[GHC] #5129: "evaluate" optimized away

[GHC]

#5129: "evaluate" optimized away
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        Reporter:  dons              |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.2
       Component:  Compiler          |              Version:  7.0.3
      Resolution:                    |             Keywords:  seq, evaluate
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13930            |  Differential Rev(s):  Phab:D615,
       Wiki Page:                    |  Phab:D4514
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"abaf43d9d88d6fdf7345b936a571d17cfe1fa140/ghc" abaf43d/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="abaf43d9d88d6fdf7345b936a571d17cfe1fa140"
 Fix seq# case of exprOkForSpeculation

 This subtle patch fixes Trac #5129 (again; comment:20
 and following).

 I took the opportunity to document seq# properly; see
 Note [seq# magic] in PrelRules, and Note [seq# and expr_ok]
 in CoreUtils.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5129#comment:36>
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