This content has not been validated; it was AI-generated following the x86-64 ISA Documentation generation process to maintain high quality. However, as no human has verified this data, errors may exist. If the accuracy of this data is critical, please consult the Intel SDM. The model used to generate this is gemma4:31b
MOVZX
MOVZX extends a u8, u16, or u32 source operand to a u32 or u64 destination operand by filling the high-order bits with zeros.
The following table covers what the source and destinations can be.
| source | destination(s) |
|---|---|
| reg | reg |
| mN | reg |
| imm | reg |
| #I | mN |
DO NOT support LOCK
MOVZX SHALL NOT be used with a memory destination. In x86-64, the destination MUST be a register. The instruction is available in both 64-bit mode and compatibility mode.
To avoid unintended behavior, ensure the source operand size is strictly smaller than the destination operand size; otherwise, the instruction is invalid. Since MOVZX performs zero-extension, it SHALL only be used for unsigned values. For signed values, MOVSX MUST be used to preserve the sign bit.