to the same padding and PartitionPoints:
elwid | | | | | | |
- 0b00 x x x x x x x x x x x x x x B1B0
- 0b01 x x x x x x B5B4 x x x x x x B1B0
- 0b10 x x B7B6 x x B5B4 x x B3B2 x x B1B0
+ 0b00 x x x x x x x x x x x x x 0 B1B0
+ 0b01 x x x x x 0 B5B4 x 0 x x x 0 B1B0
+ 0b10 x 0 B7B6 x 0 B5B4 x 0 B3B2 x 0 B1B0
+
+Note here that zero-extension also had to occur to
+bring b up to the same element width in each partition,
+at which point, "x" padding being ignored, a straight
+PartitionedAdd may be deployed because both the overall
+width and the positions of the PartitionPoints are exactly
+matched.
+
Illustrating the case where a Sliced (fixed element width) SimdSignal
is added to one which has variable-length elements that take up the