[llvm] [CodeGen] This patch fix a bug that may caused error for a self-defined target in SelectionDAG::getNode (PR #75320)

[yan zhou via llvm-commits]

zhou3968322 wrote:

> This looks OK by inspection, but do you have a test case you could add as well?

No, for current targets, there is no dag SDNode like this: 
```
t20 v2i32: TargetOpNode 
```
It only generated a v2i32 with no input operands.
while my self-defined target is still has a lot of bugs, too early to give it's example.

But I think this is only an internal change and does not affect other modules.
It  can help others want to define instr like this in td,may be proper to change.


https://github.com/llvm/llvm-project/pull/75320