[PATCH] D41813: [builtins] Enable CRT_HAS_128BIT for MSVC

[Loo Rong Jie via Phabricator via llvm-commits]

rongjiecomputer added a comment.

I am not working on this CL anymore. Changes need to be made in LLVM first to make passing of `__int128` and `long double`
works with Microsoft ABI and I don't have such knowledge to make it happen.

After LLVM and Clang are fixed, then this CL should work.

Some links that might help future contributors who want to try this:

- https://bugs.chromium.org/p/chromium/issues/detail?id=787617
- https://github.com/JuliaLang/julia/blob/3a26bbc32334253bb582eb058596683ff6fe2fb1/deps/patches/win64-int128.llvm-3.3.patch (Julia used to have a patch to fix this in LLVM, but this patch is gone in master branch for some reason. Not sure if the patch is correct or not).
- https://github.com/ziglang/zig/pull/930 (Zig wraps compiler-rt with inline assembly to conform with Microsoft ABI instead of touching LLVM).
- https://software.intel.com/en-us/articles/80-bit-long-double-math-functions-from-intel-may-conflict-with-microsoft-visual-c-64-bit


https://reviews.llvm.org/D41813