> If I compile the attach code with GHC of the newest ghc-7.0 darcs
> branch, the compiled program is much slower than byte code. This
> phenomenon does not exist in GHC 6.12.3.
>
> 6.12.3 runghc -- 6.23s user 0.59s system 98% cpu 6.912 total
> ghc -- 5.72s user 0.70s system 99% cpu 6.422 total
> ghc -O -- 5.70s user 0.67s system 99% cpu 6.376 total
> ghc -O2 -- 5.69s user 0.67s system 99% cpu 6.373 total
>
> ghc-7.0 runghc -- 6.43s user 0.10s system 99% cpu 6.593 total
> ghc -- 9.20s user 0.09s system 99% cpu 9.302 total
> ghc -O -- 9.20s user 0.09s system 99% cpu 9.298 total
> ghc -O2 -- 9.38s user 0.09s system 99% cpu 9.478 total
>
> Is this a bug?
I don't see the same results here (x86_64/Linux). This is the 7.0
branch built last night:
$ ghc-stable-nightly2 ./kazu.hs -O2 -fforce-recomp; time ./kazu
[1 of 1] Compiling Main ( kazu.hs, kazu.o )
Linking kazu ...
8.58s real 8.54s user 0.04s system 99% ./kazu
$ time runghc -f ghc-stable-nightly2 ./kazu.hs -O2 -fforce-recomp;
16.92s real 14.21s user 2.70s system 99% runghc -f
ghc-stable-nightly2 ./kazu.hs -O2 -fforce-recomp
However, there is a fairly large difference between the 7.0 branch and HEAD:
$ ghc-nightly2 ./kazu.hs -O2 -fforce-recomp; time ./kazu
[1 of 1] Compiling Main ( kazu.hs, kazu.o )
Linking kazu ...
4.17s real 4.16s user 0.01s system 99% ./kazu
HEAD is more than twice as fast on this program. Fusion not working,
perhaps?
Cheers,
Simon
> My environment is Mac which runs Snow Leopard.
>
> --Kazu
>
> ----
> import System.IO
>
> n :: Int
> n = 10000
>
> main :: IO ()
> main = withFile "/dev/null" WriteMode $ \h ->
> hPutStr h . foldr1 (++) . replicate n . replicate n $ 'a'
> ----
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