[libc++] Optimize num_get integral functions (#121795) ``` --------------------------------------------------- Benchmark old new --------------------------------------------------- BM_num_get<bool> 86.5 ns 32.3 ns BM_num_get<long> 82.1 ns 30.3 ns BM_num_get<long long> 85.2 ns 33.4 ns BM_num_get<unsigned short> 85.3 ns 31.2 ns BM_num_get<unsigned int> 84.2 ns 31.1 ns BM_num_get<unsigned long> 83.6 ns 31.9 ns BM_num_get<unsigned long long> 87.7 ns 31.5 ns BM_num_get<float> 116 ns 114 ns BM_num_get<double> 114 ns 114 ns BM_num_get<long double> 113 ns 114 ns BM_num_get<void*> 151 ns 144 ns ``` This patch applies multiple optimizations: - Stages two and three of do_get are merged and a custom integer parser has been implemented This avoids allocations, removes the need for strto{,u}ll and avoids __stage2_int_loop (avoiding extra writes to memory) - std::find has been replaced with __atoms_offset, which uses vector instructions to look for a character Fixes #158100 Fixes #158102

tree: 8f691bd970cd5b09337ce3e7677c7acf628f48f4

README.md

The LLVM Compiler Infrastructure

Welcome to the LLVM project!

This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.

C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.

Other components include: the libc++ C++ standard library, the LLD linker, and more.

Getting the Source Code and Building LLVM

Consult the Getting Started with LLVM page for information on building and running LLVM.

For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.

Getting in touch

Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.

The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.