If VL is 3, MAXVL is 5, RT is 1, and dest elwidth is 32 then the elements
RT0 to RT2 are stored:
- 0..31 32..63
- r0 unchanged unchanged
- r1 RT0.lo RT1.lo
- r2 RT2.lo unchanged
- r3 unchanged RT0.hi
- r4 RT1.hi RT2.hi
- r5 unchanged unchanged
+ LSB0: 63:32 31:0
+ MSB0: 0:31 32:63
+ r0 unchanged unchanged
+ r1 RT1.lo RT0.lo
+ r2 unchanged RT2.lo
+ r3 RT0.hi unchanged
+ r4 RT2.hi RT1.hi
+ r5 unchanged unchanged
Note that all of the LO halves start from r1, but that the HI halves
start from half-way into r3. The reason is that with MAXVL bring