Optimize Node::add_child validation

[reduz]

Adding 10k nodes is almost twice as fast.

Code I used to test:

	for count in range(1000, 10001, 1000):
		var start = Time.get_ticks_msec()
		var root = Node.new()
		var name = StringName("pepo") # worst case, triggers name conflict (vs unnamed)
		for i in count:
			var n = Node.new()
			n.set_name(name)
			root.add_child(n)
		var end = Time.get_ticks_msec()
		print("create %s\t%d" % [count, end - start])

Closes godotengine/godot-proposals#6225

[RedworkDE]

This buffer isn't deleted (the string constructor doesn't take ownership of it)

Also would it make sense to use a thread static shared buffer of like size 64 or so and only allocate this temporary buffer if that is too small?

Alternatively make this buffer a CowData<char32_t> and add a String constructor that takes ownership of it.

[reduz]

alloca() allocates on the stack. It's the most efficient way of allocation for this kind of usage and it does not need to be freed.

[RedworkDE]

Or you can just simplest solution that is already implemented; nvm then

[RedworkDE]

if (p_int < 10) return r+0;
if (p_int < 100) return r+1;
// ...

may be faster because it doesn't do divisions, but I didn't test.

[reduz]

It is probably faster, but the code is a mess, specially because this is int64 :P Still, in this context the code should be ok as-is, you won't get a really meaningful performance gain.

[akien-mga]

Thanks!

[lyuma]

I know this was already merged. I want to put a note for the future that this optimization also changed scene import behavior between Godot 4.0 and Godot 4.1:

As discovered in issue #78881, this changed the rules so that invalid characters are replaced with an underscore _ rather than removed . Given that reduz changed the test to include underscores, this was a deliberate change, and permanent. This affects Import and other things.

Neither this PR nor the commit made a note of this change in behavior. So that's why I'm writing this comment, for folks like you coming from a google search.

Prior to this commit, an object named Widget.001 coming from blender would have been imported as Widget001. Now it's named Widget_001 .

[dalexeev]

Neither this PR nor the commit made a note of this change in behavior.

See #75760 (comment) and godotengine/godot-proposals#6225 (linked).