[libcxx-commits] [PATCH] D121485: [libc++] Fix performance inconsistency between map copy-assignment and copy-constructor

[Eric Fiselier via Phabricator via libcxx-commits]

EricWF added a comment.

PS. This is removing an optimization where:

  (A) the node allocations are reused during assignment
  (B) For reused nodes, the types assignment operator is called. 

So this could be a significant regression when either

  (A) Memory allocation is slow.
  (B) The element types assignment operator is faster than its copy constructor (imagine a case where it too is reusing resources).

So I think we need more benchmarks that attempt to measure the performance in these cases.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D121485/new/

https://reviews.llvm.org/D121485