| Opcode | Instruction | Op/En | 64-Bit Mode | Compat/Leg Mode | Description | | ---------------- | ----------------- | ----- | ----------- | --------------- | -------------------------------------------------- | | 0F BE /r | MOVSX r16, r/m8 | RM | Valid | Valid | Move byte to word with sign-extension. | | 0F BE /r | MOVSX r32, r/m8 | RM | Valid | Valid | Move byte to doubleword with sign-extension. | | REX.W + 0F BE /r | MOVSX r64, r/m8 | RM | Valid | N.E. | Move byte to quadword with sign-extension. | | 0F BF /r | MOVSX r32, r/m16 | RM | Valid | Valid | Move word to doubleword, with sign-extension. | | REX.W + 0F BF /r | MOVSX r64, r/m16 | RM | Valid | N.E. | Move word to quadword with sign-extension. | | 63 /r1 | MOVSXD r16, r/m16 | RM | Valid | N.E. | Move word to word with sign-extension. | | 63 /r1 | MOVSXD r32, r/m32 | RM | Valid | N.E. | Move doubleword to doubleword with sign-extension. | | REX.W + 63 /r | MOVSXD r64, r/m32 | RM | Valid | N.E. | Move doubleword to quadword with sign-extension. |