* cgraph.h (ipa_discover_readonly_nonaddressable_vars): Declare.
(varpool_all_refs_explicit_p): New inline function.
* ipa-reference.c: Update comment.
(module_statics_written): Remove.
(get_static_decl): Remove.
(ipa_init): Do not initialize module_statics_written.
(analyze_function): Likewise.
(generate_summary): Likewise; do not compute module_statics_readonly
and do not update variable flags.
(propagate): Call ipa_discover_readonly_nonaddressable_vars.
* ipa.c: Inlucde flags.h
(cgraph_local_node_p): New.
(cgraph_remove_unreachable_nodes): Return early when not optimizing;
promote functions to local.
(ipa_discover_readonly_nonaddressable_vars): New function.
(function_and_variable_visibility): Use cgraph_local_node_p.
* varpool.c (varpool_finalize_decl): Set force_output for
DECL_PRESERVE_P vars.