March 2017 - ghc-tickets

Re: [GHC] #855: Improvements to SpecConstr
by GHC 31 Mar '17

31 Mar '17

#855: Improvements to SpecConstr -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: task | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.4.2 Resolution: | Keywords: SpecConstr Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: N/A Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by mpickering): * keywords: => SpecConstr * cc: mpickering (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/855#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #888: Implement the static argument transformation
by GHC 31 Mar '17

31 Mar '17

#888: Implement the static argument transformation -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 6.4.2 Resolution: | Keywords: | StaticArgumentTransformation Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: N/A Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by mpickering): * keywords: => StaticArgumentTransformation -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/888#comment:31> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13502: Static argument transformation should also run after specialisation
by GHC 31 Mar '17

31 Mar '17

#13502: Static argument transformation should also run after specialisation -------------------------------------+------------------------------------- Reporter: mpickering | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider the following program where we eventually want `thepayload` to simplify to the same code as `direct`. {{{#!hs {-# LANGUAGE ExistentialQuantification, RankNTypes, DeriveFunctor #-} module Foo where newtype Q a b t = Q { getQ :: forall f . Applicative f => (a -> f b) -> f t } deriving Functor instance Applicative (Q a b) where pure a = Q (\_ -> pure a) (Q ab) <*> (Q a) = (Q (\v -> ab v <*> a v)) singleQ :: a -> Q a b b singleQ a = Q (\f -> f a) data L a = Nil | L a (L a) deriving Show traverseList :: Applicative f => (a -> f b) -> L a -> f (L b) traverseList f Nil = pure Nil traverseList f (L a la) = L <$> f a <*> traverseList f la newtype Identity a = Identity { runIdentity :: a } deriving (Functor, Show) instance Applicative Identity where pure = Identity (Identity f) <*> (Identity x) = Identity (f x) thepayload :: L String -> L String thepayload l = runIdentity $ (getQ $ (traverseList singleQ l)) Identity direct :: L String -> L String direct Nil = Nil direct (L a b) = L a b }}} With `ghc-8.0.2` and `-fstatic-argument-transformation`, the specialiser will specialise the call to `traverseList` and leave us with a definition like, {{{#!hs rec (20) $ssat_worker= λ sg sc l → case l of Nil→ pure sc Nil L a la → <*> sc (fmap ($p1Applicative sc) (L a)) ($ssat_worker sg sc la) (4) thepayload = λl→ $ssat_worker $fApplicativeIdentity l }}} `$ssat_worked` is recursive in `l` but not in the other two arguments so we can also apply SAT here. Notice that `$ssat_worker` is called with a statically known dictionary in `thepayload` and so if we can inline `$ssat_worker` we would get the same code as the naive `direct`, as desired. I verified that inserting another SAT pass later in the compilation pipeline does have the desired effect but am not sure where exactly the right place would be or whether it is in general desirable. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13502> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5539: GHC panic - Simplifier ticks exhausted
by GHC 31 Mar '17

31 Mar '17

#5539: GHC panic - Simplifier ticks exhausted -------------------------------------+------------------------------------- Reporter: hvr | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.3 Resolution: | Keywords: Inlining Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: Blocked By: | Blocking: Related Tickets: #8613, #9070, | Differential Rev(s): #8319 | Wiki Page: | -------------------------------------+------------------------------------- Changes (by mpickering): * keywords: => Inlining Comment: This ticket is a bit of a mess but someone should test these examples again and make new tickets if they are still a problem. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5539#comment:64> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5075: CPR optimisation for sum types if only one constructor is used
by GHC 31 Mar '17

31 Mar '17

#5075: CPR optimisation for sum types if only one constructor is used -------------------------------------+------------------------------------- Reporter: batterseapower | Owner: simonpj Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.0.3 Resolution: | Keywords: SpecConstr Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by mpickering): * keywords: => SpecConstr -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5075#comment:27> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7944: GHC goes into an apparently infinite loop at -O2
by GHC 31 Mar '17

31 Mar '17

#7944: GHC goes into an apparently infinite loop at -O2 -------------------------------------+------------------------------------- Reporter: bos | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Resolution: | Keywords: SpecConstr Operating System: Unknown/Multiple | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: Blocked By: | Blocking: Related Tickets: #5550 #8852 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by mpickering): * keywords: => SpecConstr -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7944#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4945: Another SpecConstr infelicity
by GHC 31 Mar '17

31 Mar '17

#4945: Another SpecConstr infelicity -------------------------------------+------------------------------------- Reporter: batterseapower | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.0.1 Resolution: | Keywords: SpecConstr Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Runtime | Test Case: performance bug | simplCore/should_compile/T4945 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by mpickering): * keywords: => SpecConstr -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4945#comment:19> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13435: Segfaults on levity-polymorphic type class
by GHC 31 Mar '17

31 Mar '17

#13435: Segfaults on levity-polymorphic type class -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs {-# Language FlexibleInstances, TypeFamilies, TypeInType, MagicHash #-} import Data.Kind import GHC.Exts class Shw (a :: TYPE rep) where shw :: a -> String instance Int# ~ a => Shw (a :: TYPE IntRep) where shw a = "I#" ++ show (I# a) main = putStrLn (shw 3#) }}} induces a segfault {{{ $ runghc --version runghc 8.0.1 $ runghc test.hs I#Segmentation fault }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13435> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13503: "ghc: panic" when trying to build purescript with profiling
by GHC 31 Mar '17

31 Mar '17

#13503: "ghc: panic" when trying to build purescript with profiling -------------------------------------+------------------------------------- Reporter: rintcius | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: MacOS X Architecture: Other | Type of failure: Compile-time | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- i got the following panic when trying to build purescript with profiling (the plain build works ok) {{{ $ stack build --executable-profiling --library-profiling --ghc-options ="-fprof-auto -rtsopts" purescript-0.11.1: build Preprocessing library purescript-0.11.1... [ 23 of 145] Compiling Language.PureScript.Constants ( src/Language/PureScript/Constants.hs, .stack- work/dist/x86_64-osx/Cabal-1.24.2.0/build/Language/PureScript/Constants.p_o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-apple-darwin): kindPrimRep.go rep_sfuE Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- While building package purescript-0.11.1 using: /Users/rintciusblok/.stack/setup-exe-cache/x86_64-osx/setup-Simple- Cabal-1.24.2.0-ghc-8.0.2 --builddir=.stack- work/dist/x86_64-osx/Cabal-1.24.2.0 build lib:purescript exe:purs --ghc- options " -ddump-hi -ddump-to-file" Process exited with code: ExitFailure 1 }}} If this report needs to be reduced, I'd be happy to do that, but I would need some guidance in that case. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13503> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7401: Can't derive instance for Eq when datatype has no constructor, while it is trivial do do so.
by GHC 30 Mar '17

30 Mar '17

#7401: Can't derive instance for Eq when datatype has no constructor, while it is trivial do do so. -------------------------------------+------------------------------------- Reporter: jpbernardy | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: | Keywords: deriving, | newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: #10577, #13117 | Differential Rev(s): Phab:D978 Wiki Page: | -------------------------------------+------------------------------------- Changes (by dfeuer): * cc: dfeuer (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7401#comment:49> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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