vectorizable_load forces peeling for gaps if the vectorisation factor
is not a multiple of the group size, since in that case we'd normally load
beyond the original scalar accesses but drop the excess elements as part
of a following permute:
This isn't necessary for LOAD_LANES though, since it loads only the
data needed and does the permute itself.
Tested on aarch64-linux-gnu and x86_64-linux-gnu.
gcc/
* tree-vect-stmts.c (vectorizable_load): Reorder checks so that
load_lanes/grouped_load classification comes first. Don't check
whether the vectorization factor is a multiple of the group size
for load_lanes.
gcc/testsuite/
* gcc.dg/vect/vect-load-lanes-peeling-1.c: New test.