private int getDefaultStackDepthChange(Program prog, PrototypeModel model, int depth) {
		if (model == null) {
			model = prog.getCompilerSpec().getDefaultCallingConvention();
		}
		if (model == null) {
			return Function.UNKNOWN_STACK_DEPTH_CHANGE;
		}

		int callStackMod = model.getExtrapop();
		int callStackShift = model.getStackshift();
		if (callStackMod != PrototypeModel.UNKNOWN_EXTRAPOP) {
			// TODO: If the purge is set, the calling convention could be wrong
			//       If the purge can from a RET <X> if will be correct so should use it!
			//       Need to make sure that is happening in the program before accepting
			return callStackShift;
		}
		if (depth == Function.UNKNOWN_STACK_DEPTH_CHANGE ||
			depth == Function.INVALID_STACK_DEPTH_CHANGE) {
			return Function.UNKNOWN_STACK_DEPTH_CHANGE;
		}
		return callStackShift + depth;
	}
Get the default/assumed stack depth change for this language

@param model calling convention to use
@param depth stack depth to return if the default is unknown for the language
@return default assumed stack depth
Ghidra/Features/Base/src/main/java/ghidra/program/util/SymbolicPropogator.java