tree-optimization/105437 - BB vect with extern defs of throwing stmts

tree-optimization/105437 - BB vect with extern defs of throwing stmts

We have to watch out for vectorized stmt insert locations if the
def from the last stmt alters control flow.  We constrain region
building so we know the def is outside of the current region
and thus we can insert at the region start point.

2022-05-02  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/105437
	* tree-vect-slp.cc (vect_schedule_slp_node): Handle the
	case where last_stmt alters control flow.

	* g++.dg/vect/pr105437.cc: New testcase.

(cherry picked from commit 3a3eda000fdf4f8754c9a2535191091f1db0c2a2)