[Haskell-cafe] x86 code generation going wrong?

[Branimir Maksimovic]

>From: Chris Kuklewicz <haskell at list.mightyreason.com>
>To: haskell-cafe at haskell.org
>Subject: [Haskell-cafe] x86 code generation going wrong?
>Date: Sat, 07 Jan 2006 16:18:59 +0000
>
>Hello,
>
>   I need to ask for some help to test x86 code generation.
>
>There is a factor of two runtime difference between the code I am
>benchmarking on my OS X powerbook G4 (ghc 6.4.1) and shootout's speed on
>a linux x86 machine (ghc 6.4.1).
>
>Could someone else running on x86 test the three versions pasted below
>before I think about submitting another one to the shootout?

Here are the tests on P4 2.4 ghz and athlon 64 3000 linux test1-3 in 
respective order
of appearance (note:OPTIONS didn't do anything I have to
compile -O2 -fglasgow-exts explicitely, because I've got compile error for 
test3.hs )

[bmaxa at maxa ~/haskell/myhaskell] $ time ./test1 < sum-file-test-input
4000000

real    0m3.550s
user    0m3.440s
sys     0m0.080s
[bmaxa at maxa ~/haskell/myhaskell] $ time ./test2 < sum-file-test-input
4000000

real    0m3.708s
user    0m3.660s
sys     0m0.060s
[bmaxa at maxa ~/haskell/myhaskell] $ time ./test3 < sum-file-test-input
4000000

real    0m3.678s
user    0m3.620s
sys     0m0.050s

This is on athlon64 3000 , linux :

[bmaxa at devel64 ~]$ time ./test1 < sum-file-test-input
4000000

real    0m5.782s
user    0m5.724s
sys     0m0.056s

[bmaxa at devel64 ~]$ time ./test2 < sum-file-test-input
4000000

real    0m5.953s
user    0m5.900s
sys     0m0.052s
[bmaxa at devel64 ~]$ time ./test3 < sum-file-test-input
4000000

real    0m5.403s
user    0m5.332s
sys     0m0.072s

Greetings, Bane.

>
>To compile "ghc --make filename.hs -o program"
>
>To run "cat input-file | time ./program"
>
>where to save space, the gzip'd input file is at
>
>http://paradosso.mit.edu/~ckuklewicz/sum-file-test-input.gz
>
>-------------------------------------------------------------------------
>-- Original version
>{-# OPTIONS -O2 #-}
>import Char( ord )
>
>main :: IO ()
>main = getContents >>= print . accP 0 0
>
>accP :: Int -> Int -> String -> Int
>accP before this  []       =       before+this
>accP before this ('\n':xs) = accP (before+this) 0                        xs
>accP before this ('-' :xs) = accN  before       this                     xs
>accP before this (x   :xs) = accP  before      (this*10+ord(x)-ord('0')) xs
>
>accN :: Int -> Int -> String -> Int
>accN before this  []       =       before-this
>accN before this ('\n':xs) = accP (before-this) 0                        xs
>accN before this (x   :xs) = accN  before      (this*10+ord(x)-ord('0')) xs
>
>-------------------------------------------------------------------------
>-- Faster on G4, 2x slower on x86
>{-# OPTIONS -O2 -funbox-strict-fields #-}
>import GHC.Base
>
>data I = I !Int
>
>main = print . new (I 0) =<< getContents
>
>new (I i) []       = i
>new (I i) ('-':xs) = neg (I 0) xs
>     where neg (I n) ('\n':xs) = new (I (i - n)) xs
>           neg (I n) (x   :xs) = neg (I (parse x + (10 * n))) xs
>new (I i) (x:xs) = pos (I (parse x)) xs
>     where pos (I n) ('\n':xs) = new (I (i + n)) xs
>           pos (I n) (x   :xs) = pos (I (parse x + (10 * n))) xs
>
>parse c = ord c - ord '0'
>
>-------------------------------------------------------------------------
>-- Explicitly unboxed proposal, faster on G4
>{-# OPTIONS -fglasgow-exts -O2 #-}
>
>import GHC.Base
>
>main = print . sumFile =<< getContents
>     where sumFile = (\rest -> newLine rest 0#)
>
>newLine [] rt = (I# rt)
>newLine ('-':rest) rt = negLine rest 0#
>     where negLine ('\n':rest) soFar = newLine rest (rt -# soFar)
>           negLine ( x  :rest) soFar = negLine rest (d2i x +# (10# *# 
>soFar))
>newLine (x:rest) rt = posLine rest (d2i x)
>     where posLine ('\n':rest) soFar = newLine rest (rt +# soFar)
>           posLine ( x  :rest) soFar = posLine rest (d2i x +# (10# *# 
>soFar))
>
>d2i (C# c) = (ord# c) -# z
>     where z = ord# '0'#
>-------------------------------------------------------------------------
>
>Thanks,
>   Chris
>
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