Because the other commenter wasn’t posting the actual answer, I went to find the documentation about checking for integer overflow and it’s right here https://docs.riscv.org/reference/isa/unpriv/rv32.html#2-1-4-...

And what did I find? Yep that code is right from the manual for unsigned integer overflow.

For signed addition if you know one of the signs (eg it’s a compile time constant) the manual says

  addi t0, t1, +imm
  blt t0, t1, overflow

But the general case for signed addition if you need to check for overflow and don’t have knowledge of the signs

  add t0, t1, t2
  slti t3, t2, 0
  slt t4, t0, t1
  bne t3, t4, overflow

From what I’ve read most native compiled code doesn’t really check for overflows in optimised builds, but this is more of an issue for JavaScript et al where they may detect the overflow and switch the underlying type? I’m definitely no expert on this.