stack overflow triggered by profiling in ghc 6

[Mark Alexander Wotton]

Not sure if this counts as a bug or not, but I've got the following
program:


	import GHC.Exts
	import Data.List

	wrapper_sum xs = ub_acc_sum xs 0#
	ub_acc_sum :: [Int] -> Int# -> Int
	ub_acc_sum [] v = I# v
	ub_acc_sum ((I# x):xs) v = ub_acc_sum xs (v +# x)

	main = do
	  let l = take 10000000 [1,1..]
	  seq (last l) $ return ()
	  putStrLn "unboxed accum"
	  putStrLn $ show $ wrapper_sum l

When compiled with -O2 or -O1, and -prof and -auto-all, this runs out of
stack space. Without optimisation, it's fine: likewise, without -prof it's
fine, which seems reasonable: AFAICT, ub_acc_sum is tail-recursive.

The slight alteration

	wrapper_sum xs = I# (ub_acc_sum xs 0#)
	ub_acc_sum :: [Int] -> Int# -> Int#
	ub_acc_sum [] v = v
	ub_acc_sum ((I# x):xs) v = ub_acc_sum xs (v +# x)

is fine with all combinations of flags.

mrak

-- 
oh, he's like milk to you
half swedish and half asian
	-- Soul Coughing