[libcxx-commits] [PATCH] D121492: [libc++] Fix performance inconsistency between unordered_map copy-assignment and copy-construction

[Louis Dionne via Phabricator via libcxx-commits]

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We were not rehashing the hash table before performing assignment, which
resulted in greatly sub-optimal performance when compared to the
otherwise equivalent copy constructor.

This patch also adds a test that will start failing should a performance
difference be reintroduced in the future.

rdar://89335436


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D121492

Files:
  libcxx/include/__hash_table
  libcxx/include/unordered_map
  libcxx/include/unordered_set
  libcxx/test/libcxx/containers/unord/perf.assignment_vs_construction.pass.cpp

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