Re: [GHC] #14959: Heap overflow in optimizer

21 Mar 2018

      #14959: Heap overflow in optimizer
-------------------------------------+-------------------------------------
        Reporter:  darchon           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.4.1
      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 RyanGlScott):

 The `-ddump-rule-rewrites` output for this program is rather interesting:

 {{{
 $ ghc -O -fforce-recomp -ddump-rule-rewrites Bug.hs
 [1 of 1] Compiling Test             ( Bug.hs, Bug.o )
 <elided>
 Rule fired
     Rule: ==#
     Module: (BUILTIN)
     Before: GHC.Prim.==# ValArg x_a2Lu ValArg 9223372036854775807#
     After:  case x_a2Lu of wild_00 {
               __DEFAULT -> 0#;
               9223372036854775807# -> 1#
             }
     Cont:   StrictArg GHC.Prim.tagToEnum#
             Select nodup wild1_a2Lw
             Stop[RhsCtxt] [GHC.Integer.Type.Integer]
                           -> GHC.Integer.Type.Integer ->
 GHC.Integer.Type.Integer
 Rule fired
     Rule: tagToEnum#
     Module: (BUILTIN)
     Before: GHC.Prim.tagToEnum# TyArg GHC.Types.Bool ValArg 0#
     After:  GHC.Types.False
     Cont:   Select ok wild1_a2Lw
             Stop[BoringCtxt] [GHC.Integer.Type.Integer]
                              -> GHC.Integer.Type.Integer ->
 GHC.Integer.Type.Integer
 Rule fired
     Rule: tagToEnum#
     Module: (BUILTIN)
     Before: GHC.Prim.tagToEnum# TyArg GHC.Types.Bool ValArg 1#
     After:  GHC.Types.True
     Cont:   Select ok wild1_a2Lw
             Stop[BoringCtxt] [GHC.Integer.Type.Integer]
                              -> GHC.Integer.Type.Integer ->
 GHC.Integer.Type.Integer
 Rule fired
     Rule: bitInteger
     Module: (BUILTIN)
     Before:ghc: Out of memory
 }}}

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14959#comment:3
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