| commit | 8cf76e913b867a98a9843aa1b3d782632ed5d930 | [log] [tgz] |
|---|---|---|
| author | Martijn Vels <[email protected]> | Tue Mar 03 22:47:23 2020 |
| committer | Martijn Vels <[email protected]> | Tue Mar 03 22:49:25 2020 |
| tree | fa5642ba67ba4e49458ef20fd5c2492cf98de8cb | |
| parent | 14ac84e5c56e115d57eef01373f1f97267b38ef8 [diff] |
Partially inline basic_string copy constructor in UNSTABLE his change splits the copy constructor up inlining short initialization, and explicitly outlining long initialization into __init_copy_ctor_external() which is the externally instantiated slow path. For unstable ABI, this has the following changes: remove basic_string(const basic_string&) remove basic_string(const basic_string&, const Allocator&) add __init_copy_ctor_external(const value_type*, size_type) Quick local benchmark for Copy: Master ``` --------------------------------------------------------------- Benchmark Time CPU Iterations --------------------------------------------------------------- BM_StringCopy_Empty 3.50 ns 3.51 ns 199326720 BM_StringCopy_Small 3.50 ns 3.51 ns 199510016 BM_StringCopy_Large 15.7 ns 15.7 ns 45230080 BM_StringCopy_Huge 1503 ns 1503 ns 464896 ``` ``` --------------------------------------------------------------- Benchmark Time CPU Iterations --------------------------------------------------------------- BM_StringCopy_Empty 1.99 ns 2.00 ns 356471808 BM_StringCopy_Small 3.29 ns 3.30 ns 203425792 BM_StringCopy_Large 13.3 ns 13.3 ns 52948992 BM_StringCopy_Huge 1472 ns 1472 ns 475136 ``` Author: Martijn Vels <[email protected]> Reviewers: EricWF, mclow.list Tags: #llvm Differential Revision: https://reviews.llvm.org/D73223
This directory and its sub-directories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.
The README briefly describes how to get started with building LLVM. For more information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.
Taken from https://llvm.org/docs/GettingStarted.html.
Welcome to the LLVM project!
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 converts it into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer. It also contains basic regression tests.
C-like languages use the Clang front end. 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.
The LLVM Getting Started documentation may be out of date. The Clang Getting Started page might have more accurate information.
This is an example work-flow and configuration to get and build the LLVM source:
Checkout LLVM (including related sub-projects like Clang):
git clone https://github.com/llvm/llvm-project.git
Or, on windows, git clone --config core.autocrlf=false https://github.com/llvm/llvm-project.git
Configure and build LLVM and Clang:
cd llvm-project
mkdir build
cd build
cmake -G <generator> [options] ../llvm
Some common build system generators are:
Ninja --- for generating Ninja build files. Most llvm developers use Ninja.Unix Makefiles --- for generating make-compatible parallel makefiles.Visual Studio --- for generating Visual Studio projects and solutions.Xcode --- for generating Xcode projects.Some Common options:
-DLLVM_ENABLE_PROJECTS='...' --- semicolon-separated list of the LLVM sub-projects you'd like to additionally build. Can include any of: clang, clang-tools-extra, libcxx, libcxxabi, libunwind, lldb, compiler-rt, lld, polly, or debuginfo-tests.
For example, to build LLVM, Clang, libcxx, and libcxxabi, use -DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi".
-DCMAKE_INSTALL_PREFIX=directory --- Specify for directory the full path name of where you want the LLVM tools and libraries to be installed (default /usr/local).
-DCMAKE_BUILD_TYPE=type --- Valid options for type are Debug, Release, RelWithDebInfo, and MinSizeRel. Default is Debug.
-DLLVM_ENABLE_ASSERTIONS=On --- Compile with assertion checks enabled (default is Yes for Debug builds, No for all other build types).
cmake --build . [-- [options] <target>] or your build system specified above directly.
The default target (i.e. ninja or make) will build all of LLVM.
The check-all target (i.e. ninja check-all) will run the regression tests to ensure everything is in working order.
CMake will generate targets for each tool and library, and most LLVM sub-projects generate their own check-<project> target.
Running a serial build will be slow. To improve speed, try running a parallel build. That's done by default in Ninja; for make, use the option -j NNN, where NNN is the number of parallel jobs, e.g. the number of CPUs you have.
For more information see CMake
Consult the Getting Started with LLVM page for detailed information on configuring and compiling LLVM. You can visit Directory Layout to learn about the layout of the source code tree.