Relevant changes include:
- Lots of work for supporting ARM64EC and ARM64X
- LLD now produces more compact string tables in executables (only
relevant when including debug symbols)
- llvm-rc now supports multiplication/division expressions, like GNU
windres
- Improved support for armv7 and aarch64 in libunwind (for Itanium
ABI "forced unwinding", which I'm not aware of being used in
practice anywhere)
- Made the libunwind, libcxxabi, libcxx and compiler-rt tests pass on
armv7 and aarch64 mingw
- Made the llvm/clang tests pass on aarch64 mingw
If using Clang from /usr/bin, this makes it clear to CMake to use
$HOST-strip, as it otherwise may pick plain /usr/bin/strip, which
may not be able to strip the cross built executables.
CMAKE_ASM_COMPILER is set implicitly from CMAKE_C_COMPILER,
but the target flags aren't implied in the same way.
This fixes cross compiling LLVM with clang for an x86_64 target.
This wasn't an issue when cross compiling LLVM with clang for an
aarch64 target, because the BLAKE3 aarch64 SIMD is in the form
of a C file (with intrinsics), not a standalone .S file.
In this case, we want to incrementally build the remaining tools,
not do a full build. In case someone runs build-all.sh with CLEAN
set, the --macos-native-tools invocation of build-llvm.sh shouldn't
wipe the build directory.
Passing --instrumented=IR or --instrumented=Frontend builds
instrumented tool binaries. After running them and merging the
output profile files, run build-llvm.sh with
--profile=profile.profdata.
When cross compiling with llvm-mingw, we already implicitly use
clang and lld, but we don't need to specify these options as they
are set implicitly via the llvm-mingw wrappers.
Don't use tools from $PREFIX/bin automatically; this can be
confusing and problematic. If running with $PREFIX/bin in path,
the build at this stage gets reconfigured if rebuilding after
installing clang.
For multistage builds, install into separate toolchain
directories and add the right one to $PATH before invoking
build-llvm.sh. If one really wants to use the tools from $PREFIX
for a new build into the same directory, one has to add that
directory to the path manually.
This is an option I set outside of this script in a number of
build cases where I build with ccache; move this into the script.
In practice it has little effect though; one has to set
CCACHE_BASEDIR anyway in order to be able to share a ccache
between build directories.
If enabling ccache by adding e.g. /usr/lib/ccache to the front of
PATH, without using the COMPILER_LAUNCHER variable, this won't
get enabled.
Relevant changes in LLVM 20.1.x compared with LLVM 19.x are:
- Don't warn when doing LTO with mixed Rust/C object files, where
the target triples differ in the vendor field
(<arch>-w64-windows-gnu vs <arch>-pc-windows-gnu)
- Fix including LLVM/MSVC style import libraries in libraries linked
with --whole-archive
- Support for files over 2 GB in the libcxx fstream methods
tellg()/seekg()
- Lots of work on improved ARM64EC and ARM64X support in LLVM and LLD
- New linker flags --dependent-load-flag and --functionpadmin, similar
to the corresponding lld-link/MS link.exe flags
- Improvements in address sanitizer, supporting many more x86
instructions
- Changes to address sanitizer, that (unintentionally) makes it fail
harder than before when used together with msvcrt.dll. Using
address sanitizer with msvcrt.dll is unsupported though.
This allows using the build-llvm.sh script for doing a cross build
of LLVM, while the same directory may contain a native build
which can be out of sync with the actual source.
The main changes for mingw targets since 18.x is primarily
minor bug fixes. llvm-dlltool has also been improved to handle
cases of renamed imports, where the target of the rename doesn't
exist as a normal import.
Martin Storsjö