New script to build clang rt builtins

Author: apaillier-ledger

tools/build_clangrt_builtins.sh

@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+
+set -e
+
+TARGET_CPU=""
+OUTPUT_DIR=""
+
+while getopts "t:o:" opt
+do
+    case "$opt" in
+        t)
+            TARGET_CPU="$OPTARG"
+            ;;
+        o)
+            OUTPUT_DIR="$OPTARG"
+            ;;
+        ?)
+            exit 1
+            ;;
+    esac
+done
+shift "$((OPTIND - 1))"
+
+if [ -z "$TARGET_CPU" ] || [ -z "$OUTPUT_DIR" ]
+then
+    echo "Usage: $0 -t TARGET_CPU -o OUTPUT_FILE" >&2
+    exit 1
+fi
+
+mkdir -p "$OUTPUT_DIR"
+OUTPUT_DIR=$(realpath "$OUTPUT_DIR")
+
+# enable source repository
+sed -i 's/^\(Types: deb\)$/\1 deb-src/g' /etc/apt/sources.list.d/debian.sources
+
+apt update
+
+apt install -y --no-install-recommends \
+    dpkg-dev \
+    llvm-dev
+
+LLVM_VERSION=$(clang --version | head -n1 | rev | cut -d" " -f1 | rev)
+LLVM_MAJOR_VERSION=$(echo "$LLVM_VERSION" | cut -d. -f1)
+
+cd /tmp
+
+LLVM_DIR="llvm-toolchain-$LLVM_MAJOR_VERSION-$LLVM_VERSION"
+if [ ! -d "$LLVM_DIR" ]
+then
+    # install Debian source package
+    apt source "llvm-toolchain-$LLVM_MAJOR_VERSION"
+fi
+
+cd "$LLVM_DIR"
+rm -rf build
+mkdir build
+cd build
+
+TARGET=arm-none-eabi
+SYSROOT=/usr/lib/arm-none-eabi
+
+cmake ../compiler-rt \
+    -DCMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY \
+    -DCOMPILER_RT_OS_DIR="baremetal" \
+    -DCOMPILER_RT_BUILD_BUILTINS=ON \
+    -DCOMPILER_RT_BUILD_CRT=OFF \
+    -DCOMPILER_RT_BUILD_SANITIZERS=OFF \
+    -DCOMPILER_RT_BUILD_XRAY=OFF \
+    -DCOMPILER_RT_BUILD_LIBFUZZER=OFF \
+    -DCOMPILER_RT_BUILD_PROFILE=OFF \
+    -DCOMPILER_RT_BUILD_MEMPROF=OFF \
+    -DCOMPILER_RT_BUILD_ORC=OFF \
+    -DCMAKE_C_COMPILER="$(which clang)" \
+    -DCMAKE_C_COMPILER_TARGET="${TARGET}" \
+    -DCMAKE_ASM_COMPILER_TARGET="${TARGET}" \
+    -DCMAKE_AR="$(which llvm-ar)" \
+    -DCMAKE_NM="$(which llvm-nm)" \
+    -DCMAKE_RANLIB="$(which llvm-ranlib)" \
+    -DCOMPILER_RT_BAREMETAL_BUILD=ON \
+    -DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON \
+    -DLLVM_CONFIG_PATH="$(which llvm-config)" \
+    -DCOMPILER_RT_HAS_FPIC_FLAG=OFF \
+    -DCMAKE_C_FLAGS="-mcpu=${TARGET_CPU} -mlittle-endian -mthumb -Oz -g0 -fropi -frwpi" \
+    -DCMAKE_ASM_FLAGS="-mcpu=${TARGET_CPU} -mlittle-endian -mthumb" \
+    -DCMAKE_SYSROOT="$SYSROOT"
+make -j
+
+# Removing duplicated symbols that are also present in picolibc
+ar d lib/baremetal/libclang_rt.builtins-arm.a aeabi_memset.S.o
+ar d lib/baremetal/libclang_rt.builtins-arm.a aeabi_memmove.S.o
+ar d lib/baremetal/libclang_rt.builtins-arm.a aeabi_memcpy.S.o
+
+# Output
+mkdir -p "$OUTPUT_DIR"
+cp lib/baremetal/libclang_rt.builtins-arm.a "$OUTPUT_DIR/libclang_rt.builtins.a"