See <https://bugs.libre-soc.org/show_bug.cgi?id=230#c30>
+Note that some of these may be covered by [[remap] which is described in [[sv/propagation]]
+
# move to/from vec2/3/4
Basic idea: mv operations where either the src or dest is specifically marked as having SUBVL apply to it, but, crucially, the *other* argument does *not*. Note that this is highly unusual in SimpleV, which normally only allows SUBVL to be applied uniformly across all dest and all src.