Specifications

Intel
®
64 and IA-32 Architectures Software Developer’s Manual Documentation Changes 105
Documentation Changes
MOVSX/MOVSXD—Move with Sign-Extension
Instruction Operand Encoding
...
Opcode Instruction Op/
En
64-Bit
Mode
Compat/
Leg Mode
Description
0F BE /r MOVSX r16, r/m8 A Valid Valid Move byte to word with
sign-extension.
0F BE /r MOVSX r32, r/m8 A Valid Valid Move byte to doubleword
with sign-extension.
REX + 0F BE /r MOVSX r64, r/m8* A Valid N.E. Move byte to quadword
with sign-extension.
0F BF /r MOVSX r32,
r/m16
A Valid Valid Move word to doubleword,
with sign-extension.
REX.W + 0F BF
/r
MOVSX r64,
r/m16
A Valid N.E. Move word to quadword
with sign-extension.
REX.W** + 63 /r MOVSXD r64,
r/m32
A Valid N.E. Move doubleword to
quadword with sign-
extension.
NOTES:
* In 64-bit mode, r/m8 can not be encoded to access the following byte registers if a REX prefix is
used: AH, BH, CH, DH.
**The use of MOVSXD without REX.W in 64-bit mode is discouraged, Regular MOV should be used
instead of using MOVSXD without REX.W.
Op/En Operand 1 Operand 2 Operand 3 Operand 4
A ModRM:reg (w) ModRM:r/m (r) NA NA