re PR rtl-optimization/91164 (ICE in verify_dominators, at dominance.c:1184 (error: dominator of 114 should be 112, not 16))

	PR rtl-optimization/91164
	* dse.c (rest_of_handle_dse): If dead edges have been purged,
	invalidate dominance info.

	* g++.dg/opt/pr91164.C: New test.

From-SVN: r273522