[GHC] #11284: Lambda-lifting fails in simple Text example

[GHC]

#11284: Lambda-lifting fails in simple Text example
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:  duplicate         |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #5945, #11318     |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by sgraf):

 * cc: sgraf (added)


Comment:

 Sorry, I didn't pick your reply up in the ticket noise.

 I ''think'' we would pick it up. This is the STG binding for
 `$wloop_length`:
 https://gist.github.com/sgraf812/fcfda9e55004d19881314e31fdea4423

 As this turned into a join point anyway, no closure mentions `$wloop`, so
 there will be no positive closure growth (e.g. penalties in allocations).
 `$wloop` also has only 3 free variables, which adds with the 2 arguments
 to a fortunate 5, so there would be enough hardware registers for the
 lift.

 I don't see any reason we wouldn't have lifted it.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11284#comment:21>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler