March 2015 - ghc-tickets

[GHC] #9706: New block-structured heap organization for 64-bit
by GHC 05 Dec '15

05 Dec '15

#9706: New block-structured heap organization for 64-bit -------------------------------------+------------------------------------- Reporter: ezyang | Owner: simonmar Type: task | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I was having some discussion about GHC's block structured heap with Sergio Benitez and Adam Belay, and during the discussion it was suggested that the way GHC manages the block structured heap is suboptimal when we're on 64-bit architectures. At the moment, we allocate memory from the operating system per-megablock, storing metadata in the very first megablock. We have to do this because, on 32-bit, we can't generally be too picky about what address our memory ends up living. On 64-bits, we have a lot more flexibility. Here is the proposal: 1. Statically decide on a maximum heap size in a power of two. 2. Next, probe for some appropriately aligned chunk of available virtual address space for this. On POSIX, we can mmap /dev/null using PROT_NONE and MAP_NORESERVE. On Windows, we can use VirtualAlloc with MEM_RESERVE. (There are few other runtimes which do this trick, including GCC Go.) 3. Divide this region into blocks as before. The maximum heap size is now the megablock size, and the block size is still the same as before. Masking to find the block descriptor works as before. 4. To allocate, we keep track of the high-watermark, and mmap in 1MB pages as they are requested. We also keep track of how much metadata we need, and mmap extra pages to store metadata as necessary. We still want to request memory from the operating system in conveniently sized chunks, but we can now abolish the notion of a megablock and the megablock allocator, and work purely with block coalescing. Additionally, the recorded heap location means that we can check if a pointer is HEAP_ALLOCED using a mask and equality check, solving #8199. What do people think? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9706> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8582: Record syntax for pattern synonyms
by GHC 03 Dec '15

03 Dec '15

#8582: Record syntax for pattern synonyms ------------------------------------+------------------------------------- Reporter: cactus | Owner: cactus Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: 5144 | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Implement syntax for {{{ pattern Cons{car, cdr} = (car, cdr) }}} which can then be used just like a regular record constructor, so the following are all valid patterns: {{{ Cons (Just x) [] Cons{car = Just x} }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8582> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[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] #9651: Increasing verbosity doesn't give useful information for why we couldn't load package
by GHC 21 Nov '15

21 Nov '15

#9651: Increasing verbosity doesn't give useful information for why we couldn't load package -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I don't time to fix this now, so recording so I remember. {{{ [ezyang@hs01 ghc-nocode]$ /home/hs01/ezyang/ghc-head/inplace/bin/ghc- stage2 -package-key ghc_GE0xPzNsQzT2p10hpwDwSW --interactive -package-db libraries/bootstrapping.conf -v GHCi, version 7.9.20140929: http://www.haskell.org/ghc/ :? for help Glasgow Haskell Compiler, Version 7.9.20140929, stage 2 booted by GHC version 7.8.3 Using binary package database: /home/hs01/ezyang/ghc- head/inplace/lib/package.conf.d/package.cache Using binary package database: libraries/bootstrapping.conf/package.cache *** Deleting temp files: Deleting: *** Deleting temp dirs: Deleting: <command line>: cannot satisfy -package-key ghc_GE0xPzNsQzT2p10hpwDwSW (use -v for more information) [ezyang@hs01 ghc-nocode]$ /home/hs01/ezyang/ghc-head/inplace/bin/ghc- stage2 -package-key ghc_GE0xPzNsQzT2p10hpwDwSW --interactive -package-db libraries/bootstrapping.conf GHCi, version 7.9.20140929: http://www.haskell.org/ghc/ :? for help <command line>: cannot satisfy -package-key ghc_GE0xPzNsQzT2p10hpwDwSW (use -v for more information) [ezyang@hs01 ghc-nocode]$ /home/hs01/ezyang/ghc-head/inplace/bin/ghc- stage2 -package-key ghc_GE0xPzNsQzT2p10hpwDwSW --interactive -package-db libraries/bootstrapping.conf -v GHCi, version 7.9.20140929: http://www.haskell.org/ghc/ :? for help Glasgow Haskell Compiler, Version 7.9.20140929, stage 2 booted by GHC version 7.8.3 Using binary package database: /home/hs01/ezyang/ghc- head/inplace/lib/package.conf.d/package.cache Using binary package database: libraries/bootstrapping.conf/package.cache *** Deleting temp files: Deleting: *** Deleting temp dirs: Deleting: <command line>: cannot satisfy -package-key ghc_GE0xPzNsQzT2p10hpwDwSW (use -v for more information) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9651> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8079: Redo T7919 with a cabal file
by GHC 21 Nov '15

21 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 21 Nov '15

21 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] #10168: generalize filterM, mapAndUnzipM, zipWithM, zipWithM_, replicateM, replicateM_
by GHC 18 Nov '15

18 Nov '15

#10168: generalize filterM, mapAndUnzipM, zipWithM, zipWithM_, replicateM, replicateM_ -------------------------------------+------------------------------------- Reporter: strake888 | Owner: ekmett Type: bug | Status: new Priority: normal | Milestone: Component: Core | Version: 7.10.1-rc1 Libraries | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- These need only an Applicative constaint. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10168> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9579: Runtime suggests using +RTS when that's not possible
by GHC 15 Nov '15

15 Nov '15

#9579: Runtime suggests using +RTS when that's not possible -------------------------------------+------------------------------------- Reporter: gintas | Owner: simonmar Type: bug | Status: new Priority: low | Milestone: Component: Runtime System | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 | Type of failure: hour) | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I just ran into a stack overflow in an application, and GHC told me: Stack space overflow: current size 8388608 bytes. Use `+RTS -Ksize -RTS' to increase it. I tried to specify +RTS and got an error saying "Most RTS options are disabled. Link with -rtsopts to enable them." The runtime should not suggest using +RTS when that is not possible. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9579> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10061: Remove fun_infix from Funbind, as it is now in Match
by GHC 13 Nov '15

13 Nov '15

#10061: Remove fun_infix from Funbind, as it is now in Match -------------------------------------+------------------------------------- Reporter: alanz | Owner: Type: task | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.10.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: #9988 Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- One of the changes Phab:D538 introduced is to add m_fun_id_infix to Match {{{#!hs data Match id body = Match { m_fun_id_infix :: (Maybe (Located id,Bool)), -- fun_id and fun_infix for functions with multiple equations -- only present for a RdrName. See note [fun_id in Match] m_pats :: [LPat id], -- The patterns m_type :: (Maybe (LHsType id)), -- A type signature for the result of the match -- Nothing after typechecking m_grhss :: (GRHSs id body) } deriving (Typeable) }}} This was done to track the individual locations and fixity of the fun_id for each of the defining equations for a function when there are more than one. For example, the function (&&&) is defined with some prefix and some infix equations below. {{{#!hs (&&& ) [] [] = [] xs &&& [] = xs ( &&& ) [] ys = ys }}} This means that the fun_infix is now superfluous in the FunBind. This has not been removed as a potentially risky change just before 7.10 RC2, and so must be done after. This ticket captures that task, which includes processing these fields through the renamer and beyond. Ticket #9988 introduced these fields into Match through renaming, this ticket it to continue through type checking and then remove it from FunBind completely. The split happened so that #9988 could land in 7.10 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10061> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10172: Cross-platform sed
by GHC 11 Nov '15

11 Nov '15

#10172: Cross-platform sed -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Build | Version: 7.11 System | Operating System: Solaris Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- It's quite easy to accidentally use GNU extensions in sed expressions, which means Solaris builds start failing. See https://phabricator.haskell.org/D740 for an example. What should we do? Here are a few possibilities: * Force use of POSIX sed with `--posix` flag. I haven't tested, but maybe this won't work if Solaris sed chokes on the `--posix`. Alternately, use `$(SED)` and add `--posix` only if it's supported * Detect GNU sed in autoconfigure and use `$(SED)` in all Makefile scripts * Stop using sed in the scripts for something else I don't know if this admonition applies to other random POSIX tools we use. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10172> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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