Fold KPTR + offset in SPLIT pass.

src/lj_opt_split.c

@@ -184,6 +184,8 @@ static IRRef split_ptr(jit_State *J, IRIns *oir, IRRef ref)
   IRRef nref = oir[ref].prev;
   IRIns *ir = IR(nref);
   int32_t ofs = 4;
+  if (ir->o == IR_KPTR)
+    return lj_ir_kptr(J, (char *)ir_kptr(ir) + ofs);
   if (ir->o == IR_ADD && irref_isk(ir->op2) && !irt_isphi(oir[ref].t)) {
     /* Reassociate address. */
     ofs += IR(ir->op2)->i;