[lldb-dev] Win64 lldb build broken, llvm::call_once and _mm_mfence

[Hans Wennborg via lldb-dev]

The Win64 lldb build seems broken (at 294367).

I ran into this when trying to build the weekly snapshot
(http://www.llvm.org/builds/) which includes LLDB these days.

I suspect this might be related to Kamil's changes a few days ago. I
see Pavel committed something to fix Darwin afterwards.

Zach, do you know what's going on here? Do we have any buildbot
coverage for this?

   Creating library lib\liblldb.lib and object lib\liblldb.exp
lldbHost.lib(HostInfoWindows.cpp.obj) : error LNK2019: unresolved external symbo
l "void __cdecl llvm::sys::_mm_mfence(void)" (?_mm_mfence at sys@llvm@@YAXXZ) refer
enced in function "void __cdecl llvm::call_once<class <lambda_e212a11f7f891e804e
713e15728a6adc> >(struct llvm::once_flag &,class <lambda_e212a11f7f891e804e713e1
5728a6adc> &&)" (??$call_once at V<lambda_e212a11f7f891e804e713e15728a6adc>@@$$V at ll
vm@@YAXAEAUonce_flag at 0@$$QEAV<lambda_e212a11f7f891e804e713e15728a6adc>@@@Z)
bin\liblldb.dll : fatal error LNK1120: 1 unresolved externals
LINK failed. with 1120