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::{FxHashMap, FxHashSet};
  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 = env::var("RUST_REGION_GRAPH_NODE")
  67         .ok().and_then(|s| s.parse().map(ast::NodeId::new).ok());
  68
  69     if requested_node.is_some() && requested_node != Some(subject_node) {
  70         return;
  71     }
  72
  73     let requested_output = env::var("RUST_REGION_GRAPH");
  74     debug!("requested_output: {:?} requested_node: {:?}",
  75            requested_output,
  76            requested_node);
  77
  78     let output_path = {
  79         let output_template = match requested_output {
  80             Ok(ref s) if s == "help" => {
  81                 static PRINTED_YET: AtomicBool = AtomicBool::new(false);
  82                 if !PRINTED_YET.load(Ordering::SeqCst) {
  83                     print_help_message();
  84                     PRINTED_YET.store(true, Ordering::SeqCst);
  85                 }
  86                 return;
  87             }
  88
  89             Ok(other_path) => other_path,
  90             Err(_) => "/tmp/constraints.node%.dot".to_string(),
  91         };
  92
  93         if output_template.is_empty() {
  94             panic!("empty string provided as RUST_REGION_GRAPH");
  95         }
  96
  97         if output_template.contains('%') {
  98             let mut new_str = String::new();
  99             for c in output_template.chars() {
 100                 if c == '%' {
 101                     new_str.push_str(&subject_node.to_string());
 102                 } else {
 103                     new_str.push(c);
 104                 }
 105             }
 106             new_str
 107         } else {
 108             output_template
 109         }
 110     };
 111
 112     let constraints = &*region_vars.constraints.borrow();
 113     match dump_region_constraints_to(tcx, constraints, &output_path) {
 114         Ok(()) => {}
 115         Err(e) => {
 116             let msg = format!("io error dumping region constraints: {}", e);
 117             region_vars.tcx.sess.err(&msg)
 118         }
 119     }
 120 }
 121
 122 struct ConstraintGraph<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
 123     tcx: TyCtxt<'a, 'gcx, 'tcx>,
 124     graph_name: String,
 125     map: &'a FxHashMap<Constraint<'tcx>, SubregionOrigin<'tcx>>,
 126     node_ids: FxHashMap<Node, usize>,
 127 }
 128
 129 #[derive(Clone, Hash, PartialEq, Eq, Debug, Copy)]
 130 enum Node {
 131     RegionVid(ty::RegionVid),
 132     Region(ty::Region),
 133 }
 134
 135 // type Edge = Constraint;
 136 #[derive(Clone, PartialEq, Eq, Debug, Copy)]
 137 enum Edge<'tcx> {
 138     Constraint(Constraint<'tcx>),
 139     EnclScope(CodeExtent, CodeExtent),
 140 }
 141
 142 impl<'a, 'gcx, 'tcx> ConstraintGraph<'a, 'gcx, 'tcx> {
 143     fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>,
 144            name: String,
 145            map: &'a ConstraintMap<'tcx>)
 146            -> ConstraintGraph<'a, 'gcx, 'tcx> {
 147         let mut i = 0;
 148         let mut node_ids = FxHashMap();
 149         {
 150             let mut add_node = |node| {
 151                 if let Vacant(e) = node_ids.entry(node) {
 152                     e.insert(i);
 153                     i += 1;
 154                 }
 155             };
 156
 157             for (n1, n2) in map.keys().map(|c| constraint_to_nodes(c)) {
 158                 add_node(n1);
 159                 add_node(n2);
 160             }
 161
 162             tcx.region_maps.each_encl_scope(|sub, sup| {
 163                 add_node(Node::Region(ty::ReScope(*sub)));
 164                 add_node(Node::Region(ty::ReScope(*sup)));
 165             });
 166         }
 167
 168         ConstraintGraph {
 169             tcx: tcx,
 170             graph_name: name,
 171             map: map,
 172             node_ids: node_ids,
 173         }
 174     }
 175 }
 176
 177 impl<'a, 'gcx, 'tcx> dot::Labeller<'a> for ConstraintGraph<'a, 'gcx, 'tcx> {
 178     type Node = Node;
 179     type Edge = Edge<'tcx>;
 180     fn graph_id(&self) -> dot::Id {
 181         dot::Id::new(&*self.graph_name).unwrap()
 182     }
 183     fn node_id(&self, n: &Node) -> dot::Id {
 184         let node_id = match self.node_ids.get(n) {
 185             Some(node_id) => node_id,
 186             None => bug!("no node_id found for node: {:?}", n),
 187         };
 188         let name = || format!("node_{}", node_id);
 189         match dot::Id::new(name()) {
 190             Ok(id) => id,
 191             Err(_) => {
 192                 bug!("failed to create graphviz node identified by {}", name());
 193             }
 194         }
 195     }
 196     fn node_label(&self, n: &Node) -> dot::LabelText {
 197         match *n {
 198             Node::RegionVid(n_vid) => dot::LabelText::label(format!("{:?}", n_vid)),
 199             Node::Region(n_rgn) => dot::LabelText::label(format!("{:?}", n_rgn)),
 200         }
 201     }
 202     fn edge_label(&self, e: &Edge) -> dot::LabelText {
 203         match *e {
 204             Edge::Constraint(ref c) =>
 205                 dot::LabelText::label(format!("{:?}", self.map.get(c).unwrap())),
 206             Edge::EnclScope(..) => dot::LabelText::label(format!("(enclosed)")),
 207         }
 208     }
 209 }
 210
 211 fn constraint_to_nodes(c: &Constraint) -> (Node, Node) {
 212     match *c {
 213         Constraint::ConstrainVarSubVar(rv_1, rv_2) =>
 214             (Node::RegionVid(rv_1), Node::RegionVid(rv_2)),
 215         Constraint::ConstrainRegSubVar(r_1, rv_2) =>
 216             (Node::Region(*r_1), Node::RegionVid(rv_2)),
 217         Constraint::ConstrainVarSubReg(rv_1, r_2) =>
 218             (Node::RegionVid(rv_1), Node::Region(*r_2)),
 219         Constraint::ConstrainRegSubReg(r_1, r_2) =>
 220             (Node::Region(*r_1), Node::Region(*r_2)),
 221     }
 222 }
 223
 224 fn edge_to_nodes(e: &Edge) -> (Node, Node) {
 225     match *e {
 226         Edge::Constraint(ref c) => constraint_to_nodes(c),
 227         Edge::EnclScope(sub, sup) => {
 228             (Node::Region(ty::ReScope(sub)),
 229              Node::Region(ty::ReScope(sup)))
 230         }
 231     }
 232 }
 233
 234 impl<'a, 'gcx, 'tcx> dot::GraphWalk<'a> for ConstraintGraph<'a, 'gcx, 'tcx> {
 235     type Node = Node;
 236     type Edge = Edge<'tcx>;
 237     fn nodes(&self) -> dot::Nodes<Node> {
 238         let mut set = FxHashSet();
 239         for node in self.node_ids.keys() {
 240             set.insert(*node);
 241         }
 242         debug!("constraint graph has {} nodes", set.len());
 243         set.into_iter().collect()
 244     }
 245     fn edges(&self) -> dot::Edges<Edge<'tcx>> {
 246         debug!("constraint graph has {} edges", self.map.len());
 247         let mut v: Vec<_> = self.map.keys().map(|e| Edge::Constraint(*e)).collect();
 248         self.tcx.region_maps.each_encl_scope(|sub, sup| v.push(Edge::EnclScope(*sub, *sup)));
 249         debug!("region graph has {} edges", v.len());
 250         Cow::Owned(v)
 251     }
 252     fn source(&self, edge: &Edge<'tcx>) -> Node {
 253         let (n1, _) = edge_to_nodes(edge);
 254         debug!("edge {:?} has source {:?}", edge, n1);
 255         n1
 256     }
 257     fn target(&self, edge: &Edge<'tcx>) -> Node {
 258         let (_, n2) = edge_to_nodes(edge);
 259         debug!("edge {:?} has target {:?}", edge, n2);
 260         n2
 261     }
 262 }
 263
 264 pub type ConstraintMap<'tcx> = FxHashMap<Constraint<'tcx>, SubregionOrigin<'tcx>>;
 265
 266 fn dump_region_constraints_to<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
 267                                               map: &ConstraintMap<'tcx>,
 268                                               path: &str)
 269                                               -> io::Result<()> {
 270     debug!("dump_region_constraints map (len: {}) path: {}",
 271            map.len(),
 272            path);
 273     let g = ConstraintGraph::new(tcx, format!("region_constraints"), map);
 274     debug!("dump_region_constraints calling render");
 275     let mut v = Vec::new();
 276     dot::render(&g, &mut v).unwrap();
 277     File::create(path).and_then(|mut f| f.write_all(&v))
 278 }