Re: [GHC] #11263: "Simplifier ticks exhausted" that resolves with fsimpl-tick-factor=200

18 Jan 2016

      #11263: "Simplifier ticks exhausted" that resolves with fsimpl-tick-factor=200
-------------------------------------+-------------------------------------
        Reporter:  jberryman         |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #10527 #5539      |  Differential Rev(s):
  #8319                              |
       Wiki Page:                    |
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Comment (by thomie):

 After `cabal install hashabler`, the problem is reproducible with this
 small program and a simple tick factor as high as `130`:

 Main.hs:
 {{{#!hs
 module Main where

 import Bloom

 main = do
     key <- undefined
     lookup_ key `seq` return ()
 }}}

 Bloom.hs:
 {{{#!hs
 module Bloom where

 import Data.Hashabler

 {-# INLINE lookup_ #-}
 lookup_ :: SipKey -> Hash128 Int
 lookup_ key = siphash128 key 1
 }}}

 {{{
 $ ghc-7.10.3 Main.hs -O -fforce-recomp -fsimpl-tick-factor=130   # 135=ok
 ...Simplifier ticks exhausted...
 }}}

 Some observations:
 * Putting all code in a single module doesn't trigger the problem
 * This doesn't trigger the problem (I don't understand why not doing `key
 <- undefined` makes a difference..):
 {{{#!hs
 main = lookup_ undefined `seq` return ()
 }}}
 * ghc-8.0.1 accepts the program with a tick factor as low as `85`. Did
 something change?

 I will attach a version of `Bloom.hs` with `hashabler` inlined.

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11263#comment:6
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