2011-08-11  Richard Guenther  <rguenther@suse.de>

	PR middle-end/50040
	* gimplify.c (gimplify_modify_expr_complex_part): Mark the
	load of the other piece with TREE_NO_WARNING.
	* tree-flow.h (warn_uninit): Adjust prototype.
	* tree-ssa.c (warn_uninit): Take uninitialized SSA name,
	the base variable and the expression that is used separately.
	Properly query all TREE_NO_WARNING flags.
	(struct walk_data): Remove.
	(warn_uninitialized_var): Likewise.
	(warn_uninitialized_vars): Do not walk gimple pieces but simply
	look at all SSA uses of the statement.  Handle unused memory
	separately.
	* tree-ssa-uninit.c (warn_uninitialized_phi): Adjust.

	* g++.dg/warn/unit-1.C: Un-XFAIL.
	* gcc.dg/uninit-I.c: Likewise.

From-SVN: r177667