[libcxx-commits] [libcxx] Avoid unnecessary swaps for equal elements in __sift_down (PR #139556)
Peng Liu via libcxx-commits
libcxx-commits at lists.llvm.org
Mon May 12 07:49:14 PDT 2025
https://github.com/winner245 created https://github.com/llvm/llvm-project/pull/139556
This PR optimizes the `__sift_down` operation to avoid unnecessary swaps when the parent and child elements are equal. The current implementation continues sifting down even when the parent and child are equal, leading to redundant operations. In the worst case (all elements equal), the current implementation performs `O(log n)` swaps per `__sift_down`. The optimized version reduces this to `O(1)` when the parent and child are equal.
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