ryan, any thoughts on the (valid!) concern John Lato raises? I know you mentioned fighting ghc optimizations when writing concurrent code a while ago, and i believe I asked if you could document the issues some time so we can all think about how to make the sitch easier, could you share your thoughts?
AFAIK, there isn't a clear "this is the memory ordering rules" even in an informal sense for ghc core / stg / cmm, and maybe we need to pin down some "informal" guarantees we want to hold? -Carter On Sun, May 4, 2014 at 6:32 PM, John Lato <[email protected]> wrote: > Hello, > > IMHO I think the desire to include these features is leading to a slightly > cavalier attitude towards reordering concerns. Even assuming that the Cmm > code generator doesn't reorder reads/writes around `CallishMachOp`, I don't > see why this behavior should always be true, leading to possible future > pain. Also, it's possible that LLVM may decide to reorder memory accesses > AIUI because the underlying LLVM variables won't be synchronized. > > In a nutshell, even though everything may work now I suspect it'll become > an ill-specified mess in a few years time. I don't have a ton of > experience implementing these sorts of features in compilers though, so > probably only worth a half cent. > > John L. > On May 4, 2014 3:10 AM, "Johan Tibell" <[email protected]> wrote: > >> Hi, >> >> I found myself needing atomic operations on basic, mutable numeric >> values. I wrote a short design doc that I'd like feedback on: >> >> https://ghc.haskell.org/trac/ghc/wiki/AtomicPrimops >> >> I will try to implement these for 7.10. >> >> -- Johan >> >> >> _______________________________________________ >> ghc-devs mailing list >> [email protected] >> http://www.haskell.org/mailman/listinfo/ghc-devs >> >> > _______________________________________________ > ghc-devs mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/ghc-devs > >
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