I started learning SPARC, and wrote some simple instructions.

fmt2:   .asciz  " 100 - 15 = %dn"
fmt3:   .asciz  " 100 * 15 = %dn"
fmt4:   .asciz  " 100 / 15 = %dn"
        .align  4
        .global main
main:   save %sp, -96, %sp
        mov 100, %l4    !l4=0
        mov 15, %l5     !l4=100, l5=0
!printf(" 100 - 15 = %dn, minus);

        set fmt2, %o0
        sub %l4, %l5, %o1
        call printf
        nop

        mov %l4, %o0
        mov %l5, %o1
        call .mul
        nop

        mov %o0, %o1
        set fmt3, %o0
        call printf
        nop

        mov %l4, %o0
        mov %l5, %o1
        call .div
        nop

        mov %o0, %o1
        set fmt4, %o0
        call printf
        nop

        ret
        restore

There was an example code on the lecture and I just copied it.
It spewed all the text out and ended with a code 01, and so did the example code.
So I tried inspecting every %o0 and %o1 values with gdb compiler, but failed to understand how pipelining works.

mov %o0, %o1 and set fmt3, %o3 obviously creates a hazard but still works fine.
Is that the cause of the exit code 01?