undefined reference to `__multi3'

[9il]

LDC and LDC beta (travis),
x86

                    auto r = inlineIR!(`
                    %a = zext i64 %0 to i128
                    %b = zext i64 %1 to i128
                    %m = mul i128 %a, %b
                    %n = lshr i128 %m, 64
                    %h = trunc i128 %n to i64
                    %l = trunc i128 %m to i64
                    %agg1 = insertvalue [2 x i64] undef, i64 %l, 0
                    %agg2 = insertvalue [2 x i64] %agg1, i64 %h, 1
                    ret [2 x i64] %agg2`, ulong[2])(a, b);

[kinke]

Similar thing as for your issue #2262 - LLVM lowers the 128-bit multiplication to a __multi3() C function call. Google found an implementation in LLVM's compiler-rt libary: https://github.com/llvm-mirror/compiler-rt/blob/master/lib/builtins/multi3.c