Go to file
Kazu Hirata a7b662d0f4 [BranchProbabilityInfo] Fix eraseBlock
This patch ensures that BranchProbabilityInfo::eraseBlock(BB) deletes
all entries in Probs associated with with BB.

Without this patch, stale entries for BB may remain in Probs after
eraseBlock(BB), leading to a situation where a newly created basic
block has an edge probability associated with it even before the pass
responsible for creating the basic block adds any edge probability to
it.

Consider the current implementation of eraseBlock(BB):

  for (const_succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
    auto MapI = Probs.find(std::make_pair(BB, I.getSuccessorIndex()));
    if (MapI != Probs.end())
      Probs.erase(MapI);
  }

Notice that it uses succ_begin(BB) and succ_end(BB), which are based
on BB->getTerminator().  This means that if the terminator changes
between calls to setEdgeProbability and eraseBlock, then we may not
examine all pairs associated with BB.

This is exactly what happens in MaybeMergeBasicBlockIntoOnlyPred,
which merges basic blocks A into B if A is the sole predecessor of B,
and B is the sole successor of A.  It replaces the terminator of A
with UnreachableInst before (indirectly) calling eraseBlock(A).

The patch fixes the problem by keeping track of all edge probablities
entered with setEdgeProbability in a map from BasicBlock* to a
successor index.

Differential Revision: https://reviews.llvm.org/D90272
2020-10-27 16:14:25 -07:00
clang [OpenMP] Add Passing in Original Declaration Names To Mapper API 2020-10-27 16:09:19 -04:00
clang-tools-extra [clangd] Start using SyntaxTrees for folding ranges feature 2020-10-27 16:47:35 +01:00
compiler-rt Revert "Use uint64_t for branch weights instead of uint32_t" 2020-10-27 09:26:21 -04:00
debuginfo-tests [DebugInfo][dexter] Add dexter tests for escaped locals 2020-10-26 10:57:36 +00:00
flang [Flang][OpenMP 4.5] Add semantic check for OpenMP default clause 2020-10-27 12:38:47 -04:00
libc [libc] Add LLVM libc specific functions to llvm_libc_ext.td. 2020-10-19 18:21:25 +00:00
libclc libclc: Use find_package to find Python 3 and require it 2020-10-01 22:31:33 +02:00
libcxx [libcxx] Don't truncate intermediates to wchar_t when widening 2020-10-27 23:58:27 +02:00
libcxxabi [libc++abi] Make sure we can run the tests in Standalone mode 2020-10-26 14:26:44 -04:00
libunwind [libunwind] Add -Wno-dll-attribute-on-redeclaration when building for windows 2020-10-26 23:23:01 +02:00
lld [lld][WebAssembly] Fix memory size in dylink section for -pie exectuables 2020-10-27 16:05:52 -07:00
lldb [lldb] Support Python imports relative the to the current file being sourced 2020-10-27 09:20:45 -07:00
llvm [BranchProbabilityInfo] Fix eraseBlock 2020-10-27 16:14:25 -07:00
mlir [mlir] JitRunner: add a config option to register symbols with ExecutionEngine at runtime 2020-10-27 15:57:34 -07:00
openmp [OpenMP] Add Support for Mapping Names in Libomptarget RTL 2020-10-27 16:53:05 -04:00
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 Avoid unnecessary uses of `MDNode::getTemporary`, NFC 2020-10-26 17:03:25 -04:00
pstl [pstl] Support Threading Building Blocks 2020 (oneTBB) for "tbb" parallel backend. 2020-09-14 14:21:54 +03:00
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
.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
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.