#5671: ghc-7.2 vector code segfaults
-------------------------------+--------------------------------------------
Reporter: kosmikus | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.2.1 | Keywords:
Testcase: | Blockedby:
Os: Linux | Blocking:
Architecture: x86_64 (amd64) | Failure: Runtime crash
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The following program segfaults on x86_64 with vector-0.9
* with ghc-7.2.1 and -O
* with ghc-7.2.2 and -O
* with ghc-7.3.20111122 and -O
I does ''not'' segfault with ghc-7.0.4 or without -O.
It also segfaults on x86 if I change the number from 965 to 1934. I
haven't thoroughly tested this, but these seem to be the smallest numbers
each for which there is a segfault.
{{{
import qualified Data.Vector as U
main :: IO ()
main =
f (U.fromList (replicate 965 (((), ()), ())))
`seq` return ()
f x = g (fst (U.unzip x))
g x = U.zipWith (flip const) x (h (fst (U.unzip x)))
h x = U.zipWith op y x
where y = U.zipWith op x (U.init z)
z = U.generate (n+1) (\ i -> x U.! (if i >= n then n - 1 else i))
n = U.length x
op () () = ()
}}}
By looking at Core code a bit and comparing output from 7.0.4 and 7.2.2, I
see reversed array indexing and bounds checking. So it looks like this
might be related to bug #5658, but I'm not sure.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5671>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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