[GHC] #8832: Constant-folding regression wrt `clearBit (bit 0) 0 `

[GHC]

#8832: Constant-folding regression wrt `clearBit (bit 0) 0 `
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        Reporter:  hvr                      |            Owner:  simonpj
            Type:  bug                      |           Status:  new
        Priority:  normal                   |        Milestone:  7.8.1
       Component:  Compiler                 |          Version:  7.8.1-rc2
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  Runtime performance bug  |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"8fd7d581da448d81fc2f9d47366c36c5f57ed564/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="8fd7d581da448d81fc2f9d47366c36c5f57ed564"
 Add BuiltinRules for constant-folding not# and notI# (logical complement)

 I don't know why these constant-folding rules were implemented for
 and/or/xor but not for 'not'.

 Adding them is part of the fix for Trac #8832.
 (The other part is in Data.Bits.)
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8832#comment:4>
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