[Haskell-cafe] seg-fault in mersenne-random with SSE2 (was Performance question)

[Bayley, Alistair]

> From: haskell-cafe-bounces at haskell.org 
> [mailto:haskell-cafe-bounces at haskell.org] On Behalf Of Roel van Dijk
> 
> I replaced the standard random number generated with the one from
> mersenne-random. On my system this makes the resulting program about
> 14 times faster than the original. I also made a change to
> accumulateHit because it doesn't need to count to total. That is
> already known.


I tried this too, but got a seg fault (!), so I stripped it back to a
small test program. This is with mersenne-random, setup configured with
-fuse_sse2:


module Main (main) where

import System.Random.Mersenne
import System (getArgs)

rands :: Int -> IO [Double]
rands samples = do
  rng <- getStdGen
  rns <- randoms rng
  return (take (2*samples) rns)

main = do
  args <- getArgs
  let samples = read (head args)
  randomNumbers <- rands samples
  print randomNumbers


On WinXp with ghc-6.10.1 it always seg faults. If I rebuild without
-fuse-sse2 then it's happy.

I'm assuming that my machine has SSE2; it's a little old, but it's a P4
(3GHz), so I think it should. Is there an easy way to tell?

Alistair
*****************************************************************
Confidentiality Note: The information contained in this message,
and any attachments, may contain confidential and/or privileged
material. It is intended solely for the person(s) or entity to
which it is addressed. Any review, retransmission, dissemination,
or taking of any action in reliance upon this information by
persons or entities other than the intended recipient(s) is
prohibited. If you received this in error, please contact the
sender and delete the material from any computer.
*****************************************************************