Calls, returns and the stack

x86 call implicitly pushes a return address. RISC-V jal ra, target writes it to ra. A non-leaf function saves ra itself if it will make another call.

addi sp, sp, -16
sd   ra, 8(sp)

call child

ld   ra, 8(sp)
addi sp, sp, 16
ret

There are no base push and pop instructions. Stack movement and memory access remain visible and independently schedulable.