[GHC] #8867: newArray# fails to initialize card table correctly

[GHC]

#8867: newArray# fails to initialize card table correctly
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        Reporter:  tibbe             |            Owner:  simonmar
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Runtime System    |          Version:  7.6.3
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by Johan Tibell <johan.tibell@…>):

 In [changeset:"46d05ba03d1491cade4a3fe33f0b8c404ad3c760/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="46d05ba03d1491cade4a3fe33f0b8c404ad3c760"
 Fix two issues in stg_newArrayzh

 The implementations of newArray# and newArrayArray#, stg_newArrayzh
 and stg_newArrayArrayzh, had three issues:

  * The condition for the loop that fills the array with the initial
    element was incorrect. It would write into the card table as
    well. The condition for the loop that filled the card table was
    never executed, as its condition was also wrong. In the end this
    didn't lead to any disasters as the value of the card table doesn't
    matter for newly allocated arrays.

  * The card table was unnecessarily initialized. The card table is
    only used when the array isn't copied, which new arrays always
    are. By not writing the card table at all we save some cycles.

  * The ticky allocation accounting was wrong. The second argument to
    TICK_ALLOC_PRIM is the size of the closure excluding the header
    size, but the header size was incorrectly included.

 Fixes #8867.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8867#comment:3>
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