src/librustc/infer/region_inference/graphviz.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! This module provides linkage between libgraphviz traits and
  12 //! `rustc::middle::typeck::infer::region_inference`, generating a
  13 //! rendering of the graph represented by the list of `Constraint`
  14 //! instances (which make up the edges of the graph), as well as the
  15 //! origin for each constraint (which are attached to the labels on
  16 //! each edge).
  17
  18 /// For clarity, rename the graphviz crate locally to dot.
  19 use graphviz as dot;
  20
  21 use ty::{self, TyCtxt};
  22 use middle::region::CodeExtent;
  23 use super::Constraint;
  24 use infer::SubregionOrigin;
  25 use infer::region_inference::RegionVarBindings;
  26 use util::nodemap::{FnvHashMap, FnvHashSet};
  27
  28 use std::borrow::Cow;
  29 use std::collections::hash_map::Entry::Vacant;
  30 use std::env;
  31 use std::fs::File;
  32 use std::io;
  33 use std::io::prelude::*;
  34 use std::sync::atomic::{AtomicBool, Ordering};
  35 use syntax::ast;
  36
  37 fn print_help_message() {
  38     println!("\
  39 -Z print-region-graph by default prints a region constraint graph for every \n\
  40 function body, to the path `/tmp/constraints.nodeXXX.dot`, where the XXX is \n\
  41 replaced with the node id of the function under analysis.                   \n\
  42                                                                             \n\
  43 To select one particular function body, set `RUST_REGION_GRAPH_NODE=XXX`,   \n\
  44 where XXX is the node id desired.                                           \n\
  45                                                                             \n\
  46 To generate output to some path other than the default                      \n\
  47 `/tmp/constraints.nodeXXX.dot`, set `RUST_REGION_GRAPH=/path/desired.dot`;  \n\
  48 occurrences of the character `%` in the requested path will be replaced with\n\
  49 the node id of the function under analysis.                                 \n\
  50                                                                             \n\
  51 (Since you requested help via RUST_REGION_GRAPH=help, no region constraint  \n\
  52 graphs will be printed.                                                     \n\
  53 ");
  54 }
  55
  56 pub fn maybe_print_constraints_for<'a, 'gcx, 'tcx>(
  57     region_vars: &RegionVarBindings<'a, 'gcx, 'tcx>,
  58     subject_node: ast::NodeId)
  59 {
  60     let tcx = region_vars.tcx;
  61
  62     if !region_vars.tcx.sess.opts.debugging_opts.print_region_graph {
  63         return;
  64     }
  65
  66     let requested_node: Option<ast::NodeId> = env::var("RUST_REGION_GRAPH_NODE")
  67                                                   .ok()
  68                                                   .and_then(|s| s.parse().ok());
  69
  70     if requested_node.is_some() && requested_node != Some(subject_node) {
  71         return;
  72     }
  73
  74     let requested_output = env::var("RUST_REGION_GRAPH");
  75     debug!("requested_output: {:?} requested_node: {:?}",
  76            requested_output,
  77            requested_node);
  78
  79     let output_path = {
  80         let output_template = match requested_output {
  81             Ok(ref s) if s == "help" => {
  82                 static PRINTED_YET: AtomicBool = AtomicBool::new(false);
  83                 if !PRINTED_YET.load(Ordering::SeqCst) {
  84                     print_help_message();
  85                     PRINTED_YET.store(true, Ordering::SeqCst);
  86                 }
  87                 return;
  88             }
  89
  90             Ok(other_path) => other_path,
  91             Err(_) => "/tmp/constraints.node%.dot".to_string(),
  92         };
  93
  94         if output_template.is_empty() {
  95             bug!("empty string provided as RUST_REGION_GRAPH");
  96         }
  97
  98         if output_template.contains('%') {
  99             let mut new_str = String::new();
 100             for c in output_template.chars() {
 101                 if c == '%' {
 102                     new_str.push_str(&subject_node.to_string());
 103                 } else {
 104                     new_str.push(c);
 105                 }
 106             }
 107             new_str
 108         } else {
 109             output_template
 110         }
 111     };
 112
 113     let constraints = &*region_vars.constraints.borrow();
 114     match dump_region_constraints_to(tcx, constraints, &output_path) {
 115         Ok(()) => {}
 116         Err(e) => {
 117             let msg = format!("io error dumping region constraints: {}", e);
 118             region_vars.tcx.sess.err(&msg)
 119         }
 120     }
 121 }
 122
 123 struct ConstraintGraph<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
 124     tcx: TyCtxt<'a, 'gcx, 'tcx>,
 125     graph_name: String,
 126     map: &'a FnvHashMap<Constraint, SubregionOrigin<'tcx>>,
 127     node_ids: FnvHashMap<Node, usize>,
 128 }
 129
 130 #[derive(Clone, Hash, PartialEq, Eq, Debug, Copy)]
 131 enum Node {
 132     RegionVid(ty::RegionVid),
 133     Region(ty::Region),
 134 }
 135
 136 // type Edge = Constraint;
 137 #[derive(Clone, PartialEq, Eq, Debug, Copy)]
 138 enum Edge {
 139     Constraint(Constraint),
 140     EnclScope(CodeExtent, CodeExtent),
 141 }
 142
 143 impl<'a, 'gcx, 'tcx> ConstraintGraph<'a, 'gcx, 'tcx> {
 144     fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>,
 145            name: String,
 146            map: &'a ConstraintMap<'tcx>)
 147            -> ConstraintGraph<'a, 'gcx, 'tcx> {
 148         let mut i = 0;
 149         let mut node_ids = FnvHashMap();
 150         {
 151             let mut add_node = |node| {
 152                 if let Vacant(e) = node_ids.entry(node) {
 153                     e.insert(i);
 154                     i += 1;
 155                 }
 156             };
 157
 158             for (n1, n2) in map.keys().map(|c| constraint_to_nodes(c)) {
 159                 add_node(n1);
 160                 add_node(n2);
 161             }
 162
 163             tcx.region_maps.each_encl_scope(|sub, sup| {
 164                 add_node(Node::Region(ty::ReScope(*sub)));
 165                 add_node(Node::Region(ty::ReScope(*sup)));
 166             });
 167         }
 168
 169         ConstraintGraph {
 170             tcx: tcx,
 171             graph_name: name,
 172             map: map,
 173             node_ids: node_ids,
 174         }
 175     }
 176 }
 177
 178 impl<'a, 'gcx, 'tcx> dot::Labeller<'a> for ConstraintGraph<'a, 'gcx, 'tcx> {
 179     type Node = Node;
 180     type Edge = Edge;
 181     fn graph_id(&self) -> dot::Id {
 182         dot::Id::new(&*self.graph_name).unwrap()
 183     }
 184     fn node_id(&self, n: &Node) -> dot::Id {
 185         let node_id = match self.node_ids.get(n) {
 186             Some(node_id) => node_id,
 187             None => bug!("no node_id found for node: {:?}", n),
 188         };
 189         let name = || format!("node_{}", node_id);
 190         match dot::Id::new(name()) {
 191             Ok(id) => id,
 192             Err(_) => {
 193                 bug!("failed to create graphviz node identified by {}", name());
 194             }
 195         }
 196     }
 197     fn node_label(&self, n: &Node) -> dot::LabelText {
 198         match *n {
 199             Node::RegionVid(n_vid) => dot::LabelText::label(format!("{:?}", n_vid)),
 200             Node::Region(n_rgn) => dot::LabelText::label(format!("{:?}", n_rgn)),
 201         }
 202     }
 203     fn edge_label(&self, e: &Edge) -> dot::LabelText {
 204         match *e {
 205             Edge::Constraint(ref c) =>
 206                 dot::LabelText::label(format!("{:?}", self.map.get(c).unwrap())),
 207             Edge::EnclScope(..) => dot::LabelText::label(format!("(enclosed)")),
 208         }
 209     }
 210 }
 211
 212 fn constraint_to_nodes(c: &Constraint) -> (Node, Node) {
 213     match *c {
 214         Constraint::ConstrainVarSubVar(rv_1, rv_2) =>
 215             (Node::RegionVid(rv_1), Node::RegionVid(rv_2)),
 216         Constraint::ConstrainRegSubVar(r_1, rv_2) => (Node::Region(r_1), Node::RegionVid(rv_2)),
 217         Constraint::ConstrainVarSubReg(rv_1, r_2) => (Node::RegionVid(rv_1), Node::Region(r_2)),
 218     }
 219 }
 220
 221 fn edge_to_nodes(e: &Edge) -> (Node, Node) {
 222     match *e {
 223         Edge::Constraint(ref c) => constraint_to_nodes(c),
 224         Edge::EnclScope(sub, sup) => {
 225             (Node::Region(ty::ReScope(sub)),
 226              Node::Region(ty::ReScope(sup)))
 227         }
 228     }
 229 }
 230
 231 impl<'a, 'gcx, 'tcx> dot::GraphWalk<'a> for ConstraintGraph<'a, 'gcx, 'tcx> {
 232     type Node = Node;
 233     type Edge = Edge;
 234     fn nodes(&self) -> dot::Nodes<Node> {
 235         let mut set = FnvHashSet();
 236         for node in self.node_ids.keys() {
 237             set.insert(*node);
 238         }
 239         debug!("constraint graph has {} nodes", set.len());
 240         set.into_iter().collect()
 241     }
 242     fn edges(&self) -> dot::Edges<Edge> {
 243         debug!("constraint graph has {} edges", self.map.len());
 244         let mut v: Vec<_> = self.map.keys().map(|e| Edge::Constraint(*e)).collect();
 245         self.tcx.region_maps.each_encl_scope(|sub, sup| v.push(Edge::EnclScope(*sub, *sup)));
 246         debug!("region graph has {} edges", v.len());
 247         Cow::Owned(v)
 248     }
 249     fn source(&self, edge: &Edge) -> Node {
 250         let (n1, _) = edge_to_nodes(edge);
 251         debug!("edge {:?} has source {:?}", edge, n1);
 252         n1
 253     }
 254     fn target(&self, edge: &Edge) -> Node {
 255         let (_, n2) = edge_to_nodes(edge);
 256         debug!("edge {:?} has target {:?}", edge, n2);
 257         n2
 258     }
 259 }
 260
 261 pub type ConstraintMap<'tcx> = FnvHashMap<Constraint, SubregionOrigin<'tcx>>;
 262
 263 fn dump_region_constraints_to<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
 264                                               map: &ConstraintMap<'tcx>,
 265                                               path: &str)
 266                                               -> io::Result<()> {
 267     debug!("dump_region_constraints map (len: {}) path: {}",
 268            map.len(),
 269            path);
 270     let g = ConstraintGraph::new(tcx, format!("region_constraints"), map);
 271     debug!("dump_region_constraints calling render");
 272     let mut v = Vec::new();
 273     dot::render(&g, &mut v).unwrap();
 274     File::create(path).and_then(|mut f| f.write_all(&v))
 275 }