[libc-commits] [PATCH] D159276: [libc][gpu] Thread divergence fix on volta

[Jon Chesterfield via Phabricator via libc-commits]

JonChesterfield added inline comments.


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Comment at: libc/src/__support/RPC/rpc.h:337
 private:
   Process<T, S> &process;
   uint64_t lane_mask;
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These values may be a problem. I think Port instances usually end up on the stack in the hope that SROA will disassemble the pieces. Lane_mask and index should be invariant over the lifetime of the Port. I'm not sure what the out variable is - my recollection is that it's a cache of the outbox state, but if that's true it should be a bool.

I'd guess out/receive/owns are mutable and toggle back and forth as the machine executes.

Mutable or not, I think these should all be warp invariant, and whether that invariant is known at compile time or not is probably an emergent feature of the optimiser at the moment.


Repository:
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  https://reviews.llvm.org/D159276/new/

https://reviews.llvm.org/D159276