[GHC] #10062: Codegen on sequential FFI calls is not very good

[GHC]

#10062: Codegen on sequential FFI calls is not very good
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        Reporter:  chadaustin        |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.8.3
  (CodeGen)                          |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  Runtime           |               Test Case:
  performance bug                    |                Blocking:
      Blocked By:                    |  Differential Revisions:
 Related Tickets:                    |
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Comment (by svenpanne):

 A quick remark regarding "xorq %rax,%rax" vs. "movb $0,%al": I would
 recommend the xorq variant, we had very bad experiences with data
 dependencies between partially written registers in the v8 JavaScript JIT.
 Intel CPUs have funny performance characteristics, and these vary vastly
 between architectures and even releases of the same architecture. :-/ No
 need to repeat the pain in GHC...

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10062#comment:4>
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