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Re: [GHC] #1600: Optimisation: CPR the results of IO
by GHC 26 Nov '13

26 Nov '13

#1600: Optimisation: CPR the results of IO -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: task | Status: new Priority: lowest | Milestone: 7.6.2 Component: Compiler | Version: 6.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Runtime | Difficulty: Moderate (less performance bug | than a day) Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- Comment (by nomeata): Analysing the `typecheck` divergence yields a very interesting example of how nested CPR can go wrong, which I’d like to document here. It completely wreak havoc with this innocent function: {{{ repeat :: x -> [x] repeat x = x : repeat x }}} (This requires nesting of sum types, but just imagine for this example that `[]` was a stream data type with only one constructor, if you want). The analyizer figurs out that its demand signature is `DmdType <L,U>tm2(d,tm2(d,tm2(d,d)))`, i.e. it lazily uses its argument and will, with guaranteed convergence, produce a `:` constructor, and evaluating the second parameter thereof will also converge to a `:`, and so on. The signature could actually be infinite; my code cuts them off a a certain depth. This signature is certainly correct. So it seems this is eligible to a worker-wrapper-transformation. But when we do it we end up with (using non-core patterns for clarity): {{{ $wrepeat :: x -> (# a, a, a, [a] #) $wrepeat x = case x : repeat x of (x1:x2:x3:r) -> (# x1, x2, x3, r#) repeat x :: -> [x] repeat x = case $wrepeat x of (# x1, x2, x3, r#) -> (x1:x2:x3:r) }}} and now this diverges. I’m not entirely sure who is at fault here. Since the analysis yields a correct result, most likely the w/w transformation. But that does not seem to have enough information to prevent this. Needs more thinking. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1600#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2233: Overhaul System.Process
by GHC 26 Nov '13

26 Nov '13

#2233: Overhaul System.Process --------------------------------------+------------------------------------ Reporter: simonmar | Owner: simonmar Type: task | Status: patch Priority: normal | Milestone: _|_ Component: libraries/process | Version: 6.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------+------------------------------------ Comment (by simonmar): Heh, clearly we need to pull the `async` package into the core libraries. But the patches look ok to me. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2233#comment:21> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2233: Overhaul System.Process
by GHC 26 Nov '13

26 Nov '13

#2233: Overhaul System.Process --------------------------------------+------------------------------------ Reporter: simonmar | Owner: simonmar Type: task | Status: patch Priority: normal | Milestone: _|_ Component: libraries/process | Version: 6.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------+------------------------------------ Comment (by duncan): A few follow-up patches. The last one needs rather careful review. It's all rather subtle. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2233#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #8013: Strange closure type error building hs-kqueue on FreeBSD
by GHC 25 Nov '13

25 Nov '13

#8013: Strange closure type error building hs-kqueue on FreeBSD ---------------------------------------+---------------------------------- Reporter: ahktenzero | Owner: Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler (LLVM) | Version: 7.6.3 Resolution: | Keywords: Operating System: FreeBSD | Architecture: x86_64 (amd64) Type of failure: Compile-time crash | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: ---------------------------------------+---------------------------------- Changes (by pgj): * cc: pgj@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8013#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1600: Optimisation: CPR the results of IO
by GHC 25 Nov '13

25 Nov '13

#1600: Optimisation: CPR the results of IO -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: task | Status: new Priority: lowest | Milestone: 7.6.2 Component: Compiler | Version: 6.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Runtime | Difficulty: Moderate (less performance bug | than a day) Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- Comment (by nomeata): I’m working on nested cpr now. There a few related tickets (#1885 and #2289), but I’ll report my progress here, mostly because this has the lowest number and the fine `factIO` example. Building on a patch from SPJ I now have a branch that works in simple cases. I have some doubts about correctness (i.e. `bothDmdType` is used both for type applications and cases, but I believe these need to treat the question of convergence differently). Also, it does ''not'' work for the `factIO` example yet, probably because there is an unboxed tuple to begin with. Need to investigate. The testsuite goes through (reporting, as it seems, only differences in, well, demand signatures), but nofib’s `typecheck` fills the memory quickly, so the analysis clearly is not conservative yet.. Need to investigate. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1600#comment:19> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1885: Improve CPR analysis
by GHC 25 Nov '13

25 Nov '13

#1885: Improve CPR analysis -------------------------------------+------------------------------------ Reporter: simonpj | Owner: simonpj Type: feature request | Status: new Priority: lowest | Milestone: 7.6.2 Component: Compiler | Version: 6.8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by nomeata): * cc: mail@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1885#comment:13> 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 25 Nov '13

25 Nov '13

#5075: CPR optimisation for sum types if only one constructor is used -------------------------------------+------------------------------------ Reporter: batterseapower | Owner: simonpj Type: feature request | Status: new Priority: normal | Milestone: 7.6.2 Component: Compiler | Version: 7.0.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by nomeata): * cc: mail@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5075#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8509: Doc Formatting - Patch Included
by GHC 24 Nov '13

24 Nov '13

#8509: Doc Formatting - Patch Included -------------------------------------+------------------------------------- Reporter: cschneid | Owner: Type: bug | Status: new Priority: low | Milestone: Component: | Version: 7.6.3 libraries/directory | Operating System: Unknown/Multiple Keywords: | Type of failure: Documentation Architecture: Unknown/Multiple | bug Difficulty: Easy (less than 1 | Test Case: hour) | Blocking: Blocked By: | Related Tickets: | -------------------------------------+------------------------------------- Attached is a patch to fixup a bit of doc formatting in the removeDirectory function. The error cases rendered wrong in a few cases, was just missing a bit of markup. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8509> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7725: Operators without colons
by GHC 22 Nov '13

22 Nov '13

#7725: Operators without colons ------------------------------------------------+-------------------------- Reporter: monoidal | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.6.2 Resolution: duplicate | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC accepts invalid program | Unknown/Multiple Test Case: | Difficulty: Blocking: | Unknown | Blocked By: | Related Tickets: ------------------------------------------------+-------------------------- Changes (by monoidal): * status: new => closed * resolution: => duplicate Comment: Closing in favor of #8556. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7725#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8503: New GeneralizedNewtypeDeriving check still isn't permissive enough
by GHC 22 Nov '13

22 Nov '13

#8503: New GeneralizedNewtypeDeriving check still isn't permissive enough ------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Roman Cheplyaka writes: I just tried compiling smallcheck with GHC HEAD, and it didn't work out: {{{ Test/SmallCheck/SeriesMonad.hs:41:7: Can't make a derived instance of ‛MonadLogic (Series m)’ (even with cunning newtype deriving): it is not type-safe to use GeneralizedNewtypeDeriving on this class; ‛msplit’, at type ‛forall a. m a -> m (Maybe (a, m a))’, cannot be converted safely In the newtype declaration for ‛Series’ }}} So GHC now looks at the methods, but the problem is still there. I would agree that `msplit`'s type is problematic (due to the nested `m`'s), but Simon and Richard previously said that it should work, so I'm confused. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8503> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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