Compiled on RPI4B-8G with 6.6.47-piCore-v8 on portable SSD

Compile Flags:
## test build ##
CC='clang'
CXX='clang++'
CFLAGS='-march=armv6zk -mtune=arm1176jzf-s -mfpu=vfp -Os -pipe'
CXXFLAGS='-march=armv6zk -mtune=arm1176jzf-s -mfpu=vfp -Os -pipe'
EXTRA_C=' -L/usr/local/lib -flto -fuse-ld=gold -fuse-linker-plugin -fno-exceptions'
EXTRA_CXX=' -L/usr/local/lib -flto -fuse-ld=gold -fuse-linker-plugin -fno-exceptions -fno-rtti'
CFLAGS="${CFLAGS}${EXTRA_C}"
CXXFLAGS="${CXXFLAGS}${EXTRA_CXX}"
LDFLAGS='-Wl,-L/usr/local/lib -Wl,-O1'
export CFLAGS CXXFLAGS LDFLAGS

## actual package ##
CC='clang --gcc-install-dir=/usr/local/lib/gcc/armv7l-unknown-linux-gnueabihf/13.2.0'
CXX='clang++ --gcc-install-dir=/usr/local/lib/gcc/armv7l-unknown-linux-gnueabihf/13.2.0'
CFLAGS='-march=armv6zk -mtune=arm1176jzf-s -mfpu=vfp -Os -pipe'
CXXFLAGS='-march=armv6zk -mtune=arm1176jzf-s -mfpu=vfp -Os -pipe'
EXTRA_C=' -L/usr/local/lib -flto=full -fuse-ld=lld -fno-exceptions'
EXTRA_CXX=' -L/usr/local/lib -flto=full -fuse-ld=lld -fno-exceptions -fno-rtti'
CFLAGS="${CFLAGS}${EXTRA_C}"
CXXFLAGS="${CXXFLAGS}${EXTRA_CXX}"
LDFLAGS='-L/usr/local/lib -Wl,-O1 -Wl,-rpath=/usr/local/lib'
export CC CXX CFLAGS CXXFLAGS LDFLAGS

Dependencies:
compiletc
llvm19-dev
cmake
python3.12
ninja
clang

Commands:

sudo busybox cp $(realpath /usr/local/bin/llvm-config) /usr/local/bin/llvm-config

cd /mnt/sda1/compile-temp

VER=19.1.0

wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VER}/lld-${VER}.src.tar.xz
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VER}/libunwind-${VER}.src.tar.xz
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VER}/cmake-${VER}.src.tar.xz

tar -xf lld-${VER}.src.tar.xz
tar -xf libunwind-${VER}.src.tar.xz
tar -xf cmake-${VER}.src.tar.xz

mv libunwind-${VER}.src/include/mach-o/ lld-${VER}.src/MachO/
mv cmake-${VER}.src/ cmake/
cd lld-${VER}.src/ && mkdir build && cd build

## test builds ##
# export test flags

### GCC + GOLD ###

time cmake -DCMAKE_C_FLAGS_MINSIZEREL="$CFLAGS" -DCMAKE_CXX_FLAGS_MINSIZEREL="$CXXFLAGS" \
 -DCMAKE_BUILD_TYPE=MINSIZEREL -DLLVM_ENABLE_PROJECTS=lld -DCMAKE_INSTALL_PREFIX=/usr/local -G Ninja ..
real    0m 5.02s
user    0m 3.80s
sys     0m 1.43s

time ninja -j4
real    14m 5.70s
user    40m 44.54s
sys     1m 27.27s

DESTDIR=/mnt/sda1/compile-temp/gcc-outcome ninja install

sudo ninja install

### CLANG + LLD ###

#### LTO: -flto

time ninja -j4
real    35m 56.11s
user    1h 59m 51s
sys     1m 19.98s

#### LTO: -flto=thin

time ninja -j4
real    32m 0.75s
user    2h 2m 34s
sys     1m 20.34s

#### LTO: -flto=full

time ninja -j4
real    35m 58.42s
user    1h 59m 44s
sys     1m 21.56s

### Size comparison
tc@pi4-1:/mnt/sda1/unstripped-copies$ du -hd0 *
117.6M  gcc-outcome
62.0M   lld
61.7M   lld-full
63.7M   lld-thin
tc@pi4-1:/tmp/stripped$ du -hd0 *
102.6M  gcc-outcome
54.9M   lld
54.6M   lld-full
55.2M   lld-thin

## final package ##

#### LTO: -flto=full