[GHC] #11296: T8726 fails on arm

[GHC]

#11296: T8726 fails on arm
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        Reporter:  bgamari           |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  arm
 Type of failure:  Incorrect result  |            Test Case:  T8726
  at runtime                         |
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by hvr):

 More trimmed down repro-case:

 {{{#!hs
 {-# LANGUAGE MagicHash #-}
 {-# OPTIONS_GHC -O0 #-}

 import GHC.Integer.GMP.Internals
 import GHC.Exts

 main :: IO ()
 main = do
     print (x, isValidInteger x)
     print (y, isValidInteger y)
     print (z, isValidInteger z) -- reports (-2,False) on 32bit
   where
     z = x + y
     x =  0x0ffffffffffffffffffffffff :: Integer -- 3 limbs
     y = -0x1000000000000000000000001 :: Integer -- 4 limbs

     isValidInteger i = isTrue# (isValidInteger# i)
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11296#comment:2>
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