October 2018 - ghc-tickets

[GHC] #14366: Type family equation refuses to unify wildcard type patterns
by GHC 05 Jan '19

05 Jan '19

#14366: Type family equation refuses to unify wildcard type patterns -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 (Type checker) | Keywords: TypeFamilies, | Operating System: Unknown/Multiple TypeInType | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This typechecks: {{{#!hs {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} import Data.Kind import Data.Type.Equality type family Cast (e :: a :~: b) (x :: a) :: b where Cast Refl x = x }}} However, if you try to make the kinds `a` and `b` explicit arguments to `Cast`: {{{#!hs {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} import Data.Kind import Data.Type.Equality type family Cast (a :: Type) (b :: Type) (e :: a :~: b) (x :: a) :: b where Cast _ _ Refl x = x }}} Then GHC gets confused: {{{ GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/ryanglscott/.ghci [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:9:12: error: • Expected kind ‘_ :~: _1’, but ‘'Refl’ has kind ‘_ :~: _’ • In the third argument of ‘Cast’, namely ‘Refl’ In the type family declaration for ‘Cast’ | 9 | Cast _ _ Refl x = x | ^^^^ }}} A workaround is to explicitly write out what should be inferred by the underscores: {{{#!hs {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} import Data.Kind import Data.Type.Equality type family Cast (a :: Type) (b :: Type) (e :: a :~: b) (x :: a) :: b where Cast a a Refl x = x }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14366> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15411: urk! lookup local fingerprint
by GHC 05 Jan '19

05 Jan '19

#15411: urk! lookup local fingerprint -------------------------------------+------------------------------------- Reporter: admock | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 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: -------------------------------------+------------------------------------- When building GHC 8.6.0-alpha2 the build fails with the following error. {{{ [ghc-8.6.0.20180714] alan% make ===--- building phase 0 make --no-print-directory -f ghc.mk phase=0 phase_0_builds make[1]: Nothing to be done for 'phase_0_builds'. ===--- building phase 1 make --no-print-directory -f ghc.mk phase=1 phase_1_builds make[1]: Nothing to be done for 'phase_1_builds'. ===--- building final phase make --no-print-directory -f ghc.mk phase=final all "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/src -iutils/haddock/dist/build -Iutils/haddock/dist/build -iutils/haddock/dist/build/haddock/autogen -Iutils/haddock/dist/build/haddock/autogen -optP-DIN_GHC_TREE -optP- include -optPutils/haddock/dist/build/haddock/autogen/cabal_macros.h -package-id Cabal-2.3.0.0 -package-id array-0.5.2.0 -package-id base-4.12.0.0 -package-id bytestring-0.10.8.2 -package-id containers-0.6.0.1 -package-id deepseq-1.4.4.0 -package-id directory-1.3.3.0 -package-id filepath-1.4.2 -package-id ghc-8.6.0.20180714 -package-id ghc-boot-8.6.0.20180714 -package-id parsec-3.1.13.0.0.0.0.0 -package-id text-1.2.3.0 -package-id transformers-0.5.5.0 -package-id xhtml-3000.2.2.1 -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- api/src/Haddock/Backends/Hyperlinker/Types.hs -o utils/haddock/dist/build/Haddock/Backends/Hyperlinker/Types.dyn_o ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.6.0.20180714 for powerpc64-unknown-linux): urk! lookup local fingerprint $fEqTokenDetails [cESf79 :-> (Span, 3bafa1c9fb27c5bcc8d6a0fca267f340)] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1164:37 in ghc:Outputable pprPanic, called at compiler/iface/MkIface.hs:523:37 in ghc:MkIface Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug make[1]: *** [utils/haddock/ghc.mk:20: utils/haddock/dist/build/Haddock/Backends/Hyperlinker/Types.dyn_o] Error 1 make: *** [Makefile:127: all] Error 2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15411> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc
by GHC 04 Jan '19

04 Jan '19

#11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc -------------------------------------+------------------------------------- Reporter: pl | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 7.10.3 System | Keywords: c++ | Operating System: Unknown/Multiple exceptions | Architecture: | Type of failure: Runtime crash Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider the C++ program {{{ // Main_cc.cc #include <iostream> #include <exception> extern "C" { int func() { try { throw std::runtime_error("THIS FAILS!"); } catch(const std::runtime_error &c) { std::cerr << c.what(); } return 0; } } }}} and the Haskell program {{{#!hs -- Main.hs module Main where import Foreign.C.Types foreign import ccall func :: IO CInt main :: IO () main = print =<< func }}} When compiled with {{{ ghc --make Main.hs Main_cc.cc -lstdc++ }}} and being run on mac os x 10.11.3 the result is {{{ libc++abi.dylib: terminating with uncaught exception of type std::runtime_error: THIS FAILS! Abort trap: 6 }}} and not (as it should be): {{{ THIS FAILS!0 }}} When compiled in a similar way under windows some c++ exceptions of a larger project are not caught as well. However, these were hard to track down and I was unable to construct a simple example like the one above. As a workaround one can * write a main() function in c++ and call from there into Haskell, * compile the Haskell-Module with the options "-c -no-hs-main", and * link the application using g++ (not ghc!). When being compiled / linked this way, all c++ exceptions are being caught in mac os x as well as under windows. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11829> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13630: ByteString pinned memory can be leaky
by GHC 04 Jan '19

04 Jan '19

#13630: ByteString pinned memory can be leaky -------------------------------------+------------------------------------- Reporter: nh2 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 8.0.1 System | 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: -------------------------------------+------------------------------------- My question on IRC: {{{ How does memory allocation for pinned blocks work? Let's say pinned blocks are 4KB in size, and I allocate first a 3 KB ByteString A and then an 8-byte ByteString B. Now I GC A, no longer need it. Then according to https://ghc.haskell.org/trac/ghc/wiki/Commentary/Rts/Storage/GC/Pinned "a single pinned object keeps alive the whole block in which it resides", my small ByteString B keeps the entire block alive. But what happens with the 3KB in the front of that block? Will it be re-used by the next ByteString allocation (say 1KB)? In other words, how smart is allocatePinned as an allocator? }}} The answer: {{{ slyfox: nh2: allocatePinned it quite dump. it only allocated from free tail space }}} {{{ nh2: slyfox: that sounds like a huge potential for memory leak then slyfox: yes, fragmentation is quite bad for bytestrings }}} So it seems that I can get into the unfortunate situation where a super short `ByteString` of a few bytes can waste an entire 4 KB block of memory; some migth call this a leak. One idea to solve it seems to be to change standard `ByteStrings` to not pinned, and to allocate pinned ones explicitly when needed. This seems to be an often-discussed topic and not trivial because many `ByteString` functions are implemented using libc FFI functions. However, it seems there will always be _some_ need for pinned memory, so we should better have an efficient way to manage it in any case. Efficient here means, for example, to re-use freed memory inside a block instead of only using free tail space. It seems that `jemalloc` has a feature to use given blocks of memory and provide a `malloc()` functionality inside them: https://stackoverflow.com/questions/30836359/jemalloc-mmap-and-shared- memory Perhaps this could be used to provide GHC with a simple method to use pinned memory more efficiently? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13630> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14797: High-residency modules during GHC build
by GHC 04 Jan '19

04 Jan '19

#14797: High-residency modules during GHC build -------------------------------------+------------------------------------- Reporter: tdammers | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Runtime (amd64) | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While trying to figure out memory allocation failures on the CI server, I tracked allocations and residency on a per-module basis, and noticed that some modules require a lot more memory to compile than others. I've compiled a digest of the most memory-hungry compilation steps: {{{ "/usr/local/bin/ghc" ... compiler/stage1/build/OptCoercion.o: Max. residency: 991356584 / In use: 2094M "inplace/bin/ghc-stage1" ... compiler/stage2/build/OptCoercion.dyn_o: Max. residency: 714940528 / In use: 1471M "/usr/local/bin/ghc" ... compiler/stage1/build/X86/CodeGen.o: Max. residency: 679947656 / In use: 1497M "inplace/bin/ghc-stage1" ... libraries/Cabal/Cabal/dist- install/build/Distribution/SPDX/LicenseId.dyn_o: Max. residency: 653177496 / In use: 1355M "inplace/bin/ghc-stage1" ... compiler/stage2/build/X86/CodeGen.dyn_o: Max. residency: 641515344 / In use: 1425M "/usr/local/bin/ghc" ... -ilibraries/parsec: Max. residency: 593335568 / In use: 1355M "/usr/local/bin/ghc" ... libraries/Cabal/Cabal/dist- boot/build/Distribution/SPDX/LicenseId.o: Max. residency: 575034968 / In use: 1137M "inplace/bin/ghc-stage1" ... compiler/stage2/build/DynFlags.dyn_o: Max. residency: 402734408 / In use: 1059M "/usr/local/bin/ghc" ... compiler/stage1/build/DynFlags.o: Max. residency: 343154784 / In use: 892M "inplace/bin/ghc-stage1" ... libraries/template-haskell/dist- install/build/Language/Haskell/TH/Syntax.dyn_o: Max. residency: 266744312 / In use: 720M "/usr/local/bin/ghc" ... compiler/stage1/build/Parser.o: Max. residency: 258613584 / In use: 679M "inplace/bin/ghc-stage1" ... compiler/stage2/build/CmmOpt.dyn_o: Max. residency: 254639624 / In use: 568M "inplace/bin/ghc-stage1" ... compiler/stage2/build/Parser.dyn_o: Max. residency: 236774592 / In use: 635M "inplace/bin/ghc-stage1" ... ghc/stage2/build/GHCi/UI.dyn_o: Max. residency: 234055792 / In use: 609M "/usr/local/bin/ghc" ... compiler/stage1/build/HsExpr.o: Max. residency: 233724400 / In use: 657M "/usr/local/bin/ghc" ... compiler/stage1/build/CmmOpt.o: Max. residency: 208378888 / In use: 436M "/usr/local/bin/ghc" ... compiler/stage1/build/HscMain.o: Max. residency: 197177248 / In use: 500M "inplace/bin/ghc-stage1" ... compiler/stage2/build/HsExpr.dyn_o: Max. residency: 192780496 / In use: 521M "inplace/bin/ghc-stage1" ... libraries/Cabal/Cabal/dist- install/build/Distribution/Simple/Setup.dyn_o: Max. residency: 191649952 / In use: 521M "/usr/local/bin/ghc" ... compiler/stage1/build/HsDecls.o: Max. residency: 183441120 / In use: 508M "inplace/bin/ghc-stage1" ... compiler/stage2/build/TcSplice.dyn_o: Max. residency: 176802000 / In use: 445M "inplace/bin/ghc-stage1" ... compiler/stage2/build/TcRnDriver.dyn_o: Max. residency: 172892128 / In use: 458M "inplace/bin/ghc-stage1" ... compiler/stage2/build/HscMain.dyn_o: Max. residency: 172802688 / In use: 470M "inplace/bin/ghc-stage1" ... libraries/ghci/dist- install/build/GHCi/TH/Binary.dyn_o: Max. residency: 169775368 / In use: 455M "inplace/bin/ghc-stage1" ... compiler/stage2/build/GhcMake.dyn_o: Max. residency: 167305408 / In use: 431M "inplace/bin/ghc-stage1" ... compiler/stage2/build/PrimOp.dyn_o: Max. residency: 162532408 / In use: 455M "/usr/local/bin/ghc" ... compiler/stage1/build/HscTypes.o: Max. residency: 160814736 / In use: 421M "inplace/bin/ghc-stage1" ... compiler/stage2/build/HsDecls.dyn_o: Max. residency: 160445552 / In use: 426M "inplace/bin/ghc-stage1" ... libraries/Cabal/Cabal/dist- install/build/Language/Haskell/Extension.dyn_o: Max. residency: 159817712 / In use: 363M "/usr/local/bin/ghc" ... compiler/stage1/build/TcSplice.o: Max. residency: 156738656 / In use: 375M "/usr/local/bin/ghc" ... compiler/stage1/build/TcRnDriver.o: Max. residency: 153910768 / In use: 421M "inplace/bin/ghc-stage1" ... libraries/containers/dist- install/build/Data/Sequence/Internal.dyn_o: Max. residency: 151318224 / In use: 405M "inplace/bin/ghc-stage1" ... compiler/stage2/build/MatchLit.dyn_o: Max. residency: 150681176 / In use: 382M "/usr/local/bin/ghc" ... compiler/stage1/build/ByteCodeGen.o: Max. residency: 144579176 / In use: 389M "/usr/local/bin/ghc" ... compiler/stage1/build/GhcMake.o: Max. residency: 144411312 / In use: 379M "/usr/local/bin/ghc" ... compiler/stage1/build/MatchLit.o: Max. residency: 142596736 / In use: 382M "inplace/bin/ghc-stage1" ... compiler/stage2/build/StgCmmPrim.dyn_o: Max. residency: 141484616 / In use: 340M "inplace/bin/ghc-stage1" ... libraries/ghci/dist- install/build/GHCi/Message.dyn_o: Max. residency: 139224136 / In use: 363M "/usr/local/bin/ghc" ... compiler/stage1/build/StgCmmPrim.o: Max. residency: 137390744 / In use: 346M "inplace/bin/ghc-stage1" ... compiler/stage2/build/TcExpr.dyn_o: Max. residency: 136387128 / In use: 370M "inplace/bin/ghc-stage1" ... compiler/stage2/build/Lexer.dyn_o: Max. residency: 135228120 / In use: 337M "inplace/bin/ghc-stage1" ... compiler/stage2/build/TcTyClsDecls.dyn_o: Max. residency: 134817024 / In use: 369M "/usr/local/bin/ghc" ... compiler/stage1/build/MkIface.o: Max. residency: 134039144 / In use: 339M "inplace/bin/ghc-stage1" ... compiler/stage2/build/RnExpr.dyn_o: Max. residency: 133947600 / In use: 345M "inplace/bin/ghc-stage1" ... compiler/stage2/build/HscTypes.dyn_o: Max. residency: 133938840 / In use: 366M "inplace/bin/ghc-stage1" ... compiler/stage2/build/TcGenDeriv.dyn_o: Max. residency: 133744056 / In use: 320M "/usr/local/bin/ghc" ... compiler/stage1/build/TcExpr.o: Max. residency: 131766896 / In use: 336M "inplace/bin/ghc-stage1" ... compiler/stage2/build/GHC.dyn_o: Max. residency: 130998912 / In use: 277M "inplace/bin/ghc-stage1" ... compiler/stage2/build/ByteCodeGen.dyn_o: Max. residency: 129499464 / In use: 348M "inplace/bin/ghc-stage1" ... compiler/stage2/build/InteractiveEval.dyn_o: Max. residency: 128902944 / In use: 286M }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14797> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11962: Support induction recursion
by GHC 04 Jan '19

04 Jan '19

#11962: Support induction recursion -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: feature | Status: new request | 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: -------------------------------------+------------------------------------- Now that we have `-XTypeInType`, let's take it a step further and allow induction recursion. This feature exists in Agda and Idris. Here is a short example of what can be done in Agda: {{{ mutual -- Codes for types. data U : Set where nat : U pi : (a : U) → (El a → U) → U -- A function that interprets codes as actual types. El : U → Set El nat = ℕ El (pi a b) = (x : El a) → El (b x) }}} Note that the `U` datatype and the `El` function depend on each other. But if you look more closely, the header for `U` does not depend on `El`; only the constructors of `U` depend on `El`. So if we typecheck `U : Set` first, then `El : U → Set`, then the constructors of `U`, then the equations of `El`, we're OK. Translation into Haskell: {{{ import Data.Kind data family Sing (a :: k) -- we still require singletons data U :: Type where Nat :: U Pi :: Sing (a :: U) -> (El a -> U) -> U type family El (u :: U) :: Type where El 'Nat = Int El (Pi a b) = forall (x :: El a). Sing x -> El (b x) }}} This currently errors with {{{ • Type constructor ‘U’ cannot be used here (it is defined and used in the same recursive group) • In the kind ‘U’ }}} It needn't error. (I'm cheating a bit here, because for unrelated reasons, we can't return a `forall` on the right-hand side of a type family. But that's not the issue at hand.) I have some very sketchy notes on how we might do this [wiki:DependentHaskell/Internal#Separatingtypesignaturesfromdefinitions here]. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11962> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15155: How untagged pointers sneak into banged fields
by GHC 03 Jan '19

03 Jan '19

#15155: How untagged pointers sneak into banged fields -------------------------------------+------------------------------------- Reporter: heisenbug | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: 14677 | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- (''N.B.'' I am writing this up from memory, and cannot verify it just now, maybe someone can lend a hand, otherwise I'll do it ASAP!) Here is a way how untagged pointers to strict data can be created in banged (strict) constructor fields. This reproduction recipe **depends on the patch from #14677 applied**. We have 3 modules `A`, `B` and `C`: {{{#!hs module A where data A = X | Y | Z a = Z }}} {{{#!hs module B where import A newtype B = B A b = B a }}} {{{#!hs {-# language MagicHash #-} module C where import A import B import GHC.Exts data C = C !B c = C b main = do print (I# (reallyUnsafePtrEquality# a (coerce b))) -- prints 0, b is softlink print (I# (dataToTag# c)) -- prints 0: not entered yet print (case c of C b' -> I# (dataToTag# b')) -- prints 0? print (case c of C (B a') -> I# (dataToTag# a')) -- prints 3 }}} ------------------- == Why this happens `B.b` is a newtype to `A.a` so one would expect that both alias the same memory location (a ''hardlink'' in filesystem parlance). But currently reexports are implemented with a special type of closure `IND_STATIC` (a ''softlink'') which needs to be entered to obtain the actual (tagged pointer). The `IND_STATIC` closure's pointer is never tagged (otherwise it would never be entered, instead interpreted as a honest-to-goodness `A.A`, which causes the symptoms seen in #14677). With #14677 applied to GHC, the unfolding of `B.b` is correctly read when compiling `C` (with `-O1` and better) and thus the compiler knows that it should be a tagged pointer value. Thus the construction of `C.c` shortcuts the entering of `B.b` when filling the strict field, and (because `B.b` being a softlink, thus untagged) the field ends up carrying a 0 tag. ------------------------- == How can this be fixed? I see two possibilities one conservative and one invasive. === Conservative When seeing a coercion unfolding of a tagged value being used to initialise a strict field, do not skip the evaluatedness check, but cater for the possibility of an `IND_STATIC` closure. Check the closure type, and if confirmed, steal the pointee and use that. === Invasive Get rid of the `IND_STATIC` closures altogether. For ''intra-module'' softlinks we can have proper hardlinks (assembler `.equiv` directives, or LLVM `alias`es). ''Inter-module'' softlinks can also be eliminated by linker scripts. This would however cause more build artifacts, so I don't know how hairy it would turn out. OTOH, it would reduce binary size by eliminating indirection closures and potential dereferencing code. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15155> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15617: Unboxed tuples/sum error message on `a = show 5` in expression evaluation and interactive modes
by GHC 03 Jan '19

03 Jan '19

#15617: Unboxed tuples/sum error message on `a = show 5` in expression evaluation and interactive modes -------------------------------------+------------------------------------- Reporter: ChaiTRex | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.6.1-beta1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- With GHC 8.4.3 (`ghc` below on both Ubuntu 16.04.5 and Ubuntu 18.04.1) and recent GHC (`~/dev/ghc/inplace/bin/ghc-stage2` below on Ubuntu 16.04.5; not `HEAD` but close at `ff29fc84c03c800cfa04c2a00eb8edf6fa5f4183`), I get errors for `a = show 5`. I run the following commands, showing that `show 5` is usually fine: {{{ $ ghc -fobject-code -O2 -e 'show 5' "5" $ ghc -fobject-code -O2 -e 'let a = show 5 in a' "5" }}} But not with `a = show 5`: {{{ $ ghc -fobject-code -O2 -e 'a = show 5' <interactive>: Error: bytecode compiler can't handle unboxed tuples and sums. Possibly due to foreign import/export decls in source. Workaround: use -fobject-code, or compile this module to .o separately. }}} Running with `ghci` gives the same error: {{{ $ ghci -fobject-code -O2 GHCi, version 8.4.3: http://www.haskell.org/ghc/ :? for help Prelude> a = show 5 Error: bytecode compiler can't handle unboxed tuples and sums. Possibly due to foreign import/export decls in source. Workaround: use -fobject-code, or compile this module to .o separately. Prelude> Leaving GHCi. }}} Both errors stop when optimization is turned off: {{{ $ ghc -fobject-code -O0 -e 'a = show 5' $ ghci -fobject-code -O0 GHCi, version 8.4.3: http://www.haskell.org/ghc/ :? for help Prelude> a = show 5 Prelude> Leaving GHCi. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15617> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8611: nofib’s cacheprof’s allocations nondeterminisitic
by GHC 01 Jan '19

01 Jan '19

#8611: nofib’s cacheprof’s allocations nondeterminisitic -----------------------------------------+--------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: NoFib benchmark suite | Version: 7.6.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: -----------------------------------------+--------------------------------- This seems to be neither expected nor desired, and hence worth investigating: {{{ ./cacheprof +RTS -t <<ghc: 127588752 bytes, 243 GCs, 2261288/6551032 avg/max bytes residency (6 samples), 15M in use, 0.00 INIT (0.00 elapsed), 0.12 MUT (0.12 elapsed), 0.05 GC (0.05 elapsed) :ghc>> ./cacheprof +RTS -t <<ghc: 127392144 bytes, 242 GCs, 2261304/6551576 avg/max bytes residency (6 samples), 15M in use, 0.00 INIT (0.00 elapsed), 0.11 MUT (0.11 elapsed), 0.04 GC (0.05 elapsed) :ghc>> }}} The allocations numbers change, when they shoudn’t. Reproduced with 7.6.3 and current HEAD. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8611> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14974: 2-fold memory usage regression GHC 8.2.2 -> GHC 8.4.1 compiling `mmark` package
by GHC 30 Dec '18

30 Dec '18

#14974: 2-fold memory usage regression GHC 8.2.2 -> GHC 8.4.1 compiling `mmark` package -------------------------------------+------------------------------------- Reporter: hvr | Owner: (none) Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.4.1 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 haven't had time yet to diagnose where the memory is going to, but here's how to reproduce: {{{ cabal get mmark-0.0.5.6 && cd mmark-0.0.5.6/ cat > cabal.project <<EOF packages: . package mmark ghc-options: -Rghc-timing EOF }}} Then, `cabal new-build -w ghc-8.4.1` and ``cabal new-build -w ghc-8.2.2` will respectively output {{{ Resolving dependencies... Build profile: -w ghc-8.4.1 -O1 In order, the following will be built (use -v for more details): - mmark-0.0.5.6 (lib) (first run) Configuring library for mmark-0.0.5.6.. <<ghc: 13510872 bytes, 13 GCs, 806197/1299656 avg/max bytes residency (3 samples), 4M in use, 0.001 INIT (0.000 elapsed), 0.007 MUT (0.025 elapsed), 0.018 GC (0.018 elapsed) :ghc>> Preprocessing library for mmark-0.0.5.6.. Building library for mmark-0.0.5.6.. [1 of 9] Compiling Text.MMark.Parser.Internal.Type ( Text/MMark/Parser/Internal/Type.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Parser/Internal/Type.o ) [2 of 9] Compiling Text.MMark.Parser.Internal ( Text/MMark/Parser/Internal.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Parser/Internal.o ) [3 of 9] Compiling Text.MMark.Type ( Text/MMark/Type.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Type.o ) Text/MMark/Type.hs:38:1: warning: [-Wunused-imports] The import of ‘Data.Semigroup’ is redundant except perhaps to import instances from ‘Data.Semigroup’ To import instances alone, use: import Data.Semigroup() | 38 | import Data.Semigroup | ^^^^^^^^^^^^^^^^^^^^^ [4 of 9] Compiling Text.MMark.Trans ( Text/MMark/Trans.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Trans.o ) [5 of 9] Compiling Text.MMark.Util ( Text/MMark/Util.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Util.o ) [6 of 9] Compiling Text.MMark.Render ( Text/MMark/Render.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Render.o ) Text/MMark/Render.hs:25:1: warning: [-Wunused-imports] The import of ‘Data.Semigroup’ is redundant except perhaps to import instances from ‘Data.Semigroup’ To import instances alone, use: import Data.Semigroup() | 25 | import Data.Semigroup | ^^^^^^^^^^^^^^^^^^^^^ [7 of 9] Compiling Text.MMark.Parser ( Text/MMark/Parser.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Parser.o ) [8 of 9] Compiling Text.MMark ( Text/MMark.hs, /tmp/mmark-0.0.5.6 /dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark.o ) [9 of 9] Compiling Text.MMark.Extension ( Text/MMark/Extension.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Extension.o ) <<ghc: 89663269464 bytes, 1856 GCs, 338140365/1430147624 avg/max bytes residency (23 samples), 4130M in use, 0.000 INIT (0.000 elapsed), 58.546 MUT (62.124 elapsed), 31.536 GC (31.505 elapsed) :ghc>> <<ghc: 65387008 bytes, 50 GCs, 2189716/5047200 avg/max bytes residency (5 samples), 11M in use, 0.000 INIT (0.000 elapsed), 0.021 MUT (0.207 elapsed), 0.042 GC (0.042 elapsed) :ghc>> }}} and {{{ Resolving dependencies... Build profile: -w ghc-8.4.1 -O1 In order, the following will be built (use -v for more details): - mmark-0.0.5.6 (lib) (first run) Configuring library for mmark-0.0.5.6.. <<ghc: 13510872 bytes, 13 GCs, 806197/1299656 avg/max bytes residency (3 samples), 4M in use, 0.001 INIT (0.000 elapsed), 0.007 MUT (0.025 elapsed), 0.018 GC (0.018 elapsed) :ghc>> Preprocessing library for mmark-0.0.5.6.. Building library for mmark-0.0.5.6.. [1 of 9] Compiling Text.MMark.Parser.Internal.Type ( Text/MMark/Parser/Internal/Type.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Parser/Internal/Type.o ) [2 of 9] Compiling Text.MMark.Parser.Internal ( Text/MMark/Parser/Internal.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Parser/Internal.o ) [3 of 9] Compiling Text.MMark.Type ( Text/MMark/Type.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Type.o ) [4 of 9] Compiling Text.MMark.Trans ( Text/MMark/Trans.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Trans.o ) [5 of 9] Compiling Text.MMark.Util ( Text/MMark/Util.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Util.o ) [6 of 9] Compiling Text.MMark.Render ( Text/MMark/Render.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Render.o ) [7 of 9] Compiling Text.MMark.Parser ( Text/MMark/Parser.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Parser.o ) [8 of 9] Compiling Text.MMark ( Text/MMark.hs, /tmp/mmark-0.0.5.6 /dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark.o ) [9 of 9] Compiling Text.MMark.Extension ( Text/MMark/Extension.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.4.1/mmark-0.0.5.6/build/Text/MMark/Extension.o ) <<ghc: 89663269464 bytes, 1856 GCs, 338140365/1430147624 avg/max bytes residency (23 samples), 4130M in use, 0.000 INIT (0.000 elapsed), 58.546 MUT (62.124 elapsed), 31.536 GC (31.505 elapsed) :ghc>> <<ghc: 65387008 bytes, 50 GCs, 2189716/5047200 avg/max bytes residency (5 samples), 11M in use, 0.000 INIT (0.000 elapsed), 0.021 MUT (0.207 elapsed), 0.042 GC (0.042 elapsed) :ghc>> hvr@duo:/tmp/mmark-0.0.5.6$ cabal new-build -w ghc-8.2.2 Resolving dependencies... Build profile: -w ghc-8.2.2 -O1 In order, the following will be built (use -v for more details): - mmark-0.0.5.6 (lib) (first run) Configuring library for mmark-0.0.5.6.. <<ghc: 11200976 bytes, 11 GCs, 853349/1518976 avg/max bytes residency (3 samples), 5M in use, 0.001 INIT (0.000 elapsed), 0.017 MUT (0.037 elapsed), 0.021 GC (0.021 elapsed) :ghc>> Preprocessing library for mmark-0.0.5.6.. Building library for mmark-0.0.5.6.. [1 of 9] Compiling Text.MMark.Parser.Internal.Type ( Text/MMark/Parser/Internal/Type.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark/Parser/Internal/Type.o ) [2 of 9] Compiling Text.MMark.Parser.Internal ( Text/MMark/Parser/Internal.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark/Parser/Internal.o ) [3 of 9] Compiling Text.MMark.Type ( Text/MMark/Type.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark/Type.o ) [4 of 9] Compiling Text.MMark.Trans ( Text/MMark/Trans.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark/Trans.o ) [5 of 9] Compiling Text.MMark.Util ( Text/MMark/Util.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark/Util.o ) [6 of 9] Compiling Text.MMark.Render ( Text/MMark/Render.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark/Render.o ) [7 of 9] Compiling Text.MMark.Parser ( Text/MMark/Parser.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark/Parser.o ) [8 of 9] Compiling Text.MMark ( Text/MMark.hs, /tmp/mmark-0.0.5.6 /dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark.o ) [9 of 9] Compiling Text.MMark.Extension ( Text/MMark/Extension.hs, /tmp/mmark-0.0.5.6/dist- newstyle/build/x86_64-linux/ghc-8.2.2/mmark-0.0.5.6/build/Text/MMark/Extension.o ) <<ghc: 89565902800 bytes, 2004 GCs, 225836231/772393000 avg/max bytes residency (27 samples), 2179M in use, 0.001 INIT (0.000 elapsed), 58.237 MUT (61.472 elapsed), 25.823 GC (25.795 elapsed) :ghc>> <<ghc: 79930048 bytes, 56 GCs, 3522920/10072040 avg/max bytes residency (6 samples), 20M in use, 0.001 INIT (0.000 elapsed), 0.028 MUT (0.213 elapsed), 0.059 GC (0.059 elapsed) :ghc>> }}} Consequently, - GHC 8.2.2: **2179M in use**, 0.001 INIT (0.000 elapsed), 58.237 MUT (61.472 elapsed), 25.823 GC (25.795 elapsed) - GHC 8.4.1: **4130M in use**, 0.000 INIT (0.000 elapsed), 58.546 MUT (62.124 elapsed), 31.536 GC (31.505 elapsed) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14974> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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