Simd instructions

[bearophile]

As a final step to compute the product of two complex numbers I 
perform a simd operation on double2:

x3 = [x3.array[1] - x2.array[1], x3.array[0] + x2.array[0]];

But ldc2 compiles that quite badly (I don't know who's to blame, 
if necessary I will open a LLVM bug report), so I have tried to 
use an instruction addsubpd.

To do it I have imported ldc.gccbuiltins_x86 and then I use:

x3 = __builtin_ia32_addsubpd(x3, x2);

but ldc2 gives me:

LLVM ERROR: Cannot select: intrinsic %llvm.x86.sse3.addsub.pd
Stack dump:
0.      Running pass 'X86 DAG->DAG Instruction Selection' on 
function 
'@"\01__D12complex_mul217__T8compMul6Vk12Z8compMul6FNaNbNfKG12NhG2dKG12NhG2dKG12NhG2dZv"'

Can you help me?

Bye,
bearophile