private void generateShiftWithPrevLeg(MethodVisitor rv, int bitShift, int index) {
		// [...,prevLegIn]
		rv.visitLdcInsn(Integer.SIZE - bitShift);
		rv.visitInsn(ISHR);
		// [...,prevLegIn:SLACK]
		rv.visitVarInsn(ILOAD, index);
		// [...,prevLegIn:SLACK,legIn]
		rv.visitInsn(DUP_X1);
		// [...,legIn,prevLegIn:SLACK,legIn]
		rv.visitLdcInsn(bitShift);
		rv.visitInsn(IUSHR);
		// [...,legIn,prevLegIn:SLACK,legIn:SHIFT]
		rv.visitInsn(IOR);
		// [...,legIn,legOut]
		rv.visitVarInsn(ISTORE, index);
		// [...,legIn]
	}
<b>WIP</b>: Assumes the previous (next more significant) leg is on the stack and the current
(unshifted) leg is in the given variable. Computes the resulting output leg and puts in into
the given local variable, but leaves a copy of the current unshifted leg on the stack.

@param rv the method visitor
@param bitShift the number of <em>bits</em> to shift
@param index the index of the local variable for the current leg
Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/emu/jit/gen/op/SubPieceOpGen.java