June 2017 - ghc-tickets

[GHC] #8578: Improvements to SpinLock implementation
by GHC 24 Sep '18

24 Sep '18

#8578: Improvements to SpinLock implementation ------------------------------------+------------------------------------- Reporter: parcs | Owner: parcs Type: task | Status: new Priority: normal | Milestone: Component: Runtime System | 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: | ------------------------------------+------------------------------------- The SpinLock implementation has a number of deficiencies. Here is a pair of patches that improves its implementation. Let me know what you think. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8578> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10193: TypeRep Show instance doesn't add parens around type operators
by GHC 24 Sep '18

24 Sep '18

#10193: TypeRep Show instance doesn't add parens around type operators -------------------------------------+------------------------------------- Reporter: | Owner: pawel.nowak | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1-rc3 Component: | Operating System: Unknown/Multiple libraries/base | Type of failure: Incorrect result Keywords: | at runtime Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The following code {{{#!hs {-# LANGUAGE AutoDeriveTypeable #-} {-# LANGUAGE TypeOperators #-} import Data.Typeable data a :*: b = Pair a b main = print (typeOf (Pair 'a' 'b')) }}} prints {{{#!hs :*: Char Char }}} which is not valid Haskell. I belive it should print {{{#!hs (:*:) Char Char }}} In my particular case I am using Hint to interpret a type involving type operators. Hint uses showed TypeRep as a type annotation: {{{#!hs let type_str = show $ Data.Typeable.typeOf wit ... let expr_typesig = concat [parens e, " :: ", type_str] }}} What results in a parse error. I can write a patch if someone confirms that's the desired behavior and doesn't break anything. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10193> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11155: Trivial error thunk gives "undefined reference to stg_ap_0_upd_info"
by GHC 23 Sep '18

23 Sep '18

#11155: Trivial error thunk gives "undefined reference to stg_ap_0_upd_info" -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 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: -------------------------------------+------------------------------------- This error popped up when Alan was coding the solution for #11028. The error is utterly unrelated to what Alan was working on. Here's a reproducer {{{ {-# OPTIONS_GHC -O -fno-full-laziness #-} module Main where foo :: Bool {-# NOINLINE foo #-} foo = error "rk" bar x = let t :: Char t = case foo of { True -> 'v'; False -> 'y' } in [t] main = print (bar ()) }}} Just compile that and you get {{{ Foo.o: In function `c1Sm_info': (.text+0x29a): undefined reference to `stg_ap_0_upd_info' }}} Why do we get that unresolved symbol? The STG code for `bar` looks like {{{ Main.bar :: forall t_aup. t_aup -> [GHC.Types.Char] [GblId, Arity=1, Str=DmdType <L,A>m2, Unf=OtherCon []] = \r srt:SRT:[rf :-> Main.foo] [x_s1RR] let { sat_s1RT [Occ=Once] :: GHC.Types.Char [LclId, Str=DmdType] = \u srt:SRT:[rf :-> Main.foo] [] Main.foo; } in : [sat_s1RT GHC.Types.[]]; }}} Look at that: an updatable thunk saying `sat_s1RT = Main.foo`! The error message is terrible, but the problem is a thunk whose only payload is a single variable. Why does that happen? The Core is {{{ bar = \ (@ t_aup) _ -> let t::Char = case foo of wild_00 { } in : @ Char t ([] @ Char) }}} The `case` is needed to change `foo`'s type from `Bool` to `Char`. The Core-to-STG pass drops the empty case alternatives as useless (rightly), but leaves a bare variable as the RHS, which confuses the code generator. We should clearly substitute `Main.foo` for `t`, either in Core-to-STG, or during code generation. Why hasn't this happened before now? It is quite hard to provoke, because floating the thunk for `t` to top level stops it happening. So it only happens if you switch off full laziness (as my test case here does), or if some very delicate inlining happens after the last float-out. The latter is very rare, but it's what happened to Alan. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11155> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8281: The impossible happened: primRepToFFIType
by GHC 21 Sep '18

21 Sep '18

#8281: The impossible happened: primRepToFFIType -----------------------------------+--------------------------------------- Reporter: tibbe | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- I ran into this error while trying to use GHCi on the hashable package: {{{ $ cabal repl Preprocessing library hashable-1.2.0.10... GHCi, version 7.6.2: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package array-0.4.0.1 ... linking ... done. Loading package deepseq-1.3.0.1 ... linking ... done. Loading package bytestring-0.10.0.2 ... linking ... done. Loading package text-0.11.3.1 ... linking ... done. Loading object (static) dist/build/cbits/fnv.o ... done Loading object (static) dist/build/cbits/getRandomBytes.o ... done final link ... done [1 of 4] Compiling Data.Hashable.RandomSource ( Data/Hashable/RandomSource.hs, interpreted ) [flags changed] [2 of 4] Compiling Data.Hashable.Class ( Data/Hashable/Class.hs, interpreted ) [flags changed] ghc: panic! (the 'impossible' happened) (GHC version 7.6.2 for x86_64-apple-darwin): primRepToFFIType Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8281> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13700: GHCi command listing possible type class instances
by GHC 21 Sep '18

21 Sep '18

#13700: GHCi command listing possible type class instances -------------------------------------+------------------------------------- Reporter: Iceland_jack | 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: -------------------------------------+------------------------------------- This is a reminder ticket, I want to be able to list possible instances, {{{ >>> :insts Product (Functor f, Functor g) => Functor (Product f g) (Applicative f, Applicative g) => Applicative (Product f g) ... >>> :insts Product Identity Functor g => Functor (Product Identity g) Applicative g => Applicative (Product Identity g) Monad g => Monad (Product Identity g) MonadFix g => MonadFix (Product Identity g) MonadZip g => MonadZip (Product Identity g) ... >>> :insts Product Identity Identity Functor (Product Identity Identity) Applicative (Product Identity Identity) Monad (Product Identity Identity) MonadFix (Product Identity Identity) MonadZip (Product Identity Identity) }}} Would be so useful for `GeneralizedNewtypeDeriving` {{{#!hs newtype Pair a = P (Product Identity Identity a) deriving (Functor, Applicative, Monad, MonadFix, MonadZip, ...) -- pattern (:#) :: a -> a -> Pair a -- pattern a1 :# a2 = P (Identity a1 `Pair` Identity a2) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13700> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11671: Allow labels starting with uppercase with OverloadedLabels
by GHC 21 Sep '18

21 Sep '18

#11671: Allow labels starting with uppercase with OverloadedLabels -------------------------------------+------------------------------------- Reporter: inaki | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc1 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: -------------------------------------+------------------------------------- The following program {{{#!hs {-# LANGUAGE OverloadedLabels, DataKinds, FlexibleInstances, MultiParamTypeClasses #-} import GHC.OverloadedLabels instance IsLabel "Three" Int where fromLabel _ = 3 test :: Int test = #Three main :: IO () main = print test }}} fails to compile in ghc 8.0 with a parse error (while it works as expected if we replace "Three" -> "three"). This may be a conscious design decision, but if not I figured I would ask if it would be possible to allow such labels starting with uppercase letters. I run into this when working on adding support for OverloadedLabels to the gobject-introspection bindings (autogenerated bindings for gtk, etc.), where it would be natural in a few places to write overloaded labels starting with a capital letter. Not hugely important, but sometimes aesthetically more pleasing (imho), and I am not aware of a good reason to forbid them. Perhaps there is one? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11671> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13233: typePrimRep panic while compiling GHC with profiling
by GHC 20 Sep '18

20 Sep '18

#13233: typePrimRep panic while compiling GHC with profiling -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I am seeing this panic while compiling GHC stage2, {{{ ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.1.20170124 for x86_64-unknown-linux): runtimeRepPrimRep typePrimRep (a :: TYPE k0) k0 Call stack: ?callStack, called at compiler/utils/Util.hs:1352:50 in ghc:Util prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1166:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1170:37 in ghc:Outputable pprPanic, called at compiler/simplStg/RepType.hs:360:5 in ghc:RepType Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug <<ghc: 1038844096 bytes, 158 GCs, 21564561/73278928 avg/max bytes residency (8 samples), 148M in use, 0.000 INIT (0.000 elapsed), 1.113 MUT (1.125 elapsed), 0.935 GC (0.940 elapsed) :ghc>> compiler/ghc.mk:582: recipe for target 'compiler/stage2/build/StgCmmMonad.p_o' failed }}} This appears to be due to my enabling of profiling. `build.mk` contains, {{{ BuildFlavour=prof ifneq "$(BuildFlavour)" "" include mk/flavours/$(BuildFlavour).mk endif HADDOCK_DOCS=YES compiler_HC_OPTS += -fprof-auto-exported }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13233> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11295: Figure out what LLVM passes are fruitful
by GHC 19 Sep '18

19 Sep '18

#11295: Figure out what LLVM passes are fruitful -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 (LLVM) | 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: -------------------------------------+------------------------------------- Builds using GHC's LLVM backend are currently substantially slower than GHC's own native code generator. There are a few possible reasons for this, 1. the cost of forking processes and serializing/parsing LLVM's intermediate representation 2. the cost of the more powerful optimizations responsible for LLVM's (hopefully) better code generation 3. the cost of redundant optimizations overlapping effort already expended by GHC Given that some architecture (e.g. ARM) are only supported by LLVM and therefore suffer considerably at the hand of our slow builds, we should try to reduce # -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11295> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12100: GHC 8.0.1 build segmentation fault in haddock
by GHC 19 Sep '18

19 Sep '18

#12100: GHC 8.0.1 build segmentation fault in haddock -------------------------------------+------------------------------------- Reporter: ilovezfs | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: MacOS X Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Skylake iMac OS X 10.11.5. Xcode 7.3.1. march=native. This happens each time I attempt to build 8.0.1. The release candidates were not affected: {{{ "inplace/bin/ghc-stage2" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -H32m -O -Wall -hide-all-packages -i -iutils/haddock/driver -iutils/haddock/haddock-api/src -iutils/haddock/haddock- library/vendor/attoparsec-0.12.1.1 -iutils/haddock/haddock-library/src -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP- DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package-id Cabal-1.24.0.0 -package-id array-0.5.1.1 -package-id base-4.9.0.0 -package-id bytestring-0.10.8.1 -package-id containers-0.5.7.1 -package-id deepseq-1.4.2.0 -package-id directory-1.2.6.2 -package-id filepath-1.4.1.0 -package-id ghc-8.0.1 -package-id ghc-boot-8.0.1 -package-id transformers-0.5.2.0 -package-id xhtml-3000.2.1 -funbox-strict-fields -Wall -fwarn-tabs -O2 -threaded -XHaskell2010 -no-user-package-db -rtsopts -Wno-unused-imports -Wno-deprecations -Wnoncanonical-monad- instances -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build -c utils/haddock/haddock- library/src/Documentation/Haddock/Types.hs -o utils/haddock/dist/build/Documentation/Haddock/Types.dyn_o "inplace/bin/ghc-stage2" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -H32m -O -Wall -hide-all-packages -i -iutils/haddock/driver -iutils/haddock/haddock-api/src -iutils/haddock/haddock- library/vendor/attoparsec-0.12.1.1 -iutils/haddock/haddock-library/src -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP- DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package-id Cabal-1.24.0.0 -package-id array-0.5.1.1 -package-id base-4.9.0.0 -package-id bytestring-0.10.8.1 -package-id containers-0.5.7.1 -package-id deepseq-1.4.2.0 -package-id directory-1.2.6.2 -package-id filepath-1.4.1.0 -package-id ghc-8.0.1 -package-id ghc-boot-8.0.1 -package-id transformers-0.5.2.0 -package-id xhtml-3000.2.1 -funbox-strict-fields -Wall -fwarn-tabs -O2 -threaded -XHaskell2010 -no-user-package-db -rtsopts -Wno-unused-imports -Wno-deprecations -Wnoncanonical-monad- instances -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build -c utils/haddock/dist/build/autogen/Paths_haddock.hs -o utils/haddock/dist/build/Paths_haddock.dyn_o "inplace/bin/ghc-stage2" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -H32m -O -Wall -hide-all-packages -i -iutils/haddock/driver -iutils/haddock/haddock-api/src -iutils/haddock/haddock- library/vendor/attoparsec-0.12.1.1 -iutils/haddock/haddock-library/src -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP- DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package-id Cabal-1.24.0.0 -package-id array-0.5.1.1 -package-id base-4.9.0.0 -package-id bytestring-0.10.8.1 -package-id containers-0.5.7.1 -package-id deepseq-1.4.2.0 -package-id directory-1.2.6.2 -package-id filepath-1.4.1.0 -package-id ghc-8.0.1 -package-id ghc-boot-8.0.1 -package-id transformers-0.5.2.0 -package-id xhtml-3000.2.1 -funbox-strict-fields -Wall -fwarn-tabs -O2 -threaded -XHaskell2010 -no-user-package-db -rtsopts -Wno-unused-imports -Wno-deprecations -Wnoncanonical-monad- instances -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build -c utils/haddock/haddock- library/src/Documentation/Haddock/Utf8.hs -o utils/haddock/dist/build/Documentation/Haddock/Utf8.dyn_o make[1]: *** [utils/haddock/dist/build/Haddock/Backends/Hyperlinker/Types.dyn_o] Segmentation fault: 11 make[1]: *** Waiting for unfinished jobs.... make[1]: *** [utils/haddock/dist/build/Documentation/Haddock/Types.dyn_o] Segmentation fault: 11 make[1]: *** [utils/haddock/dist/build/Haddock/GhcUtils.dyn_o] Segmentation fault: 11 make[1]: *** [utils/haddock/dist/build/Paths_haddock.dyn_o] Segmentation fault: 11 make[1]: *** [utils/haddock/dist/build/ResponseFile.dyn_o] Segmentation fault: 11 make: *** [all] Error 2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12100> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13279: Check known-key lists
by GHC 19 Sep '18

19 Sep '18

#13279: Check known-key lists -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I noticed that `fmap` (for example) has a known key {{{#!hs fmapName = varQual gHC_BASE (fsLit "fmap") fmapClassOpKey fmapClassOpKey = mkPreludeMiscIdUnique 173 }}} but its `RdrName` doesn't refer to it. {{{#!hs fmap_RDR = varQual_RDR gHC_BASE (fsLit "fmap") }}} Is there a reason for this? If not, it seems likely that we could get a bit of a speed-up by using `fmapName` here. We may also consider making `liftA2` known-key for `Traversable` deriving. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13279> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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