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Optimize number of comparisons in associative containers assignment and copy #62571

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ldionne opened this issue May 5, 2023 · 1 comment
Open

Optimize number of comparisons in associative containers assignment and copy #62571

ldionne opened this issue May 5, 2023 · 1 comment
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libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. performance

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ldionne commented May 5, 2023

When we copy construct or copy-assign a std::map, instead of doing something akin to map.insert(begin, end) (which requires a bunch of comparisons), we could copy the underlying RB tree without having to perform any comparisons, since we know the incoming tree is already structured appropriately.
@ldionne ldionne added libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. performance labels May 5, 2023
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ldionne commented May 5, 2023

This is related to https://reviews.llvm.org/D121485#inline-1161875

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