woot, solved it, at least in a way thats OK for now. if I mark the prefetchValue operations as has_side_effects=True, the core lint failure goes away! I'm not sure if thats the right semantics in the long term, but it does give me a simple way to make sure it works safely for 7.10
pardon all the noise -Carter On Sun, Nov 23, 2014 at 4:26 PM, Carter Schonwald < carter.schonw...@gmail.com> wrote: > ok, i'm getting a let/app invariant failure when i build my test case with > O1 or O2 but not without > > http://lpaste.net/114881 > > any help would be appreciated on how to address that > > On Sun, Nov 23, 2014 at 4:13 PM, Carter Schonwald < > carter.schonw...@gmail.com> wrote: > >> yup, i have that! >> >> wrapFetch prefetchValue0# (error "this shouldn't get evaluated") >> >> in the test suite! >> >> in contrast >> wrapFetch prefetchValue0# $! (error "this shouldn't get evaluated") >> does explode >> >> shall I add a "should fail" test with the latter? (it doesn't seem >> worthwhile) >> >> On Sun, Nov 23, 2014 at 3:53 PM, Edward Kmett <ekm...@gmail.com> wrote: >> >>> Maybe test for laziness in the argument by just putting something in >>> that goes boom when forced, e.g. 'undefined'? >>> >>> >>> On Sun, Nov 23, 2014 at 2:04 PM, Carter Schonwald < >>> carter.schonw...@gmail.com> wrote: >>> >>>> Hey All, >>>> as part of trying to get some fixups for how prefetch works into 7.10, >>>> i'm adding a "prefetchValue" primop that prefetchs the memory location >>>> of a lifted heap value >>>> >>>> namely >>>> >>>> several operations of the following form >>>> >>>> primop PrefetchValueOp1 "prefetchValue1#" GenPrimOp >>>> a -> State# s -> State# s >>>> with strictness = { \ _arity -> mkClosedStrictSig [botDmd, topDmd] >>>> topRes } >>>> >>>> I'd like some feedback on the strictness information design by someone >>>> who's familiar with how that piece of GHC. the idea being that >>>> prefetchValue is lazy in its polymorphic argument (it doesn't force it, it >>>> just does a prefetch on the heap location, which may or may not be >>>> evaluated). >>>> >>>> https://phabricator.haskell.org/D350 >>>> >>>> is the code in question. And i *believe* i'm testing for being lazy in >>>> that argument correctly. >>>> >>>> thoughts? >>>> >>>> many thanks! >>>> -Carter >>>> >>>> >>>> _______________________________________________ >>>> ghc-devs mailing list >>>> ghc-devs@haskell.org >>>> http://www.haskell.org/mailman/listinfo/ghc-devs >>>> >>>> >>> >> >
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