July 2017 - ghc-tickets

Re: [GHC] #12913: Port SplitSections to Windows
by GHC 07 Jul '17

07 Jul '17

#12913: Port SplitSections to Windows -------------------------------------+------------------------------------- Reporter: olsner | Owner: (none) Type: task | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Linking) | Resolution: | Keywords: Operating System: Windows | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #8405 | Differential Rev(s): Phab:D3382 Wiki Page: | Phab:D3383 Phab:D3523 -------------------------------------+------------------------------------- Comment (by Tamar Christina <tamar@…>): In [changeset:"bd4fdc6aa34a85268f3e9a2bd3f4142a97724ce4/ghc" bd4fdc6/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="bd4fdc6aa34a85268f3e9a2bd3f4142a97724ce4" Implement split-sections support for windows. Summary: Initial implementation of split-section on Windows. This also corrects section namings and uses the platform convention of `$` instead of `.` to separate sections. Implementation is based on @awson's patches to binutils. Binutils requires some extra help when compiling the libraries for GHCi usage. We drop the `-T` and use implicit scripts to amend the linker scripts instead of replacing it. Because of these very large GHCi object files, we need big-obj support, which will be added by another patch. Test Plan: ./validate Reviewers: awson, austin, bgamari Subscribers: dfeuer, rwbarton, thomie, snowleopard, #ghc_windows_task_force GHC Trac Issues: #12913 Differential Revision: https://phabricator.haskell.org/D3383 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12913#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 0

[GHC] #13936: initTc: unsolved constraints
by GHC 07 Jul '17

07 Jul '17

#13936: initTc: unsolved constraints --------------------------------------+--------------------------------- Reporter: junkbondtrader | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Windows Architecture: x86_64 (amd64) | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+--------------------------------- {{{ Prelude> lucky (7.0 :: Num) ghc.exe: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-mingw32): initTc: unsolved constraints WC {wc_insol = [W] lucky_afgR :: t_afgQ[tau:1] (CHoleCan: lucky) [W] lucky_afhl :: t_afhk[tau:1] (CHoleCan: lucky)} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} {{{#!hs lucky :: Num -> String lucky 7 = "LUCKY NUMBER SEVEN!" lucky x = "Sorry, you're out of luck, pal!" }}} I believe that above function declaration doesn't actually make sense, but it caused a panic that asked for a bug report so I'm doing it. Apologies for my newness :) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13936> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 3

Re: [GHC] #8033: add AVX register support to llvm calling convention
by GHC 07 Jul '17

07 Jul '17

#8033: add AVX register support to llvm calling convention -------------------------------------+------------------------------------- Reporter: carter | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Resolution: | Keywords: SIMD Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * cc: ekmett@… (added) Comment: The patch has been accepted and will hopefully be merged shortly. I'll flip on the GHC calling conventions bits by default in HEAD once this happens. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8033#comment:35> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 0

[GHC] #13872: Strange Typeable error message involving TypeInType
by GHC 07 Jul '17

07 Jul '17

#13872: Strange Typeable error message involving TypeInType -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: TypeInType, | Operating System: Unknown/Multiple Typeable | Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I originally discovered this when tinkering with #13871. This program: {{{#!hs {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} module Foo where import Data.Kind import Data.Typeable data Foo (a :: Type) (b :: Type) where MkFoo :: (a ~ Int, b ~ Char) => Foo a b data family Sing (a :: k) data SFoo (z :: Foo a b) where SMkFoo :: SFoo MkFoo f :: String f = show $ typeOf SMkFoo }}} Fails in GHC 8.0.1, 8.0.2, and 8.2 (after applying Phab:D3671) with a rather unsightly error message: {{{ GHCi, version 8.3.20170624: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Foo ( Foo.hs, interpreted ) Foo.hs:19:12: error: • No instance for (Typeable <>) arising from a use of ‘typeOf’ • In the second argument of ‘($)’, namely ‘typeOf SMkFoo’ In the expression: show $ typeOf SMkFoo In an equation for ‘f’: f = show $ typeOf SMkFoo | 19 | f = show $ typeOf SMkFoo | ^^^^^^^^^^^^^ }}} I'm not sure what this mysterious `<>` is, but I'm pretty sure it shouldn't be making an appearance here. (See also #13780, where `<>` also makes a surprise guest appearance.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13872> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 4

[GHC] #13871: GHC panic in 8.2 only: typeIsTypeable(Coercion)
by GHC 07 Jul '17

07 Jul '17

#13871: GHC panic in 8.2 only: typeIsTypeable(Coercion) -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 8.2.1-rc2 (Type checker) | Keywords: TypeInType, | Operating System: Unknown/Multiple Typeable | Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This code works fine in GHC 8.0.1 and 8.0.2: {{{#!hs {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} module Foo where import Data.Kind data Foo (a :: Type) (b :: Type) where MkFoo :: (a ~ Int, b ~ Char) => Foo a b data family Sing (a :: k) data SFoo (z :: Foo a b) where SMkFoo :: SFoo MkFoo }}} But in GHC 8.2 and HEAD, it panics: {{{ $ /opt/ghc/8.2.1/bin/ghci Bug.hs GHCi, version 8.2.0.20170622: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Foo ( Bug.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.2.0.20170622 for x86_64-unknown-linux): typeIsTypeable(Coercion) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13871> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 9

[GHC] #13908: sameMutableArray equivalent for Array
by GHC 07 Jul '17

07 Jul '17

#13908: sameMutableArray equivalent for Array -------------------------------------+------------------------------------- Reporter: winter | 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: -------------------------------------+------------------------------------- Sometime it is useful to compare reference equality for immutable arrays, for example when comparing vectors which are slices of arrays, we may want to know if two vectors are slices of the same array. But currently we only have `sameMutableXXXArray` primitives. A workaround may look like this: {{{ sameArray :: Array a -> Array a -> Bool sameArray arr1 arr2 = runST (do marr1 <- unsafeThawArray arr1 marr2 <- unsafeThawArray arr2 return (sameMutableArray marr1 marr2) ) }}} But the problem is for boxed arrays, this code will push an unchanged array to mutable list if it's already on older generations. Next GC will have to scan it(at least will scan its card table). I can see two solutions here, first one is to add `sameXXXArray` for all array types. The second one is somehow more complex: Currently we simply rewrite array's header to `MUT_ARR_PTRS_FROZEN0/SMALL_MUT_ARR_PTRS_FROZEN0` when we do `unsafeFreeze`. But for mutable array with no write happend, e.g. the ones with `MUT_ARR_PTRS_CLEAN/SMALL_MUT_ARR_PTRS_CLEAN` header. we can safely rewrite the header to `MUT_ARR_PTRS_FROZEN/SMALL_MUT_ARR_PTRS_FROZEN`, so that we can keep it from next GC. Then to fix previous code, we can add a freeze before returning. Of course we can do these two solutions all together ; ) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13908> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 9

[GHC] #13917: The line on which to locate the error indication is bad.
by GHC 07 Jul '17

07 Jul '17

#13917: The line on which to locate the error indication is bad. -------------------------------------+------------------------------------- Reporter: vanto | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | error/warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ module Qwer where a = {-# LANGUAGE KindSignatures #-} main :: IO () main = print (if True then () else ()) }}} Reply from GHC\\ {{{ Prelude> :l qwer.hs [1 of 1] Compiling Qwer ( qwer.hs, interpreted ) qwer.hs:5:1: error: parse error (possibly incorrect indentation or mismatched brackets) | 5 | main :: IO () | ^ Failed, modules loaded: none. }}} The error is located on line 3.\\ GHCi, version 8.2.0.20170507 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13917> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 8

[GHC] #13739: Very slow linking of profiled executables
by GHC 07 Jul '17

07 Jul '17

#13739: Very slow linking of profiled executables -------------------------------------+------------------------------------- Reporter: duog | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Compile-time (amd64) | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While building profiled executables with 8.2.1rc2 I've noticed the link times seem to have significantly regressed. I don't have a minimal test case. Testing on cabal head source tree {{{ cabal --version >cabal-install version 2.1.0.0 >compiled using version 2.1.0.0 of the Cabal library cabal new-configure --enable-profiling --enable-newer --with- ghc=/opt/ghc-8.2.1/bin/ghc cabal build cabal-install # hit Ctrl-C during linking time cabal build cabal-install }}} gives real 1m54.833s user 1m52.936s sys 0m1.620s doing the same with 8.0.2 links in less than a second -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13739> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 43

[GHC] #13931: GHC incorrectly considers type family instances conflicting?
by GHC 06 Jul '17

06 Jul '17

#13931: GHC incorrectly considers type family instances conflicting? -------------------------------------+------------------------------------- Reporter: vagarenko | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I asked this on stackoverflow first https://stackoverflow.com/questions/44958114/why-these-type-family- instances-conflicting I'm using GHC-8.0.1. This code (requires singletons lib): {{{#!hs {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE TypeInType #-} module Bug where import Data.Kind import Data.Singletons type family MkCtx (kx :: Type) (kc :: Type) (c :: kc) (x :: kx) :: Constraint type instance MkCtx kx (kx ~> Constraint) c x = Apply c x type instance MkCtx kx (kx -> Constraint) c x = c x }}} with the message: {{{ Conflicting family instance declarations: forall kx (x :: kx) (c :: kx ~> Constraint). MkCtx kx (kx ~> Constraint) c x = Apply c x forall kx (x :: kx) (c :: kx -> Constraint). MkCtx kx (kx -> Constraint) c x = c x }}} Why GHC considers these instances conflicting? I don't see how they overlap. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13931> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 5

Re: [GHC] #7741: Add SIMD support to x86/x86_64 NCG
by GHC 05 Jul '17

05 Jul '17

#7741: Add SIMD support to x86/x86_64 NCG -------------------------------------+------------------------------------- Reporter: shelarcy | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (NCG) | Version: 7.7 Resolution: | Keywords: SIMD Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #3557 | Differential Rev(s): Wiki Page: wiki:SIMD | -------------------------------------+------------------------------------- Comment (by bgamari): It depends upon who steps up to implement this plan :) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7741#comment:17> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 0