ghc-7.2 vector code segfaults

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 (closed), but I'm not sure.

Trac metadata

Trac field	Value
Version	7.2.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture