Re: [GHC] #15673: heap overflow with Bits.shift and Integer

26 Sep 2018

      #15673: heap overflow with Bits.shift and Integer
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        Reporter:  mcmayer           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:  x86_64
 Type of failure:  GHC doesn't work  |  (amd64)
  at all                             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14959            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"d25fa45e377253cfbe26e410075dda9d58bb869c/ghc"
 d25fa45e/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d25fa45e377253cfbe26e410075dda9d58bb869c"
 Fix constant-folding for Integer shifts

 In this patch
     commit 869f69fd4a78371c221e6d9abd69a71440a4679a
     Author: Simon Peyton Jones <simonpj@microsoft.com>
     Date:   Wed Dec 11 18:19:34 2013 +0000

     Guarding against silly shifts

 we deal with silly shifts like (Sll 1 9223372036854775807).  But
 I only dealt with primops that Int# and Word#.

 Alas, the same problem affects shifts of Integer, as Trac #15673
 showed.  Fortunately, the problem is easy to fix.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15673#comment:10>
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