June 2017 - ghc-tickets

[GHC] #11353: DWARF call frame information incorrect in the presence of unsafe foreign calls
by GHC 03 Mar '19

03 Mar '19

#11353: DWARF call frame information incorrect in the presence of unsafe foreign calls -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 7.10.3 (CodeGen) | Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 | Type of failure: Debugging (amd64) | information is incorrect Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Unsafe foreign calls result in adjustments to `$rsp` made in the NCG to comply with calling convention alignment requirements (see `X86.CodeGen.genCCall64'`). Unfortunately, this happens after we've generated unwind information. This results in incorrect unwinding information for `$rsp` when inside of a foreign call. The results can be quite catastrophic (e.g. segmentation faults while unwinding). Unfortunately it's really not clear what can be done about this given that these adjustments aren't present in the Cmm representation that we use to produce frame information. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11353> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12397: Support for PDB debug information generation
by GHC 03 Mar '19

03 Mar '19

#12397: Support for PDB debug information generation -------------------------------------+------------------------------------- Reporter: varosi | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Debugging) | Keywords: | Operating System: Windows Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- It would be great if GHC support PDB files for debugging. This will help in Windows debugging and it will gain more stronger positions on Windows platform. Here I found format description. I'm not sure if it is similar to DWARF so it could be easily generated from existing DWARF implementation. https://github.com/Microsoft/microsoft-pdb -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12397> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12948: Implement unwind rules for non-Intel architectures
by GHC 03 Mar '19

03 Mar '19

#12948: Implement unwind rules for non-Intel architectures -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: task | 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: -------------------------------------+------------------------------------- To support DWARF-based stack unwinding, a platform needs a few things, * Valid unwind records in `stg_stop_thread` (defined in `rts/StgStartup.cmm`) * Support in the native code generator (by implementing the `generateUnwindTable` field of `NcgImpl`) * A mapping of register numbers to DWARF register numbers (see `dwarfRegNo` in `nativeGhc/Dwarf/Constants.hs`) * For unwinding support in the runtime system: * Unwinding support in `libdw` * a `set_initial_registers` implementation (see `rts/Libdw.c`) Currently the only platforms that has all of these implemented is x86_64 and i386. Someone should pick up the other platforms. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12948> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13866: -g doesn't work with -pgma=clang++
by GHC 03 Mar '19

03 Mar '19

#13866: -g doesn't work with -pgma=clang++ -------------------------------------+------------------------------------- Reporter: niteria | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.3 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: -------------------------------------+------------------------------------- This is a follow-up to #11202. The fix there is platform specific, but the problem is compiler/assembler specific. Sample of errors: {{{ /tmp/ghc4044980_0/ghc_2.s:681:2: error: error: unknown directive .hword 4 ^ | 681 | .hword 4 | ^ }}} Repro command: {{{ $ cat A.hs module A where main = putStrLn "Hello" $ ./inplace/bin/ghc-stage2 -g -pgma=clang++ A.hs }}} One workaround that I've found: {{{ $ ./inplace/bin/ghc-stage2 -g -pgma=clang++ -opta=-no-integrated-as A.hs # succeeds }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13866> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10841: Run handler on STM retry
by GHC 03 Mar '19

03 Mar '19

#10841: Run handler on STM retry -------------------------------------+------------------------------------- Reporter: shlevy | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: libraries | Version: 7.10.2 (other) | Keywords: stm | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- It would be nice to have a function like: {{{#!hs -- | Perform a series of STM actions atomically. -- -- Whenever the transaction retries, run the handler. If it doesn't return 'Nothing', -- stop the retrying and return the value given by the handler. atomicallyWithRetryHandler :: STM a -> IO (Maybe a) -> IO a }}} This would allow tracking retry statistics, printing debug messages on each retry, etc. without resorting to unsafeIOToSTM which can't safely do things like printing. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10841> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13002: :set -O does not work in .ghci file
by GHC 03 Mar '19

03 Mar '19

#13002: :set -O does not work in .ghci file --------------------------------------+---------------------------- Reporter: George | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.1 Keywords: | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: Other Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+---------------------------- {{{#!hs {-# OPTIONS_GHC -Wall #-} module Foo where testFromTo :: Int -> Int testFromTo n = length ([0..(10^n)] :: [Int]) }}} {{{ cat ~/.ghci :set +s :set -fobject-code :set -O bash-3.2$ touch Foo.hs bash-3.2$ ghci GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /Users/gcolpitts/.ghci Prelude> :load Foo :load Foo [1 of 1] Compiling Foo ( Foo.hs, Foo.o ) Ok, modules loaded: Foo (Foo.o). (0.15 secs,) Prelude Foo> testFromTo 5 testFromTo 5 100001 (0.02 secs, 8,885,888 bytes) Prelude Foo> :quit :quit Leaving GHCi. bash-3.2$ touch Foo.hs bash-3.2$ ghci -fobject-code -O GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /Users/gcolpitts/.ghci Prelude> :load Foo :load Foo [1 of 1] Compiling Foo ( Foo.hs, Foo.o ) Ok, modules loaded: Foo (Foo.o). (0.15 secs,) Prelude Foo> testFromTo 5 testFromTo 5 100001 (0.02 secs, 98,400 bytes) }}} While supplying -fobject-code -O as an argument to ghci seems like an easy workaround that isn't feasible as far as I know when using emacs thus setting priority to normal rather than low. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13002> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12847: ghci -fobject-code -O2 doesn't do the same optimisations as ghc --make -O2
by GHC 03 Mar '19

03 Mar '19

#12847: ghci -fobject-code -O2 doesn't do the same optimisations as ghc --make -O2 -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Other Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- From IRC: I have a module that takes around 10 seconds to compile on ghc --make -O2, but only around 3 seconds on ghci -fobject-code -O2. > bgamari: that is surprising I've put the -v timing output of the two cases into https://gist.github.com/nh2/e9bc4732111bfe422d8e606c10f8f0ac I'm comparing the 2 files with `meld` for spotting differences easily. Check e.g. `Result size of Tidy Core` which seems to have 3x as many terms for ghc, and `Simplifier [Mymodule]` doesn't seem to run in ghci The first time terms are different is at `Desugar, the first time a factor 3 comes in is after `Specialize`. > bgamari: wow, it sounds like the simplifier isn't getting run as aggressively in GHCi I'm running this on Ubuntu 16.04 inside nix (but happens the same way outside nix). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12847> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11503: TypeError woes (incl. pattern match checker)
by GHC 01 Mar '19

01 Mar '19

#11503: TypeError woes (incl. pattern match checker) -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 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: -------------------------------------+------------------------------------- When I say {{{ {-# LANGUAGE DataKinds, GADTs, KindSignatures, TypeFamilies, UndecidableInstances #-} {-# OPTIONS_GHC -fwarn-incomplete-patterns #-} module Bug where import GHC.TypeLits import GHC.Exts ( Constraint ) type family NotInt a where NotInt Int = TypeError (Text "That's Int, silly.") NotInt _ = (() :: Constraint) data T a where MkT1 :: a -> T a MkT2 :: NotInt a => T a foo :: T Int -> Int foo (MkT1 x) = x }}} I get {{{ Bug.hs:19:1: warning: Pattern match(es) are non-exhaustive In an equation for ‘foo’: Patterns not matched: MkT2 }}} But I shouldn't. Even worse, perhaps, GHC accepts my pattern-match against `MkT2` if I add it. If I change the `TypeError` to `False ~ True`, I get the correct behavior. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11503> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9121: Presence of dyn_o files not checked? upon recompilation
by GHC 28 Feb '19

28 Feb '19

#9121: Presence of dyn_o files not checked? upon recompilation ------------------------------------+------------------------------------- Reporter: andreas.abel | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- When I interrupt a compilation (initiated with cabal), and then recompile (with cabal), it can happen that gcc fails with missing .dyn_o file. I have "shared:True" in my .cabal/config file. [I can of course do cabal clean to work around, but since a full recompilation is about 10 min, I try to avoid this.] time cabal install --disable-library-profiling --disable-documentation Resolving dependencies... In order, the following will be installed: Agda-2.3.3 (latest: 2.3.2.2) (reinstall) Warning: Note that reinstalls are always dangerous. Continuing anyway... Configuring Agda-2.3.3... Building Agda-2.3.3... Preprocessing library Agda-2.3.3... [116 of 273] Compiling Agda.TypeChecking.Monad.Base[boot] ( src/full/Agda/TypeChecking/Monad/Base.hs-boot, dist/build/Agda/TypeChecking/Monad/Base.o-boot ) ... [239 of 273] Compiling Agda.TypeChecking.Conversion ( src/full/Agda/TypeChecking/Conversion.hs, dist/build/Agda/TypeChecking/Conversion.o ) [Agda.Syntax.Translation.InternalToAbstract changed] ^Cmake: *** [install-bin] Interrupt time cabal install --disable-library-profiling --disable-documentation Resolving dependencies... In order, the following will be installed: Agda-2.3.3 (latest: 2.3.2.2) (reinstall) Warning: Note that reinstalls are always dangerous. Continuing anyway... Configuring Agda-2.3.3... Building Agda-2.3.3... Preprocessing library Agda-2.3.3... [116 of 273] Compiling Agda.TypeChecking.Monad.Base[boot] ( src/full/Agda/TypeChecking/Monad/Base.hs-boot, dist/build/Agda/TypeChecking/Monad/Base.o-boot ) ... [273 of 273] Compiling Agda.Main ( src/full/Agda/Main.hs, dist/build/Agda/Main.o ) [Agda.Compiler.Epic.Compiler changed] gcc: error: dist/build/Agda/TypeChecking/Conversion.dyn_o: No such file or directory Failed to install Agda-2.3.3 cabal: Error: some packages failed to install: Agda-2.3.3 failed during the building phase. The exception was: ExitFailure 1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9121> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13408: Consider inferring a higher-rank kind for type synonyms
by GHC 27 Feb '19

27 Feb '19

#13408: Consider inferring a higher-rank kind for type synonyms -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: TypeInType | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In terms, a definition comprising one non-recursive equation may have a higher-rank type inferred. For example: {{{#!hs f :: (forall a. a -> a -> a) -> Int f z = z 0 1 g = f }}} `g` gets an inferred type equal to `f`'s. However, this fails at the type level: {{{#!hs type F (z :: forall a. a -> a -> a) = z 0 1 type G = F }}} If anything is strange here, it's that the term-level definition is accepted. GHC should not be in the business of inferring higher-rank types. But there is an exception for definitions comprising one non- recursive equation. This ticket proposes expanding this behavior to the type level, allowing `G` to be accepted. This is spun off from #13399, but is not tightly coupled to that ticket. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13408> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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