[GHC] #14619: Output value of program changes upon compiling with -O optimizations

[GHC]

#14619: Output value of program changes upon compiling with -O optimizations
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        Reporter:  sheaf             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:
Operating System:  Windows           |         Architecture:  x86_64
 Type of failure:  Incorrect result  |  (amd64)
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Phyx-):

 > That would be easier to fix; but wouldn't that affect all platforms
 equally?

 Yes, but I'm honestly still a bit puzzled as to what makes this failure
 Windows only. While on Windows `xmm6` is a callee save register we seem to
 be handling that correctly. Also the sequence has no branches in between.
 Only jumps so it shouldn't matter.

 It's also very fragile. Small alterations to the test program trying to
 reduce makes the issue go away.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14619#comment:27>
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