[GHC] #10346: Cross-module SpecConstr

[GHC]

#10346: Cross-module SpecConstr
-------------------------------------+-------------------------------------
        Reporter:  simonpj           |                Owner:  ckoparkar
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.1
      Resolution:                    |             Keywords:  SpecConstr,
                                     |  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13016            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by ckoparkar):

 I did use that patch. However, I couldn't get it to do what we want. Not
 sure if I did something wrong. I'm using the example given in the
 description:

 {{{
 module M where

 {-# INLINABLE foo #-}
 foo True  y     = y
 foo False (a,b) = foo True (a+b,b)

 baz = foo False (1,2)

 -----------------------------------

 module X where

 import M

 bar = foo False (3,4)

 }}}

 and compiling it with `ghc-stage2 -fforce-recomp -ddump-spec -ddump-rules
 -O X.hs`.

 Relevant Core output:

 {{{
 baz :: (Integer, Integer)
 [LclIdX,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False,
          WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 240 0}]
 baz = foo_aZc GHC.Types.False (1, 2)

 }}}
 where `foo_aZc` is the specialized version of `foo`.  On the other hand,
 `bar` still uses the regular `foo`.

 {{{
 bar :: (Integer, Integer)
 [LclIdX,
  Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False,
          WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 250 0}]
 bar = foo @ Integer GHC.Num.$fNumInteger GHC.Types.False (3, 4)
 }}}


 I'm going to use that patch as a starting point though.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10346#comment:15>
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