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

[GHC]

#8834: 64-bit windows cabal.exe segfaults in GC
----------------------------------+----------------------------------
        Reporter:  awson          |            Owner:
            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:
----------------------------------+----------------------------------

Comment (by thoughtpolice):

 It's not true that those are the *only* things enabled by -O2 - you must
 also search for `optLevel`, which client code can depend on for specific
 instances if they wish (for example, maybe it's *not* an entire Core->Core
 pass, but an otherwise small micro-optimization).

 Actually, now that I'm searching and thinking about it - the only other
 case where we do this is when we short-cut PAPs - see
 4d1ea482885481073d2fee0ea0355848b9d853a1 and `Note [avoid intermediate
 PAPs]` in `StgCmmLayout`. Simon committed this a while ago.

 I also have a Win32 build going, so I'll test this.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8834#comment:25>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler