* cgraph.h (struct varpool_node): Add const_value_known.
	(varpool_decide_const_value_known): Declare.
	* tree-ssa-ccp.c (fold_const_aggregate_ref): Update initializer folding.
	* lto-cgraph.c (lto_output_varpool_node): Store const_value_known.
	(input_varpool_node): Restore const_value_known.
	* tree-ssa-loop-ivcanon (constant_after_peeling): Check varpool for
	initializer folding.
	* ipa.c (ipa_discover_readonly_nonaddressable_var,
	function_and_variable_visibility): Compute const_value_known.
	* gimple-fold.c (get_symbol_constant_value): Use varpool for initializer
	folding.
	* varpool.c (varpool_decide_const_value_known): New function.

From-SVN: r163808