for a total of 14 "words".
```
- # r5: n count
- # r6: x ptr
- # r7: y ptr
- # fp1: a mul-scalar
+ # r5: n count; r6: x ptr; r7: y ptr; fp1: a
1 mtctr 5 # move n to CTR
2 addi r10,r6,0 # copy y-ptr into r10 (y')
3 .L2
in memory, and critically relies on y overwrite.
```
- # r5: n count
- # r6: x ptr
- # r7: y ptr
- # fp1: a mul-scalar
+ # r5: n count; r6: x ptr; r7: y ptr; fp1: a
1 mtctr 5 # move n to CTR
2 .L2
3 setvl MAXVL=32,VL=CTR # actually VL=MIN(MAXVL,CTR)