I don't know where the logic is to handle how Svelte can know about changes at compile time.

Hello..
After reading this article, I understood how Svelte recognizes changes with the actual DOM.

Link: https://svelte.dev/blog/virtual-dom-is-pure-overhead

However, in the actual svelte source code, I can't find out what logic does the processing.

Can you tell me which file in the svelte source code handles that logic?