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
STUI
Stores the upper portion of a register into the destination operand.
The table after the description covers what the source and destinations can be.
| source | destination(s) |
|---|---|
| reg | mN |
| reg | reg |
| imm | #I |
| mN | #I |
DO NOT support LOCK
This instruction is only available when the processor is operating in compatibility mode. It SHALL NOT be used in 64-bit mode.
Ensure that the destination operand size matches the expected width of the upper portion being stored to avoid memory corruption or unintended data truncation.