[libcxx-commits] [PATCH] D128021: [libc++] Don't call key_eq in unordered_map/set rehashing routine

[Ivan via Phabricator via libcxx-commits]

itrofimow added inline comments.


================
Comment at: libcxx/benchmarks/unordered_set_operations.bench.cpp:311
+    getRandomStringInputs)->Arg(TestNumInputs);
+
 BENCHMARK_MAIN();
----------------
This is with the patch:
BM_Rehash/unordered_set_string_arg/1024      44848 ns        44846 ns        96172

This is on trunk:
BM_Rehash/unordered_set_string_arg/1024      55711 ns        55706 ns        74198

full output: https://pastebin.com/7DMcNTna


This benchmark doesn't mean there is an immense speedup in rehashing, it just shows that there is a speedup - `max_load_factor(3)` was used to be sure that there will be collisions and key_eq branch in rehashing would be hit. So this just measures how long it takes to compare long random strings, but with the patch we don't compare them at all.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D128021/new/

https://reviews.llvm.org/D128021