re PR tree-optimization/49115 (invalid return value optimization (?) when exception is thrown and caught)

2011-05-23  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/49115
	* tree-ssa-alias.c (stmt_kills_ref_p_1): If the assignment
	is not necessarily carried out, do not claim it kills the ref.
	* tree-ssa-dce.c (mark_aliased_reaching_defs_necessary_1): Likewise.

	* g++.dg/torture/pr49115.C: New testcase.

From-SVN: r174066