Beyond Linux® From Scratch (systemd Edition) - Version 10.0

Chapter 13. Programming

LLVM-10.0.1

Introduction to LLVM

The LLVM package contains a collection of modular and reusable compiler and toolchain technologies. The Low Level Virtual Machine (LLVM) Core libraries provide a modern source and target-independent optimizer, along with code generation support for many popular CPUs (as well as some less common ones!). These libraries are built around a well specified code representation known as the LLVM intermediate representation ("LLVM IR").

The optional Clang and Compiler RT packages provide new C, C++, Objective C and Objective C++ front-ends and runtime libraries for the LLVM and are required by some packages which use Rust, for example firefox.

This package is known to build and work properly using an LFS-10.0 platform.

Package Information

Optional Downloads

Clang

Compiler RT

LLVM Dependencies

Required

CMake-3.18.1

Optional

Doxygen-1.8.19, git-2.28.0, Graphviz-2.44.1, libxml2-2.9.10, Python-2.7.18, rsync-3.2.3 (for tests), texlive-20200406 (or install-tl-unx), Valgrind-3.16.1, PyYAML-5.3.1, Zip-3.0, OCaml, psutil, recommonmark, Sphinx, and Z3

User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/llvm

Installation of LLVM

If you have downloaded the optional packages, install them into the source tree by running the following commands: 

tar -xf ../clang-10.0.1.src.tar.xz -C tools          &&
tar -xf ../compiler-rt-10.0.1.src.tar.xz -C projects &&

mv tools/clang-10.0.1.src tools/clang &&
mv projects/compiler-rt-10.0.1.src projects/compiler-rt

Install LLVM by running the following commands: 

mkdir -v build &&
cd       build &&

CC=gcc CXX=g++                                  \
cmake -DCMAKE_INSTALL_PREFIX=/usr               \
      -DLLVM_ENABLE_FFI=ON                      \
      -DCMAKE_BUILD_TYPE=Release                \
      -DLLVM_BUILD_LLVM_DYLIB=ON                \
      -DLLVM_LINK_LLVM_DYLIB=ON                 \
      -DLLVM_ENABLE_RTTI=ON                     \
      -DLLVM_TARGETS_TO_BUILD="host;AMDGPU;BPF" \
      -DLLVM_BUILD_TESTS=ON                     \
      -Wno-dev -G Ninja ..                      &&
ninja

If you have installed Sphinx and recommonmark and wish to generate the html documentation and manual pages, issue the following commands: 

cmake -DLLVM_ENABLE_SPHINX=ON         \
      -DSPHINX_WARNINGS_AS_ERRORS=OFF \
      -Wno-dev -G Ninja ..            &&
ninja docs-llvm-html  docs-llvm-man

If you have downloaded the optional packages, the clang documentation can be built too: 

ninja docs-clang-html docs-clang-man

To test the results, issue: ninja check-all. Tests are built with all available cores, but run using the number of online processors. (The difference is that available cores can be limited using taskset, but taking them offline requires echoing 0 to /sys/devices/system/cpu/cpu<N>/online by the root user and makes them temporarily unusable by all jobs on the machine.) Note that the Sanitizer based tests (6 of more than 41000 tests run) are known to fail.

Now, as the root user: 

ninja install

If you have built the the llvm documentation, install it by running the following commands as the root user: 

install -v -m644 docs/man/* /usr/share/man/man1             &&
install -v -d -m755 /usr/share/doc/llvm-10.0.1/llvm-html     &&
cp -Rv docs/html/* /usr/share/doc/llvm-10.0.1/llvm-html

If you have built the clang documentation, it can be installed in the same way (again as the root user): 

install -v -m644 tools/clang/docs/man/* /usr/share/man/man1 &&
install -v -d -m755 /usr/share/doc/llvm-10.0.1/clang-html    &&
cp -Rv tools/clang/docs/html/* /usr/share/doc/llvm-10.0.1/clang-html

Command Explanations

-DLLVM_ENABLE_FFI=ON: This switch enables LLVM to use libffi.

-DLLVM_BUILD_LLVM_DYLIB=ON: builds libraries as static and links all of them into an unique shared one. This is the recommended way of building a shared library.

-DCMAKE_BUILD_TYPE=Release: This switch enables compiler optimizations in order to speed up the code and reduce its size. It also disables some compile checks which are not necessary on a production system.

-DLLVM_TARGETS_TO_BUILD="host;AMDGPU;BPF": This switch enables building for the same target as the host, and also for the r600 AMD GPU used by the Mesa r600 and radeonsi drivers. The BPF target is required to build v4l-utils-1.20.0. Default is all. You can use a semicolon separated list. Valid targets are: host, X86, Sparc, PowerPC, ARM, AArch64, Mips, Hexagon, Xcore, MSP430, NVPTX, SystemZ, AMDGPU, BPF, CppBackend, or all.

-DLLVM_LINK_LLVM_DYLIB=ON: Used in conjunction with -DLLVM_BUILD_LLVM_DYLIB=ON, this switch enables linking the tools against the shared library instead of the static ones. It also slightly reduces their size and also ensures that llvm-config will correctly use libLLVM-10.0.so.

-DLLVM_ENABLE_RTTI=ON: Used to build LLVM with run-time type information. This is required for building Mesa-20.1.5.

-DBUILD_SHARED_LIBS=ON: if used instead of -DLLVM_BUILD_LLVM_DYLIB=ON and -DLLVM_LINK_LLVM_DYLIB=ON, builds all the LLVM libraries (about 60) as shared libraries instead of static.

-DLLVM_ENABLE_DOXYGEN: Enables the generation of browsable HTML documentation if you have installed Doxygen-1.8.19. You should run make doxygen-html afterwards, and install the generated documentation manually.

Contents

Installed Programs: bugpoint, c-index-test, clang, clang++ (symlinks to clang-<version>), clang-<version>, clang-check, clang-cl, clang-cpp (last two symlinks to clang), clang-format, clang-extdef-mapping, clang-import-test, clang-offload-bundler, clang-offload-wrapper, clang-refactor, clang-rename, clang-scan-deps, diagtool, dsymutil, git-clang-format, hmap-tool, llc, lli, llvm-addr2line, llvm-ar, llvm-as, llvm-bcanalyzer, llvm-cat, llvm-cfi-verify, llvm-config, llvm-cov, llvm-c-test, llvm-cvtres, llvm-cxxdump, llvm-cxxfilt, llvm-cxxmap, llvm-diff, llvm-dis, llvm-dlltool (symlink to llvm-ar), llvm-dwarfdump, llvm-dwp, llvm-elfabi, llvm-exegenesis, llvm-extract, llvm-ifs, llvm-install-name-tool (symlink to llvm-objcopy), llvm-jitlink, llvm-lib (symlink to llvm-ar), llvm-link, llvm-lipo, llvm-lto, llvm-lto2, llvm-mc, llvm-mca, llvm-modextract, llvm-mt, llvm-nm, llvm-objcopy, llvm-objdump, llvm-opt-report, llvm-pdbutil, llvm-profdata, llvm-ranlib (symlink to llvm-ar), llvm-rc, llvm-readelf (symlink to llvm-readobj), llvm-readobj, llvm-reduce, llvm-rtdyld, llvm-size, llvm-split, llvm-stress, llvm-strings, llvm-strip (symlink to llvm-objcopy), llvm-symbolizer, llvm-tblgen, llvm-undname, llvm-xray, obj2yaml, opt, sancov, sanstats, scan-build, scan-view, verify-uselistorder, and yaml2obj
Installed Libraries: libLLVM.so, libLLVM*.a (75 libraries), libLTO.so, libRemarks.so, libclang.so, and libclang*.a (63 libraries)
Installed Directories: /usr/include/{clang,clang-c,llvm,llvm-c}, /usr/lib/{clang,cmake/{clang,llvm}}, /usr/share/{clang,opt-viewer,scan-build,scan-view}, and /usr/share/doc/llvm-10.0.1

Short Descriptions

bugpoint

is the automatic test case reduction tool.

c-index-test

is used to test the libclang API and demonstrate its usage.

clang

is the Clang C, C++, and Objective-C compiler.

clang-check

is a tool to perform static code analysis and display Abstract Syntax Trees (AST).

clang-extdef-mapping

is a tool to collect the USR name and location of external definitions in a source file.

clang-format

is a tool to format C/C++/Java/JavaScript/Objective-C/Protobuf code.

clang-offload-bundler

is a tool to bundle/unbundle openMP offloaded files associated with a common source file.

clang-offload-bundler

is a tool to create wrapper bitcode for offload target binaries.

clang-refactor

is a Clang-based refactoring tool for C, C++ and Objective-C.

clang-rename

is a tool to rename symbols in C/C++ programs.

clang-scan-deps

is a tool to scan for dependencies in a source file.

diagtool

is a combination of tools for dealing with diagnostics in clang.

dsymutil

is a tool used to manipulate archived DWARF debug symbol files, compatible with the Darwin command dsymutil.

git-clang-format

runs clang-format on git generated patches (requires git-2.28.0)

hmaptool

is a Python tool to dump and construct header maps.

llc

is the LLVM static compiler.

lli

is used to directly execute programs from LLVM bitcode.

llvm-addr2line

is a tool used to convert addresses into file names and line numbers.

llvm-ar

is the LLVM archiver.

llvm-as

is the LLVM assembler.

llvm-bcanalyzer

is the LLVM bitcode analyzer.

llvm-cat

is a tool to concatenate llvm modules.

llvm-cfi-verify

identifies whether Control Flow Integrity protects all indirect control flow instructions in the provided object file, DSO, or binary.

llvm-config

Prints LLVM compilation options.

llvm-cov

is used to emit coverage information.

llvm-c-test

is a bytecode disassembler.

llvm-cvtres

is a tool to convert Microsoft resource files to COFF.

llvm-cxxdump

is used as a C++ ABI Data Dumper.

llvm-cxxfilt

is used to demangle C++ symbols in llvm code.

llvm-cxxmap

is used to remap C++ mangled symbols.

llvm-diff

is the LLVM structural 'diff'.

llvm-dis

is the LLVM disassembler.

llvm-dwarfdump

prints the content of DWARF sections in object files.

llvm-dwp

merges split DWARF files.

llvm-elfabi

is used to read information about an ELF binary's ABI.

llvm-exegesis

is a benchmarking tool that uses information available in LLVM to measure host machine instruction characteristics like latency or port decomposition.

llvm-extract

is used to extract a function from an LLVM module.

llvm-ifs

is used to merge interface stubs with object files.

llvm-install-name-tool

is used to rewrite load commands into MachO binary format.

llvm-jitlink

is used to parse relocatable object files to make their contents executable in a target process.

llvm-link

is the LLVM linker.

llvm-lipo

is used to create universal binaries from MachO files.

llvm-lto

is the LLVM LTO (link time optimization) linker.

llvm-lto2

is a test harness for the resolution based LTO interface.

llvm-mc

is a standalone machine code assembler/disassembler.

llvm-mca

is a is a performance analysis tool to statically measure the performance of machine code.

llvm-modextract

is a tool to extract one module from multimodule bitcode files.

llvm-mt

is a tool to generate signed files and catalogs from a side-by-side assembly manifest (used for Microsoft SDK).

llvm-nm

is used to list LLVM bitcode and object file's symbol table.

llvm-objcopy

is LLVM's version of an objcopy tool.

llvm-objdump

is an LLVM object file dumper.

llvm-opt-report

is a tool to generate an optimization report from YAML optimization record files.

llvm-pdbutil

is a PDB (Program Database) dumper. PDB is a Microsoft format.

llvm-profdata

is a small tool to manipulate and print profile data files.

llvm-ranlib

is used to generate an index for a LLVM archive.

llvm-rc

is a platform-independent tool to compile resource scripts into binary resource files.

llvm-readobj

displays low-level format-specific information about object files.

llvm-reduce

is used to automatically reduce testcases when running a test suite.

llvm-rtdyld

is the LLVM MC-JIT tool.

llvm-size

is the LLVM object size dumper.

llvm-split

is the LLVM module splitter.

llvm-stress

is used to generate random .ll files.

llvm-strings

print strings found in a binary (object file, executable, or archive library).

llvm-symbolizer

converts adresses into source code locations.

llvm-tblgen

is the LLVM Target Description To C++ Code Generator.

llvm-undname

is a tool to demangle names.

llvm-xray

is an implementation of Google's XRay function call tracing system.

obj2yaml

takes an object file, and produces a YAML representation of the file.

opt

is the LLVM optimizer.

sancov

is the sanitizer coverage processing tool.

sanstats

is the sanitizer statistics processing tool.

scan-build

is a Perl script that invokes the Clang static analyzer.

scan-view

is a viewer for Clang static analyzer results.

verify-uselistorder

is the LLVM tool to verify use-list order.

yaml2obj

takes a YAML representation of an object file and converts it to a binary file.

Last updated on 2020-08-16 21:12:39 -0700