OR: RISC-V instruction reference

orBitwise OR 
Sets the first register to the bitwise OR of the second and third.
RISC-V manual: or 
Used in Arithmetic, logic and bitsRISC-V assembly
The snake gameRISC-V assembly
Flappy ASMRISC-V assembly
 
Forms  or , ,   
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. 
 .text
li t0, 13
li t1, 5
# t0=13, t1=5; or writes 13 to t2.
or t2, t0, t1