July 2015 - ghc-tickets

[GHC] #9953: Pattern synonyms don't work with GADTs
by GHC 06 Aug '15

06 Aug '15

#9953: Pattern synonyms don't work with GADTs -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Consider this variant of test `T8968-1`: {{{ {-# LANGUAGE GADTs, KindSignatures, PatternSynonyms #-} module ShouldCompile where data X :: * -> * where Y :: a -> X (Maybe a) pattern C :: a -> X (Maybe a) pattern C x = Y x foo :: X t -> t foo (C x) = Just x }}} * If we had `(Y x)` instead of `(C x)` in the LHS of `foo`, then this is an ordinary GADT program and typechecks fine. * If we omit the pattern signature, it typechecks fine, and `:info C` says {{{ pattern C :: t ~ Maybe a => a -> X t -- Defined in ‘ShouldCompile’ }}} * But as written, it fails with {{{ Foo.hs:11:6: Couldn't match type ‘t’ with ‘Maybe a0’ ‘t’ is a rigid type variable bound by the type signature for: foo :: X t -> t at Foo.hs:10:8 Expected type: X t Actual type: X (Maybe a0) Relevant bindings include foo :: X t -> t (bound at Foo.hs:11:1) In the pattern: C x In an equation for ‘foo’: foo (C x) = Just x }}} Moreover, `:info C` says {{{ pattern C :: a -> X (Maybe a) -- Defined at Foo.hs:8:9 }}} Do you see the difference? In the former, the "prov_theta" equality constraint is explicit, but in the latter it's implicit. The exact thing happens for `DataCons`. It's handled via the `dcEqSpec` field. Essentially `PatSyn` should have a new field for the implicit equality constraints. And, just as for data consructors, we need to generate the equality constraints, and the existentials that are needed, when we process the signature. Use the code in `TcTyClsDecls.rejigConRes` (perhaps needs a better name). This is all pretty serious. Without fixing it, GADT-style pattern signatures are all but useless. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9953> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9848: List.all does not fuse
by GHC 05 Aug '15

05 Aug '15

#9848: List.all does not fuse -------------------------------------+------------------------------------- Reporter: klapaucius | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: libraries/base | Version: 7.9 Keywords: | Operating System: Windows Architecture: x86 | Type of failure: Runtime Difficulty: Easy (less than 1 | performance bug hour) | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- {{{ primes = 2:3:filter isPrime [5,7..] :: [Int] isPrime x = all (/= 0) . map (x `rem`) . takeWhile ((<= x) . (^2)) $ primes main = print . length . takeWhile (<= 2^24) $ primes }}} {{{ 12,133,812,164 bytes allocated in the heap 53,433,372 bytes copied during GC 14,235,488 bytes maximum residency (7 sample(s)) 1,110,916 bytes maximum slop 30 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 56357 colls, 0 par 0.094s 0.125s 0.0000s 0.0001s Gen 1 7 colls, 0 par 0.031s 0.034s 0.0049s 0.0154s INIT time 0.000s ( 0.000s elapsed) MUT time 8.094s ( 8.069s elapsed) GC time 0.125s ( 0.159s elapsed) EXIT time 0.000s ( 0.003s elapsed) Total time 8.219s ( 8.231s elapsed) %GC time 1.5% (1.9% elapsed) Alloc rate 1,499,158,259 bytes per MUT second Productivity 98.5% of total user, 98.3% of total elapsed }}} {{{ Rec { $sgo1_r2RE :: GHC.Prim.Int# -> [Int] -> Data.Monoid.All [GblId, Arity=2, Caf=NoCafRefs, Str=DmdType <L,U><L,U>] $sgo1_r2RE = \ (sc_s2PS :: GHC.Prim.Int#) (sc1_s2PT :: [Int]) -> case sc_s2PS of _ [Occ=Dead] { __DEFAULT -> go_r2RF sc1_s2PT; 0 -> GHC.Types.False `cast` (Sym Data.Monoid.NTCo:All[0] :: Bool ~R# Data.Monoid.All) } go_r2RF :: [Int] -> Data.Monoid.All [GblId, Arity=1, Caf=NoCafRefs, Str=DmdType <S,1*U>] go_r2RF = \ (ds_a1YK :: [Int]) -> case ds_a1YK of _ [Occ=Dead] { [] -> GHC.Types.True `cast` (Sym Data.Monoid.NTCo:All[0] :: Bool ~R# Data.Monoid.All); : y_a1YP ys_a1YQ -> case y_a1YP of _ [Occ=Dead] { GHC.Types.I# x_a1Tk -> case x_a1Tk of _ [Occ=Dead] { __DEFAULT -> go_r2RF ys_a1YQ; 0 -> GHC.Types.False `cast` (Sym Data.Monoid.NTCo:All[0] :: Bool ~R# Data.Monoid.All) } } } end Rec } lvl4_r2RG :: Int -> Data.Monoid.All [GblId, Arity=1, Str=DmdType] lvl4_r2RG = \ (x_aqY [OS=ProbOneShot] :: Int) -> case x_aqY of _ [Occ=Dead] { GHC.Types.I# y_a1Uc -> case GHC.Prim.tagToEnum# @ Bool (GHC.Prim.<=# 4 y_a1Uc) of _ [Occ=Dead] { False -> GHC.Types.True `cast` (Sym Data.Monoid.NTCo:All[0] :: Bool ~R# Data.Monoid.All); True -> $sgo1_r2RE (GHC.Prim.remInt# y_a1Uc 2) (letrec { go1_a1S5 [Occ=LoopBreaker] :: [Int] -> [Int] [LclId, Arity=1, Str=DmdType <S,1*U>] go1_a1S5 = \ (ds_a1S6 :: [Int]) -> case ds_a1S6 of _ [Occ=Dead] { [] -> GHC.Types.[] @ Int; : y1_X1T4 ys_X1T6 -> case y1_X1T4 of _ [Occ=Dead] { GHC.Types.I# x1_X1VM -> case GHC.Prim.tagToEnum# @ Bool (GHC.Prim.<=# (GHC.Prim.*# x1_X1VM x1_X1VM) y_a1Uc) of _ [Occ=Dead] { False -> GHC.Types.[] @ Int; True -> GHC.Types.: @ Int (case x1_X1VM of wild5_a1TE { __DEFAULT -> case GHC.Prim.remInt# y_a1Uc wild5_a1TE of wild6_a1TJ { __DEFAULT -> GHC.Types.I# wild6_a1TJ }; (-1) -> GHC.Real.$fIntegralInt1; 0 -> GHC.Real.divZeroError @ Int }) (go1_a1S5 ys_X1T6) } } }; } in go1_a1S5 Main.main3) } } }}} foldr, however, fuse just fine: {{{ primes = 2:3:filter isPrime [5,7..] :: [Int] isPrime x = foldr (&&) True . map (/= 0) . map (x `rem`) . takeWhile ((<= x) . (^2)) $ primes main = print . length . takeWhile (<= 2^24) $ primes }}} {{{ 365,770,752 bytes allocated in the heap 48,197,488 bytes copied during GC 13,031,232 bytes maximum residency (7 sample(s)) 1,570,524 bytes maximum slop 28 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 694 colls, 0 par 0.016s 0.029s 0.0000s 0.0005s Gen 1 7 colls, 0 par 0.031s 0.032s 0.0046s 0.0146s INIT time 0.000s ( 0.000s elapsed) MUT time 3.438s ( 3.439s elapsed) GC time 0.047s ( 0.062s elapsed) EXIT time 0.000s ( 0.003s elapsed) Total time 3.484s ( 3.504s elapsed) %GC time 1.3% (1.8% elapsed) Alloc rate 106,406,036 bytes per MUT second Productivity 98.7% of total user, 98.1% of total elapsed }}} {{{ lvl4_r2qr :: Int -> Bool [GblId, Arity=1, Str=DmdType] lvl4_r2qr = \ (x_aqW [OS=ProbOneShot] :: Int) -> case x_aqW of _ [Occ=Dead] { GHC.Types.I# y_a1tq -> case GHC.Prim.tagToEnum# @ Bool (GHC.Prim.<=# 4 y_a1tq) of _ [Occ=Dead] { False -> GHC.Types.True; True -> case GHC.Prim.remInt# y_a1tq 2 of _ [Occ=Dead] { __DEFAULT -> letrec { go_a1ud [Occ=LoopBreaker] :: [Int] -> Bool [LclId, Arity=1, Str=DmdType <S,1*U>] go_a1ud = \ (ds_a1ue :: [Int]) -> case ds_a1ue of _ [Occ=Dead] { [] -> GHC.Types.True; : y1_X1vf ys_X1vh -> case y1_X1vf of _ [Occ=Dead] { GHC.Types.I# x1_X1x9 -> case GHC.Prim.tagToEnum# @ Bool (GHC.Prim.<=# (GHC.Prim.*# x1_X1x9 x1_X1x9) y_a1tq) of _ [Occ=Dead] { False -> GHC.Types.True; True -> case x1_X1x9 of wild6_X1x3 { __DEFAULT -> case GHC.Prim.remInt# y_a1tq wild6_X1x3 of _ [Occ=Dead] { __DEFAULT -> go_a1ud ys_X1vh; 0 -> GHC.Types.False }; (-1) -> GHC.Types.False; 0 -> case GHC.Real.divZeroError of wild7_00 { } } } } }; } in go_a1ud Main.main3; 0 -> GHC.Types.False } } } }}} And List.all from ghc 7.8 base library does fuse, so this is regression. Windows 8.1 x64, ghc --info: {{{ [("Project name","The Glorious Glasgow Haskell Compilation System") ,("GCC extra via C opts"," -fwrapv") ,("C compiler command","$topdir/../mingw/bin/gcc.exe") ,("C compiler flags"," -U__i686 -march=i686 -fno-stack-protector") ,("C compiler link flags","") ,("Haskell CPP command","$topdir/../mingw/bin/gcc.exe") ,("Haskell CPP flags","-E -undef -traditional ") ,("ld command","$topdir/../mingw/bin/ld.exe") ,("ld flags","") ,("ld supports compact unwind","YES") ,("ld supports build-id","NO") ,("ld supports filelist","NO") ,("ld is GNU ld","YES") ,("ar command","$topdir/../mingw/bin/ar.exe") ,("ar flags","q") ,("ar supports at file","YES") ,("touch command","$topdir/touchy.exe") ,("dllwrap command","$topdir/../mingw/bin/dllwrap.exe") ,("windres command","$topdir/../mingw/bin/windres.exe") ,("libtool command","") ,("perl command","$topdir/../perl/perl.exe") ,("target os","OSMinGW32") ,("target arch","ArchX86") ,("target word size","4") ,("target has GNU nonexec stack","False") ,("target has .ident directive","True") ,("target has subsections via symbols","False") ,("Unregisterised","NO") ,("LLVM llc command","llc") ,("LLVM opt command","opt") ,("Project version","7.9.20141129") ,("Project Git commit id","447f592697fef04d1e19a2045ec707cfcd1eb59f") ,("Booter version","7.8.3") ,("Stage","2") ,("Build platform","i386-unknown-mingw32") ,("Host platform","i386-unknown-mingw32") ,("Target platform","i386-unknown-mingw32") ,("Have interpreter","YES") ,("Object splitting supported","YES") ,("Have native code generator","YES") ,("Support SMP","YES") ,("Tables next to code","YES") ,("RTS ways","l debug thr thr_debug thr_l thr_p ") ,("Support dynamic-too","NO") ,("Support parallel --make","YES") ,("Support reexported-modules","YES") ,("Support thinning and renaming package flags","YES") ,("Uses package keys","YES") ,("Dynamic by default","NO") ,("GHC Dynamic","NO") ,("Leading underscore","YES") ,("Debug on","False") ,("LibDir","D:\\msys32\\usr\\local\\lib") ,("Global Package DB","D:\\msys32\\usr\\local\\lib\\package.conf.d") ] }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9848> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10615: Panic; no skolem info (partial type signatures)
by GHC 05 Aug '15

05 Aug '15

#10615: Panic; no skolem info (partial type signatures) -------------------------------------+------------------------------------- Reporter: holzensp | 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: | -------------------------------------+------------------------------------- This rather minimal program {{{#!hs f :: _ => _f f = const }}} results in this: {{{ GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( Panic.hs, interpreted ) Panic.hs:1:6: Found hole ‘_’ with inferred constraints: () To use the inferred type, enable PartialTypeSignatures In the type signature for ‘f’: _ => _f Panic.hs:2:5: Couldn't match expected type ‘_f’ with actual type ‘a0 -> b0 -> a0’ ‘_f’ is untouchable inside the constraints () bound by the inferred type of f :: _f at Panic.hs:2:1-9ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-apple-darwin): No skolem info: _f_alF[sk] }}} The newest open bugs (that reporter could find at the time of reporting) with "no skolem info" in their description are #10404 and #10432. The newest bug (which is closed) is #10503. It seems likely, though, that the above comes from the PartialTypeSignatures implementation (considering the simplicity of the repro). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10615> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10704: Can't lookup fixities of infix types in Template Haskell
by GHC 05 Aug '15

05 Aug '15

#10704: Can't lookup fixities of infix types in Template Haskell -------------------------------------+------------------------------------- Reporter: | Owner: RyanGlScott | Type: feature | Status: new request | Priority: normal | Milestone: Component: Template | Version: 7.10.1 Haskell | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Currently, Template Haskell allows you to reify the fixity of regular functions, typeclass functions, and data constructors: {{{ λ> import Language.Haskell.TH λ> $(reify '($) >>= stringE . show) "VarI GHC.Base.$ (ForallT [KindedTV a_822083586 StarT,KindedTV b_822083587 (ConT GHC.Prim.OpenKind)] [] (AppT (AppT ArrowT (AppT (AppT ArrowT (VarT a_822083586)) (VarT b_822083587))) (AppT (AppT ArrowT (VarT a_822083586)) (VarT b_822083587)))) Nothing (Fixity 0 InfixR)" λ> $(reify '(+) >>= stringE . show) "ClassOpI GHC.Num.+ (ForallT [KindedTV a_1627404054 StarT] [AppT (ConT GHC.Num.Num) (VarT a_1627404054)] (AppT (AppT ArrowT (VarT a_1627404054)) (AppT (AppT ArrowT (VarT a_1627404054)) (VarT a_1627404054)))) GHC.Num.Num (Fixity 6 InfixL)" λ> $(reify '(:%) >>= stringE . show) "DataConI GHC.Real.:% (ForallT [KindedTV a_1627412324 StarT] [] (AppT (AppT ArrowT (VarT a_1627412324)) (AppT (AppT ArrowT (VarT a_1627412324)) (AppT (ConT GHC.Real.Ratio) (VarT a_1627412324))))) GHC.Real.Ratio (Fixity 9 InfixL)" }}} However, you can't do the same for infix typeclasses, type constructors, or type families: {{{ λ> :set -XTypeOperators -XTypeFamilies -XMultiParamTypeClasses λ> class a :=> b; infixr 5 :=> λ> $(reify ''(:=>) >>= stringE . show) "ClassI (ClassD [] Ghci5.:=> [KindedTV a_1627424666 StarT,KindedTV b_1627424667 StarT] [] []) []" λ> type a :+: b = Either a b; infixr 5 :+: λ> $(reify ''(:+:) >>= stringE . show) "TyConI (TySynD Ghci7.:+: [KindedTV a_1627426783 StarT,KindedTV b_1627426784 StarT] (AppT (AppT (ConT Data.Either.Either) (VarT a_1627426783)) (VarT b_1627426784)))" λ> $(reify ''(:*:) >>= stringE . show) "FamilyI (FamilyD TypeFam Ghci9.:*: [KindedTV a_1627426938 StarT,KindedTV b_1627426939 StarT] (Just StarT)) []" }}} We should add a {{{Fixity}}} field to {{{ClassI}}}, {{{TyConI}}}, and {{{FamilyI}}} to make them consistent with the other {{{Info}}} constructors that allow for infix things. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10704> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10706: Make -fcpr-off a dynamic flag
by GHC 05 Aug '15

05 Aug '15

#10706: Make -fcpr-off a dynamic flag -------------------------------------+------------------------------------- Reporter: darchon | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I've run into a situation where I wanted to turn off CPR analysis for a single module in my project, but could not do that because {{{-fcpr-off}}} is a static flag. I will supply a patch that makes {{{-fcpr-off}}} a dynamic flag. From what I understand, this would also bring us one step closer to the desired goal of getting rid of static flags entirely. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10706> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9430: implement more arithmetic operations natively in the LLVM backend
by GHC 05 Aug '15

05 Aug '15

#9430: implement more arithmetic operations natively in the LLVM backend -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (LLVM) | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Moderate (less | Type of failure: Runtime than a day) | performance bug Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- There are a number of arithmetic operations that have native implementations on x86 but use the generic fallback on LLVM. Implementing these with LLVM intrinsics could improve small Integer performance on ARM substantially! {{{ MO_Add2 @llvm.uadd.with.overflow.* MO_AddIntC @llvm.sadd.with.overflow.* MO_SubIntC @llvm.ssub.with.overflow.* MO_U_Mul2 mul i64/i128? MO_U_QuotRem2 udiv i64/i128? }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9430> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9233: Compiler performance regression
by GHC 04 Aug '15

04 Aug '15

#9233: Compiler performance regression ------------------------------------+--------------------------------- Reporter: augustss | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Windows Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+--------------------------------- Compiling all of our Haskell modules (about 1300 modules, 310 kLOC) takes about 30% longer with ghc 7.8 than it did with ghc 7.2. (Using 32-bit Windows.) Sorry, I can't really provide any simple test case. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9233> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10676: silly assembly for comparing the result of comparisons that return Int# against 0#
by GHC 04 Aug '15

04 Aug '15

#10676: silly assembly for comparing the result of comparisons that return Int# against 0# -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 (CodeGen) | Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 | Type of failure: Runtime (amd64) | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Consider the module {{{ {-# LANGUAGE MagicHash #-} module Min where import GHC.Exts fgood :: Int# -> Int# -> Int fgood x# y# = case isTrue# (x# <# y#) of False -> I# y# True -> I# x# fbad :: Int# -> Int# -> Int fbad x# y# = case x# <# y# of 0# -> I# y# _ -> I# x# }}} The code for `fgood` looks fine: {{{ 0000000000000130 <Min_fgood_info>: 130: 49 83 c4 10 add $0x10,%r12 134: 4d 3b a5 58 03 00 00 cmp 0x358(%r13),%r12 13b: 77 1a ja 157 <Min_fgood_info+0x27> 13d: 49 39 f6 cmp %rsi,%r14 140: 7c 29 jl 16b <Min_fgood_info+0x3b> 142: 49 c7 44 24 f8 00 00 movq $0x0,-0x8(%r12) 149: 00 00 147: R_X86_64_32S ghczmprim_GHCziTypes_Izh_con_info 14b: 49 89 34 24 mov %rsi,(%r12) 14f: 49 8d 5c 24 f9 lea -0x7(%r12),%rbx 154: ff 65 00 jmpq *0x0(%rbp) 157: 49 c7 85 88 03 00 00 movq $0x10,0x388(%r13) 15e: 10 00 00 00 162: bb 00 00 00 00 mov $0x0,%ebx 163: R_X86_64_32 Min_fgood_closure 167: 41 ff 65 f8 jmpq *-0x8(%r13) 16b: 49 c7 44 24 f8 00 00 movq $0x0,-0x8(%r12) 172: 00 00 170: R_X86_64_32S ghczmprim_GHCziTypes_Izh_con_info 174: 4d 89 34 24 mov %r14,(%r12) 178: 49 8d 5c 24 f9 lea -0x7(%r12),%rbx 17d: ff 65 00 jmpq *0x0(%rbp) }}} But the code for `fbad` has several problems: {{{ 0000000000000018 <Min_fbad_info>: 18: 48 8d 45 f0 lea -0x10(%rbp),%rax 1c: 4c 39 f8 cmp %r15,%rax 1f: 72 3a jb 5b <Min_fbad_info+0x43> 21: 48 89 f0 mov %rsi,%rax 24: 4c 89 f3 mov %r14,%rbx 27: 49 39 f6 cmp %rsi,%r14 2a: 0f 9c c1 setl %cl 2d: 0f b6 c9 movzbl %cl,%ecx 30: 48 85 c9 test %rcx,%rcx 33: 75 51 jne 86 <c1Sm_info+0xe> 35: 49 83 c4 10 add $0x10,%r12 39: 4d 3b a5 58 03 00 00 cmp 0x358(%r13),%r12 40: 0f 87 aa 00 00 00 ja f0 <c1Su_info+0x10> 46: 49 c7 44 24 f8 00 00 movq $0x0,-0x8(%r12) 4d: 00 00 4b: R_X86_64_32S ghczmprim_GHCziTypes_Izh_con_info 4f: 49 89 04 24 mov %rax,(%r12) 53: 49 8d 5c 24 f9 lea -0x7(%r12),%rbx 58: ff 65 00 jmpq *0x0(%rbp) 5b: bb 00 00 00 00 mov $0x0,%ebx 5c: R_X86_64_32 Min_fbad_closure 60: 41 ff 65 f8 jmpq *-0x8(%r13) ... ; c1Sm_info is the other case with its own heap check and GC entry code ; c1Su_info is another GC entry ; in total, another 160 bytes of code }}} For some reason, the heap checks were moved into the alternatives, which was not a good decision in this case. But the silly thing here is the `cmp/setl/movzbl/test/jne` sequence in `Min_fbad_info`, which should be replaced by a `cmp/jl` as in `Min_fgood_info`. Same behavior in 7.8 and HEAD. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10676> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10664: T8131 times out on master
by GHC 03 Aug '15

03 Aug '15

#10664: T8131 times out on master -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- The testsuite test `codeGen/should_fail/T8131` appears to time out on the `master` branch as of today. This isn't counted as a testsuite failure as it is a should-fail test, but nevertheless something is not right as it doesn't terminate despite being allowed to run for several minutes. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10664> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10711: Defining mapM_ in terms of traverse_ causes substantial blow-up in ByteCodeAsm
by GHC 03 Aug '15

03 Aug '15

#10711: Defining mapM_ in terms of traverse_ causes substantial blow-up in ByteCodeAsm -------------------------------------+------------------------------------- Reporter: bgamari | Owner: bgamari Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: ghcirun004 | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Phab:D924 has proposed that we redefine `mapM_`, currently, {{{ mapM_ = foldr ((>>) . f) (return ()) }}} as, {{{ mapM_ = foldr ((*>) . f) (return ()) = traverse_ }}} as part of the AMP proposal. However, this appears to have severe effects on the performance characteristics of the `Assembler` monad defined in `ByteCodeAsm`. In particular, the `mapM_` use in `ByteCodeAsm.assembleBCO` blows up severely, increasing the runtime of the `ghcirun004` testcase from 4 seconds to over 5 minutes. Intriguingly, defining `(*>) = (>>)` in `Assembler`'s `Applicative` instance (as done in Phab:D1097) restores reasonable runtime. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10711> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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