tc-build: Add initial scripts and update README

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

README.md

@@ -1,2 +1,59 @@
-# tc-build
-A set of scripts to build LLVM and binutils
+# Toolchain build scripts
+
+There are times where a tip of tree LLVM build will have some issue fixed and it isn't available to you, maybe because it isn't in a release or it isn't available through your distribution's package management system. At that point, to get that fix, LLVM needs to be compiled, which sounds scary but is [rather simple](https://llvm.org/docs/GettingStarted.html). The `build-llvm.sh` script takes it a step farther by trying to optimize both LLVM's build time by:
+
+* Trimming down a lot of things that kernel developers don't care about:
+  * Documentation
+  * LLVM tests
+  * Ocaml bindings
+  * libfuzzer
+* Building with the faster tools available (in order of fastest to slowest):
+  * clang + lld
+  * clang/gcc + ld.gold
+  * clang/gcc + ld.bfd
+
+It also aims to make kernel compilation go a little bit faster by generating a toolchain that is optimized for the host CPU (using `-O2 -march=native -mtune=native`).
+
+## Getting started
+
+These scripts have been tested in a Docker image of the following distributions, with the following packages installed:
+
+* ### Debian/Ubuntu
+
+  ```
+  apt install ca-certificates ccache clang cmake curl file gcc g++ git make ninja-build python texinfo zlib1g-dev
+  ```
+
+  On Debian Buster or Ubuntu Bionic/Cosmic/Disco, `apt-get install lld` should be added as well for faster compiles.
+
+* ### Fedora
+
+  ```
+  dnf install ccache clang cmake gcc gcc-c++ git lld ninja-build python zlib-devel
+  ```
+
+* ### Arch Linux
+
+  ```
+  pacman -S base-devel ccache clang cmake git lld ninja python
+  ```
+
+These scripts should be distribution agnostic. Please feel free to add different distribution install commands here through a pull request.
+
+## build-llvm.sh
+
+By default, `./build-llvm.sh` will clone LLVM, grab the latest binutils tarball (for the LLVMgold.so plugin), and build LLVM, clang, and lld. Run `./build-llvm.sh -h` for more options.
+
+## build-binutils.sh
+
+This script builds a standalone copy of binutils. This might be needed because certain distributions like Arch Linux (whose options the script uses) might symlink `/usr/lib/LLVMgold.so` to `/usr/lib/bfd-plugins` ([source](https://bugs.archlinux.org/task/28479)), which can cause issues when using the system's linker for LTO (even with `LD_LIBRARY_PATH`):
+
+```
+bfd plugin: LLVM gold plugin has failed to create LTO module: Unknown attribute kind (60) (Producer: 'LLVM9.0.0svn' Reader: 'LLVM 7.0.1')
+```
+
+Having a standalone copy of binutils (ideally in the same folder at the LLVM toolchain so that one `PATH` modification is needed) works around this without any adverse side effects. Another workaround is bind mounting the new `LLVMgold.so` to `/usr/lib/LLVMgold.so`.
+
+## Getting help
+
+Please open an issue on this repo and include your distribution, shell, the command you ran, and the error output.

build-binutils-usage.txt

@@ -0,0 +1,20 @@
+Usage: ./build-binutils.sh [options]
+
+Description: Fetchs and builds binutils
+
+Parameters:
+    -I | --install-folder:
+        By default, the script will create a "usr" folder in the same folder as this script
+        and install binutils there. If you'd like to have it installed somewhere else, pass
+        it to this parameter. This can either be an absolute or relative path.
+
+        For example: -I ~/binutils
+
+    -t | --target:
+        The script can build binutils targeting arm-linux-gnueabi, aarch64-linux-gnu,
+        powerpc-linux-gnu, powerpc64le-linux-gnu, and x86_64-linux-gnu (host if on x86_64).
+
+        You can either pass the full target or just the first part (arm, aarch64, etc) or all
+        if you want to build all targets.
+
+        Example: -t all, -t aarch64, -t arm-linux-gnueabi

build-binutils.sh

@@ -0,0 +1,144 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC2191
+# SPDX-License-Identifier: Apache-2.0
+# Copyright (C) 2019 The ClangBuiltLinux Authors
+# Description: Builds a standalone copy of binutils
+
+
+# Properly set target if on x86_64 machine
+function x86_64_target() {
+    if [[ $(uname -m) = "x86_64" ]]; then
+        echo "host"
+    else
+        echo "x86_64-linux-gnu"
+    fi
+}
+
+
+# Initialize helper functions and export current working directory for absolute paths later
+function script_setup {
+    # Move into the folder that this script is called from (no message because this will never happen)
+    cd "$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")" || exit
+    source common.sh
+    ROOT=${PWD}
+}
+
+
+# Parse the script parameters
+function parse_parameters() {
+    TARGETS=()
+    while (( ${#} )); do
+        case ${1} in
+            "-t"|"--target")
+                shift
+                [[ ${#} -lt 1 ]] && die "-t flag requires a value!"
+                case ${1} in
+                    "all") TARGETS=( aarch64-linux-gnu arm-linux-gnueabi
+                                     powerpc-linux-gnu powerpc64le-linux-gnu
+                                     "$(x86_64_target)" ) ;;
+                    arm*) TARGETS+=( arm-linux-gnueabi ) ;;
+                    aarch64*) TARGETS+=( aarch64-linux-gnu ) ;;
+                    powerpc64le*) TARGETS+=( powerpc64-linux-gnu ) ;;
+                    powerpc*) TARGETS+=( powerpc-linux-gnu ) ;;
+                    x86*|"host") TARGETS+=( "$(x86_64_target)" ) ;;
+                esac ;;
+            "-h"|"--help") cat build-binutils-usage.txt; builtin exit 0 ;;
+            *) die "Invalid parameter '${1}' specified! Run './build-binutils.sh -h' to see all options." ;;
+        esac
+        shift
+    done
+    [[ -z ${TARGETS[*]} ]] && die "No targets specified! Please run './build-binutils.sh' to see all the options."
+}
+
+
+# Setup the build folder
+function setup_build_folder() {
+    BUILD_FOLDER=${ROOT}/build/binutils/${TARGET}
+    rm -rf "${BUILD_FOLDER}"
+    mkdir -p "${BUILD_FOLDER}"
+    cd "${BUILD_FOLDER}" || die "Couldn't create build folder??"
+}
+
+
+# Configure binutils
+function configure_binutils() {
+    COMMON_FLAGS=( --prefix="${INSTALL_FOLDER:="${ROOT}"/usr}"
+                   --enable-deterministic-archives
+                   --enable-gold
+                   --enable-ld=default
+                   --enable-plugins
+                   --quiet
+                   CFLAGS="-O2 -march=native -mtune=native"
+                   CXXFLAGS="-O2 -march=native -mtune=native" )
+    CONFIGURE=${ROOT}/${BINUTILS}/configure
+
+    case ${TARGET} in
+        arm-*|aarch64-*)
+            "${CONFIGURE}" \
+                --disable-multilib \
+                --disable-nls \
+                --program-prefix="${TARGET}"- \
+                --target="${TARGET}" \
+                --with-gnu-as \
+                --with-gnu-ld \
+                --with-sysroot="${INSTALL_FOLDER}/${TUPLE}" \
+                "${COMMON_FLAGS[@]}" ;;
+        powerpc*)
+            "${CONFIGURE}" \
+                --enable-lto \
+                --enable-relro \
+                --enable-shared \
+                --enable-threads \
+                --disable-gdb \
+                --disable-sim \
+                --disable-werror \
+                --program-prefix="${TARGET}"- \
+                --target="${TARGET}" \
+                --with-pic \
+                --with-system-zlib \
+                "${COMMON_FLAGS[@]}" ;;
+        x86*|host)
+            "${CONFIGURE}" \
+                --enable-lto \
+                --enable-relro \
+                --enable-shared \
+                --enable-targets=x86_64-pep \
+                --enable-threads \
+                --disable-gdb \
+                --disable-werror \
+                "$([[ $(uname -m) != x86_64 ]] && echo "--program-prefix=${TARGET}- --target=${TARGET}")" \
+                --with-pic \
+                --with-system-zlib \
+                "${COMMON_FLAGS[@]}"
+            [[ ${TARGET} = "host" ]] && make -s configure-host V=0 ;;
+    esac
+}
+
+
+# Build binutils
+function build_binutils() {
+    time make -s -j"$(nproc)" V=0 || die "Error building ${TARGET} binutils"
+}
+
+
+# Install binutils
+function install_binutils {
+    make -s prefix="${INSTALL_FOLDER}" install V=0 || die "Error installing ${TARGET} binutils"
+}
+
+
+# Main for loop
+function for_all_targets() {
+    for TARGET in "${TARGETS[@]}"; do
+        setup_build_folder
+        configure_binutils
+        build_binutils
+        install_binutils
+    done
+}
+
+
+script_setup
+parse_parameters "${@}"
+dwnld_binutils
+for_all_targets

build-llvm-usage.txt

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+Usage: ./build-llvm.sh [options]
+
+Description: Fetchs LLVM and binutils then builds a LLVM, clang, lld, and the LLVMgold plugin.
+
+Environment variables:
+    The script can take into account specific environment variables. They can be
+    invoked in one of three ways:
+        $ export VAR=value && ./build-llvm.sh
+        $ VAR=value ./build-llvm.sh
+        $ ./build-llvm.sh VAR=value
+
+    CC:
+        Path to or name of the C compiler. If unset, the script will try to use
+        clang if it is available, falling back to gcc if necessary.
+
+    CXX:
+        Path to or name of the C++ compiler. If unset, the script will use clang++
+        if CC is clang or g++ if CC is gcc.
+
+    LD:
+        Path to or name of the linker. If unset and using clang, the script will
+        attempt to find ld.lld then ld.gold, falling back to ld.bfd (because they
+        are objectively faster).
+
+Parameters:
+    -b | --branch:
+        By default, the script builds the master branch (tip of tree) of LLVM. If you would
+        like to build an older branch, use this parameter. This may be helpful in tracking
+        down an older bug to properly bisect. This value is just passed along to 'git checkout'
+        so it can be a branch name, tag name, or hash.
+
+        NOTE: Some of the cmake defines may not work on older branches!
+
+        Example: -b release/8.x
+
+    -d | --debug:
+        By default, the script builds LLVM in the release configuration with all of
+        the tests turned off and optimization at O2. This disables that optimization,
+        builds the tests, and changes the configuration to debug. This can help with
+        reporting problems to LLVM developers but will make compilation of both LLVM
+        and the kernel go slower.
+
+    -i | --incremental:
+        By default, the script removes all build artifacts from previous compiles. This
+        prevents that, allowing for dirty builds and faster compiles.
+
+    -I | --install-folder:
+        By default, the script will create a "usr" folder in the same folder as this script
+        and install the LLVM toolchain there. If you'd like to have it installed somewhere
+        else, pass it to this parameter. This can either be an absolute or relative path.
+
+        Example: -I ~/llvm
+
+    -n | --no-pull:
+        By default, the script always updates the LLVM repo before building. This prevents
+        that, which can be helpful during something like bisecting.
+
+    -p | --projects:
+        Currently, the script only enables the clang, compiler-rt, and lld folders in LLVM. If
+        you would like to override this, you can use this parameter and supply a list that is
+        supported by LLVM_ENABLE_PROJECTS.
+
+        See step #5 here: https://llvm.org/docs/GettingStarted.html#getting-started-quickly-a-summary
+
+        Example: -p "clang;lld;libcxx"
+
+    -t | --targets:
+        LLVM is multitargeted by default. Currently, this script only enables the arm32, aarch64,
+        powerpc, and x86 backends because that's what the Linux kernel is currently concerned with.
+        If you would like to override this, you can use this parameter and supply a list that is
+        supported by LLVM_TARGETS_TO_BUILD: https://llvm.org/docs/CMake.html#llvm-specific-variables
+
+        Example: -t "AArch64;X86"