[GHC] #11565: Restore code to handle '-fmax-worker-args' flag

[GHC]

#11565: Restore code to handle '-fmax-worker-args' flag
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        Reporter:  slyfox            |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Sergei Trofimovich <siarheit@…>):

 In [changeset:"a48de37dcca98e7d477040b0ed298bcd1b3ab303/ghc" a48de37/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a48de37dcca98e7d477040b0ed298bcd1b3ab303"
 restore -fmax-worker-args handling (Trac #11565)

 maxWorkerArgs handling was accidentally lost 3 years ago
 in a major update of demand analysis
     commit 0831a12ea2fc73c33652eeec1adc79fa19700578

 Old regression is noticeable as:
 - code bloat (requires stack reshuffling)
 - compilation slowdown (more code to optimise/generate)
 - and increased heap usage (DynFlags unboxing/reboxing?)

 On a simple compile benchmark this change causes heap
 allocation drop from 70G don to 67G (ghc perf build).

 Signed-off-by: Sergei Trofimovich <siarheit at google.com>

 Reviewers: simonpj, ezyang, goldfire, austin, bgamari

 Reviewed By: simonpj, ezyang

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2503

 GHC Trac Issues: #11565
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11565#comment:8>
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