Function codearith

lua/src/lcode.c:1444–1458

** Code arithmetic operators ('+', '-', ...). If second operand is a ** constant in the proper range, use variant opcodes with K operands. */

** constant in the proper range, use variant opcodes with K operands.
*/
static void codearith (FuncState *fs, BinOpr opr,
                       expdesc *e1, expdesc *e2, int flip, int line) {
  TMS event = cast(TMS, opr + TM_ADD);
  if (tonumeral(e2, NULL) && luaK_exp2K(fs, e2)) {  /* K operand? */
    int v2 = e2->u.info;  /* K index */
    OpCode op = cast(OpCode, opr + OP_ADDK);
    finishbinexpval(fs, e1, e2, op, v2, flip, line, OP_MMBINK, event);
  }
  else {  /* 'e2' is neither an immediate nor a K operand */
    OpCode op = cast(OpCode, opr + OP_ADD);
    if (flip)
      swapexps(e1, e2);  /* back to original order */
    codebinexpval(fs, op, e1, e2, line);  /* use standard operators */
  }
}


/*