October 2014 - ghc-tickets

Re: [GHC] #670: External Core is broken
by GHC 19 Oct '14

19 Oct '14

#670: External Core is broken -------------------------------------+------------------------------------- Reporter: | Owner: tim KirstenChevalier | Status: closed Type: bug | Milestone: ⊥ Priority: normal | Version: 6.8.2 Component: External | Keywords: Core | Architecture: Unknown/Multiple Resolution: wontfix | Difficulty: Moderate (less Operating System: | than a day) Unknown/Multiple | Blocked By: Type of failure: GHC | Related Tickets: rejects valid program | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by monoidal): * status: new => closed * resolution: => wontfix Comment: External Core was removed. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/670#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9377: forkProcess unnecessarily sets wait_foreign in hs_exit_
by GHC 18 Oct '14

18 Oct '14

#9377: forkProcess unnecessarily sets wait_foreign in hs_exit_ -------------------------------------+------------------------------------- Reporter: edsko | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | 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: Phab:D99 -------------------------------------+------------------------------------- During normal course of action in `real_main` a process is terminated with a call to {{{#!hs shutdownHaskellAndExit(exit_status, 0 /* !fastExit */); }}} which is defined as {{{#!hs void shutdownHaskellAndExit(int n, int fastExit) { if (!fastExit) { // even if hs_init_count > 1, we still want to shut down the RTS // and exit immediately (see #5402) hs_init_count = 1; // we're about to exit(), no need to wait for foreign calls to return. hs_exit_(rtsFalse); } stg_exit(n); } }}} However, when we call `forkProcess`, the child process does ''not'' terminate in this manner, but instead calls {{{#!hs hs_exit(); // clean up and exit stg_exit(EXIT_SUCCESS); }}} instead, where `hs_exit` is defined as {{{#!hs void hs_exit(void) { hs_exit_(rtsTrue); // be safe; this might be a DLL } }}} Crucially, this means that, unlike the parent, the child process ''does'' wait for foreign calls to be terminated (it calls `hs_exit_` with `rtsTrue` instead of `rtsFalse`). I don't see a reason why the child process should terminate in a different manner to the parent, so I propose to change this so that `forkProcess` calls `shutdownHaskellAndExit`, just like `real_main` does. Incidentally, this is the immediate cause for https://ghc.haskell.org/trac/ghc/ticket/9284 , although the patch proposed in this ticket is not sufficient to solve the problems with termination of the I/O manager in the general case (but I will let Andreas explain that in more detail :). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9377> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9340: Implement new `clz` inline primop
by GHC 18 Oct '14

18 Oct '14

#9340: Implement new `clz` inline primop -------------------------------------+------------------------------------- Reporter: hvr | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 7.8.2 (CodeGen) | Differential Revisions: Keywords: primop clz | Architecture: Operating System: Unknown/Multiple | Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- From a draft for #9281, I had to use a C FFI and using a gcc/clang `__builtin` to get access to the [http://en.wikipedia.org/wiki/Find_first_set CLZ instruction]: {{{#!hs -- | Compute base-2 log of 'Word#' -- -- This is internally implemented as count-leading-zeros machine instruction. foreign import ccall unsafe "integer_gmp_word_log2" wordLog2# :: Word# -> Int# }}} {{{#!c HsWord integer_gmp_word_log2(HsWord x) { #if (SIZEOF_HSWORD) == (SIZEOF_INT) return x ? (WORD_SIZE_IN_BITS-1) - __builtin_clz(x) : -1; #elif (SIZEOF_HSWORD) == (SIZEOF_LONG) return x ? (WORD_SIZE_IN_BITS-1) - __builtin_clzl(x) : -1; #elif (SIZEOF_HSWORD) == (SIZEOF_LONG_LONG) return x ? (WORD_SIZE_IN_BITS-1) - __builtin_clzll(x) : -1; #else # error unsupported SIZEOF_HSWORD #endif } }}} Since a `clz`-like operation should be available on most cpus GHC should expose that as a primop ({{{clz# :: Word# -> Int#}}}). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9340> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 17 Oct '14

17 Oct '14

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Difficult (2-5 Type of failure: Other | days) Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Comment (by Joachim Breitner <mail@…>): In [changeset:"a477e8118137b7483d0a7680c1fd337a007a023b/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="a477e8118137b7483d0a7680c1fd337a007a023b" Avoid printing uniques in specialization rules Akio found an avoidable cause of non-determinisim: The names of RULES generated by Specialise had uniques in them: "SPEC $cshowsPrec_a2QX @ [GHC.Types.Char]" [ALWAYS] forall ... By using showSDocForUser instead of showSDocDump when building the rule name, this is avoided: "SPEC $cshowsPrec @ [Char]" [ALWAYS] forall ... See #4012, comments 61ff. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:67> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 17 Oct '14

17 Oct '14

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Difficult (2-5 Type of failure: Other | days) Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Comment (by nomeata): Simple patch, pushed at Phab:D346 for validation. Will push as soon as that goes through. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:66> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 17 Oct '14

17 Oct '14

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Difficult (2-5 Type of failure: Other | days) Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Comment (by simonpj): Whoa! The name of an auto-generated rule is itself auto-generated, so that a (savvy) user can track back to which function is being specialised. But nothing will go wrong if two rules accidentally have the same name, which seems entirely possible if you suppress the unique. I can see that this is a rather gratuitous source of non-determinism. Joachim, do go ahead and suppress the unique (with an accompanying Note!). Thanks. Simon -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:65> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 17 Oct '14

17 Oct '14

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Difficult (2-5 Type of failure: Other | days) Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Comment (by nomeata): I think I can root out this instance of non-determinism. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:64> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 17 Oct '14

17 Oct '14

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Difficult (2-5 Type of failure: Other | days) Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Comment (by nomeata): Nice example. Here is the diff between such interface files. {{{ -"SPEC $cshowsPrec_a2QX @ [GHC.Types.Char]" [ALWAYS] forall $dShow :: GHC.Show.Show +"SPEC $cshowsPrec_a2Q6 @ [GHC.Types.Char]" [ALWAYS] forall $dShow :: GHC.Show.Show [GHC.Types.Char] }}} It looks similar in 7.6.3 and in HEAD. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:63> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 17 Oct '14

17 Oct '14

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Difficult (2-5 Type of failure: Other | days) Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Changes (by akio): * cc: tkn.akio@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:62> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 17 Oct '14

17 Oct '14

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Difficult (2-5 Type of failure: Other | days) Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Comment (by akio): Here is one example where the interface changes while there is no code change at all. On my computer (with GHC 7.8.3 on Linux), the attached shell script compiles Main.hs 4 times rather than just once. B.hi seems to contain some rules whose name is not stable. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:61> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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