public Varnode getStackPointerVarnode() {
		if (stackVarnode != null) {
			return stackVarnode;
		}

		// figure out what register is used for return values, it must be assumed to be unknown upon return.
		Register stackReg = program.getCompilerSpec().getStackPointer();
		if (stackReg == null) {
			return null;
		}

		stackVarnode = new Varnode(stackReg.getAddress(), stackReg.getMinimumByteSize());
		return stackVarnode;
	}
@return Varnode that represents the stack pointer register
Ghidra/Features/Base/src/main/java/ghidra/util/state/ResultsState.java