Complex Mul and Div using sse Instructions

Question

Is performing complex multiplication and division beneficial through SSE instructions? I know that addition and subtraction perform better when using SSE. Can someone tell me ho

Answer 1

Just for completeness, the Intel® 64 and IA-32 Architectures Optimization Reference Manual that can be downloaded here contains assembly for complex multiply (Example 6-9) and complex divide (Example 6-10).

Here's for example the multiply code:

// Multiplication of (ak + i bk ) * (ck + i dk )
// a + i b can be stored as a data structure
movsldup xmm0, src1; load real parts into the destination, a1, a1, a0, a0
movaps xmm1, src2; load the 2nd pair of complex values, i.e. d1, c1, d0, c0
mulps xmm0, xmm1; temporary results, a1d1, a1c1, a0d0, a0c0
shufps xmm1, xmm1, b1; reorder the real and imaginary parts, c1, d1, c0, d0
movshdup xmm2, src1; load imaginary parts into the destination, b1, b1, b0, b0
mulps xmm2, xmm1; temporary results, b1c1, b1d1, b0c0, b0d0
addsubps xmm0, xmm2; b1c1+a1d1, a1c1 -b1d1, b0c0+a0d0, ; a0c0-b0d0

The assembly maps directly to gccs X86 intrinsics (just predicate each instruction with __builtin_ia32_).