[GHC] #11735: Optimize coercionKind

[GHC]

#11735: Optimize coercionKind
-------------------------------------+-------------------------------------
        Reporter:  goldfire          |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by tdammers):

 Effect of D4394 on compilation of `Grammar.hs`:

 Compiling with GHC HEAD (`02b3dad195`), built with the `quick` profile:
 {{{
 tobias at zoidberg:~/well-typed/devel/ghc-T14683/ > time
 ../ghc/HEAD/inplace/bin/ghc-stage2 grammar-hs/Grammar.hs -fforce-recomp
 -O2
 [1 of 1] Compiling Grammar          ( grammar-hs/Grammar.hs, grammar-
 hs/Grammar.o )
 ../ghc/HEAD/inplace/bin/ghc-stage2 grammar-hs/Grammar.hs -fforce-recomp
 -O2  465.26s user 0.52s system 100% cpu 7:45.42 total
 }}}

 Compiling with D4394 applied (`6493976fdb`), built with the `quick`
 profile:
 {{{
 tobias at zoidberg:~/well-typed/devel/ghc-T14683/ > time
 ../ghc/D4394/inplace/bin/ghc-stage2 grammar-hs/Grammar.hs -fforce-recomp
 -O2
 [1 of 1] Compiling Grammar          ( grammar-hs/Grammar.hs, grammar-
 hs/Grammar.o )
 ../ghc/D4394/inplace/bin/ghc-stage2 grammar-hs/Grammar.hs -fforce-recomp
 -O2  25.95s user 0.36s system 94% cpu 27.977 total
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11735#comment:80>
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