Re: [GHC] #14511: indexArray# getting poorly deferred

22 Nov 2017

      #14511: indexArray# getting poorly deferred
-------------------------------------+-------------------------------------
        Reporter:  reinerp           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      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:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 Good point. Works fine in HEAD, as a result of this (post-8.2) patch
 {{{
 commit 751996e90a964026a3f86853338f10c82db6b610
 Author: Simon Peyton Jones 
 Date:   Fri Apr 7 17:10:07 2017 +0100

     Kill off complications in CoreFVs

 ...

     * The code around floating case-expressions turned out to be
       very delicate, because can_fail primops (which we want to
       float inwards) can't be floated outwards; so we have to be
       careful never to float them too far. Note [Floating primops]
       has the details
 }}}
 I'll augment the Note to add your use-case.

 I'm not sure we can do much for 8.2; how important is it for you?

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14511#comment:1
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler