re PR tree-optimization/77808 (ICE in duplicate_ssa_name_ptr_info, at tree-ssanames.c:630 starting with r240439)

Fix PR tree-optimization/77808

gcc/
	PR tree-optimization/77808
	* tree-ssa-loop-prefetch.c (issue_prefetch_ref): Check base_addr
	and addr are different before copying points-to information.

gcc/testsuite/
	PR tree-optimization/77808
	* gcc.dg/tree-ssa/pr77808.c: New testcase.

From-SVN: r240749