Re: [GHC] #11533: Stack check not optimized out even if it could be

9 Feb 2016

      #11533: Stack check not optimized out even if it could be
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        Reporter:  jscholl           |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
  (CodeGen)                          |
      Resolution:                    |             Keywords:  cmm
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1881
       Wiki Page:                    |
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Comment (by Ben Gamari ):

 In [changeset:"4ec61411930495fc109be27993c176fd7aaf486d/ghc"
 4ec61411/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="4ec61411930495fc109be27993c176fd7aaf486d"
 Fix the removal of unnecessary stack checks

 The module CmmLayoutStack removes stack checks if a function does not
 use stack space. However, it can only recognize checks of the form
 Sp < SpLim. However, these checks get sometimes rewritten to
 Sp >= SpLim (with both branches swapped), so we better recognize these
 checks too.

 Test Plan: ./validate

 Reviewers: austin, bgamari, simonpj

 Reviewed By: simonpj

 Subscribers: simonpj, thomie

 Differential Revision: https://phabricator.haskell.org/D1881

 GHC Trac Issues: #11533
 }}}

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11533#comment:2
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