#4276: -O0 runs in constant space, -O1 and -O2 don't
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Reporter: guest | Owner: igloo
Type: bug | Status: closed
Priority: normal | Milestone: 7.2.1
Component: Compiler | Version: 6.12.1
Resolution: duplicate | Keywords: optimization space leak
Testcase: | Blockedby:
Difficulty: | Os: Windows
Blocking: | Architecture: x86
Failure: Runtime performance bug |
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Changes (by igloo):
* status: new => closed
* resolution: => duplicate
Comment:
This looks like another full-laziness issue, with [0..] being shared.
If you compile with `-O1 -fno-full-laziness` then space usage matches
`-O0`.
Here's a smaller program:
{{{
module Main (main) where
import Data.List
sum' :: [Double] -> Double
sum' xs = foldl' (+) 0 xs
go :: Double -> [Double]
go w = sum' xs : go (w / 2)
where xs = takeWhile (<= 23) [k*w | k <- [0..]]
main :: IO ()
main = mapM_ print $ take 20 $ go 22
}}}
Closing as a duplicate of #917.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4276#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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