August 2014 - ghc-tickets

[GHC] #8098: Faulty Word64 arithmetic if optimized
by GHC 02 Dec '15

02 Dec '15

#8098: Faulty Word64 arithmetic if optimized ----------------------------+--------------------------------- Reporter: achp | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.4.2 Keywords: | Operating System: Windows Architecture: x86 | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------+--------------------------------- The following program produces different results depending on optimization: Checked.hs: {{{ module Checked ((.-.)) where (.-.) :: (Bounded a, Integral a) => a -> a -> Maybe a x .-. y | x >= 0 && y < 0 = if z > x then Just z else Nothing | x >= 0 = if z <= x then Just z else Nothing | x < 0 && y > 0 = if z < x then Just z else Nothing | otherwise = Just z where z = x - y }}} Main.hs: {{{ module Main (main) where import Data.Maybe import Data.Word import Numeric import Checked main :: IO () main = print $ showHex (fromJust ((0xFFFFFFFF00000000 :: Word64) .-. 0x00000000FFFFFFFF)) "" }}} {{{ D:\dev\haskell\ch1>ghc --make Checked.hs Main.hs [1 of 2] Compiling Checked ( Checked.hs, Checked.o ) [2 of 2] Compiling Main ( Main.hs, Main.o ) Linking Main.exe ... D:\dev\haskell\ch1>Main.exe "fffffffe00000001" D:\dev\haskell\ch1>del *.hi *.o *.exe D:\dev\haskell\ch1>ghc --make -O2 Checked.hs Main.hs [1 of 2] Compiling Checked ( Checked.hs, Checked.o ) [2 of 2] Compiling Main ( Main.hs, Main.o ) Linking Main.exe ... D:\dev\haskell\ch1>Main.exe "fffe00000001" D:\dev\haskell\ch1> }}} The bug disappears if definition and usage of (.-.) are in the same module. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8098> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8079: Redo T7919 with a cabal file
by GHC 22 Nov '15

22 Nov '15

#8079: Redo T7919 with a cabal file -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Compile-time Difficulty: Easy (less than 1 | crash hour) | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Right now T7919 fails because the new dynamic-by-default GHC means that Template Haskell must be built with dynamic; of course, GHC isn't clever enough to figure this out. If we Cabalize the test, the example should start building again (and if they don't, well, that's a bug!) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8079> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8199: Get rid of HEAP_ALLOCED
by GHC 22 Nov '15

22 Nov '15

#8199: Get rid of HEAP_ALLOCED ----------------------------------------------+---------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 7.7 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Project (more than a week) | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: ----------------------------------------------+---------------------------- This bug is to track progress of removing HEAP_ALLOCED from GHC, promising faster GC, as long as we can keep the cost of indirections down. The relevant wiki article: http://ghc.haskell.org/trac/ghc/wiki/Commentary/Rts/Storage/HeapAlloced ; we are implementing method 2. The attached patchset is *almost* able to support GHC itself; a ghc-stage2 built this way can compile most files, but is much slower in some cases, and probably has some correctness bugs. Improvements possible: * Don't pay for a double indirection when -fPIC is turned on. Probably the easiest way to do this is to *not* bake in the indirections into compiled code when it is -fPIC'd, and instead scribble over the GOT. However, I don't know how to go backwards from a symbol to a GOT entry, so we might need some heinous assembly hacks to get this working. * Closure tables should have their indirections short-circuited by the initialization code. * We are paying an indirection when a GC occurs when the closure is not in R1. According to the wiki page, technically this is not needed, but I don't know how to eliminate references to the closure itself from stg_gc_fun. * Properly handle the Windows DLL case (e.g. SRTs); this should be simpler now that everything is an indirection. * Bikeshed hs_main API changes (because closures are not valid prior to RTS initialization, so you have to pass in an indirection instead) * Improve static indirection and stable pointer registration, avoiding binary bloat from `__attribute(constructor)__` stubs. * Need to implement a new megablock tracking structure so we can free/check for lost blocks -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8199> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9297: Packages linked against certain Windows .dll files give warnings at runtime
by GHC 22 Oct '15

22 Oct '15

#9297: Packages linked against certain Windows .dll files give warnings at runtime ----------------------------------+--------------------------------- Reporter: RyanGlScott | Owner: simonmar Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.8.2 Keywords: | Operating System: Windows Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+--------------------------------- I am using GHC 7.8.3 on Windows 7, x86_64. When GHC loads certain packages at runtime, it gives some interesting warnings: {{{ > ghci -package haskeline GHCi, version 7.8.3: 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-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package bytestring-0.10.4.0 ... linking ... done. Loading package Win32-2.3.0.2 ... linking ... done. Loading package containers-0.5.5.1 ... linking ... done. Loading package filepath-1.3.0.2 ... linking ... done. Loading package old-locale-1.0.0.6 ... linking ... done. Loading package time-1.4.2 ... linking ... done. Loading package directory-1.2.1.0 ... linking ... done. Loading package transformers-0.3.0.0 ... linking ... done. Loading package haskeline-0.7.1.2 ... linking ... ghc.exe: warning: SetConsoleCursorPosition from kernel32 is linked instead of __imp_SetConsoleCursorPosition ghc.exe: warning: FillConsoleOutputCharacterA from kernel32 is linked instead of __imp_FillConsoleOutputCharacterA ghc.exe: warning: FillConsoleOutputAttribute from kernel32 is linked instead of __imp_FillConsoleOutputAttribute done. Prelude> }}} Besides {{{haskeline}}}, other packages with similar problems include {{{unix-compat}}}, {{{network}}}, and {{{regex-posix}}}. To see them all at once, you can run the [{{{hermit-web}}} https://github.com/ku-fpg /hermit-web] executable: {{{ > hermit-web Last.hs [starting HERMIT-Web v0.1.0.0 on Last.hs] [starting HERMIT v0.5.0.0 on Last.hs] % ghc Last.hs -fforce-recomp -O2 -dcore-lint -fsimple-list-literals -fexpose-all-unfoldings -fplugin=HERMIT.Web -fplugin-opt=HERMIT.Web:*: [1 of 1] Compiling Main ( Last.hs, Last.o ) Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package array-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package bytestring-0.10.4.0 ... linking ... done. Loading package containers-0.5.5.1 ... linking ... done. Loading package Win32-2.3.0.2 ... linking ... done. Loading package filepath-1.3.0.2 ... linking ... done. Loading package old-locale-1.0.0.6 ... linking ... done. Loading package time-1.4.2 ... linking ... done. Loading package directory-1.2.1.0 ... linking ... done. Loading package pretty-1.1.1.1 ... linking ... done. Loading package process-1.2.0.0 ... linking ... done. Loading package Cabal-1.18.1.3 ... linking ... done. Loading package binary-0.7.1.0 ... linking ... done. Loading package bin-package-db-0.0.0.0 ... linking ... done. Loading package hoopl-3.10.0.1 ... linking ... done. Loading package hpc-0.6.0.1 ... linking ... done. Loading package template-haskell ... linking ... done. Loading package transformers-0.3.0.0 ... linking ... done. Loading package ghc-7.8.3 ... linking ... done. Loading package haskeline-0.7.1.2 ... linking ... ghc: warning: SetConsoleCursorPosition from kernel32 is linked instead of __imp_SetConsoleCursorPosition ghc: warning: FillConsoleOutputCharacterA from kernel32 is linked instead of __imp_FillConsoleOutputCharacterA ghc: warning: FillConsoleOutputAttribute from kernel32 is linked instead of __imp_FillConsoleOutputAttribute done. Loading package text-1.1.1.3 ... linking ... done. Loading package hashable-1.2.2.0 ... linking ... done. Loading package scientific-0.3.2.2 ... linking ... done. Loading package attoparsec-0.12.1.0 ... linking ... done. Loading package dlist-0.7.1 ... linking ... done. Loading package mtl-2.1.3.1 ... linking ... done. Loading package syb-0.4.2 ... linking ... done. Loading package unordered-containers-0.2.5.0 ... linking ... done. Loading package primitive-0.5.3.0 ... linking ... done. Loading package vector-0.10.11.0 ... linking ... done. Loading package aeson-0.7.0.6 ... linking ... done. Loading package blaze-builder-0.3.3.2 ... linking ... done. Loading package data-default-class-0.0.1 ... linking ... done. Loading package data-default-instances-base-0.0.1 ... linking ... done. Loading package data-default-instances-containers-0.0.1 ... linking ... done. Loading package data-default-instances-dlist-0.0.1 ... linking ... done. Loading package data-default-instances-old-locale-0.0.1 ... linking ... done. Loading package data-default-0.5.3 ... linking ... done. Loading package ansi-terminal-0.6.1.1 ... linking ... done. Loading package kure-2.16.2 ... linking ... done. Loading package marked-pretty-0.1 ... linking ... done. Loading package random-1.0.1.1 ... linking ... done. Loading package operational-0.2.3.2 ... linking ... done. Loading package stm-2.4.3 ... linking ... done. Loading package exceptions-0.6.1 ... linking ... done. Loading package temporary-1.2.0.3 ... linking ... done. Loading package hermit-0.5.0.0 ... linking ... done. Loading package case-insensitive-1.2.0.0 ... linking ... done. Loading package http-types-0.8.5 ... linking ... done. Loading package transformers-base-0.4.2 ... linking ... done. Loading package monad-control-0.3.3.0 ... linking ... done. Loading package lifted-base-0.2.3.0 ... linking ... done. Loading package mmorph-1.0.3 ... linking ... done. Loading package resourcet-1.1.2.2 ... linking ... done. Loading package nats-0.2 ... linking ... done. Loading package semigroups-0.15.1 ... linking ... done. Loading package void-0.6.1 ... linking ... done. Loading package conduit-1.1.6 ... linking ... done. Loading package regex-base-0.93.2 ... linking ... done. Loading package regex-posix-0.95.2 ... linking ... ghc: warning: isupper from msvcrt is linked instead of __imp_isupper ghc: warning: toupper from msvcrt is linked instead of __imp_toupper ghc: warning: tolower from msvcrt is linked instead of __imp_tolower ghc: warning: isalpha from msvcrt is linked instead of __imp_isalpha ghc: warning: isalpha from msvcrt is linked instead of __imp_isalpha ghc: warning: isalpha from msvcrt is linked instead of __imp_isalpha ghc: warning: iscntrl from msvcrt is linked instead of __imp_iscntrl ghc: warning: isupper from msvcrt is linked instead of __imp_isupper ghc: warning: isgraph from msvcrt is linked instead of __imp_isgraph ghc: warning: isprint from msvcrt is linked instead of __imp_isprint ghc: warning: ispunct from msvcrt is linked instead of __imp_ispunct ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalpha from msvcrt is linked instead of __imp_isalpha ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum ghc: warning: isalnum from msvcrt is linked instead of __imp_isalnum done. Loading package regex-compat-0.95.1 ... linking ... done. Loading package parsec-3.1.5 ... linking ... done. Loading package network-2.5.0.0 ... linking ... ghc: warning: WSACleanup from ws2_32 is linked instead of __imp_WSACleanup ghc: warning: WSAStartup from ws2_32 is linked instead of __imp_WSAStartup ghc: warning: WSACleanup from ws2_32 is linked instead of __imp_WSACleanup ghc: warning: accept from ws2_32 is linked instead of __imp_accept ghc: warning: inet_ntoa from ws2_32 is linked instead of __imp_inet_ntoa ghc: warning: getnameinfo from ws2_32 is linked instead of __imp_getnameinfo ghc: warning: getaddrinfo from ws2_32 is linked instead of __imp_getaddrinfo ghc: warning: freeaddrinfo from ws2_32 is linked instead of __imp_freeaddrinfo done. Loading package vault-0.3.0.3 ... linking ... done. Loading package wai-3.0.0.2 ... linking ... done. Loading package base64-bytestring-1.0.0.1 ... linking ... done. Loading package fast-logger-2.1.5 ... linking ... done. Loading package zlib-0.5.4.1 ... linking ... done. Loading package streaming-commons-0.1.3.1 ... linking ... done. Loading package stringsearch-0.3.6.5 ... linking ... done. Loading package byteorder-1.0.4 ... linking ... done. Loading package wai-logger-2.1.1 ... linking ... done. Loading package word8-0.0.4 ... linking ... done. Loading package wai-extra-3.0.1 ... linking ... done. Loading package conduit-extra-1.1.1 ... linking ... done. Loading package simple-sendfile-0.2.15 ... linking ... done. Loading package unix-compat-0.4.1.3 ... linking ... ghc: warning: GetVersionExA from kernel32 is linked instead of __imp_GetVersionExA ghc: warning: GetModuleHandleA from kernel32 is linked instead of __imp_GetModuleHandleA ghc: warning: GetProcAddress from kernel32 is linked instead of __imp_GetProcAddress ghc: warning: _snprintf from msvcrt is linked instead of __imp__snprintf ghc: warning: GetSystemInfo from kernel32 is linked instead of __imp_GetSystemInfo ghc: warning: GetSystemMetrics from user32 is linked instead of __imp_GetSystemMetrics ghc: warning: GetVersionExA from kernel32 is linked instead of __imp_GetVersionExA ghc: warning: _snprintf from msvcrt is linked instead of __imp__snprintf ghc: warning: GetSystemInfo from kernel32 is linked instead of __imp_GetSystemInfo ghc: warning: GetComputerNameA from kernel32 is linked instead of __imp_GetComputerNameA ghc: warning: CryptAcquireContextA from advapi32 is linked instead of __imp_CryptAcquireContextA ghc: warning: CryptGenRandom from advapi32 is linked instead of __imp_CryptGenRandom ghc: warning: _stat64 from msvcrt is linked instead of __imp__stat64 ghc: warning: _open from msvcrt is linked instead of __imp__open ghc: warning: _stat64 from msvcrt is linked instead of __imp__stat64 done. Loading package warp-3.0.0.4 ... linking ... done. Loading package scotty-0.8.1 ... linking ... done. Loading package hermit-web-0.1.0.0 ... linking ... done. Setting phasers to stun... (port 3000) (ctrl-c to quit) }}} These warnings seem to be related to Windows-specific {{{.dll}}} files, including {{{kernel32.dll}}}, {{{user32.dll}}}, {{{msvcrt.dll}}}, {{{advapi32.dll}}}, and {{{ws2_32.dll}}}. As far as I can tell, there are no problems other than the warnings themselves, but I can't be sure. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9297> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8957: ghci's :l -> internal error: evacuate: strange closure type 8306
by GHC 21 Oct '15

21 Oct '15

#8957: ghci's :l -> internal error: evacuate: strange closure type 8306 ----------------------------------+------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.6.3 Keywords: | Operating System: Windows Architecture: x86_64 (amd64) | Type of failure: GHCi crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------- GHCi crashes when :loading a file. Unfortunately I can't reproduce the bug, so this one's gonna be lots of information that probably will help very little. This is the actual error message: {{{ *CommonStatistics Data.List> :l SimpleCellularALife [1 of 2] Compiling CommonStatistics ( CommonStatistics.hs, interpreted ) <interactive>: internal error: evacuate: strange closure type 8306 (GHC version 7.6.3 for i386_unknown_mingw32) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. }}} This one was the error I was working on, i.e. the (legit) error in the previous call: (Including this because it gives you a clue what I was working on, I was mostly fiddling around with parens in placeAgents' gnd function) {{{ *CommonStatistics Data.List> :l SimpleCellularALife [1 of 2] Compiling CommonStatistics ( CommonStatistics.hs, interpreted ) [2 of 2] Compiling SimpleCellularALife ( SimpleCellularALife.hs, interpreted ) SimpleCellularALife.hs:70:28: Couldn't match expected type `Array i0 e0' with actual type `Ground' In the return type of a call of `ground' In the first argument of `(!)', namely `ground (tiles w)' In the expression: (ground (tiles w) ! (fst $ head grp)) SimpleCellularALife.hs:70:36: Couldn't match expected type `Tile' with actual type `Array Coordinates Tile' In the return type of a call of `tiles' In the first argument of `ground', namely `(tiles w)' In the first argument of `(!)', namely `ground (tiles w)' Failed, modules loaded: CommonStatistics. }}} Included Source Files - CommonStatistics.hs: {{{ module CommonStatistics where type Memory = [Int]--Internal state of an Agent. data StatUpdate = StatUpdate{ newVictories :: [Int] -- by agentID } deriving (Show) data Agent = Agent{ agentID :: Int, sourcePath :: FilePath, --path to .hs source file. relative to executable doFunc :: [String] -> Memory -> (Memory, [String]), evFunc :: [String] -> Memory -> (Memory, String), personalMemory :: Memory } instance Show Agent where show (Agent { agentID = aID, sourcePath = path, doFunc = forgetit, evFunc = forgetittoo, personalMemory = mem }) = show (aID, path, mem) }}} And SimpleCellularALife.hs: (I am not exactly confident that this is the version that caused the error. I sadly can't reproduce it, so there's no confirming that. {{{ module SimpleCellularALife where import Data.Array import Data.List import System.Random import CommonStatistics data Ground = Ground { food :: Int } data Entity = Entity{ ai :: Agent, health :: Int } data Tile = Tile{ ground :: Ground, entities :: [Entity] } data World = World { tiles :: Array Coordinates Tile } type Coordinates = (Int, Int) getRandomPosition :: RandomGen t => World -> t -> (t, Coordinates) getRandomPosition w rand = let ((minx, miny), (maxx, maxy)) = bounds $ tiles w (x, rand2) = randomR (minx, maxx) rand (y, rand3) = randomR (miny, maxy) rand2 in (rand3, (x, y)) placeAgents :: RandomGen t => World -> [Agent] -> t -> (t, World) placeAgents w agents rand = let createTileUpdates (ag:ags) wrld rnd = let (rnd2, coords) = getRandomPosition wrld rnd (rnd3, restUpd) = createTileUpdates ags wrld rnd2 in (rnd3, (coords, ag) : restUpd) createTileUpdates [] wrld rnd = (rnd, []) (rand2, assocList) = createTileUpdates agents w rand groupedAssocList = groupBy (\(c1, a1) (c2, a2) -> c1 == c2) $ sortBy (\(c1, a1) (c2, a2) -> compare c1 c2) assocList gnd grp = ground ((tiles w) ! (fst $ head grp)) condenseGroup grp = (fst $ head grp, Tile{ground = gnd grp, entities = snd $ unzip grp}) --map condenseGroup groupedAssocList --::(Coordinates, Tile) in (rand, w) --placeAgents (placeAgent w firstAg x y) agents rand3 }}} Someone suggested that this might've been GHCI running out of memory. I am as of writing this at 66% out of 4GB used. The GHCI instance was opened for an extended period of time, so it might have racked up quite a bit of RAM usage. I can say though that considering the file sizes, 1.3GB of RAM usage seems unreasonable. And because I haven't yet written enough, here are all the variations of the line I was working on that could've caused it. Pulled them out of my text editor's buffer. {{{ gnd grp = (ground (tiles w) ! fst $ head grp) gnd grp = (ground (tiles w) ! (fst $ head grp) gnd grp = (ground (tiles w) ! (fst $ head grp)) gnd grp = (ground ((tiles w) ! (fst $ head grp)) gnd grp = ground ((tiles w) ! (fst $ head grp)) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8957> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8687: Strange closure type 9983
by GHC 21 Oct '15

21 Oct '15

#8687: Strange closure type 9983 ------------------------------------+------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Windows Architecture: Unknown/Multiple | Type of failure: GHCi crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------- {{{ *Main> :main C:\\Windows\\Media\\onestop.mid <interactive>: internal error: evacuate: strange closure type 9983 (GHC version 7.6.3 for i386_unknown_mingw32) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. }}} This happened to me on {{{ghci playmidi.hs}}} from the {{{examples/}}} folder of {{{http://hackage.haskell.org/package/hmidi-0.2.1.0}}} (downloaded the tar and fixed the parsec import, removing the {{{"parsec2"}}} package import and fixing a type checking error, replacing {{{selectOutputDevice Nothing}}} by {{{selectOutputDevice "Select midi output device" Nothing}}}. (We also fixed those compile errors at https://github.com/vahokif/hmidi/tree/2124a8.) I have not been able to reproduce it since the first time :( -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8687> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8648: Initialization of C statics broken in threaded runtime
by GHC 20 Oct '15

20 Oct '15

#8648: Initialization of C statics broken in threaded runtime ------------------------------------+------------------------------------- Reporter: edsko | Owner: simonmar Type: bug | 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: | ------------------------------------+------------------------------------- Consider a tiny package `static-value`, consisting of one Haskell file {{{ foreign import ccall unsafe "returnStaticValue" c_returnStaticValue :: IO CInt printStaticValue :: IO () printStaticValue = print =<< c_returnStaticValue }}} and one corresponding C file {{{ static int theStaticValue = 0; int returnStaticValue() { // Modify the static so the C compiler doesn't optimize it away return theStaticValue++; } }}} (test case is attached). If we call `printStaticValue` using the GHC API: {{{ runGhc (Just libdir) $ do flags0 <- getSessionDynFlags void $ setSessionDynFlags flags0 { hscTarget = HscInterpreted , ghcLink = LinkInMemory , ghcMode = CompManager } setContext $ [ IIDecl $ simpleImportDecl $ mkModuleName "StaticValue" ] _ <- runStmt "StaticValue.printStaticValue" RunToCompletion }}} then we see "0", as expected. However, if we compile this code using the threaded runtime, and we wrap the above code in a call to either `forkIO` or `forkOS`, then we see a different value printed (-907777, whatever that value is). Some notes: * I have been unable to reproduce this bug without using GHC as API; in particular, calling `printStaticValue` directly, wrapped in `forkIO` or `forkOS` or not, always works as expected. * If I change the initialization value of `staticValue` from 0 to anything else (say, 1234), we always get the right answer, never the uninitialized value. Presumably this is because non-zero values require some explicit code to be run (and it does get run), while a zero value gets initialized differently (and apparently, that's where the bug is). * I have reproduced this bug in both ghc 7.4 and 7.7.20131227. This ticket is the result of tracking down a problem with calling `createProcess` from within the GHC API, which would cause the parent process to stall. As it turns out, `runProcess.c` (from the `process` library) declares a `static long max_fd = 0`, and in `runInteractiveProcess` checks for this value to be 0, and if it is, does a syscall to figure out what the maximum FD is. But since this static does not get initialized properly (the bug reported in this ticket), it gets left at its (random? but always the same) value (281474975802879), so that the child process proceeds to close rather too many file descriptors (if close_fds was set to True) and the parent stalls. Indeed, changing the initialization to `static long max_fd = -1` (and adjusting the later check for zero accordingly) fixes this (so this is a viable workaround in `process` if we cannot track down the bug in GHC). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8648> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9360: GHCi: Behave nicely on `-e`, like `ghc` and other programs
by GHC 19 Oct '15

19 Oct '15

#9360: GHCi: Behave nicely on `-e`, like `ghc` and other programs -------------------------------------+------------------------------------- Reporter: mcandre | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Like many programming language environments, GHC offers a handy `-e` option for evaluating an expression, then returning to the shell. {{{ $ ghc -e '2 + 2' 4 }}} One would expect the interpreter, GHCi, to offer a similar flag, but it surprisingly rejects it. {{{ ghci -e '2 + 2' ghc: on the commandline: cannot use `--interactive' with `-e' Usage: For basic information, try the `--help' option. }}} I think this behavior is quite unintuitive--when I pass `-e <exp>` to ghci, or pass `--interactive -e <exp>` to ghc, I expect the expression to be evaluated as the leading expression in an interactive interpreter session. Could we please tweak ghc like this to make it slightly more intuitive when these flags are used together? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9360> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9319: nofib-analyze doesn’t provide per-benchmark compile time/alloc numbers
by GHC 09 Oct '15

09 Oct '15

#9319: nofib-analyze doesn’t provide per-benchmark compile time/alloc numbers -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: NoFib benchmark | Version: 7.8.2 suite | Differential Revisions: Keywords: | Architecture: Operating System: Unknown/Multiple | Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- The compile time and allocation numbers calculated by nofib are only available per module. While this is useful to find the cause of problems, it would be nice if these numbers were also accumulated for each benchmark, for easy of general analysis and uniformity, especially with automated monitoring of benchmark numbers. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9319> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9058: System.IO.openTempFile does not scale
by GHC 07 Oct '15

07 Oct '15

#9058: System.IO.openTempFile does not scale ------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | 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: | ------------------------------------+------------------------------------- In search of a bug in darcs http://bugs.darcs.net/issue2364 i've notice very bad property of openTempFile: it's pattern is very predictable and has O(n^2) of already created temp files. Predictability allows very fun bugs survive in buggy programs, like: {{{ thread1: (fn, fh) <- openTempFile "." "hello" renameFile fn "something" -- some time after when (some_rare_buggy_condition) $ -- oops, reused temp name, but too late, other thread killed it writeFileFile fn thread2: (fn, fh) <- openTempFile "." "hello" workWithFn fn -- nobody should touch it, right? }}} It's _very_ hard to debug data corruption when all temp files are named "foo${pid}" and sometimes "foo${pid+1}". And more serious bug: the more threads you have trying to create similar temps performance drops significantly: Attached program shows the following numbers: {{{ $ time ./bench-temps same 2000 real 0m2.795s user 0m1.516s sys 0m1.190s $ time ./bench-temps diff 2000 real 0m0.161s user 0m0.043s sys 0m0.115s }}} It's O(N^2) growing open() storm. https://github.com/ghc/ghc/blob/master/libraries/base/System/IO.hs#L465 {{{ FileExists -> findTempName (x + 1) }}} This is the source of the problem. I'd suggest always using random name for it. For portability reasons I suggest adding at least insecure random '''rand()''' value from C library. That way we will succeed in opening temp file at the first attempt. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9058> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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