415 lines
17 KiB
Rust
415 lines
17 KiB
Rust
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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Finds items that are externally reachable, to determine which items
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// need to have their metadata (and possibly their AST) serialized.
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// All items that can be referred to through an exported name are
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// reachable, and when a reachable thing is inline or generic, it
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// makes all other generics or inline functions that it references
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// reachable as well.
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use core::prelude::*;
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use core::iterator::IteratorUtil;
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use middle::resolve;
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use middle::ty;
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use middle::typeck;
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use core::hashmap::HashSet;
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use syntax::ast::*;
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use syntax::ast;
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use syntax::ast_map;
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use syntax::ast_util::def_id_of_def;
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use syntax::attr;
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use syntax::codemap;
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use syntax::parse::token;
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use syntax::visit::Visitor;
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use syntax::visit;
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// Returns true if the given set of attributes contains the `#[inline]`
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// attribute.
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fn attributes_specify_inlining(attrs: &[attribute]) -> bool {
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attr::attrs_contains_name(attrs, "inline")
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}
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// Returns true if the given set of generics implies that the item it's
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// associated with must be inlined.
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fn generics_require_inlining(generics: &Generics) -> bool {
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!generics.ty_params.is_empty()
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}
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// Returns true if the given item must be inlined because it may be
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// monomorphized or it was marked with `#[inline]`. This will only return
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// true for functions.
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fn item_might_be_inlined(item: @item) -> bool {
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if attributes_specify_inlining(item.attrs) {
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return true
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}
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match item.node {
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item_fn(_, _, _, ref generics, _) => {
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generics_require_inlining(generics)
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}
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_ => false,
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}
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}
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// Returns true if the given type method must be inlined because it may be
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// monomorphized or it was marked with `#[inline]`.
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fn ty_method_might_be_inlined(ty_method: &ty_method) -> bool {
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attributes_specify_inlining(ty_method.attrs) ||
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generics_require_inlining(&ty_method.generics)
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}
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// Returns true if the given trait method must be inlined because it may be
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// monomorphized or it was marked with `#[inline]`.
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fn trait_method_might_be_inlined(trait_method: &trait_method) -> bool {
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match *trait_method {
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required(ref ty_method) => ty_method_might_be_inlined(ty_method),
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provided(_) => true
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}
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}
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// Information needed while computing reachability.
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struct ReachableContext {
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// The type context.
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tcx: ty::ctxt,
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// The method map, which links node IDs of method call expressions to the
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// methods they've been resolved to.
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method_map: typeck::method_map,
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// The set of items which must be exported in the linkage sense.
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reachable_symbols: @mut HashSet<node_id>,
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// A worklist of item IDs. Each item ID in this worklist will be inlined
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// and will be scanned for further references.
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worklist: @mut ~[node_id],
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}
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impl ReachableContext {
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// Creates a new reachability computation context.
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fn new(tcx: ty::ctxt, method_map: typeck::method_map)
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-> ReachableContext {
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ReachableContext {
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tcx: tcx,
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method_map: method_map,
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reachable_symbols: @mut HashSet::new(),
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worklist: @mut ~[],
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}
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}
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// Step 1: Mark all public symbols, and add all public symbols that might
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// be inlined to a worklist.
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fn mark_public_symbols(&self, crate: @crate) {
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let reachable_symbols = self.reachable_symbols;
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let worklist = self.worklist;
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let visitor = visit::mk_vt(@Visitor {
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visit_item: |item, _, visitor| {
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match item.node {
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item_fn(*) => {
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reachable_symbols.insert(item.id);
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if item_might_be_inlined(item) {
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worklist.push(item.id)
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}
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}
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item_struct(ref struct_def, _) => {
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match struct_def.ctor_id {
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None => {}
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Some(ctor_id) => {
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reachable_symbols.insert(ctor_id);
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}
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}
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}
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item_enum(ref enum_def, _) => {
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for enum_def.variants.each |variant| {
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reachable_symbols.insert(variant.node.id);
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}
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}
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item_impl(ref generics, trait_ref, _, ref methods) => {
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// XXX(pcwalton): We conservatively assume any methods
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// on a trait implementation are reachable, when this
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// is not the case. We could be more precise by only
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// treating implementations of reachable or cross-
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// crate traits as reachable.
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// Mark all public methods as reachable.
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for methods.each |method| {
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if method.vis == public || trait_ref.is_some() {
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reachable_symbols.insert(method.id);
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}
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}
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if generics_require_inlining(generics) {
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// If the impl itself has generics, add all public
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// symbols to the worklist.
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for methods.each |method| {
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if method.vis == public ||
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trait_ref.is_some() {
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worklist.push(method.id)
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}
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}
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} else {
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// Otherwise, add only public methods that have
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// generics to the worklist.
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for methods.each |method| {
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let generics = &method.generics;
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let attrs = &method.attrs;
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if generics_require_inlining(generics) ||
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attributes_specify_inlining(*attrs) ||
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method.vis == public ||
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trait_ref.is_some() {
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worklist.push(method.id)
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}
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}
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}
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}
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item_trait(_, _, ref trait_methods) => {
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// Mark all provided methods as reachable.
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for trait_methods.each |trait_method| {
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match *trait_method {
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provided(method) => {
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reachable_symbols.insert(method.id);
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worklist.push(method.id)
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}
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required(_) => {}
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}
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}
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}
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_ => {}
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}
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if item.vis == public {
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visit::visit_item(item, (), visitor)
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}
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},
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.. *visit::default_visitor()
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});
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visit::visit_crate(crate, (), visitor)
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}
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// Returns true if the given def ID represents a local item that is
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// eligible for inlining and false otherwise.
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fn def_id_represents_local_inlined_item(tcx: ty::ctxt, def_id: def_id)
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-> bool {
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if def_id.crate != local_crate {
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return false
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}
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let node_id = def_id.node;
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match tcx.items.find(&node_id) {
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Some(&ast_map::node_item(item, _)) => {
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match item.node {
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item_fn(*) => item_might_be_inlined(item),
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_ => false,
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}
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}
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Some(&ast_map::node_trait_method(trait_method, _, _)) => {
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match *trait_method {
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required(_) => false,
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provided(_) => true,
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}
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}
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Some(&ast_map::node_method(method, impl_did, _)) => {
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if generics_require_inlining(&method.generics) ||
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attributes_specify_inlining(method.attrs) {
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true
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} else {
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// Check the impl. If the generics on the self type of the
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// impl require inlining, this method does too.
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assert!(impl_did.crate == local_crate);
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match tcx.items.find(&impl_did.node) {
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Some(&ast_map::node_item(item, _)) => {
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match item.node {
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item_impl(ref generics, _, _, _) => {
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generics_require_inlining(generics)
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}
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_ => false
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}
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}
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Some(_) => {
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tcx.sess.span_bug(method.span,
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"method is not inside an \
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impl?!")
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}
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None => {
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tcx.sess.span_bug(method.span,
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"the impl that this method is \
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supposedly inside of doesn't \
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exist in the AST map?!")
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}
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}
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}
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}
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Some(_) => false,
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None => tcx.sess.bug("def ID not in def map?!"),
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}
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}
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// Helper function to set up a visitor for `propagate()` below.
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fn init_visitor(&self) -> visit::vt<()> {
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let (worklist, method_map) = (self.worklist, self.method_map);
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let (tcx, reachable_symbols) = (self.tcx, self.reachable_symbols);
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visit::mk_vt(@visit::Visitor {
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visit_expr: |expr, _, visitor| {
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match expr.node {
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expr_path(_) => {
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let def = match tcx.def_map.find(&expr.id) {
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Some(&def) => def,
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None => {
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tcx.sess.span_bug(expr.span,
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"def ID not in def map?!")
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}
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};
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let def_id = def_id_of_def(def);
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if ReachableContext::
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def_id_represents_local_inlined_item(tcx,
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def_id) {
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worklist.push(def_id.node)
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}
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reachable_symbols.insert(def_id.node);
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}
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expr_method_call(*) => {
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match method_map.find(&expr.id) {
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Some(&typeck::method_map_entry {
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origin: typeck::method_static(def_id),
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_
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}) => {
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if ReachableContext::
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def_id_represents_local_inlined_item(
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tcx,
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def_id) {
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worklist.push(def_id.node)
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}
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reachable_symbols.insert(def_id.node);
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}
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Some(_) => {}
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None => {
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tcx.sess.span_bug(expr.span,
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"method call expression \
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not in method map?!")
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}
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}
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}
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_ => {}
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}
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visit::visit_expr(expr, (), visitor)
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},
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..*visit::default_visitor()
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})
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}
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// Step 2: Mark all symbols that the symbols on the worklist touch.
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fn propagate(&self) {
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let visitor = self.init_visitor();
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let mut scanned = HashSet::new();
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while self.worklist.len() > 0 {
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let search_item = self.worklist.pop();
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if scanned.contains(&search_item) {
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loop
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}
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scanned.insert(search_item);
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self.reachable_symbols.insert(search_item);
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// Find the AST block corresponding to the item and visit it,
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// marking all path expressions that resolve to something
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// interesting.
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match self.tcx.items.find(&search_item) {
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Some(&ast_map::node_item(item, _)) => {
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match item.node {
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item_fn(_, _, _, _, ref search_block) => {
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visit::visit_block(search_block, (), visitor)
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}
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_ => {
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self.tcx.sess.span_bug(item.span,
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"found non-function item \
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in worklist?!")
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}
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}
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}
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Some(&ast_map::node_trait_method(trait_method, _, _)) => {
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match *trait_method {
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required(ref ty_method) => {
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self.tcx.sess.span_bug(ty_method.span,
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"found required method in \
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worklist?!")
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}
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provided(ref method) => {
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visit::visit_block(&method.body, (), visitor)
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}
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}
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}
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Some(&ast_map::node_method(ref method, _, _)) => {
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visit::visit_block(&method.body, (), visitor)
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}
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Some(_) => {
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let ident_interner = token::get_ident_interner();
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let desc = ast_map::node_id_to_str(self.tcx.items,
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search_item,
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ident_interner);
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self.tcx.sess.bug(fmt!("found unexpected thingy in \
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worklist: %s",
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desc))
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}
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None => {
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self.tcx.sess.bug(fmt!("found unmapped ID in worklist: \
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%d",
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search_item))
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}
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}
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}
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}
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// Step 3: Mark all destructors as reachable.
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||
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//
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// XXX(pcwalton): This is a conservative overapproximation, but fixing
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// this properly would result in the necessity of computing *type*
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// reachability, which might result in a compile time loss.
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fn mark_destructors_reachable(&self) {
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for self.tcx.destructor_for_type.each |_, destructor_def_id| {
|
||
|
|
if destructor_def_id.crate == local_crate {
|
||
|
|
self.reachable_symbols.insert(destructor_def_id.node);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
pub fn find_reachable(tcx: ty::ctxt,
|
||
|
|
method_map: typeck::method_map,
|
||
|
|
crate: @crate)
|
||
|
|
-> @mut HashSet<node_id> {
|
||
|
|
// XXX(pcwalton): We only need to mark symbols that are exported. But this
|
||
|
|
// is more complicated than just looking at whether the symbol is `pub`,
|
||
|
|
// because it might be the target of a `pub use` somewhere. For now, I
|
||
|
|
// think we are fine, because you can't `pub use` something that wasn't
|
||
|
|
// exported due to the bug whereby `use` only looks through public
|
||
|
|
// modules even if you're inside the module the `use` appears in. When
|
||
|
|
// this bug is fixed, however, this code will need to be updated. Probably
|
||
|
|
// the easiest way to fix this (although a conservative overapproximation)
|
||
|
|
// is to have the name resolution pass mark all targets of a `pub use` as
|
||
|
|
// "must be reachable".
|
||
|
|
|
||
|
|
let reachable_context = ReachableContext::new(tcx, method_map);
|
||
|
|
|
||
|
|
// Step 1: Mark all public symbols, and add all public symbols that might
|
||
|
|
// be inlined to a worklist.
|
||
|
|
reachable_context.mark_public_symbols(crate);
|
||
|
|
|
||
|
|
// Step 2: Mark all symbols that the symbols on the worklist touch.
|
||
|
|
reachable_context.propagate();
|
||
|
|
|
||
|
|
// Step 3: Mark all destructors as reachable.
|
||
|
|
reachable_context.mark_destructors_reachable();
|
||
|
|
|
||
|
|
// Return the set of reachable symbols.
|
||
|
|
reachable_context.reachable_symbols
|
||
|
|
}
|
||
|
|
|