[Concepts] Constraint Satisfaction Caching

Authored by saar.raz on Jan 21 2020, 4:50 PM.


[Concepts] Constraint Satisfaction Caching

Add a simple cache for constraint satisfaction results. Whether or not this simple caching
would be permitted in final C++2a is currently being discussed but it is required for
acceptable performance so we use it in the meantime, with the possibility of adding some
cache invalidation mechanisms later.

Differential Revision: https://reviews.llvm.org/D72552