[GHC] #13390: Strict literal float-out during desugaring regresses T1969 at -O0

[GHC]

#13390: Strict literal float-out during desugaring regresses T1969 at -O0
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.0.1
      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:                    |
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Comment (by dfeuer):

 OK, so I guess the reason for this is pretty clear: with floating,
 `$cc_a1i7` looks small enough to inline (even at `-O0`), and it inlines,
 and so we then lose the "phantom CSE" that we got from inlining the
 defaults instead. It's not clear to me that there's much we could do that
 would obviously improve matters in general.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13390#comment:5>
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