[GHC] #9430: implement more arithmetic operations natively in the LLVM backend

[GHC]

#9430: implement more arithmetic operations natively in the LLVM backend
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        Reporter:  rwbarton          |                   Owner:  michalt
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler (LLVM)   |                 Version:  7.9
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"82ffc80df573512f788524c4616db3c08fc9f125/ghc"
 82ffc80d/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="82ffc80df573512f788524c4616db3c08fc9f125"
 LlvmCodeGen: add support for MO_U_Mul2 CallishMachOp

 This adds support MO_U_Mul2 to the LLVM backend by simply using 'mul'
 instruction but operating at twice the bit width (e.g., for 64 bit
 words we will generate mul that operates on 128 bits and then extract
 the two 64 bit values for the result of the CallishMachOp).

 Test Plan: validate

 Reviewers: rwbarton, austin, bgamari

 Reviewed By: bgamari

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D1068

 GHC Trac Issues: #9430
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9430#comment:9>
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