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Juneyoung Lee d9a4a24413 Add CanonicalizeFreezeInLoops pass
Summary:
If an induction variable is frozen and used, SCEV yields imprecise result
because it doesn't say anything about frozen variables.

Due to this reason, performance degradation happened after
https://reviews.llvm.org/D76483 is merged, causing
SCEV yield imprecise result and preventing LSR to optimize a loop.

The suggested solution here is to add a pass which canonicalizes frozen variables
inside a loop. To be specific, it pushes freezes out of the loop by freezing
the initial value and step values instead & dropping nsw/nuw flags from instructions used by freeze.
This solution was also mentioned at https://reviews.llvm.org/D70623 .

Reviewers: spatel, efriedma, lebedev.ri, fhahn, jdoerfert

Reviewed By: fhahn

Subscribers: nikic, mgorny, hiraditya, javed.absar, llvm-commits, sanwou01, nlopes

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77523
2020-05-21 09:29:29 +09:00
clang [clang-format][docfix] Update predefined styles in docs 2020-05-20 20:03:53 -04:00
clang-tools-extra [clangd-remote] Replace YAML serialization with proper Protobuf messages 2020-05-19 17:07:38 +02:00
compiler-rt [sanitizer_symbolizer] Add __isinf to symbols list. 2020-05-20 12:39:40 -07:00
debuginfo-tests Only run pretty-printer tests for builds with debug-info. 2020-05-14 09:19:43 +02:00
flang [flang] Constraint checks C751 to C760 2020-05-15 18:50:14 -07:00
libc [libc] Add memset and bzero implementations 2020-05-20 06:35:13 +00:00
libclc libclc: Pass system libraries to the linker after llvm libraries 2020-04-29 15:34:54 -07:00
libcxx [libcxx][test] Portability fix for some locale-dependent tests. 2020-05-20 14:35:18 -04:00
libcxxabi [demangler] Support for 'this' expressions 2020-05-13 22:28:51 -04:00
libunwind unwind: fix unwind build without heap 2020-05-15 14:45:22 -07:00
lld [LLD] Make scoped timers thread safe 2020-05-20 16:16:08 -07:00
lldb [lldb/Test] Support arbitrary file extensions in TestPositionalArgs.test 2020-05-20 14:09:19 -07:00
llvm Add CanonicalizeFreezeInLoops pass 2020-05-21 09:29:29 +09:00
mlir [mlir] NFC - Appease GCC 5 again.. 2020-05-20 17:58:18 -04:00
openmp [openmp] Fixed hang if detached task was serialized. 2020-05-18 15:32:13 +03:00
parallel-libs [arcconfig] Delete subproject arcconfigs 2020-02-24 16:20:36 -08:00
polly Make Value::getPointerAlignment() return an Align, not a MaybeAlign. 2020-05-20 16:37:20 -07:00
pstl [pstl] A fix for move placement-new (and destroy) allocated objects from raw memory. 2020-05-18 17:00:13 +03:00
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.