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Reid Kleckner 270d3faf6e [COFF] Add and use a zero-copy tokenizer for .drectve 
This generalizes the main Windows command line tokenizer to be able to
produce StringRef substrings as well as freshly copied C strings. The
implementation is still shared with the normal tokenizer, which is
important, because we have unit tests for that.

.drective sections can be very long. They can potentially list up to
every symbol in the object file by name. It is worth avoiding these
string copies.

This saves a lot of memory when linking chrome.dll with PGO
instrumentation:

             BEFORE      AFTER      % IMP
peak memory: 6657.76MB   4983.54MB  -25%
real:        4m30.875s   2m26.250s  -46%

The time improvement may not be real, my machine was noisy while running
this, but that the peak memory usage improvement should be real.

This change may also help apps that heavily use dllexport annotations,
because those also use linker directives in object files. Apps that do
not use many directives are unlikely to be affected.

Reviewed By: thakis

Differential Revision: https://reviews.llvm.org/D79262
 		2020-05-02 10:47:02 -07:00
clang Don't stash types that aren't copyable or moveable into a SmallVector 2020-05-02 19:13:06 +02:00
clang-tools-extra std::isspace -> llvm::isSpace (where locale should be ignored) 2020-05-02 15:36:04 +02:00
compiler-rt scudo: Exclude previous tag when retagging freed memory. 2020-05-01 09:35:38 -07:00
debuginfo-tests [debuginfo-tests] Update Python variable in lit.site.cfg.py 2020-04-30 10:51:45 -07:00
flang [IndexedAccessorRange] Only offset the base if the index is non-zero. 2020-05-01 11:56:39 -07:00
libc [libc] Add definitions of double_t and float_t to math.h. 2020-04-30 11:59:11 -07:00
libclc libclc: Pass system libraries to the linker after llvm libraries 2020-04-29 15:34:54 -07:00
libcxx [libc++][P1115][C++20] Improving the Return Value of Erase-Like Algorithms II: Free erase/erase if. 2020-05-02 14:04:50 +02:00
libcxxabi [libc++abi] Add -Wno-unreachable-code when building test for throwing incomplete types 2020-05-01 15:29:40 -04:00
libunwind [libcxx][libcxxabi][libunwind] Use libgcc on Android 2020-04-30 15:42:32 -07:00
lld [COFF] Add and use a zero-copy tokenizer for .drectve 2020-05-02 10:47:02 -07:00
lldb [ARM64] Remove more dead code. NFC. 2020-05-01 15:05:42 -07:00
llvm [COFF] Add and use a zero-copy tokenizer for .drectve 2020-05-02 10:47:02 -07:00
mlir [MLIR] Ensure that out-of-tree users have an mlir-generic-headers target 2020-05-01 22:19:58 -07:00
openmp [libomptarget] Initialize reference parameter IsNew within Device::getOrAllocTgtPtr 2020-04-24 15:33:37 -05:00
parallel-libs [arcconfig] Delete subproject arcconfigs 2020-02-24 16:20:36 -08:00
polly Use components instead of libraries in Polly linkage step 2020-04-28 09:44:10 +02:00
pstl [pstl] Added missing double-underscore prefixes to some types 2020-04-15 22:06:58 +02:00
utils/arcanist Use in-tree clang-format-diff.py as Arcanist linter 2020-04-06 12:02:20 -04:00
.arcconfig [arcconfig] Default base to previous revision 2020-02-24 16:20:25 -08:00
.arclint Fix .arclint on Windows 2020-04-28 09:55:48 -07:00
.clang-format
…
.clang-tidy - Update .clang-tidy to ignore parameters of main like functions for naming violations in clang and llvm directory 2020-01-31 16:49:45 +00:00
.git-blame-ignore-revs Add some libc++ revisions to .git-blame-ignore-revs 2020-03-17 17:30:20 -04:00
.gitignore Add a newline at the end of the file 2019-09-04 06:33:46 +00:00
CONTRIBUTING.md Add contributing info to CONTRIBUTING.md and README.md 2019-12-02 15:47:15 +00:00
README.md Revert "This is a test commit." 2020-04-11 15:55:07 -07:00

README.md

The LLVM Compiler Infrastructure

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.

Getting Started with the LLVM System

Taken from https://llvm.org/docs/GettingStarted.html.

Overview

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.

Getting the Source Code and Building LLVM

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:

  1. 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

  2. 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.