codedump.c: print two operands `R(x)` and `R(x+1)` for clarity.
@@ -463,7 +463,7 @@ codedump(mrb_state *mrb, const mrb_irep *irep)
print_lv_a(mrb, irep, a);
break;
CASE(OP_STRCAT, B):
- printf("OP_STRCAT\tR%d\t", a);
+ printf("OP_STRCAT\tR%d\tR%d", a, a+1);
print_lv_a(mrb, irep, a);
break;
CASE(OP_HASH, BB):
