Performance regression 7.0.1 -> 7.0.1.20110201
Submitted by Kazu Yamamoto on glasgow-haskell-users.
This program
import System.IO
n :: Int
n = 10000
main :: IO ()
main = withFile "/dev/null" WriteMode $ \h ->
hPutStr h . foldr1 (++) . replicate n . replicate n $ 'a'runs much more slowly with the current 7.0 branch than with either 7.0.1 or HEAD.
He also reported that the program runs faster interpreted with runghc than when compiled. I think this is due to #917 (full-laziness), so that's a separate issue. THe regression reported in this ticket is in compiled performance relative to 7.0.1 and HEAD.
I don't see any obvious differences in the simplified output, so the difference could be in library code. I'm using libraries compiled with -O2 in all cases.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.0.1 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | highest |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |