int getPurge() {
		if (isFowardEntry() && purge == -1) {
			processForwardedEntry();
		}

		if (purge == -2) {
			purge = -1;
		}

		return purge;
	}
Returns the purge value of the function related
to this exported symbol. The purge value
is the number of bytes purged from the stack
when the function returns.

-2 purge value is used to prevent infinite loops in recursion.

@return the purge value of the function or -1 (if unable to resolve the purge value)
Ghidra/Features/Base/src/main/java/ghidra/app/util/opinion/LibraryExportedSymbol.java