[GHC] #8834: 64-bit windows cabal.exe segfaults in GC

[GHC]

#8834: 64-bit windows cabal.exe segfaults in GC
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        Reporter:  awson          |            Owner:  jstolarek
            Type:  bug            |           Status:  patch
        Priority:  highest        |        Milestone:  7.8.1
       Component:  Compiler       |          Version:  7.8.1-rc2
      Resolution:                 |         Keywords:
Operating System:  Windows        |     Architecture:  x86_64 (amd64)
 Type of failure:  Runtime crash  |       Difficulty:  Unknown
       Test Case:                 |       Blocked By:
        Blocking:                 |  Related Tickets:
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Comment (by awson):

 Replying to [comment:52 jstolarek]:
 > According to my experiments you can fix Windows build easily by changing
 definition of `isTrivial` in !CmmSink to:
 >
 > {{{
 > isTrivial :: CmmExpr -> Bool
 > isTrivial (CmmReg (CmmLocal _)) = True
 > isTrivial (CmmLit _) = True
 > isTrivial _          = False
 > }}}

 Hmm, on my experiments changing `isTrivial` to
 {{{
 isTrivial :: CmmExpr -> Bool
 isTrivial (CmmReg (CmmLocal _)) = True
 -- isTrivial (CmmLit _) = True
 isTrivial _ = False
 }}}
 alone was not enough to fix things - see my comment 19. So doing `CmmLit`
 branch `True` makes this work?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8834#comment:54>
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