public void branch(int rel) {
		index += rel - 1; // -1 because we already advanced
		if (!(0 <= index && index <= code.size())) {
			throw new LowlevelError("Bad p-code branch");
		}
	}
Perform an internal branch, relative to the <em>current op</em>.

<p>
Because index advances before execution of each op, the index is adjusted by an extra -1.

@param rel the adjustment to the index
Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/exec/PcodeFrame.java