SH3ADD - RISC-V instruction reference

sh3addShift left by 3 and add 
Sets t1 to t2 shifted left by 3, plus t3.
RISC-V manual: sh3add 
Forms  sh3add , ,   
Operands t1 Any integer register, x0 to x31, or its named alias, such as zero, t0 or t6. 
t2 An integer register. It may be the same register as t1. 
t3 An integer register. It may be the same register as t1. 
One instruction for indexing an array of double words
 .text
li t0, 13
li t1, 5
# t0=13, t1=5; sh3add writes 109 to t2.
sh3add t2, t0, t1