[GHC] #10571: GHC 7.10.1 segfaults when shiftL-ing Integers by negative amounts

[GHC]

#10571: GHC 7.10.1 segfaults when shiftL-ing Integers by negative amounts
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        Reporter:  anders_           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  MacOS X           |            Architecture:  x86_64
 Type of failure:  Runtime crash     |  (amd64)
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by hvr):

 Replying to [comment:4 rwbarton]:
 > BTW, I'm curious why the program is segfaulting, rather than reporting
 an out-of-memory condition like it does if I try to evaluate {{{2 `shiftL`
 1000000000000000}}}.

 Most likely because `integer_gmp_mpn_lshift` gets called with unsound
 parameters, leading to `memset(3)` overwriting memory it isn't supposed to
 touch...

 The low-level api in `integer-gmp` has very little safeguards (for one to
 avoid having to check the same conditions multiple times, but also because
 we can't report errors), I've tried to document all pre-conditions on
 input-arguments which are required to be satisfied to avoid segfaults. To
 some degree this also a result of having to use `Int#` for quantities
 which then are converted into a `Word#` rightaway...

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10571#comment:5>
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