ARM64汇编中“MSL”（低位补1左移）的英文全称是什么？

Great question! The MSL suffix in ARM64 assembly (exemplified in your movi v30.2S, #0x3c, msl #0x8 instruction) stands for Masked Shift Left.

To break this down alongside the familiar LSL (Logical Shift Left):

• LSL performs a logical left shift, filling any vacated lower bits with zeros.
• MSL does a left shift, but fills those empty lower bits with ones (which matches your example where 0x3c becomes 0x3cff after shifting left 8 bits and filling the low byte with 1s).

This naming makes sense because "masked" here refers to using a full-ones mask to fill the shifted-out positions, as opposed to the zero-filled logical shift of LSL.

内容的提问来源于stack exchange，提问作者rfalke