Function luaK_posfix

lib/lua/src/lcode.c:1705–1779

** Finalize code for binary operation, after reading 2nd operand. */

** Finalize code for binary operation, after reading 2nd operand.
*/
void luaK_posfix (FuncState *fs, BinOpr opr,
                  expdesc *e1, expdesc *e2, int line) {
  luaK_dischargevars(fs, e2);
  if (foldbinop(opr) && constfolding(fs, opr + LUA_OPADD, e1, e2))
    return;  /* done by folding */
  switch (opr) {
    case OPR_AND: {
      lua_assert(e1->t == NO_JUMP);  /* list closed by 'luaK_infix' */
      luaK_concat(fs, &e2->f, e1->f);
      *e1 = *e2;
      break;
    }
    case OPR_OR: {
      lua_assert(e1->f == NO_JUMP);  /* list closed by 'luaK_infix' */
      luaK_concat(fs, &e2->t, e1->t);
      *e1 = *e2;
      break;
    }
    case OPR_CONCAT: {  /* e1 .. e2 */
      luaK_exp2nextreg(fs, e2);
      codeconcat(fs, e1, e2, line);
      break;
    }
    case OPR_ADD: case OPR_MUL: {
      codecommutative(fs, opr, e1, e2, line);
      break;
    }
    case OPR_SUB: {
      if (finishbinexpneg(fs, e1, e2, OP_ADDI, line, TM_SUB))
        break; /* coded as (r1 + -I) */
      /* ELSE */
    }  /* FALLTHROUGH */
    case OPR_DIV: case OPR_IDIV: case OPR_MOD: case OPR_POW: {
      codearith(fs, opr, e1, e2, 0, line);
      break;
    }
    case OPR_BAND: case OPR_BOR: case OPR_BXOR: {
      codebitwise(fs, opr, e1, e2, line);
      break;
    }
    case OPR_SHL: {
      if (isSCint(e1)) {
        swapexps(e1, e2);
        codebini(fs, OP_SHLI, e1, e2, 1, line, TM_SHL);  /* I << r2 */
      }
      else if (finishbinexpneg(fs, e1, e2, OP_SHRI, line, TM_SHL)) {
        /* coded as (r1 >> -I) */;
      }
      else  /* regular case (two registers) */
       codebinexpval(fs, opr, e1, e2, line);
      break;
    }
    case OPR_SHR: {
      if (isSCint(e2))
        codebini(fs, OP_SHRI, e1, e2, 0, line, TM_SHR);  /* r1 >> I */
      else  /* regular case (two registers) */
        codebinexpval(fs, opr, e1, e2, line);
      break;