As the preinstalled CMake on the windows-11-arm runners currently
is an x86_64 build, we need to explicitly specify
CMAKE_SYSTEM_PROCESSOR, and CMAKE_SYSTEM_NAME to make CMake
consider it a cross compilation (otherwise CMAKE_SYSTEM_PROCESSOR
gets overridden by CMAKE_HOST_SYSTEM_PROCESSOR, which gets influenced
by the x86_64 as CMake is running emulated).
We also need to set LLVM_HOST_TRIPLE, as the autodetection of
it relies on CMAKE_HOST_SYSTEM_PROCESSOR. The host triple needs
to be in normalized form with "-windows-gnu", otherwise a couple
dozens of tests fail.
We also include the AArch64 target, to make sure the built compiler
can generate code for the host.
Since 07bc54bf4554398b199f4dc849e5193b98422f23 in llvm-project
(May 5th), these tests should pass on aarch64 too.
Martin Storsjö
218ddb0bbd