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load.rs
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load.rs
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// 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.
//! Code to save/load the dep-graph from files.
use rustc::dep_graph::{DepNode, WorkProductId};
use rustc::hir::def_id::DefId;
use rustc::hir::map::DefPathHash;
use rustc::hir::svh::Svh;
use rustc::ich::Fingerprint;
use rustc::session::Session;
use rustc::ty::TyCtxt;
use rustc_data_structures::fx::{FxHashSet, FxHashMap};
use rustc_serialize::Decodable as RustcDecodable;
use rustc_serialize::opaque::Decoder;
use std::default::Default;
use std::path::{Path};
use IncrementalHashesMap;
use super::data::*;
use super::dirty_clean;
use super::hash::*;
use super::fs::*;
use super::file_format;
use super::work_product;
// The key is a dirty node. The value is **some** base-input that we
// can blame it on.
pub type DirtyNodes = FxHashMap<DepNode<DefPathHash>, DepNode<DefPathHash>>;
/// If we are in incremental mode, and a previous dep-graph exists,
/// then load up those nodes/edges that are still valid into the
/// dep-graph for this session. (This is assumed to be running very
/// early in compilation, before we've really done any work, but
/// actually it doesn't matter all that much.) See `README.md` for
/// more general overview.
pub fn load_dep_graph<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
incremental_hashes_map: &IncrementalHashesMap) {
if tcx.sess.opts.incremental.is_none() {
return;
}
match prepare_session_directory(tcx) {
Ok(true) => {
// We successfully allocated a session directory and there is
// something in it to load, so continue
}
Ok(false) => {
// We successfully allocated a session directory, but there is no
// dep-graph data in it to load (because this is the first
// compilation session with this incr. comp. dir.)
return
}
Err(()) => {
// Something went wrong while trying to allocate the session
// directory. Don't try to use it any further.
return
}
}
let _ignore = tcx.dep_graph.in_ignore();
load_dep_graph_if_exists(tcx, incremental_hashes_map);
}
fn load_dep_graph_if_exists<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
incremental_hashes_map: &IncrementalHashesMap) {
let dep_graph_path = dep_graph_path(tcx.sess);
let dep_graph_data = match load_data(tcx.sess, &dep_graph_path) {
Some(p) => p,
None => return // no file
};
let work_products_path = work_products_path(tcx.sess);
let work_products_data = match load_data(tcx.sess, &work_products_path) {
Some(p) => p,
None => return // no file
};
match decode_dep_graph(tcx, incremental_hashes_map, &dep_graph_data, &work_products_data) {
Ok(dirty_nodes) => dirty_nodes,
Err(err) => {
tcx.sess.warn(
&format!("decoding error in dep-graph from `{}` and `{}`: {}",
dep_graph_path.display(),
work_products_path.display(),
err));
}
}
}
fn load_data(sess: &Session, path: &Path) -> Option<Vec<u8>> {
match file_format::read_file(sess, path) {
Ok(Some(data)) => return Some(data),
Ok(None) => {
// The file either didn't exist or was produced by an incompatible
// compiler version. Neither is an error.
}
Err(err) => {
sess.err(
&format!("could not load dep-graph from `{}`: {}",
path.display(), err));
}
}
if let Err(err) = delete_all_session_dir_contents(sess) {
sess.err(&format!("could not clear incompatible incremental \
compilation session directory `{}`: {}",
path.display(), err));
}
None
}
/// Try to convert a DepNode from the old dep-graph into a DepNode in the
/// current graph by mapping the DefPathHash to a valid DefId. This will fail
/// if the DefPathHash refers to something that has been removed (because
/// there is no DefId for that thing anymore).
fn retrace(tcx: TyCtxt, dep_node: &DepNode<DefPathHash>) -> Option<DepNode<DefId>> {
dep_node.map_def(|def_path_hash| {
tcx.def_path_hash_to_def_id.as_ref().unwrap().get(def_path_hash).cloned()
})
}
/// Decode the dep graph and load the edges/nodes that are still clean
/// into `tcx.dep_graph`.
pub fn decode_dep_graph<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
incremental_hashes_map: &IncrementalHashesMap,
dep_graph_data: &[u8],
work_products_data: &[u8])
-> Result<(), String>
{
// Decode the list of work_products
let mut work_product_decoder = Decoder::new(work_products_data, 0);
let work_products = <Vec<SerializedWorkProduct>>::decode(&mut work_product_decoder)?;
// Deserialize the directory and dep-graph.
let mut dep_graph_decoder = Decoder::new(dep_graph_data, 0);
let prev_commandline_args_hash = u64::decode(&mut dep_graph_decoder)?;
if prev_commandline_args_hash != tcx.sess.opts.dep_tracking_hash() {
if tcx.sess.opts.debugging_opts.incremental_info {
println!("incremental: completely ignoring cache because of \
differing commandline arguments");
}
// We can't reuse the cache, purge it.
debug!("decode_dep_graph: differing commandline arg hashes");
for swp in work_products {
delete_dirty_work_product(tcx, swp);
}
// No need to do any further work
return Ok(());
}
let serialized_dep_graph = SerializedDepGraph::decode(&mut dep_graph_decoder)?;
let edge_map: FxHashMap<DepNode<DefPathHash>, Vec<DepNode<DefPathHash>>> = {
let capacity = serialized_dep_graph.edge_list_data.len();
let mut edge_map = FxHashMap::with_capacity_and_hasher(capacity, Default::default());
for (node_index, source) in serialized_dep_graph.nodes.iter().enumerate() {
let (start, end) = serialized_dep_graph.edge_list_indices[node_index];
let targets =
(&serialized_dep_graph.edge_list_data[start as usize .. end as usize])
.into_iter()
.map(|&node_index| serialized_dep_graph.nodes[node_index].clone())
.collect();
edge_map.insert(source.clone(), targets);
}
edge_map
};
// Compute the set of nodes from the old graph where some input
// has changed or been removed. These are "raw" source nodes,
// which means that they still use the original `DefPathIndex`
// values from the encoding, rather than having been retraced to a
// `DefId`. The reason for this is that this way we can include
// nodes that have been removed (which no longer have a `DefId` in
// the current compilation).
let dirty_raw_nodes = initial_dirty_nodes(tcx,
incremental_hashes_map,
&serialized_dep_graph.hashes);
let dirty_raw_nodes = transitive_dirty_nodes(&edge_map, dirty_raw_nodes);
// Recreate the edges in the graph that are still clean.
let mut clean_work_products = FxHashSet();
let mut dirty_work_products = FxHashSet(); // incomplete; just used to suppress debug output
let mut extra_edges = vec![];
for (source, targets) in &edge_map {
for target in targets {
process_edges(tcx, source, target, &edge_map, &dirty_raw_nodes,
&mut clean_work_products, &mut dirty_work_products, &mut extra_edges);
}
}
// 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) = retrace(tcx, bootstrap_output) {
if let DepNode::WorkProduct(ref wp) = n {
clean_work_products.insert(wp.clone());
}
tcx.dep_graph.with_task(n, (), (), create_node);
fn create_node((): (), (): ()) {
// just 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:
//
// Hir(X) -> Foo(Y) -> Bar
//
// Note that the `Hir(Y)` is not an input to `Foo(Y)` -- this
// almost never happens, but can happen in some obscure
// scenarios. In that case, if `Y` is removed, then we can't
// recreate `Foo(Y)` (the def-id `Y` no longer exists); what we do
// then is to push the edge `Hir(X) -> Bar` onto `extra_edges`
// (along with any other targets of `Foo(Y)`). We will then add
// the edge from `Hir(X)` to `Bar` (or, if `Bar` itself cannot be
// recreated, to the targets of `Bar`).
while let Some((source, target)) = extra_edges.pop() {
process_edges(tcx, source, target, &edge_map, &dirty_raw_nodes,
&mut clean_work_products, &mut dirty_work_products, &mut extra_edges);
}
// Add in work-products that are still clean, and delete those that are
// dirty.
reconcile_work_products(tcx, work_products, &clean_work_products);
dirty_clean::check_dirty_clean_annotations(tcx, &dirty_raw_nodes);
load_prev_metadata_hashes(tcx,
&mut *incremental_hashes_map.prev_metadata_hashes.borrow_mut());
Ok(())
}
/// Computes which of the original set of def-ids are dirty. Stored in
/// a bit vector where the index is the DefPathIndex.
fn initial_dirty_nodes<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
incremental_hashes_map: &IncrementalHashesMap,
serialized_hashes: &[SerializedHash])
-> DirtyNodes {
let mut hcx = HashContext::new(tcx, incremental_hashes_map);
let mut dirty_nodes = FxHashMap();
let print_removed_message = |dep_node: &DepNode<_>| {
if tcx.sess.opts.debugging_opts.incremental_dump_hash {
println!("node {:?} is dirty as it was removed", dep_node);
}
debug!("initial_dirty_nodes: {:?} is dirty as it was removed", dep_node);
};
for hash in serialized_hashes {
if let Some(dep_node) = retrace(tcx, &hash.dep_node) {
if let Some(current_hash) = hcx.hash(&dep_node) {
if current_hash == hash.hash {
debug!("initial_dirty_nodes: {:?} is clean (hash={:?})",
dep_node.map_def(|&def_id| Some(tcx.def_path(def_id))).unwrap(),
current_hash);
continue;
}
if tcx.sess.opts.debugging_opts.incremental_dump_hash {
println!("node {:?} is dirty as hash is {:?} was {:?}",
dep_node.map_def(|&def_id| Some(tcx.def_path(def_id))).unwrap(),
current_hash,
hash.hash);
}
debug!("initial_dirty_nodes: {:?} is dirty as hash is {:?}, was {:?}",
dep_node.map_def(|&def_id| Some(tcx.def_path(def_id))).unwrap(),
current_hash,
hash.hash);
} else {
print_removed_message(&hash.dep_node);
}
} else {
print_removed_message(&hash.dep_node);
}
dirty_nodes.insert(hash.dep_node.clone(), hash.dep_node.clone());
}
dirty_nodes
}
fn transitive_dirty_nodes(edge_map: &FxHashMap<DepNode<DefPathHash>, Vec<DepNode<DefPathHash>>>,
mut dirty_nodes: DirtyNodes)
-> DirtyNodes
{
let mut stack: Vec<(DepNode<DefPathHash>, DepNode<DefPathHash>)> = vec![];
stack.extend(dirty_nodes.iter().map(|(s, b)| (s.clone(), b.clone())));
while let Some((source, blame)) = stack.pop() {
// we know the source is dirty (because of the node `blame`)...
assert!(dirty_nodes.contains_key(&source));
// ...so we dirty all the targets (with the same blame)
if let Some(targets) = edge_map.get(&source) {
for target in targets {
if !dirty_nodes.contains_key(target) {
dirty_nodes.insert(target.clone(), blame.clone());
stack.push((target.clone(), blame.clone()));
}
}
}
}
dirty_nodes
}
/// Go through the list of work-products produced in the previous run.
/// Delete any whose nodes have been found to be dirty or which are
/// otherwise no longer applicable.
fn reconcile_work_products<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
work_products: Vec<SerializedWorkProduct>,
clean_work_products: &FxHashSet<WorkProductId>) {
debug!("reconcile_work_products({:?})", work_products);
for swp in work_products {
if !clean_work_products.contains(&swp.id) {
debug!("reconcile_work_products: dep-node for {:?} is dirty", swp);
delete_dirty_work_product(tcx, swp);
} else {
let mut all_files_exist = true;
for &(_, ref file_name) in swp.work_product.saved_files.iter() {
let path = in_incr_comp_dir_sess(tcx.sess, file_name);
if !path.exists() {
all_files_exist = false;
if tcx.sess.opts.debugging_opts.incremental_info {
println!("incremental: could not find file for up-to-date work product: {}",
path.display());
}
}
}
if all_files_exist {
debug!("reconcile_work_products: all files for {:?} exist", swp);
tcx.dep_graph.insert_previous_work_product(&swp.id, swp.work_product);
} else {
debug!("reconcile_work_products: some file for {:?} does not exist", swp);
delete_dirty_work_product(tcx, swp);
}
}
}
}
fn delete_dirty_work_product(tcx: TyCtxt,
swp: SerializedWorkProduct) {
debug!("delete_dirty_work_product({:?})", swp);
work_product::delete_workproduct_files(tcx.sess, &swp.work_product);
}
fn load_prev_metadata_hashes(tcx: TyCtxt,
output: &mut FxHashMap<DefId, Fingerprint>) {
if !tcx.sess.opts.debugging_opts.query_dep_graph {
return
}
debug!("load_prev_metadata_hashes() - Loading previous metadata hashes");
let file_path = metadata_hash_export_path(tcx.sess);
if !file_path.exists() {
debug!("load_prev_metadata_hashes() - Couldn't find file containing \
hashes at `{}`", file_path.display());
return
}
debug!("load_prev_metadata_hashes() - File: {}", file_path.display());
let data = match file_format::read_file(tcx.sess, &file_path) {
Ok(Some(data)) => data,
Ok(None) => {
debug!("load_prev_metadata_hashes() - File produced by incompatible \
compiler version: {}", file_path.display());
return
}
Err(err) => {
debug!("load_prev_metadata_hashes() - Error reading file `{}`: {}",
file_path.display(), err);
return
}
};
debug!("load_prev_metadata_hashes() - Decoding hashes");
let mut decoder = Decoder::new(&data, 0);
let _ = Svh::decode(&mut decoder).unwrap();
let serialized_hashes = SerializedMetadataHashes::decode(&mut decoder).unwrap();
debug!("load_prev_metadata_hashes() - Mapping DefIds");
assert_eq!(serialized_hashes.index_map.len(), serialized_hashes.entry_hashes.len());
let def_path_hash_to_def_id = tcx.def_path_hash_to_def_id.as_ref().unwrap();
for serialized_hash in serialized_hashes.entry_hashes {
let def_path_hash = serialized_hashes.index_map[&serialized_hash.def_index];
if let Some(&def_id) = def_path_hash_to_def_id.get(&def_path_hash) {
let old = output.insert(def_id, serialized_hash.hash);
assert!(old.is_none(), "already have hash for {:?}", def_id);
}
}
debug!("load_prev_metadata_hashes() - successfully loaded {} hashes",
serialized_hashes.index_map.len());
}
fn process_edges<'a, 'tcx, 'edges>(
tcx: TyCtxt<'a, 'tcx, 'tcx>,
source: &'edges DepNode<DefPathHash>,
target: &'edges DepNode<DefPathHash>,
edges: &'edges FxHashMap<DepNode<DefPathHash>, Vec<DepNode<DefPathHash>>>,
dirty_raw_nodes: &DirtyNodes,
clean_work_products: &mut FxHashSet<WorkProductId>,
dirty_work_products: &mut FxHashSet<WorkProductId>,
extra_edges: &mut Vec<(&'edges DepNode<DefPathHash>, &'edges DepNode<DefPathHash>)>)
{
// If the target is dirty, skip the edge. If this is an edge
// that targets a work-product, we can print the blame
// information now.
if let Some(blame) = dirty_raw_nodes.get(target) {
if let DepNode::WorkProduct(ref wp) = *target {
if tcx.sess.opts.debugging_opts.incremental_info {
if dirty_work_products.insert(wp.clone()) {
// Try to reconstruct the human-readable version of the
// DepNode. This cannot be done for things that where
// removed.
let readable_blame = if let Some(dep_node) = retrace(tcx, blame) {
dep_node.map_def(|&def_id| Some(tcx.def_path(def_id).to_string(tcx)))
.unwrap()
} else {
blame.map_def(|def_path_hash| Some(format!("{:?}", def_path_hash)))
.unwrap()
};
println!("incremental: module {:?} is dirty because {:?} \
changed or was removed",
wp,
readable_blame);
}
}
}
return;
}
// If the source is dirty, the target will be dirty.
assert!(!dirty_raw_nodes.contains_key(source));
// Retrace the source -> target edges to def-ids and then create
// an edge in the graph. Retracing may yield none if some of the
// data happens to have been removed.
if let Some(source_node) = retrace(tcx, source) {
if let Some(target_node) = retrace(tcx, target) {
let _task = tcx.dep_graph.in_task(target_node);
tcx.dep_graph.read(source_node);
if let DepNode::WorkProduct(ref wp) = *target {
clean_work_products.insert(wp.clone());
}
} else {
// As discussed in `decode_dep_graph` above, sometimes the
// target cannot be recreated again, in which case we add
// edges to go from `source` to the targets of `target`.
extra_edges.extend(
edges[target].iter().map(|t| (source, t)));
}
} else {
// It's also possible that the source can't be created! But we
// can ignore such cases, because (a) if `source` is a HIR
// node, it would be considered dirty; and (b) in other cases,
// there must be some input to this node that is clean, and so
// we'll re-create the edges over in the case where target is
// undefined.
}
}