title: MOVDDUP
text: # MOVDDUP
  
  In the x86 assembly programming language, MOVDDUP is the name for a specific action performable by modern x86 processors with 3rd-generation Streaming SIMD Extensions (SSE3). This action involves copying a number to temporary space in the processor for use in other computations.
  
  Specifically, MOVDDUP causes one, double-precision, floating-point source to be copied to both the lower half and upper half of an XMM register.
  
  ## Usage
  
  | Opcode | F2 0F 12 /r |
  | - | - |
  | Assembly (Intel syntax) | MOVDDUP xmm1, xmm2/m64 |
  | Assembly (AT&T syntax) | MOVDDUP xmm2/m64, xmm1 |
  | icc intrinsic equivalent(s) | __m128d _mm_movedup_pd(__m128d a) __m128d _mm_load_pd1(const double * mem_addr) |
  | gcc built-in(s) | v2df __builtin_ia32_movddup(v2df) |
  
  The source operand can be either an XMM register (xmm2) or a memory address (m64). When the source operand is an XMM register, the lower half of the register is used in the operation. When the source operand is a memory address, it is assumed to be the address of an 8-byte region, the value at which is used in the operation.
  
  The destination operand must be an XMM register (xmm1).
  
  