47:20 PM, you wrote:
> >
> > > I discovered something today I didn't know.
> > > gcc -O2 can optimise out the computed jumps GHC produces in tight loops.
> >
> > seems that decision to use native backend in ghc -O2 was too early?
>
> Though note that the native backend never introduced the computed jump.
>
> I think it's clear that -fvia-C -O should imply -optc-O2 if it does not
> already. gcc -O0 is for painfully obvious C translation into assembler,
> -O is for quick optimisations. gcc -O2 is the "standard" optimisation
> level used for building packages for most distros.
Another idea:
should -fstrictness be on by default?
I run into too many users writing little tail recursive Int loops, and
not using optimisations, with the impression that compiling, e.g.
ghc A.hs
should just work.
-- Don
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