src/librustc_incremental/assert_dep_graph.rs

   1 //! This pass is only used for the UNIT TESTS and DEBUGGING NEEDS
   2 //! around dependency graph construction. It serves two purposes; it
   3 //! will dump graphs in graphviz form to disk, and it searches for
   4 //! `#[rustc_if_this_changed]` and `#[rustc_then_this_would_need]`
   5 //! annotations. These annotations can be used to test whether paths
   6 //! exist in the graph. These checks run after codegen, so they view the
   7 //! the final state of the dependency graph. Note that there are
   8 //! similar assertions found in `persist::dirty_clean` which check the
   9 //! **initial** state of the dependency graph, just after it has been
  10 //! loaded from disk.
  11 //!
  12 //! In this code, we report errors on each `rustc_if_this_changed`
  13 //! annotation. If a path exists in all cases, then we would report
  14 //! "all path(s) exist". Otherwise, we report: "no path to `foo`" for
  15 //! each case where no path exists. `compile-fail` tests can then be
  16 //! used to check when paths exist or do not.
  17 //!
  18 //! The full form of the `rustc_if_this_changed` annotation is
  19 //! `#[rustc_if_this_changed("foo")]`, which will report a
  20 //! source node of `foo(def_id)`. The `"foo"` is optional and
  21 //! defaults to `"Hir"` if omitted.
  22 //!
  23 //! Example:
  24 //!
  25 //! ```
  26 //! #[rustc_if_this_changed(Hir)]
  27 //! fn foo() { }
  28 //!
  29 //! #[rustc_then_this_would_need(codegen)] //~ ERROR no path from `foo`
  30 //! fn bar() { }
  31 //!
  32 //! #[rustc_then_this_would_need(codegen)] //~ ERROR OK
  33 //! fn baz() { foo(); }
  34 //! ```
  35
  36 use graphviz as dot;
  37 use rustc::dep_graph::{DepGraphQuery, DepNode, DepKind};
  38 use rustc::dep_graph::debug::{DepNodeFilter, EdgeFilter};
  39 use rustc::hir::def_id::DefId;
  40 use rustc::ty::TyCtxt;
  41 use rustc_data_structures::fx::FxHashSet;
  42 use rustc_data_structures::graph::implementation::{
  43     Direction, INCOMING, OUTGOING, NodeIndex
  44 };
  45 use rustc::hir;
  46 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
  47 use rustc::ich::{ATTR_IF_THIS_CHANGED, ATTR_THEN_THIS_WOULD_NEED};
  48 use std::env;
  49 use std::fs::{self, File};
  50 use std::io::Write;
  51 use syntax::ast;
  52 use syntax_pos::Span;
  53
  54 pub fn assert_dep_graph(tcx: TyCtxt<'_>) {
  55     tcx.dep_graph.with_ignore(|| {
  56         if tcx.sess.opts.debugging_opts.dump_dep_graph {
  57             dump_graph(tcx);
  58         }
  59
  60         // if the `rustc_attrs` feature is not enabled, then the
  61         // attributes we are interested in cannot be present anyway, so
  62         // skip the walk.
  63         if !tcx.features().rustc_attrs {
  64             return;
  65         }
  66
  67         // Find annotations supplied by user (if any).
  68         let (if_this_changed, then_this_would_need) = {
  69             let mut visitor = IfThisChanged { tcx,
  70                                             if_this_changed: vec![],
  71                                             then_this_would_need: vec![] };
  72             visitor.process_attrs(hir::CRATE_HIR_ID, &tcx.hir().krate().attrs);
  73             tcx.hir().krate().visit_all_item_likes(&mut visitor.as_deep_visitor());
  74             (visitor.if_this_changed, visitor.then_this_would_need)
  75         };
  76
  77         if !if_this_changed.is_empty() || !then_this_would_need.is_empty() {
  78             assert!(tcx.sess.opts.debugging_opts.query_dep_graph,
  79                     "cannot use the `#[{}]` or `#[{}]` annotations \
  80                     without supplying `-Z query-dep-graph`",
  81                     ATTR_IF_THIS_CHANGED, ATTR_THEN_THIS_WOULD_NEED);
  82         }
  83
  84         // Check paths.
  85         check_paths(tcx, &if_this_changed, &then_this_would_need);
  86     })
  87 }
  88
  89 type Sources = Vec<(Span, DefId, DepNode)>;
  90 type Targets = Vec<(Span, ast::Name, hir::HirId, DepNode)>;
  91
  92 struct IfThisChanged<'tcx> {
  93     tcx: TyCtxt<'tcx>,
  94     if_this_changed: Sources,
  95     then_this_would_need: Targets,
  96 }
  97
  98 impl IfThisChanged<'tcx> {
  99     fn argument(&self, attr: &ast::Attribute) -> Option<ast::Name> {
 100         let mut value = None;
 101         for list_item in attr.meta_item_list().unwrap_or_default() {
 102             match list_item.ident() {
 103                 Some(ident) if list_item.is_word() && value.is_none() =>
 104                     value = Some(ident.name),
 105                 _ =>
 106                     // FIXME better-encapsulate meta_item (don't directly access `node`)
 107                     span_bug!(list_item.span(), "unexpected meta-item {:?}", list_item),
 108             }
 109         }
 110         value
 111     }
 112
 113     fn process_attrs(&mut self, hir_id: hir::HirId, attrs: &[ast::Attribute]) {
 114         let def_id = self.tcx.hir().local_def_id(hir_id);
 115         let def_path_hash = self.tcx.def_path_hash(def_id);
 116         for attr in attrs {
 117             if attr.check_name(ATTR_IF_THIS_CHANGED) {
 118                 let dep_node_interned = self.argument(attr);
 119                 let dep_node = match dep_node_interned {
 120                     None => def_path_hash.to_dep_node(DepKind::Hir),
 121                     Some(n) => {
 122                         match DepNode::from_label_string(&n.as_str(), def_path_hash) {
 123                             Ok(n) => n,
 124                             Err(()) => {
 125                                 self.tcx.sess.span_fatal(
 126                                     attr.span,
 127                                     &format!("unrecognized DepNode variant {:?}", n));
 128                             }
 129                         }
 130                     }
 131                 };
 132                 self.if_this_changed.push((attr.span, def_id, dep_node));
 133             } else if attr.check_name(ATTR_THEN_THIS_WOULD_NEED) {
 134                 let dep_node_interned = self.argument(attr);
 135                 let dep_node = match dep_node_interned {
 136                     Some(n) => {
 137                         match DepNode::from_label_string(&n.as_str(), def_path_hash) {
 138                             Ok(n) => n,
 139                             Err(()) => {
 140                                 self.tcx.sess.span_fatal(
 141                                     attr.span,
 142                                     &format!("unrecognized DepNode variant {:?}", n));
 143                             }
 144                         }
 145                     }
 146                     None => {
 147                         self.tcx.sess.span_fatal(
 148                             attr.span,
 149                             "missing DepNode variant");
 150                     }
 151                 };
 152                 self.then_this_would_need.push((attr.span,
 153                                                 dep_node_interned.unwrap(),
 154                                                 hir_id,
 155                                                 dep_node));
 156             }
 157         }
 158     }
 159 }
 160
 161 impl Visitor<'tcx> for IfThisChanged<'tcx> {
 162     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 163         NestedVisitorMap::OnlyBodies(&self.tcx.hir())
 164     }
 165
 166     fn visit_item(&mut self, item: &'tcx hir::Item) {
 167         self.process_attrs(item.hir_id, &item.attrs);
 168         intravisit::walk_item(self, item);
 169     }
 170
 171     fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
 172         self.process_attrs(trait_item.hir_id, &trait_item.attrs);
 173         intravisit::walk_trait_item(self, trait_item);
 174     }
 175
 176     fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
 177         self.process_attrs(impl_item.hir_id, &impl_item.attrs);
 178         intravisit::walk_impl_item(self, impl_item);
 179     }
 180
 181     fn visit_struct_field(&mut self, s: &'tcx hir::StructField) {
 182         self.process_attrs(s.hir_id, &s.attrs);
 183         intravisit::walk_struct_field(self, s);
 184     }
 185 }
 186
 187 fn check_paths<'tcx>(tcx: TyCtxt<'tcx>, if_this_changed: &Sources, then_this_would_need: &Targets) {
 188     // Return early here so as not to construct the query, which is not cheap.
 189     if if_this_changed.is_empty() {
 190         for &(target_span, _, _, _) in then_this_would_need {
 191             tcx.sess.span_err(
 192                 target_span,
 193                 "no `#[rustc_if_this_changed]` annotation detected");
 194
 195         }
 196         return;
 197     }
 198     let query = tcx.dep_graph.query();
 199     for &(_, source_def_id, ref source_dep_node) in if_this_changed {
 200         let dependents = query.transitive_predecessors(source_dep_node);
 201         for &(target_span, ref target_pass, _, ref target_dep_node) in then_this_would_need {
 202             if !dependents.contains(&target_dep_node) {
 203                 tcx.sess.span_err(
 204                     target_span,
 205                     &format!("no path from `{}` to `{}`",
 206                              tcx.def_path_str(source_def_id),
 207                              target_pass));
 208             } else {
 209                 tcx.sess.span_err(
 210                     target_span,
 211                     "OK");
 212             }
 213         }
 214     }
 215 }
 216
 217 fn dump_graph(tcx: TyCtxt<'_>) {
 218     let path: String = env::var("RUST_DEP_GRAPH").unwrap_or_else(|_| "dep_graph".to_string());
 219     let query = tcx.dep_graph.query();
 220
 221     let nodes = match env::var("RUST_DEP_GRAPH_FILTER") {
 222         Ok(string) => {
 223             // Expect one of: "-> target", "source -> target", or "source ->".
 224             let edge_filter = EdgeFilter::new(&string).unwrap_or_else(|e| {
 225                 bug!("invalid filter: {}", e)
 226             });
 227             let sources = node_set(&query, &edge_filter.source);
 228             let targets = node_set(&query, &edge_filter.target);
 229             filter_nodes(&query, &sources, &targets)
 230         }
 231         Err(_) => {
 232             query.nodes()
 233                  .into_iter()
 234                  .collect()
 235         }
 236     };
 237     let edges = filter_edges(&query, &nodes);
 238
 239     { // dump a .txt file with just the edges:
 240         let txt_path = format!("{}.txt", path);
 241         let mut file = File::create(&txt_path).unwrap();
 242         for &(ref source, ref target) in &edges {
 243             write!(file, "{:?} -> {:?}\n", source, target).unwrap();
 244         }
 245     }
 246
 247     { // dump a .dot file in graphviz format:
 248         let dot_path = format!("{}.dot", path);
 249         let mut v = Vec::new();
 250         dot::render(&GraphvizDepGraph(nodes, edges), &mut v).unwrap();
 251         fs::write(dot_path, v).unwrap();
 252     }
 253 }
 254
 255 pub struct GraphvizDepGraph<'q>(FxHashSet<&'q DepNode>,
 256                                 Vec<(&'q DepNode, &'q DepNode)>);
 257
 258 impl<'a, 'q> dot::GraphWalk<'a> for GraphvizDepGraph<'q> {
 259     type Node = &'q DepNode;
 260     type Edge = (&'q DepNode, &'q DepNode);
 261     fn nodes(&self) -> dot::Nodes<'_, &'q DepNode> {
 262         let nodes: Vec<_> = self.0.iter().cloned().collect();
 263         nodes.into()
 264     }
 265     fn edges(&self) -> dot::Edges<'_, (&'q DepNode, &'q DepNode)> {
 266         self.1[..].into()
 267     }
 268     fn source(&self, edge: &(&'q DepNode, &'q DepNode)) -> &'q DepNode {
 269         edge.0
 270     }
 271     fn target(&self, edge: &(&'q DepNode, &'q DepNode)) -> &'q DepNode {
 272         edge.1
 273     }
 274 }
 275
 276 impl<'a, 'q> dot::Labeller<'a> for GraphvizDepGraph<'q> {
 277     type Node = &'q DepNode;
 278     type Edge = (&'q DepNode, &'q DepNode);
 279     fn graph_id(&self) -> dot::Id<'_> {
 280         dot::Id::new("DependencyGraph").unwrap()
 281     }
 282     fn node_id(&self, n: &&'q DepNode) -> dot::Id<'_> {
 283         let s: String =
 284             format!("{:?}", n).chars()
 285                               .map(|c| if c == '_' || c.is_alphanumeric() { c } else { '_' })
 286                               .collect();
 287         debug!("n={:?} s={:?}", n, s);
 288         dot::Id::new(s).unwrap()
 289     }
 290     fn node_label(&self, n: &&'q DepNode) -> dot::LabelText<'_> {
 291         dot::LabelText::label(format!("{:?}", n))
 292     }
 293 }
 294
 295 // Given an optional filter like `"x,y,z"`, returns either `None` (no
 296 // filter) or the set of nodes whose labels contain all of those
 297 // substrings.
 298 fn node_set<'q>(query: &'q DepGraphQuery, filter: &DepNodeFilter)
 299                 -> Option<FxHashSet<&'q DepNode>>
 300 {
 301     debug!("node_set(filter={:?})", filter);
 302
 303     if filter.accepts_all() {
 304         return None;
 305     }
 306
 307     Some(query.nodes().into_iter().filter(|n| filter.test(n)).collect())
 308 }
 309
 310 fn filter_nodes<'q>(query: &'q DepGraphQuery,
 311                     sources: &Option<FxHashSet<&'q DepNode>>,
 312                     targets: &Option<FxHashSet<&'q DepNode>>)
 313                     -> FxHashSet<&'q DepNode>
 314 {
 315     if let &Some(ref sources) = sources {
 316         if let &Some(ref targets) = targets {
 317             walk_between(query, sources, targets)
 318         } else {
 319             walk_nodes(query, sources, OUTGOING)
 320         }
 321     } else if let &Some(ref targets) = targets {
 322         walk_nodes(query, targets, INCOMING)
 323     } else {
 324         query.nodes().into_iter().collect()
 325     }
 326 }
 327
 328 fn walk_nodes<'q>(query: &'q DepGraphQuery,
 329                   starts: &FxHashSet<&'q DepNode>,
 330                   direction: Direction)
 331                   -> FxHashSet<&'q DepNode>
 332 {
 333     let mut set = FxHashSet::default();
 334     for &start in starts {
 335         debug!("walk_nodes: start={:?} outgoing?={:?}", start, direction == OUTGOING);
 336         if set.insert(start) {
 337             let mut stack = vec![query.indices[start]];
 338             while let Some(index) = stack.pop() {
 339                 for (_, edge) in query.graph.adjacent_edges(index, direction) {
 340                     let neighbor_index = edge.source_or_target(direction);
 341                     let neighbor = query.graph.node_data(neighbor_index);
 342                     if set.insert(neighbor) {
 343                         stack.push(neighbor_index);
 344                     }
 345                 }
 346             }
 347         }
 348     }
 349     set
 350 }
 351
 352 fn walk_between<'q>(query: &'q DepGraphQuery,
 353                     sources: &FxHashSet<&'q DepNode>,
 354                     targets: &FxHashSet<&'q DepNode>)
 355                     -> FxHashSet<&'q DepNode>
 356 {
 357     // This is a bit tricky. We want to include a node only if it is:
 358     // (a) reachable from a source and (b) will reach a target. And we
 359     // have to be careful about cycles etc.  Luckily efficiency is not
 360     // a big concern!
 361
 362     #[derive(Copy, Clone, PartialEq)]
 363     enum State { Undecided, Deciding, Included, Excluded }
 364
 365     let mut node_states = vec![State::Undecided; query.graph.len_nodes()];
 366
 367     for &target in targets {
 368         node_states[query.indices[target].0] = State::Included;
 369     }
 370
 371     for source in sources.iter().map(|&n| query.indices[n]) {
 372         recurse(query, &mut node_states, source);
 373     }
 374
 375     return query.nodes()
 376                 .into_iter()
 377                 .filter(|&n| {
 378                     let index = query.indices[n];
 379                     node_states[index.0] == State::Included
 380                 })
 381                 .collect();
 382
 383     fn recurse(query: &DepGraphQuery,
 384                node_states: &mut [State],
 385                node: NodeIndex)
 386                -> bool
 387     {
 388         match node_states[node.0] {
 389             // known to reach a target
 390             State::Included => return true,
 391
 392             // known not to reach a target
 393             State::Excluded => return false,
 394
 395             // backedge, not yet known, say false
 396             State::Deciding => return false,
 397
 398             State::Undecided => { }
 399         }
 400
 401         node_states[node.0] = State::Deciding;
 402
 403         for neighbor_index in query.graph.successor_nodes(node) {
 404             if recurse(query, node_states, neighbor_index) {
 405                 node_states[node.0] = State::Included;
 406             }
 407         }
 408
 409         // if we didn't find a path to target, then set to excluded
 410         if node_states[node.0] == State::Deciding {
 411             node_states[node.0] = State::Excluded;
 412             false
 413         } else {
 414             assert!(node_states[node.0] == State::Included);
 415             true
 416         }
 417     }
 418 }
 419
 420 fn filter_edges<'q>(query: &'q DepGraphQuery,
 421                     nodes: &FxHashSet<&'q DepNode>)
 422                     -> Vec<(&'q DepNode, &'q DepNode)>
 423 {
 424     query.edges()
 425          .into_iter()
 426          .filter(|&(source, target)| nodes.contains(source) && nodes.contains(target))
 427          .collect()
 428 }