May 2016 - ghc-tickets

[GHC] #10647: Notice about lack of SIMD support.
by GHC 12 Jul '16

12 Jul '16

#10647: Notice about lack of SIMD support. -------------------------------------+------------------------------------- Reporter: mniip | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- In some cases, when SIMD primitives are used without the `-fllvm` flag, instead of giving the friendly `SIMD vector instructions require the LLVM back-end.`, GHC crashes with varying messages. The simplest example is {{{#!hs {-# LANGUAGE MagicHash #-} module Foo where import GHC.Prim data V = V Int8X16# }}} In 7.8.4 this crashes with {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.8.4 for x86_64-unknown-linux): Size.intSize W128 }}} According to osa1, in HEAD this still crashes, but with {{{ ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150717 for x86_64-unknown-linux): Format.intFormat W128 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10647> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8308: Resurrect ticky code for counting constructor arity
by GHC 12 Jul '16

12 Jul '16

#8308: Resurrect ticky code for counting constructor arity ----------------------------------------------+---------------------------- Reporter: jstolarek | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Profiling | Version: 7.7 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Moderate (less than a day) | Type of failure: Other Blocked By: | Test Case: Related Tickets: | Blocking: ----------------------------------------------+---------------------------- There is a dead piece of ticky profiling code that computes histograms of data constructor arities (including tuples) and size of vector returns. The function responsible is `bumpHistogram` in [[GhcFile(compiler/codeGen/StgCmmTicky.hs)]], which masks the commented out function `bumpHistogramE`. We can improve ticky profiling by resurrecting this dead code. There are following things that need to be done: 1. Replace current no-op `bumpHistogram` with `bumpHistogramE`. Note that current implementation of `bumpHistogramE` computes constructor arity at runtime. This is unnecessary because we know arity at compile time so we can avoid runtime check by doing sth like this: {{{ bumpHistogram lbl n = do let offset = n `min` 8 emit (addToMem cLong (cmmIndexExpr cLongWidth (CmmLit (CmmLabel (mkRtsDataLabel lbl))) (CmmReg (CmmInt (fromIntegral offset) cLongWidth))) 1) }}} Note that `mkRtsDataLabel` function does not exist anymore but we should be able to replace that call with `mkCmmDataLabel rtsPackageId lbl` (speculation). 2. We need to declare arrays that will store histogram values. Declarations of variables used for storing ticky statistics are in [[GhcFile(includes/stg/Ticky.h)]]. We also need to initialize the declared array to contain only zeros. 3. Having declared the arrays we need to fix printing of computed arities. This is done in [[GhcFile(rts/Ticky.c)]]. Note that there is a lot of code that is commented out (`/* krc: comment out some of this stuff temporarily */`) or disabled with `#if FALSE` pragma. We need to resurect *some* of it. There is a `PR_HST` macro for printing one histogram entry. This seems bad. We should probably rework the part of code responsible for printing out results of historgams. 4. Current code counts arities from 0 to 8. Everything above 8 is put into the same bin as 8. This magical 8 is spread all over the code. We should declare a constant that is visible both in Haskell sources (see `bumpHistogram` in 1.) and RTS files and have all code behave properly depending on that constant - we should have loops instead of statically printing 9 elements of histogram array. 5. Some ticky functions that count arity histograms are not used. For example `tickyReturnNewCon` should probably be called by `cgConApp` like this: {{{ ; emit =<< fcode_init ; tickyReturnNewCon ; emitReturn [idInfoToAmode idinfo] } }}} The above is a an outline, which should be fairly accurate, but unexpected things may show up along the way. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8308> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12127: ghc-8.0.1: panic! (the 'impossible' happened) filterImports/combine (double import)
by GHC 12 Jul '16

12 Jul '16

#12127: ghc-8.0.1: panic! (the 'impossible' happened) filterImports/combine (double import) -------------------------------------+------------------------------------- Reporter: slyfox | Owner: 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: -------------------------------------+------------------------------------- It's a distilled example or repa-devil-0.3.2.6 build failure: {{{#!hs -- Cursored.hs: {-# LANGUAGE TypeFamilies #-} module Cursored where class Source r where data Array r instance Source () where data Array () = F { f :: Int } }}} {{{#!hs -- Bug.hs: module DevIL () where import Cursored (Array(..), Source(..)) }}} {{{ [1 of 2] Compiling Cursored ( Cursored.hs, Cursored.o ) [2 of 2] Compiling DevIL ( Bug.hs, Bug.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-linux): filterImports/combine (Array, Array{Array, F, f}, Nothing) (Array, Source{Source, Array}, Nothing) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} The error is the same as #11959 but involved entities are slightly different. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12127> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11554: Self quantification in GADT data declarations
by GHC 12 Jul '16

12 Jul '16

#11554: Self quantification in GADT data declarations -------------------------------------+------------------------------------- Reporter: Rafbill | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc2 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: -------------------------------------+------------------------------------- GHC hangs on this (it was panicking on the same code before : [https://github.com/goldfirere/ghc/issues/56](https://github.com/goldfirere/… : {{{#!hs {-# LANGUAGE GADTs, TypeInType #-} import Data.Kind data A :: Type where B :: forall (a :: A). A }}} I guess the typechecker tries to infer the kind of A from the type of the constructors and hangs. Maybe recursive occurrences of a type as a kind in its constructors should only be allowed when its kind signature is specified and can be used to typecheck the constructors. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11554> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12026: Pattern match failure in RnNames.hs
by GHC 12 Jul '16

12 Jul '16

#12026: Pattern match failure in RnNames.hs -------------------------------------+------------------------------------- Reporter: davean | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- When compiling dimensional-1.0.1.1 after patching numtype-dk with the patch at https://github.com/bjornbm/numtype-dk/issues/12 GHC does the "impossible": [ 3 of 16] Compiling Numeric.Units.Dimensional.Dimensions.TypeLevel ( src/Numeric/Units/Dimensional/Dimensions/TypeLevel.hs, dist/dist-sandbox- 68389a1a/build/Numeric/Units/Dimensional/Dimensions/TypeLevel.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.0.20160421 for x86_64-unknown-linux): Pattern match failure in do expression at compiler/rename/RnNames.hs:902:12-50 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12026> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12094: Unlifted types and pattern synonym signatures
by GHC 12 Jul '16

12 Jul '16

#12094: Unlifted types and pattern synonym signatures -------------------------------------+------------------------------------- Reporter: akio | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: pattern | Operating System: Unknown/Multiple synonyms | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following program is rejected by ghc-8.0.1: {{{#!hs {-# LANGUAGE MagicHash #-} {-# LANGUAGE PatternSynonyms #-} module Foo where import GHC.Exts (Int#) pattern Zero :: Int# -- commenting out this line works pattern Zero <- 0# }}} {{{ % ghc-stage2 unlifted-pattern-synonym.hs [1 of 1] Compiling Foo ( unlifted-pattern-synonym.hs, unlifted-pattern-synonym.o ) unlifted-pattern-synonym.hs:7:17: error: • Expecting a lifted type, but ‘Int#’ is unlifted • In the type ‘Int#’ }}} Commenting out the type signature removes the error. GHC 7.10.3 accepts this program, with and without the type signature. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12094> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11690: stage 1 compiler silently ignores plugins
by GHC 12 Jul '16

12 Jul '16

#11690: stage 1 compiler silently ignores plugins -------------------------------------+------------------------------------- Reporter: osa1 | Owner: osa1 Type: feature | Status: new request | Priority: lowest | Milestone: Component: Compiler | Version: 7.10.3 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: -------------------------------------+------------------------------------- It can't load plugins but it shouldn't just silently ignore IMHO. At least a warning would be nice. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11690> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10886: Remove the magic from `Any`
by GHC 11 Jul '16

11 Jul '16

#10886: Remove the magic from `Any` -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: task | Status: new Priority: normal | Milestone: 8.0.1 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 Revisions: | -------------------------------------+------------------------------------- The `Any` type used to be very highly magical: a poly-kinded type in a mono-kinded world. Then it became only normally magical: a datatype with a return kind of `k` (instead of `*`). Then it became only a bit magical: a closed type family with no equations. Now that we have non-magical empty closed type families, I believe that we can remove the last bit of magic and just define {{{ type family Any :: k where { } }}} somewhere (`GHC.Types`?), wire it in (like, e.g., `Bool`), and be done with it. Objections? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10886> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10311: package name returned from tyConPackage is garbled
by GHC 08 Jul '16

08 Jul '16

#10311: package name returned from tyConPackage is garbled -------------------------------------+------------------------------------- Reporter: j.waldmann | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- I am using tyConPackage (etc.) to programmatically generate links to haddock documentation (e.g., from a typed edit widget). This is now broken: {{{ import Data.Map import Data.Typeable tyConPackage $ typeRepTyCon $ typeOf $ fromList [(1,2)] in ghc-7.8.4: "containers-0.5.5.1" in ghc-7.10.1: "conta_47ajk3tbda43DFWyeF3oHQ" }}} and I don't see how to get the actual package name. Cf. http://stackoverflow.com/questions/29638177/tyconpackage-changed-from- ghc-7-8-to-ghc-7-10 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10311> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9625: ghc: panic using --enable-executable-dynamic
by GHC 08 Jul '16

08 Jul '16

#9625: ghc: panic using --enable-executable-dynamic -------------------------------------+------------------------------------- Reporter: CoreyOConnor | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Compile- Blocked By: | time crash Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- (from: https://github.com/haskell/cabal/issues/2039) Using --enable-executable-dynamic leads to a ghc panic. Reproduction steps: 1. clone https://github.com/coreyoconnor/executable-dynamic-issue 2. cabal configure --enable-tests --enable-executable-dynamic 3. cabal test Expected results: Test executes and passes. Actual results: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.8.2 for x86_64 -unknown-linux): Don't understand library name verify-foo }}} Actual results varies based on the name of "verify-foo" test suite. Other names tried: "verifyFoo", "VerifyFoo". All of which also fail. Removing "--enable-executable-dynamic" results in a pass regardless of test suite name. Reproduced on GHC 7.8.2, GHC 7.8.3, Cabal 1.18, Cabal 1.20. Ubuntu. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9625> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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