[llvm-dev] compiler-rt builtins on MSVC

[Hao Wei via llvm-dev]

Hi,

compiler-rt builtins currently doesn't build on MSVC; it's ignored in
the CMakeLists and if you force it to build MSVC explodes because it
uses syntax not supported by MSVC.

What is one supposed to use when building LLVM as a library for a
compiler on MSVC in order to satisfy imports like __powidf2 etc? What
does Clang do?

(Context: I'm trying to build Rust on MSVC without using MinGW at all.
Currently what Rust does is build the rest of LLVM and the Rust's C
bits itself with MSVC but use gcc to create libcompiler-rt for
builtins.. which is horribly hacky, though it works quite well thanks
to MinGW.)

Thanks.