5.12.3 .set noautoextend

By default, MIPS16 instructions are automatically extended to 32 bits when necessary. The directive .set noautoextend will turn this off. When .set noautoextend is in effect, any 32-bit instruction must be explicitly extended with the .e modifier (e.g., li.e $4,1000). The directive .set autoextend may be used to once again automatically extend instructions when necessary.