Change std::hash<int> to hash_combine #1557
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This exposes the collision found for 8 nodes * 4 gpus.
These hashes use hash<int> which is the identity function. So no hashing occurs at all!
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Description of changes:
A user was trying to use this with 32 gpus and got the following error:
LEGION ERROR: ERROR: ShardingID 486726351 has already been used by another sharding functor.Turns out the hash function in MachineView doesn't work. Changed all but one place where std::hash is used. Cherry-picked improved hash_combine from master.
There's still this spot that uses std::hash:
https://github.com/flexflow/FlexFlow/blob/3a825ed6ae7425ea3578006e458cfcaf19e038a5/src/runtime/graph.cc#L1868-L1872
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