January 2017 - ghc-tickets

[GHC] #12622: Unboxed static pointers lead to missing SPT entries
by GHC 14 Jan '17

14 Jan '17

#12622: Unboxed static pointers lead to missing SPT entries -------------------------------------+------------------------------------- Reporter: mboes | Owner: facundominguez Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I found what appears to be a regression following the merge of the new FloatOut based static pointers support. See github.com/mboes/bug-ptr-not- in-spt for a fully developed minimal example. It seems to be quite hard to trigger this bug: * I need to be using distributed-closure (not bare `StaticPtr`). * The static pointer needs to be defined in a separate module. * The static pointer must refer to a value with at least one polymorphic argument. * Compiler optimization level 1 needs to be turned on. At any rate, I wasn't able to trigger it without all conditions above being true. Initial investigations by facundominguez point to static pointer unpacking in distributed-closure as the culprit. Likely unpacked static pointers are no longer recognized as such by the FloatOut pass and therefore never floated to top-level, hence breaking a fundamental invariant about static pointers. This might explain why sometimes static pointers don't get added to the static pointer table (SPT), as in the above minimal example. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12622> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12090: Document Weverything/Wall/Wextra/Wdefault in user's guide
by GHC 13 Jan '17

13 Jan '17

#12090: Document Weverything/Wall/Wextra/Wdefault in user's guide -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 8.0.2 Component: Documentation | Version: 8.0.1 Keywords: warnings | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: Design/Warnings -------------------------------------+------------------------------------- The user's guide needs to be updated to reflect the feature implemented in phab:D1850 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12090> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13085: -fregs-graph is ignored but this is undocumented
by GHC 12 Jan '17

12 Jan '17

#13085: -fregs-graph is ignored but this is undocumented -------------------------------------+------------------------------------- Reporter: jberryman | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Documentation | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This is bad since it can be a time sink experimenting with knobs, especially if you're staring at assembly, etc. so this is a documentation bug. I'm confused about what happened with this flag. It was ignored at some point, recently restored but then that was reverted without fixing the docs I guess: https://phabricator.haskell.org/rGHC6a5d13c4ade5bbb84873970065a1acd1546f6c31 https://phabricator.haskell.org/rGHC55dfd21e1969b4b8e40196ecf29e4c9c73273966 https://ghc.haskell.org/trac/ghc/ticket/13033 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13085> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7679: Regression in -fregs-graph performance
by GHC 12 Jan '17

12 Jan '17

#7679: Regression in -fregs-graph performance -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler (NCG) | Version: 7.6.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #7192, #8657 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by tjakway): * cc: tjakway (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7679#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11695: On GHCi prompt the arrow (movement) keys create strange character sequences
by GHC 12 Jan '17

12 Jan '17

#11695: On GHCi prompt the arrow (movement) keys create strange character sequences --------------------------------------+--------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.1 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+--------------------------------- Fire up `GHCi` and sit on the arrow down (or left) keys. This is what I get after constantly pressing for some time: {{{ $ ghci GHCi, version 8.1.20160202: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/ggreif/.ghci Prelude> OBOBOBBOBOBOBOBOBOBOBCOCCOCOCCOCCOC <interactive>:1:1: error: Data constructor not in scope: OBOBOBBOBOBOBOBOBOBOBCOCCOCOCCOCCOC }}} When such a strange letter appears, there is also a blinking of the terminal. It is not happening on Windows. I have seen it on RHEL5 and RHEL6. Pretty annoying, especially when you want to quickly navigate in the repl. This is probably a `haskeline` bug, but I am coming here to see whether others suffer from it too, i.e. is it reproducible for elseone? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11695> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13106: impossible happened: initTc: unsolved constraints
by GHC 12 Jan '17

12 Jan '17

#13106: impossible happened: initTc: unsolved constraints -------------------------------------+------------------------------------- Reporter: codygman | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: initTc | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Below is the error: I got the following error: ghc: panic! (the 'impossible' happened) (GHC version 8.0.1.20161213 for x86_64-unknown-linux): initTc: unsolved constraints WC {wc_insol = [W] cp_a6SB :: t_a6SA[tau:1] (CHoleCan: cp) [W] minimal_a6SI :: t_a6SH[tau:1] (CHoleCan: minimal) [W] frames_a6SL :: t_a6SK[tau:1] (CHoleCan: frames) [W] ps_a6Tb :: t_a6Ta[tau:1] (CHoleCan: ps) [W] minimal_a6Ti :: t_a6Th[tau:1] (CHoleCan: minimal) [W] frames_a6Tm :: t_a6Tl[tau:1] (CHoleCan: frames) [W] map_hd_a6Tv :: t_a6Tu[tau:1] (CHoleCan: map_hd) [W] ps_a6Ty :: t_a6Tx[tau:1] (CHoleCan: ps)} It was created with this repo: https://github.com/codygman/minimal-frames- lookup-map/blob/master/src/Main.hs Apologies for the setup needed, but I also had to download judy-0.3.0 manually and then include it for it to build (not sure why, but unrelated problem I think). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13106> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11781: Improve common sub-expression
by GHC 12 Jan '17

12 Jan '17

#11781: Improve common sub-expression -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): Phab:D2074 | Wiki Page: -------------------------------------+------------------------------------- I wrote a patch that refactors and improves the CSE pass. It's in `wip/cse-code-desmelling`, and Phab:D2074 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11781> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10083: ghc: panic! (the 'impossible' happened)
by GHC 12 Jan '17

12 Jan '17

#10083: ghc: panic! (the 'impossible' happened) -------------------------------------+------------------------------------- Reporter: hedayaty | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: MacOS X Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I used hprotoc to generate some code for Google protocol buffers. The QueryValue.proto file is attached. You can install hprotoc tool using cabal. then use ''hprotoc QueryValue.proto'' to generate code. Then create a minimal cabal file. ''cabal init -m --is-library -n'' Then if you build it with '''optimization enabled''', the build will fail ghc: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-apple-darwin): Simplifier ticks exhausted When trying UnfoldingDone $j_sEMq{v} [lid] To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 59242 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10083> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12789: "Simplifier ticks exhausted" compiling mutually recursive modules with GHC 8.
by GHC 12 Jan '17

12 Jan '17

#12789: "Simplifier ticks exhausted" compiling mutually recursive modules with GHC 8. ----------------------------------------+--------------------------------- Reporter: rdwebster | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: MacOS X Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- I encountered the "Simplifier ticks exhausted" error when compiling some code generated by hprotoc in GHC 8.0.1. It works with -O0, but fails with -O1. The code compiles successfully with GHC 7.10, but fails with 8.0.1. Specifying a larger value for 'simpl-tick-factor' doesn't seem to help. The original code was generated by hprotoc, but a much simplified version is attached. Here is the output with '-ddump-simpl-stats' enabled: {{{ stack build cycle-test --ghc-options -ddump-simpl-stats cycle-test-0.1.0.0: configure Configuring cycle-test-0.1.0.0... cycle-test-0.1.0.0: build Preprocessing library cycle-test-0.1.0.0... [1 of 4] Compiling Thing2[boot] ( src/Thing2.hs-boot, .stack- work/dist/x86_64-osx/Cabal-1.24.0.0/build/Thing2.o-boot ) [2 of 4] Compiling Thing1 ( src/Thing1.hs, .stack- work/dist/x86_64-osx/Cabal-1.24.0.0/build/Thing1.o ) [3 of 4] Compiling Thing2 ( src/Thing2.hs, .stack- work/dist/x86_64-osx/Cabal-1.24.0.0/build/Thing2.o ) [4 of 4] Compiling Box ( src/Box.hs, .stack- work/dist/x86_64-osx/Cabal-1.24.0.0/build/Box.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-apple-darwin): Simplifier ticks exhausted When trying UnfoldingDone $fxEqThing2 To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed Total ticks: 6442 1681 PreInlineUnconditionally 280 $dEq_a1AB 280 ds_a1AC 280 ds_i28z 280 ds1_i28A 279 ds_i29a 279 ds1_i29b 1 ds_a1As 1 ds_d28r 1 ds_d28s 280 PostInlineUnconditionally 280 ds1_a1AD 1120 UnfoldingDone 280 $fEqMaybe_$c== 280 $fEqThing1_$c== 279 $fxEqThing2 279 $fEqThing2_$c== 1 $c==_a289 1 not 279 RuleFired 279 Class op == 2241 BetaReduction 280 a_a1AA 280 $dEq_a1AB 280 ds_a1AC 280 ds1_a1AD 280 ds_i28z 280 ds1_i28A 279 ds_i29a 279 ds1_i29b 1 ds_a1As 1 ds_d28r 1 ds_d28s 1 CaseOfCase 1 wild_a1At 840 KnownBranch 840 wild_a1At }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12789> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7206: Implement cheap build
by GHC 12 Jan '17

12 Jan '17

#7206: Implement cheap build -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 7.4.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #8763 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * related: => #8763 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7206#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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