message: Add atan2 to the binary op registry
diff: @@ -77,6 +77,7 @@ LookupBinaryFn(const HloInstruction* inst) {
  HloOpcode opcode = inst->opcode();
  switch (opcode) {
  case HloOpcode::kAdd: return popstd::add;
  + case HloOpcode::kAtan2: return popstd::atan2;
  case HloOpcode::kDivide: return popstd::div;
  case HloOpcode::kEq: return popstd::eq;
  case HloOpcode::kGt: return popstd::gt;
  