Function codeexpval

src/Chain/libraries/glua/lcode.cpp:794–822

** Code for binary and unary expressions that "produce values" ** (arithmetic operations, bitwise operations, concat, length). First ** try to do constant folding (only for numeric [arithmetic and ** bitwise] operations, which is what 'lua_arith' accepts). ** Expression to produce final result will be encoded in 'e1'. */

** Expression to produce final result will be encoded in 'e1'.
*/
static void codeexpval(FuncState *fs, OpCode op,
    expdesc *e1, expdesc *e2, int line) {
    lua_assert(op >= OP_ADD);
    if (op <= OP_BNOT && constfolding(fs, (op - OP_ADD) + LUA_OPADD, e1, e2))
        return;  /* result has been folded */
    else {
        int o1, o2;
        /* move operands to registers (if needed) */
        if (op == OP_UNM || op == OP_BNOT || op == OP_LEN) {  /* unary op? */
            o2 = 0;  /* no second expression */
            o1 = luaK_exp2anyreg(fs, e1);  /* cannot operate on constants */
        }
        else {  /* regular case (binary operators) */
            o2 = luaK_exp2RK(fs, e2);  /* both operands are "RK" */
            o1 = luaK_exp2RK(fs, e1);
        }
        if (o1 > o2) {  /* free registers in proper order */
            freeexp(fs, e1);
            freeexp(fs, e2);
        }
        else {
            freeexp(fs, e2);
            freeexp(fs, e1);
        }
        e1->u.info = luaK_codeABC(fs, op, 0, o1, o2);  /* generate opcode */
        e1->k = VRELOCABLE;  /* all those operations are relocatable */
        luaK_fixline(fs, line);
    }
}


static void codecomp(FuncState *fs, OpCode op, int cond, expdesc *e1,