[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):

 `memchr` implemented in C and I think MS' own C compiler is right. At
 least `memchr` extracted from static counterpart of `msvcrt` is good:
 {{{
 test   %r8,%r8
 je     11 <memchr+0x11>
 cmp    %dl,(%rcx)
 je     11 <memchr+0x11>
 inc    %rcx
 dec    %r8
 jne    5 <memchr+0x5>
 neg    %r8
 sbb    %rax,%rax
 and    %rcx,%rax
 retq
 }}}

 And it touches `R5` (`r8`).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8834#comment:64>
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