[GHC] #7116: Missing optimisation: strength reduction of floating-point multiplication

[GHC]

#7116: Missing optimisation: strength reduction of floating-point multiplication
--------------------------------------------+------------------------------
        Reporter:  simonmar                 |            Owner:
            Type:  bug                      |           Status:  patch
        Priority:  normal                   |        Milestone:  7.8.1
       Component:  Compiler                 |          Version:  7.4.2
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  Runtime performance bug  |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
--------------------------------------------+------------------------------

Comment (by jan.stolarek@…):

 commit 838e2fda9892e61da85187803cce45b3f815b86e
 {{{
 Author: Jan Stolarek <jan.stolarek at p.lodz.pl>
 Date:   Mon Jul 8 16:20:43 2013 +0100

     Add strength reduction rules (Fixes #7116)

     This patch adds rules for converting floating point multiplication
     of the form 2.0 * x and x * 2.0 into addition x + x.

  compiler/prelude/PrelRules.lhs |   33 +++++++++++++++++++++++++++------
  1 file changed, 27 insertions(+), 6 deletions(-)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7116#comment:9>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler