#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