[GHC] #6146: Segmentation fault with eager blackholing

[GHC]

#6146: Segmentation fault with eager blackholing
----------------------------------+-----------------------------------------
    Reporter:  emcdowell          |       Owner:  simonmar     
        Type:  bug                |      Status:  new          
    Priority:  high               |   Milestone:  7.4.2        
   Component:  Runtime System     |     Version:  7.4.1        
    Keywords:  eager blackholing  |          Os:  Windows      
Architecture:  x86                |     Failure:  Runtime crash
  Difficulty:  Unknown            |    Testcase:               
   Blockedby:                     |    Blocking:               
     Related:                     |  
----------------------------------+-----------------------------------------

Comment(by marlowsd@…):

 commit 21a53a1cd5a9784aca7b78cc972f917e71938124
 {{{
 Author: Simon Marlow <marlowsd at gmail.com>
 Date:   Thu Jun 7 15:45:32 2012 +0100

     Fix for earger blackholing of thunks with no free variables (#6146)

     A thunk with no free variables was not getting blackholed when
     -feager-blackholing was on, but we were nevertheless pushing the
     stg_bh_upd_frame version of the update frame that expects to see a
     black hole.

     I fixed this twice for good measure:

      - we now call blackHoleOnEntry when pushing the update frame to check
        whether the closure was actually blackholed, and so that we use the
        same predicate in both places

      - we now black hole thunks even if they have no free variables.
        These only occur when optimisation is off, but presumably if you
 say
        -feager-blackholing then that's what you want to happen.

  compiler/codeGen/CgClosure.lhs    |    7 ++++---
  compiler/codeGen/ClosureInfo.lhs  |    2 +-
  compiler/codeGen/StgCmmBind.hs    |   17 ++++++++++-------
  compiler/codeGen/StgCmmClosure.hs |    2 +-
  4 files changed, 16 insertions(+), 12 deletions(-)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6146#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler