[GHC] #13629: sqrt should use machine instruction on x86_64

[GHC]

#13629: sqrt should use machine instruction on x86_64
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler (NCG)    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13570            |  Differential Rev(s):  Phab:D3508
       Wiki Page:                    |
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Description changed by kavon:

@@ -4,0 +4,3 @@
+
+ See discussion [https://mail.haskell.org/pipermail/ghc-
+ devs/2017-April/014168.html here] as well.

New description:

 The NCG currently implements the square root MachOp with an out-of-line
 call. This resulted in a large performance regression in `n-body` (see
 #13570). Fix this.

 See discussion [https://mail.haskell.org/pipermail/ghc-
 devs/2017-April/014168.html here] as well.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13629#comment:5>
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