Initial pr

bootstrap.sh

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+set -eu
+
+LLVM_URL=https://github.com/llvm/llvm-project.git
+
+function update_llvm () {
+  pushd llvm-project
+  git fetch --depth 1
+  git reset --hard origin/main
+  popd
+}
+
+function fetch_llvm () {
+  git clone --depth=1 $LLVM_URL --branch main --single-branch
+}
+
+function get_or_fetch_llvm () {
+  if [[ -d llvm-project ]]; then
+    update_llvm
+  else
+    fetch_llvm
+  fi;
+}
+
+function bootstrap_compiler_rt () {
+  #rm -rf sysroot
+  mkdir -p sysroot
+  SYSROOT=$(readlink -f sysroot)
+  CC=$(which clang)
+  CXX=$(which clang++)
+
+  #rm -rf llvm-project/compiler-rt/build
+  mkdir -p llvm-project/compiler-rt/build
+  pushd llvm-project/compiler-rt/build
+  cmake -D CMAKE_BUILD_TYPE=Release \
+    -D CMAKE_CXX_COMPILER=$CXX \
+    -D CMAKE_CXX_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D CMAKE_C_COMPILER=$CC \
+    -D CMAKE_C_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D COMPILER_RT_BUILD_LIBFUZZER=NO \
+    -D COMPILER_RT_BUILD_MEMPROF=NO \
+    -D COMPILER_RT_BUILD_ORC=NO \
+    -D COMPILER_RT_BUILD_PROFILE=NO \
+    -D COMPILER_RT_BUILD_SANITIZERS=NO \
+    -D COMPILER_RT_BUILD_XRAY=NO \
+    -D COMPILER_RT_DEFAULT_TARGET_TRIPLE=x86_64-unknown-linux-musl \
+    -D LLVM_ENABLE_PROJECTS="compiler-rt;" \
+    -D LLVM_TARGETS_TO_BUILD="X86;" \
+    -G Ninja \
+    -S ..
+    #-D CMAKE_INSTALL_LIBDIR=lib \
+    #-D CMAKE_INSTALL_PREFIX=woof \
+    #-D COMPILER_RT_INSTALL_PATH=woof \
+    #-D COMPILER_RT_INSTALL_LIBRARY_DIR=woof \
+  ninja compiler-rt
+  DESTDIR=$SYSROOT ninja install
+  popd
+}
+
+get_or_fetch_llvm
+bootstrap_compiler_rt
+./kernel.sh
+./musl.sh

kernel.sh

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+set -eu
+
+LINUX_URL=https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+
+function update_linux () {
+  pushd linux
+  git fetch --depth 1
+  git reset --hard origin/master
+  popd
+}
+
+function fetch_linux () {
+  git clone --depth=1 $LINUX_URL --branch master --single-branch
+}
+
+function get_or_fetch_linux_kernel () {
+  if [[ -d linux ]]; then
+    update_linux
+  else
+    fetch_linux
+  fi;
+}
+
+function build_kernel_headers () {
+  if [[ -d kernel-headers ]]; then
+    return
+  fi
+
+  pushd linux
+  make LLVM=1 INSTALL_HDR_PATH=../kernel-headers mrproper headers_install -j$(nproc)
+  popd
+}
+
+get_or_fetch_linux_kernel
+build_kernel_headers

musl.sh

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+set -eu
+
+MUSL_URL=git://git.musl-libc.org/musl
+
+function update_musl () {
+  pushd musl
+  git fetch --depth 1
+  git reset --hard origin/master
+  popd
+}
+
+function fetch_musl () {
+  git clone --depth=1 $MUSL_URL --branch master --single-branch
+}
+
+function get_or_fetch_musl () {
+  if [[ -d musl ]]; then
+    update_musl
+  else
+    fetch_musl
+  fi;
+}
+
+function build_musl () {
+  # TODO: something better than this...like if we updated musl.
+  if [[ -d sysroot/usr/local/include ]]; then
+    if [[ -n "$(find sysroot/usr/local/include -type f | wc -l)" ]]; then
+      return
+    fi;
+  fi;
+
+  BUILTINS=$(readlink -f sysroot/usr/local/lib/linux/libclang_rt.builtins-x86_64.a)
+  CC=$(which clang)
+  SYSROOT=$(readlink -f sysroot)
+  rm -rf musl/build
+  mkdir -p musl/build
+  pushd musl/build
+  LIBCC=$BUILTINS CC=$CC ../configure \
+    --prefix=/usr/local/ \
+    --host=x86_64-unknown-linux-musl \
+    --syslibdir=/usr/local/lib \
+    --disable-static
+
+  make -j$(nproc) AR=llvm-ar RANLIB=llvm-ranlib
+  make DESTDIR=$SYSROOT install-libs install-headers -j$(nproc)
+
+  # TODO: hack
+  pushd $SYSROOT/usr/local/lib
+  ln -sf libc.so ld-musl-x86_64.so.1
+  popd
+  popd
+  ./test_lib.sh
+}
+
+get_or_fetch_musl
+build_musl

test_lib.sh

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+set -eu
+
+cat << EOF > test.c
+#include <stdio.h>
+int main() { puts("hello world"); }
+EOF
+
+# -fuse-ld: use LLD rather than BFD.
+# -rtlib: use compiler-rt rather than libgcc.
+# -Xlinker --dynamic-linker: use musl's dynamic loader as the program
+#                            interperter.
+# --target: use musl rather than glibc.
+# -resource-dir: use our compiler-rt builtins.
+# --sysroot: use our libc headers
+clang test.c \
+  -fuse-ld=lld \
+  -rtlib=compiler-rt \
+  -Xlinker --dynamic-linker=sysroot/usr/local/lib/ld-musl-x86_64.so.1 \
+  --target=x86_64-unknown-linux-musl \
+  -resource-dir=sysroot/usr/local \
+  --sysroot=sysroot/usr/local
+
+./a.out
+rm -f test.c a.out