Mike Ash 630aff7b19 [Runtime] Change SimpleGlobalCache to use ConcurrentReadableHashMap instead of ConcurrentMap. ...

This gives us faster lookups and a small advantage in memory usage. Most of these maps need stable addresses for their entries, so we add a level of indirection to ConcurrentReadableHashMap for these cases to accommodate that. This costs some extra memory, but it's still a net win.

A new StableAddressConcurrentReadableHashMap type handles this indirection and adds a convenience getOrInsert to take advantage of it.

ConcurrentReadableHashMap is tweaked to avoid any global constructors or destructors when using it as a global variable.

ForeignWitnessTables does not need stable addresses and it now uses ConcurrentReadableHashMap directly.

rdar://problem/70056398

2020-10-08 14:57:39 -04:00

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