re PR tree-optimization/18291 (ICE in merge_alias_info)

re PR tree-optimization/18291 (ICE in merge_alias_info)

	PR tree-optimization/18291
	* tree-ssa-copy.c (merge_alias_info): Fix merging of
	flow-sensitive alias information.  If the new pointer has no
	name tag, copy it from the original pointer.  Otherwise, make
	sure that the pointed-to sets have a common intersection.

testsuite/ChangeLog

	PR tree-optimization/18291
	* testsuite/gcc.c-torture/compile/pr18291.c: New test.

From-SVN: r91574