#5658: Strict bindings are wrongly floated out of case alternatives.
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Reporter: benl | Owner: benl
Type: bug | Status: new
Priority: normal | Milestone: 7.4.1
Component: Compiler | Version: 7.2.1
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: Runtime crash
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by rl):
As requested, here is a small program that demonstrated this. Note the
difference between 7.2 and 7.4 when compiling with -O2.
{{{
{-# LANGUAGE MagicHash, BangPatterns #-}
module T where
import GHC.Prim
foo :: ByteArray# -> ByteArray# -> Int# -> Int# -> Bool
foo xs ys m n = go 0# 0#
where
go i j = case i >=# m of
False -> let !x = indexIntArray# xs i in
case j >=# n of
False -> case x ==# indexIntArray# ys j of
False -> False
True -> go (i +# 1#) (j +# 1#)
True -> False
True -> case j >=# n of
False -> let !y = indexIntArray# ys i in False
True -> True
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5658#comment:16>
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