Some notable changes since LLVM 21.x related to mingw:
- Handle an uncommon error code in libcxx's std::filesystem,
avoiding spurious test failures if running the libcxx test suite
(noted at least occasionally on Github Actions)
- Reinstate x86 stack probe functions in compiler-rt, that we earlier
beleived weren't used - but turned out to be used by GCC in i386
mode
- Fix interpretation of a few corner case aarch64 SEH unwind opcodes
- Support for FAT LTO (compile with -ffat-lto-objects, link with
-Wl,--fat-lto-objects)
- llvm-objcopy: Support the -p option for COFF targets
- llvm-readobj: A new option --coff-pseudoreloc for dumping information
and symbols for mingw runtime pseudo relocations
- Lots of various fixes for the cygwin target
- Improve linking a custom CRT with binutils ld (by passing the custom
CRT -l option at the same place as the original default -lmsvcrt)
- Make lld use the right mingw specific DLL entry point implicitly,
improving some Rust use cases
- Fix running the libcxx tests with optimization for mingw targets,
allowing more test coverage of the code generation paths
According to https://github.com/mstorsjo/llvm-mingw/issues/533,
if OCaml support is detected and the LLVM OCaml bindings are built,
they are attempted to be installed in a path that require root access.
This version fixes catching pointer data types by reference in C++.
This version also fixes throwing C++ exceptions on aarch64 with
a debugger attached to the process.
Finally, this version fixes delayimport calling of C++ methods that
return structs on aarch64.
This allows overriding which linker to use.
Currently, building LLVM on Ubuntu 25.10 with these scripts fails,
if LLD is available. This, because the GCC on that distribution
produces object files that LLD (and gold) rejects during linking - see
https://github.com/llvm/llvm-project/issues/156667 for details.
By building with --use-linker=bfd, linking does succeed in that
configuration.
Also pass the same option through from build-all.sh.
In this case it's usually an option that wasn't recognized
(although the misrecognized option may have been an earlier
option and the current one may be the intended prefix).
These variable expansions/modifications work the same if the
option "--pgo" is specified - so either we can simplify the
stripping of the "--pgo=" prefix, or we can just skip the check,
similar to the case above with --instrumented.
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.
Martin Storsjö