February 2014 - ghc-tickets

[GHC] #8724: CAS and Xchange in SMP.h don't use quadword instructions on x86_64 systems
by GHC 01 Feb '14

01 Feb '14

#8724: CAS and Xchange in SMP.h don't use quadword instructions on x86_64 systems ----------------------------------+------------------------------------- Reporter: carter | Owner: Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: Compiler | Version: 7.8.1-rc1 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------------- Ryan Newton pointed out on the mailing list that CAS wasn't behaving correctly in his heavy concurrency benchmarks. http://www.haskell.org/pipermail/ghc-devs/2014-February/003944.html upon looking at the inline ASM, it looks like both CAS and Xchng were probably using the 32bit versions of their asm operations, or at least thats my strawman interpretation. https://github.com/cartazio/ghc/compare/ghc:ghc-7.8...fix_64bit_intel_cas is the patch, which should be tested and confirmed to resolve this issue before getting merged in. This patch makes the 64 bit versions of CAS and xchg use the quad word instructions -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8724> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4426: Simplify the rules for implicit quantification
by GHC 01 Feb '14

01 Feb '14

#4426: Simplify the rules for implicit quantification -------------------------------------+------------------------------------ Reporter: simonpj | Owner: Type: feature request | Status: patch Priority: low | Milestone: 7.10.1 Component: Compiler | Version: 6.12.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: #7880 -------------------------------------+------------------------------------ Changes (by monoidal): * milestone: 7.6.2 => 7.10.1 Comment: I've updated the patches again - three above files are ready for GHC 7.10. The warning is enabled by default, and the plan is that GHC 7.12 will give an error with implicit quantification on contexts. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4426#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8720: ghc crash
by GHC 01 Feb '14

01 Feb '14

#8720: ghc crash ------------------------------------------------+-------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.6.3 Keywords: ghci crash mvar thread block | Operating System: Architecture: x86_64 (amd64) | Windows Difficulty: Unknown | Type of failure: GHCi Blocked By: | crash Related Tickets: | Test Case: | Blocking: ------------------------------------------------+-------------------------- ghc.exe: panic! (the 'impossible' happened) (GHC version 7.6.3 for i386-unknown-mingw32): thread blocked indefinitely in an MVar operation Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug I didn't try to reproduce it, but figured someone might want it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8720> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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