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detect "bootstrap outputs" when serializing the dep-graph
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nikomatsakis committed Feb 22, 2017
1 parent 3954c70 commit b576abd
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Showing 6 changed files with 82 additions and 3 deletions.
5 changes: 5 additions & 0 deletions src/librustc_incremental/persist/data.rs
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,11 @@ use super::directory::DefPathIndex;
pub struct SerializedDepGraph {
pub edges: Vec<SerializedEdgeSet>,

/// These are output nodes that have no incoming edges. We track
/// these separately so that when we reload all edges, we don't
/// lose track of these nodes.
pub bootstrap_outputs: Vec<DepNode<DefPathIndex>>,

/// These are hashes of two things:
/// - the HIR nodes in this crate
/// - the metadata nodes from dependent crates we use
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12 changes: 12 additions & 0 deletions src/librustc_incremental/persist/load.rs
Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,18 @@ pub fn decode_dep_graph<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
}
}

// Recreate bootstrap outputs, which are outputs that have no incoming edges (and hence cannot
// be dirty).
for bootstrap_output in &serialized_dep_graph.bootstrap_outputs {
if let Some(n) = retraced.map(bootstrap_output) {
if let DepNode::WorkProduct(ref wp) = n {
clean_work_products.insert(wp.clone());
}

tcx.dep_graph.with_task(n, || ()); // create the node with no inputs
}
}

// Subtle. Sometimes we have intermediate nodes that we can't recreate in the new graph.
// This is pretty unusual but it arises in a scenario like this:
//
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21 changes: 19 additions & 2 deletions src/librustc_incremental/persist/preds/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@
use rustc::dep_graph::{DepGraphQuery, DepNode};
use rustc::hir::def_id::DefId;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::graph::Graph;
use rustc_data_structures::graph::{Graph, NodeIndex};

use super::hash::*;
use ich::Fingerprint;
Expand All @@ -28,6 +28,14 @@ pub struct Predecessors<'query> {
// of the graph down.
pub reduced_graph: Graph<&'query DepNode<DefId>, ()>,

// These are output nodes that have no incoming edges. We have to
// track these specially because, when we load the data back up
// again, we want to make sure and recreate these nodes (we want
// to recreate the nodes where all incoming edges are clean; but
// since we ordinarily just serialize edges, we wind up just
// forgetting that bootstrap outputs even exist in that case.)
pub bootstrap_outputs: Vec<&'query DepNode<DefId>>,

// For the inputs (hir/foreign-metadata), we include hashes.
pub hashes: FxHashMap<&'query DepNode<DefId>, Fingerprint>,
}
Expand Down Expand Up @@ -57,7 +65,7 @@ impl<'q> Predecessors<'q> {

// Reduce the graph to the most important nodes.
let compress::Reduction { graph, input_nodes } =
compress::reduce_graph(&query.graph, HashContext::is_hashable, is_output);
compress::reduce_graph(&query.graph, HashContext::is_hashable, |n| is_output(n));

let mut hashes = FxHashMap();
for input_index in input_nodes {
Expand All @@ -67,8 +75,17 @@ impl<'q> Predecessors<'q> {
.or_insert_with(|| hcx.hash(input).unwrap());
}

let bootstrap_outputs: Vec<&'q DepNode<DefId>> =
(0 .. graph.len_nodes())
.map(NodeIndex)
.filter(|&n| graph.incoming_edges(n).next().is_none())
.map(|n| *graph.node_data(n))
.filter(|n| is_output(n))
.collect();

Predecessors {
reduced_graph: graph,
bootstrap_outputs: bootstrap_outputs,
hashes: hashes,
}
}
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7 changes: 6 additions & 1 deletion src/librustc_incremental/persist/save.rs
Original file line number Diff line number Diff line change
Expand Up @@ -204,11 +204,15 @@ pub fn encode_dep_graph(preds: &Predecessors,
}

// Create the serialized dep-graph.
let bootstrap_outputs = preds.bootstrap_outputs.iter()
.map(|n| builder.map(n))
.collect();
let edges = edges.into_iter()
.map(|(k, v)| SerializedEdgeSet { source: k, targets: v })
.collect();
let graph = SerializedDepGraph {
edges: edges,
bootstrap_outputs,
edges,
hashes: preds.hashes
.iter()
.map(|(&dep_node, &hash)| {
Expand All @@ -221,6 +225,7 @@ pub fn encode_dep_graph(preds: &Predecessors,
};

if tcx.sess.opts.debugging_opts.incremental_info {
println!("incremental: {} nodes in reduced dep-graph", preds.reduced_graph.len_nodes());
println!("incremental: {} edges in serialized dep-graph", graph.edges.len());
println!("incremental: {} hashes in serialized dep-graph", graph.hashes.len());
}
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18 changes: 18 additions & 0 deletions src/test/incremental/issue-39828/auxiliary/generic.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// revisions:rpass1 rpass2
// compile-flags: -Z query-dep-graph

#![rustc_partition_reused(module="__rustc_fallback_codegen_unit", cfg="rpass2")]
#![feature(rustc_attrs)]

#![crate_type="rlib"]
pub fn foo<T>() { }
22 changes: 22 additions & 0 deletions src/test/incremental/issue-39828/issue-39828.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// Regression test for #39828. If you make use of a module that
// consists only of generics, no code is generated, just a dummy
// module. The reduced graph consists of a single node (for that
// module) with no inputs. Since we only serialize edges, when we
// reload, we would consider that node dirty since it is not recreated
// (it is not the target of any edges).

// revisions:rpass1 rpass2
// aux-build:generic.rs

extern crate generic;
fn main() { }

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