-optc-O2 considered useful

Don Stewart dons at galois.com
Thu May 15 18:37:26 EDT 2008

> 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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