Arduino: Confused about wdtFeed, esp_yield and yield

[supersjimmie]

I have some trouble with the latest SoftwareSerial library:
https://github.com/esp8266/Arduino/issues/1426
and I am wondering if this could be fixed with either

    ESP.wdtFeed();
    esp_yield();
    yield();

But what is the difference and how could any of them help to avoid WDT Resets?

[supersjimmie]

Never mind, if I look closer to where the softwareserial crashes, I don't think a yield or wdtfeed will help.
Closing this.

[Defozo]

I'd like to know what is the difference between these functions?