Add a hash_combine function for mixing hash values.
This hash function is derived from Boost's function of the same name. Author: Andres Freund, Thomas Munro Discussion: https://postgr.es/m/CAEepm%3D3rdgjfxW4cKvJ0OEmya2-34B0qHNG1xV0vK7TGPJGMUQ%40mail.gmail.com Discussion: https://postgr.es/m/20170731210844.3cwrkmsmbbpt4rjc%40alap3.anarazel.de
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/*
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* Utilities for working with hash values.
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*
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* Portions Copyright (c) 2017, PostgreSQL Global Development Group
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*/
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#ifndef HASHUTILS_H
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#define HASHUTILS_H
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/*
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* Combine two hash values, resulting in another hash value, with decent bit
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* mixing.
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*
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* Similar to boost's hash_combine().
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*/
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static inline uint32
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hash_combine(uint32 a, uint32 b)
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{
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a ^= b + 0x9e3779b9 + (a << 6) + (a >> 2);
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return a;
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}
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#endif /* HASHUTILS_H */
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