[libcxx-commits] [PATCH] D144734: [libcxx] Enable support for static and debug Windows runtimes

Mon Feb 27 05:36:30 PST 2023

mstorsjo added a comment.

In D144734#4154997 <https://reviews.llvm.org/D144734#4154997>, @mstorsjo wrote:

>> Testing on Windows requires compiler-rt builtins.
>
> Currently it doesn't (the tests run without it), and regular use of libc++ in clang-cl mode wouldn't normally add that option. I know this would be useful for getting int128 handling fixed, but to get it fixed in practice and not only in tests, we'd also need to make sure that all users link with `-rtlib=compiler-rt` - and for users linking by invoking `link.exe` or `lld-link` directly instead of via the compiler wrapper, that's not happening. So this aspect is also a larger policy decision that needs to be split out and agreed upon by relevant stakeholders on its own, not just slipped into a giant refactoring patch.

Also, we can't generally assume that compiler-rt builtins are available for these targets; not all clang-cl distributions ship with the builtins available, in particular not for all 4 relevant architecture targets. MSVC itself does ship with compiler-rt builtins for x86 and x64, but not for arm and arm64. So if we'd suddenly start requiring it, we'd break a bunch of currently working setups.

I.e., this is definitely a larger policy change that needs to be signaled and handled across stakeholders.

Repository:
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  https://reviews.llvm.org/D144734/new/

https://reviews.llvm.org/D144734