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Re: [GHC] #7542: GHC doesn't optimize (strict) composition with id
by GHC 14 Jan '13

14 Jan '13

#7542: GHC doesn't optimize (strict) composition with id ---------------------------------+------------------------------------------ Reporter: shachaf | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: Runtime performance bug Difficulty: Unknown | Testcase: Blockedby: | Blocking: Related: | ---------------------------------+------------------------------------------ Changes (by jwlato): * cc: jwlato@… (added) -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7542#comment:4> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #7578: Instance selection regression from 7.4 to 7.6
by GHC 14 Jan '13

14 Jan '13

#7578: Instance selection regression from 7.4 to 7.6 -----------------------------+---------------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Component: Compiler (Type checker) Version: 7.6.1 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: -----------------------------+---------------------------------------------- The following code (useless due to minification) works in GHC 7.4.1: {{{ {-# LANGUAGE FlexibleInstances, UndecidableInstances, OverlappingInstances #-} class CollectArgs a where randomEvaluate :: a -> () instance CollectArgs b => CollectArgs (a -> b) where randomEvaluate f = randomEvaluate (f undefined) where () = randomEvaluate (f undefined) instance Show a => CollectArgs a where randomEvaluate x = () }}} In 7.6.2-rc1, I get this error message {{{ test.hs:8:20: Could not deduce (Show b) arising from a use of `randomEvaluate' from the context (CollectArgs b) bound by the instance declaration at test.hs:6:10-46 Possible fix: add (Show b) to the context of the instance declaration In the expression: randomEvaluate (f undefined) In a pattern binding: () = randomEvaluate (f undefined) In an equation for `randomEvaluate': randomEvaluate f = randomEvaluate (f undefined) where () = randomEvaluate (f undefined) }}} The error message goes away if I remove the {{{() = randomEvaluate (f undefined)}}} binding, i.e. the first recursive use of {{{randomEvaluate}}} works fine. (This came up at http://stackoverflow.com/questions/14294802/evaluating- function-at-random-arguments-using-quickcheck/14295179#14295179) -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7578> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7534: allocateRegsAndSpill: Cannot read from uninitialized register
by GHC 14 Jan '13

14 Jan '13

#7534: allocateRegsAndSpill: Cannot read from uninitialized register --------------------------+------------------------------------------------- Reporter: erikd | Owner: simonmar Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 7.7 Keywords: | Os: Linux Architecture: powerpc64 | Failure: Building GHC failed Difficulty: Unknown | Testcase: Blockedby: | Blocking: Related: | --------------------------+------------------------------------------------- Comment(by PHO): Replying to [comment:7 simonmar]: > I don't immediately see the connection to #7442? Just a thought. Even though PPC/Linux doesn't have the problem described in the note `[inconsistent-pic-reg]`, `PIC.initialisePicBase_ppc` still semms to be assuming only the first block is an entry point. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7534#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7562: Parse error with {-# UNPACK #-} Int
by GHC 14 Jan '13

14 Jan '13

#7562: Parse error with {-# UNPACK #-} Int -----------------------------+---------------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Component: Compiler Version: 7.6.1 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: -----------------------------+---------------------------------------------- Comment(by simonpj@…): commit deec5b74dee7f676b8a9f840ec7b5a813e7e0956 {{{ Author: Simon Peyton Jones <simonpj(a)microsoft.com> Date: Thu Jan 10 16:50:25 2013 +0000 Be willing to parse {-# UNPACK #-} without '!' This change gives a more helpful error message when the user says data T = MkT {-# UNPACK #-} Int which should have a strictness '!' as well. Rather than just a parse error, we get T7562.hs:3:14: Warning: UNPACK pragma lacks '!' on the first argument of `MkT' Fixes Trac #7562 compiler/basicTypes/DataCon.lhs | 40 +++++++++++++++++++++------------- compiler/basicTypes/MkId.lhs | 29 +++++++++++++++++------- compiler/deSugar/DsMeta.hs | 4 +- compiler/hsSyn/Convert.lhs | 4 +- compiler/iface/MkIface.lhs | 2 +- compiler/main/PprTyThing.hs | 4 +- compiler/parser/Parser.y.pp | 10 ++++++-- compiler/typecheck/TcSplice.lhs | 11 +++++---- compiler/typecheck/TcTyClsDecls.lhs | 13 +++++++---- 9 files changed, 73 insertions(+), 44 deletions(-) }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7562#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7372: Lint failure in GHC 7.6.1
by GHC 14 Jan '13

14 Jan '13

#7372: Lint failure in GHC 7.6.1 -------------------------------+-------------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.6.1 Resolution: fixed | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: -------------------------------+-------------------------------------------- Comment(by simonpj): Thanks for checking, monoidal Simon -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7372#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7534: allocateRegsAndSpill: Cannot read from uninitialized register
by GHC 14 Jan '13

14 Jan '13

#7534: allocateRegsAndSpill: Cannot read from uninitialized register --------------------------+------------------------------------------------- Reporter: erikd | Owner: simonmar Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 7.7 Keywords: | Os: Linux Architecture: powerpc64 | Failure: Building GHC failed Difficulty: Unknown | Testcase: Blockedby: | Blocking: Related: | --------------------------+------------------------------------------------- Comment(by simonmar): I don't immediately see the connection to #7442? -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7534#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1241: Functional dependency Coverage Condition is lifted, and should not be
by GHC 13 Jan '13

13 Jan '13

#1241: Functional dependency Coverage Condition is lifted, and should not be --------------------------------------+------------------------------------- Reporter: guest | Owner: Type: bug | Status: closed Priority: normal | Milestone: _|_ Component: Compiler (Type checker) | Version: 6.6 Resolution: fixed | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: --------------------------------------+------------------------------------- Changes (by diatchki): * status: new => closed * failure: => None/Unknown * resolution: => fixed -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1241#comment:21> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7436: Derived Foldable and Traversable instances become extremely inefficient due to eta-expansion
by GHC 13 Jan '13

13 Jan '13

#7436: Derived Foldable and Traversable instances become extremely inefficient due to eta-expansion --------------------------------------+------------------------------------- Reporter: shachaf | Owner: Type: bug | Status: merge Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: fixed | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: Runtime performance bug | Difficulty: Unknown Testcase: perf/should_runt/T7436 | Blockedby: Blocking: | Related: --------------------------------------+------------------------------------- Changes (by jwlato): * cc: jwlato@… (added) -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7436#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2247: GHC accepts FD violations, unless the conflicing instances are used
by GHC 13 Jan '13

13 Jan '13

#2247: GHC accepts FD violations, unless the conflicing instances are used --------------------------------------+------------------------------------- Reporter: claus | Owner: Type: bug | Status: new Priority: normal | Milestone: _|_ Component: Compiler (Type checker) | Version: 6.9 Resolution: | Keywords: TF vs FD Os: Unknown/Multiple | Architecture: Unknown/Multiple Difficulty: Unknown | Testcase: --------------------------------------+------------------------------------- Comment(by iavor.diatchki@…): commit fe61599ffebb27924c4beef47b6237542644f3f4 {{{ Author: Iavor S. Diatchki <iavor.diatchki(a)gmail.com> Date: Sun Jan 13 16:29:10 2013 -0800 Use a version of the coverage condition even with UndecidableInstances. This fixes bug #1241 and #2247. When UndecidableInstances are on, we use the "Liberal Coverage Condition", which is what GHC used to do in the past. This is the gist of the check: class C a b | a -> b instance theta => C t1 t2 we check that `fvs t2` is a subset of `fd-closure(theta,fvs t1)`. This is strictly more general than the coverage condition, while it still guarantees consistency with the FDs of the class. This check is completely orthogonal to termination (it by no means guarantees it). I am not sure of the role of the "coverage condition" in termination--- the comments suggest that it is important. This is why, for the moment, we only use this check when UndecidableInstances are on. compiler/typecheck/TcValidity.lhs | 8 ++++- compiler/types/FunDeps.lhs | 65 ++++++++++++++++++++++++++++++++++++- 2 files changed, 71 insertions(+), 2 deletions(-) }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2247#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1241: Functional dependency Coverage Condition is lifted, and should not be
by GHC 13 Jan '13

13 Jan '13

#1241: Functional dependency Coverage Condition is lifted, and should not be ----------------------------------------+----------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: _|_ Component: Compiler (Type checker) | Version: 6.6 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Difficulty: Unknown Testcase: | ----------------------------------------+----------------------------------- Comment(by iavor.diatchki@…): commit fe61599ffebb27924c4beef47b6237542644f3f4 {{{ Author: Iavor S. Diatchki <iavor.diatchki(a)gmail.com> Date: Sun Jan 13 16:29:10 2013 -0800 Use a version of the coverage condition even with UndecidableInstances. This fixes bug #1241 and #2247. When UndecidableInstances are on, we use the "Liberal Coverage Condition", which is what GHC used to do in the past. This is the gist of the check: class C a b | a -> b instance theta => C t1 t2 we check that `fvs t2` is a subset of `fd-closure(theta,fvs t1)`. This is strictly more general than the coverage condition, while it still guarantees consistency with the FDs of the class. This check is completely orthogonal to termination (it by no means guarantees it). I am not sure of the role of the "coverage condition" in termination--- the comments suggest that it is important. This is why, for the moment, we only use this check when UndecidableInstances are on. compiler/typecheck/TcValidity.lhs | 8 ++++- compiler/types/FunDeps.lhs | 65 ++++++++++++++++++++++++++++++++++++- 2 files changed, 71 insertions(+), 2 deletions(-) }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1241#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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