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Improves runtime by around 20 to 40%. (1.3x to 1.7x) ``` Benchmark Time CPU Time Old Time New CPU Old CPU New ------------------------------------------------------------------------------------------------------------------------------------------------ BM_LexicallyRelative/small_path/2 -0.2111 -0.2082 229 181 228 180 BM_LexicallyRelative/small_path/4 -0.2579 -0.2550 455 338 452 337 BM_LexicallyRelative/small_path/8 -0.2643 -0.2616 844 621 838 619 BM_LexicallyRelative/small_path/16 -0.2582 -0.2556 1562 1158 1551 1155 BM_LexicallyRelative/small_path/32 -0.2518 -0.2496 3023 2262 3004 2254 BM_LexicallyRelative/small_path/64 -0.2806 -0.2775 6344 4564 6295 4549 BM_LexicallyRelative/small_path/128 -0.2165 -0.2137 11762 9216 11683 9186 BM_LexicallyRelative/small_path/256 -0.2672 -0.2645 24499 17953 24324 17891 BM_LexicallyRelative/large_path/2 -0.3268 -0.3236 426 287 422 285 BM_LexicallyRelative/large_path/4 -0.3274 -0.3248 734 494 729 492 BM_LexicallyRelative/large_path/8 -0.3586 -0.3560 1409 904 1399 901 BM_LexicallyRelative/large_path/16 -0.3978 -0.3951 2764 1665 2743 1659 BM_LexicallyRelative/large_path/32 -0.3934 -0.3908 5323 3229 5283 3218 BM_LexicallyRelative/large_path/64 -0.3629 -0.3605 10340 6587 10265 6564 BM_LexicallyRelative/large_path/128 -0.3450 -0.3423 19379 12694 19233 12649 BM_LexicallyRelative/large_path/256 -0.3097 -0.3054 36293 25052 35943 24965 ``` --------- Co-authored-by: Nikolas Klauser <nikolasklauser@berlin.de>
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===========================================
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Libc++ 22.0.0 (In-Progress) Release Notes
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===========================================
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.. contents::
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:local:
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:depth: 2
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Written by the `Libc++ Team <https://libcxx.llvm.org>`_
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.. warning::
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These are in-progress notes for the upcoming libc++ 22.0.0 release.
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Release notes for previous releases can be found on
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`the Download Page <https://releases.llvm.org/download.html>`_.
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Introduction
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============
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This document contains the release notes for the libc++ C++ Standard Library,
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part of the LLVM Compiler Infrastructure, release 22.0.0. Here we describe the
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status of libc++ in some detail, including major improvements from the previous
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release and new feature work. For the general LLVM release notes, see `the LLVM
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documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM releases may
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be downloaded from the `LLVM releases web site <https://llvm.org/releases/>`_.
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For more information about libc++, please see the `Libc++ Web Site
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<https://libcxx.llvm.org>`_ or the `LLVM Web Site <https://llvm.org>`_.
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Note that if you are reading this file from a Git checkout or the
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main Libc++ web page, this document applies to the *next* release, not
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the current one. To see the release notes for a specific release, please
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see the `releases page <https://llvm.org/releases/>`_.
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What's New in Libc++ 22.0.0?
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==============================
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Implemented Papers
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------------------
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- P2321R2: ``zip`` (`Github <https://github.com/llvm/llvm-project/issues/105169>`__) (The paper is partially implemented. ``zip_transform_view`` is implemented in this release)
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- P3168R2: Give ``std::optional`` Range Support (`Github <https://github.com/llvm/llvm-project/issues/105430>`__)
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Improvements and New Features
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-----------------------------
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- The performance of ``map::map(const map&)`` has been improved up to 2.3x
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- The performance of ``map::operator=(const map&)`` has been improved by up to 11x
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- The performance of ``unordered_set::unordered_set(const unordered_set&)`` has been improved by up to 3.3x.
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- The performance of ``unordered_set::operator=(const unordered_set&)`` has been improved by up to 5x.
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- The performance of ``map::erase`` and ``set::erase`` has been improved by up to 2x
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- The performance of ``find(key)`` in ``map``, ``set``, ``multimap`` and ``multiset`` has been improved by up to 2.3x
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- Some reallocations are now avoided in `std::filesystem::path::lexically_relative`, resulting in a performance improvement of up to 1.7x.
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Deprecations and Removals
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-------------------------
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Potentially breaking changes
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----------------------------
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Announcements About Future Releases
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-----------------------------------
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ABI Affecting Changes
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---------------------
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Build System Changes
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--------------------
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