#5522: mc03 -O -fliberate-case -fspec-constr runs out of memory -------------------------------------+------------------------------------- Reporter: btutt | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 7.3 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: Compile- | Blocked By: time performance bug | Related Tickets: Test Case: mc03 | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * difficulty: => Unknown * os: Windows => Unknown/Multiple * architecture: x86 => Unknown/Multiple Comment: The immediate issue here is fixed. Test `5522.hs` from comment:2 does not run out of memory anymore. The reason seems to be that HEAD now reduces ''monad'' comprehensions such as `[x0 + x1 | x0 <- [0], x1 <- [1]]` to just `[1]` at compile time, just as 7.8.3 and earlier already did with ''list'' comprehensions. Maybe the real bug is just covered up? This is the output of `ghc -fforce-recomp --make 5522.hs -O -fliberate-case -fspec-constr -ddump-simpl`: {{{ ==================== Tidy Core ==================== Result size of Tidy Core = {terms: 7, types: 5, coercions: 0} Foo.output1 :: Int [GblId, Caf=NoCafRefs, Str=DmdType m, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}] Foo.output1 = GHC.Types.I# 450 output :: [Int] [GblId, Caf=NoCafRefs, Str=DmdType m2, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 30}] output = GHC.Types.: @ Int Foo.output1 (GHC.Types.[] @ Int) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/5522#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler