To my question about -O in ghc-6.8.1-candidate
Don Stewart wrote on Wed, Oct 17
> By default cabal uses ghc -O to build projects, so you won't see any
> difference if you comment it out of the cabal file. You will however
> if you explicitly turn off optimisations:
I see now, thank you.
> I'd recommend using -O2 these days, particularly for a library like
> docon where performance matters.
>
> ghc-options: -O2
No, -O2 is worse than -O !
Build the public docon with ghc-6.8.1-candidate
under -O and under -O2.
Under -O2
1) it is 10% larger and 10% longer to build,
2) demotest/Main runs 10% slower.
And the following is close to a bug report:
cd demotest
ghc $doconCpOpt -O --make Main -- building docon test
compiles long and takes 900 Mb of RAM,
and after this I kill the process.
The same is for ghc $doconCpOpt -O2 --make Main
I think, there is not any particular reason to compile the test under
-O, usually I apply -Onot here.
But still, this very long compilation and 900 Mb are suspicious.
Regards,
-----------------
Serge Mechveliani
[EMAIL PROTECTED]
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