Wikipedia
MOVAPD
In the x86 assembly programming language, MOVAPD is the name for a specific action performable by modern x86 processors with 2nd-generation Streaming SIMD Extensions (SSE2). This action involves copying a pair of numbers to temporary space in the processor for use in other computations. MOVAPD is one of the fastest ways to accomplish this effect.
Specifically, MOVAPD causes a 16-byte-aligned packed- doubles source to be copied to an XMM register or a 16-byte memory region.