#5859: unsafeInterleaveIO duplicates computation when evaluated by multiple
threads
---------------------------------+------------------------------------------
Reporter: joeyadams | Owner: simonpj
Type: bug | Status: new
Priority: high | Milestone: 7.4.2
Component: libraries/base | Version: 7.2.2
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: Incorrect result at runtime
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by simonpj):
I tried disabling the use of the state hack (`isStateHackType`, via
`isOneShotBndr`) in
{{{
simplCore/Simplify.lhs
simplCore/OccurAnal.lhs
simplCore/FloatIn.lhs
}}}
(the only other state hack uses are in `coreSyn/CoreArity.lhs`).
This resulted in `perf/compiler/parsing001` failing slightly, and
`perf/should_run/T5536` failing a lot. I looked into the latter. The
attached program has
{{{
484268840 bytes allocated with the full state hack
2085048512 bytes allocated with the state hack modified as above
}}}
Replacing either of the "if" expressions in the last few lines with just
its "else" branch fixes the problem.
I've also attached the `-ddump-simpl` output.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5859#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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