[libc-commits] [PATCH] D79828: [libc] Add implementation of call_once from threads.h.

[Fangrui Song via Phabricator via libc-commits]

MaskRay added a comment.

I think the logic is correct now, but my pthread_once argument persists. pthread_once provides strictly more features (pthread cancel) and people don't care about the performance of C11 call_once (nobody/few use it).
Piggybacking call_once on top of pthread_once is fine and likely favorable because this makes the code/binary sizes smaller.



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Comment at: libc/src/threads/linux/call_once.cpp:21
+
+static constexpr unsigned int START = 0x1111;
+static constexpr unsigned int WAITING = 0x2222;
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I don't think we need such special magic numbers instead of sequential 0, 1, 2, 3..

Larger immediates are slower (may require more than one insn) to load on some RISC architectures.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D79828/new/

https://reviews.llvm.org/D79828