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Philip Reames b06a2ad94f [LoopVectorizer] Lower uniform loads as a single load (instead of relying on CSE) 
A uniform load is one which loads from a uniform address across all lanes. As currently implemented, we cost model such loads as if we did a single scalar load + a broadcast, but the actual lowering replicates the load once per lane.

This change tweaks the lowering to use the REPLICATE strategy by marking such loads (and the computation leading to their memory operand) as uniform after vectorization. This is a useful change in itself, but it's real purpose is to pave the way for a following change which will generalize our uniformity logic.

In review discussion, there was an issue raised with coupling cost modeling with the lowering strategy for uniform inputs.  The discussion on that item remains unsettled and is pending larger architectural discussion.  We decided to move forward with this patch as is, and revise as warranted once the bigger picture design questions are settled.

Differential Revision: https://reviews.llvm.org/D91398
 		2020-11-23 15:32:17 -08:00
.github/workflows GitHub Actions: Add job for automatically updating the main branch 2020-11-20 22:26:11 -08:00
clang APINotes: add property models for YAML attributes 2020-11-23 21:29:17 +00:00
clang-tools-extra [clang-tidy] Use compiled regex for AllowedRegexp in macro usage check 2020-11-23 20:46:43 +00:00
compiler-rt [compiler-rt] [profile] Silence a warning about an unused function on mingw targets 2020-11-21 22:14:35 +02:00
debuginfo-tests Added GDB pretty printer for StringMap 2020-11-18 16:33:34 -08:00
flang Add Semantic check for Flang OpenMP 4.5 - 2.7.1 ordered and collapse clause 2020-11-22 18:38:57 +05:30
libc [libc] Make more of the libc unit testing llvm independent 2020-11-21 00:27:08 +00:00
libclc libclc: Use find_package to find Python 3 and require it 2020-10-01 22:31:33 +02:00
libcxx [libcxx] Resolve LWG 2724 protected -> private. 2020-11-23 14:27:22 -08:00
libcxxabi [libc++] [libc++abi] Use C++20 standard. 2020-11-22 15:57:25 +01:00
libunwind [libunwind] Delete unused handlerNotFound in unwind_phase1 2020-11-21 12:38:00 -08:00
lld [lib/Object] - Generalize the RelocationResolver API. 2020-11-20 10:32:49 +03:00
lldb [lldb/test] Remove flaky `process connect` test. 2020-11-23 12:49:50 -08:00
llvm [LoopVectorizer] Lower uniform loads as a single load (instead of relying on CSE) 2020-11-23 15:32:17 -08:00
mlir [mlir] Support WsLoopOp in OpenMP to LLVM dialect conversion 2020-11-23 23:28:02 +01:00
openmp Revert "[OpenMP] Add support for Intel's umonitor/umwait" 2020-11-20 12:16:34 +03:00
parallel-libs Reapply "Try enabling -Wsuggest-override again, using add_compile_options instead of add_compile_definitions for disabling it in unittests/ directories." 2020-07-22 17:50:19 -07:00
polly [Polly] Use LocationSize::unknown() (NFC) 2020-11-19 20:26:43 +01:00
pstl [pstl] Replace direct use of assert() with _PSTL_ASSERT 2020-11-02 18:35:54 -05:00
utils/arcanist Fix arc lint's clang-format rule: only format the file we were asked to format. 2020-10-11 14:24:23 -07:00
.arcconfig [arcconfig] Default base to previous revision 2020-02-24 16:20:25 -08:00
.arclint PR46997: don't run clang-format on clang's testcases. 2020-08-04 17:53:25 -07:00
.clang-format
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.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 NFC: Add whitespace-changing revisions to .git-blame-ignore-revs 2020-09-21 20:17:24 -04:00
.gitignore [NFC] Adding pythonenv* to .gitignore 2020-09-03 22:42:27 -04:00
CONTRIBUTING.md
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README.md Revert "This is a test commit" 2020-10-21 09:34:15 +08:00

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.