[GHC] #10010: LLVM/optimized code for sqrt incorrect for negative values

[GHC]

#10010: LLVM/optimized code for sqrt incorrect for negative values
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        Reporter:  glguy             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (LLVM)   |              Version:  7.8.4
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by George):

 This appears to be fixed in ghc 8.4.1 and llvm 6.0. The supported llvm for
 8.4.1 is 5.0 but I have 6.0 as I'm on a Mac and did a brew update which
 overwrote 5.0 and installed 6.0. Can somebody verify with llvm 5.0?

 The following shows it works as described above:

 {{{
 bash-3.2$ ghc --version
 The Glorious Glasgow Haskell Compilation System, version 8.4.1
 bash-3.2$ opt -version
 LLVM (http://llvm.org/):
   LLVM version 6.0.0
   Optimized build.
   Default target: x86_64-apple-darwin17.4.0
   Host CPU: nehalem
 bash-3.2$ llc -version
 LLVM (http://llvm.org/):
   LLVM version 6.0.0
   Optimized build.
   Default target: x86_64-apple-darwin17.4.0
   Host CPU: nehalem
 ...

  ghc -O -fllvm Sqrt.hs
 [1 of 1] Compiling Main             ( Sqrt.hs, Sqrt.o )
 You are using an unsupported version of LLVM!
 Currently only 5.0 is supported.
 We will try though...
 Linking Sqrt ...
 bash-3.2$ ./Sqrt
 NaN
 bash-3.2$
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10010#comment:5>
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