+
+ pub fn is_generic_fn(&self) -> bool {
+ match *self {
+ MonoItem::Fn(ref instance) => {
+ instance.substs.non_erasable_generics().next().is_some()
+ }
+ MonoItem::Static(..) |
+ MonoItem::GlobalAsm(..) => false,
+ }
+ }
+
+ pub fn symbol_name(&self, tcx: TyCtxt<'tcx, 'tcx>) -> SymbolName {
+ match *self {
+ MonoItem::Fn(instance) => tcx.symbol_name(instance),
+ MonoItem::Static(def_id) => {
+ tcx.symbol_name(Instance::mono(tcx, def_id))
+ }
+ MonoItem::GlobalAsm(hir_id) => {
+ let def_id = tcx.hir().local_def_id_from_hir_id(hir_id);
+ SymbolName {
+ name: InternedString::intern(&format!("global_asm_{:?}", def_id))
+ }
+ }
+ }
+ }
+
+ pub fn instantiation_mode(&self, tcx: TyCtxt<'tcx, 'tcx>) -> InstantiationMode {
+ let inline_in_all_cgus =
+ tcx.sess.opts.debugging_opts.inline_in_all_cgus.unwrap_or_else(|| {
+ tcx.sess.opts.optimize != OptLevel::No
+ }) && !tcx.sess.opts.cg.link_dead_code;
+
+ match *self {
+ MonoItem::Fn(ref instance) => {
+ let entry_def_id = tcx.entry_fn(LOCAL_CRATE).map(|(id, _)| id);
+ // If this function isn't inlined or otherwise has explicit
+ // linkage, then we'll be creating a globally shared version.
+ if self.explicit_linkage(tcx).is_some() ||
+ !instance.def.requires_local(tcx) ||
+ Some(instance.def_id()) == entry_def_id
+ {
+ return InstantiationMode::GloballyShared { may_conflict: false }
+ }
+
+ // At this point we don't have explicit linkage and we're an
+ // inlined function. If we're inlining into all CGUs then we'll
+ // be creating a local copy per CGU
+ if inline_in_all_cgus {
+ return InstantiationMode::LocalCopy
+ }
+
+ // Finally, if this is `#[inline(always)]` we're sure to respect
+ // that with an inline copy per CGU, but otherwise we'll be
+ // creating one copy of this `#[inline]` function which may
+ // conflict with upstream crates as it could be an exported
+ // symbol.
+ match tcx.codegen_fn_attrs(instance.def_id()).inline {
+ InlineAttr::Always => InstantiationMode::LocalCopy,
+ _ => {
+ InstantiationMode::GloballyShared { may_conflict: true }
+ }
+ }
+ }
+ MonoItem::Static(..) |
+ MonoItem::GlobalAsm(..) => {
+ InstantiationMode::GloballyShared { may_conflict: false }
+ }
+ }
+ }
+
+ pub fn explicit_linkage(&self, tcx: TyCtxt<'tcx, 'tcx>) -> Option<Linkage> {
+ let def_id = match *self {
+ MonoItem::Fn(ref instance) => instance.def_id(),
+ MonoItem::Static(def_id) => def_id,
+ MonoItem::GlobalAsm(..) => return None,
+ };
+
+ let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
+ codegen_fn_attrs.linkage
+ }
+
+ /// Returns `true` if this instance is instantiable - whether it has no unsatisfied
+ /// predicates.
+ ///
+ /// In order to codegen an item, all of its predicates must hold, because
+ /// otherwise the item does not make sense. Type-checking ensures that
+ /// the predicates of every item that is *used by* a valid item *do*
+ /// hold, so we can rely on that.
+ ///
+ /// However, we codegen collector roots (reachable items) and functions
+ /// in vtables when they are seen, even if they are not used, and so they
+ /// might not be instantiable. For example, a programmer can define this
+ /// public function:
+ ///
+ /// pub fn foo<'a>(s: &'a mut ()) where &'a mut (): Clone {
+ /// <&mut () as Clone>::clone(&s);
+ /// }
+ ///
+ /// That function can't be codegened, because the method `<&mut () as Clone>::clone`
+ /// does not exist. Luckily for us, that function can't ever be used,
+ /// because that would require for `&'a mut (): Clone` to hold, so we
+ /// can just not emit any code, or even a linker reference for it.
+ ///
+ /// Similarly, if a vtable method has such a signature, and therefore can't
+ /// be used, we can just not emit it and have a placeholder (a null pointer,
+ /// which will never be accessed) in its place.
+ pub fn is_instantiable(&self, tcx: TyCtxt<'tcx, 'tcx>) -> bool {
+ debug!("is_instantiable({:?})", self);
+ let (def_id, substs) = match *self {
+ MonoItem::Fn(ref instance) => (instance.def_id(), instance.substs),
+ MonoItem::Static(def_id) => (def_id, InternalSubsts::empty()),
+ // global asm never has predicates
+ MonoItem::GlobalAsm(..) => return true
+ };
+
+ tcx.substitute_normalize_and_test_predicates((def_id, &substs))
+ }
+
+ pub fn to_string(&self, tcx: TyCtxt<'tcx, 'tcx>, debug: bool) -> String {
+ return match *self {
+ MonoItem::Fn(instance) => {
+ to_string_internal(tcx, "fn ", instance, debug)
+ },
+ MonoItem::Static(def_id) => {
+ let instance = Instance::new(def_id, tcx.intern_substs(&[]));
+ to_string_internal(tcx, "static ", instance, debug)
+ },
+ MonoItem::GlobalAsm(..) => {
+ "global_asm".to_string()
+ }
+ };
+
+ fn to_string_internal<'tcx>(
+ tcx: TyCtxt<'tcx, 'tcx>,
+ prefix: &str,
+ instance: Instance<'tcx>,
+ debug: bool,
+ ) -> String {
+ let mut result = String::with_capacity(32);
+ result.push_str(prefix);
+ let printer = DefPathBasedNames::new(tcx, false, false);
+ printer.push_instance_as_string(instance, &mut result, debug);
+ result
+ }
+ }
+
+ pub fn local_span(&self, tcx: TyCtxt<'tcx, 'tcx>) -> Option<Span> {
+ match *self {
+ MonoItem::Fn(Instance { def, .. }) => {
+ tcx.hir().as_local_hir_id(def.def_id())
+ }
+ MonoItem::Static(def_id) => {
+ tcx.hir().as_local_hir_id(def_id)
+ }
+ MonoItem::GlobalAsm(hir_id) => {
+ Some(hir_id)
+ }
+ }.map(|hir_id| tcx.hir().span_by_hir_id(hir_id))
+ }