With D125787, the size of the RVV portion of the stack is a
16-byte-aligned to help maintain the overall alignment of the stack as a
whole. Alignments of the RVV objects themselves are also correctly
The naive implementation in that patch ensured these alignments while
ignoring the effect that the implicit multiplication by VLENB has on
alignment. Since VLEN is a power of two we often take on extra
alignment when calculating the final object offsets.
This patch now takes VLEN into account when calculating RVV object
offsets by reducing the required alignment by the known 8-byte multiple
we receive from VLEN.