getCPUTime on x86_64 Mac OS X 10.6

I have GHC 6.10.4 installed on a recent Mac Mini, which is running a 32-bit kernel (Snow Leopard, 10.6) but has 64-bit GHC installed, using MacPorts. I've compiled a very large commercial product with this installation (with FFI etc) and the product's testsuite passes, so I'm fairly confident that GHC is working ... except that "getCPUTime" is giving bogus values.

This simple program:

import CPUTime
fn = do t <- getCPUTime
        putStrLn ("t = " ++ show t)
        fn
main :: IO ()
main = fn

ought to produce increasing values of "t". However, the output jumps around wildly, from 10^22^, to 10^24^, to 10^15^.

Trac metadata

Trac field	Value
Version	6.10.4
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
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