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android / toolchain / rustc / e3116c451e01eb38f24b3e9d055a1a9d3ad19471 / . / compiler / rustc_query_system / src / dep_graph / graph.rs
blob: 0f25572170f53dae1d539a43fcb26662d17862fa [file] [log] [blame]
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::profiling::QueryInvocationId;
use rustc_data_structures::sharded::{self, Sharded};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::sync::{AtomicU32, AtomicU64, Lock, LockGuard, Lrc, Ordering};
use rustc_data_structures::unlikely;
use rustc_errors::Diagnostic;
use rustc_index::vec::{Idx, IndexVec};
use rustc_serialize::{Encodable, Encoder};
use parking_lot::{Condvar, Mutex};
use smallvec::{smallvec, SmallVec};
use std::collections::hash_map::Entry;
use std::env;
use std::hash::Hash;
use std::marker::PhantomData;
use std::mem;
use std::ops::Range;
use std::sync::atomic::Ordering::Relaxed;
use super::debug::EdgeFilter;
use super::prev::PreviousDepGraph;
use super::query::DepGraphQuery;
use super::serialized::SerializedDepNodeIndex;
use super::{DepContext, DepKind, DepNode, HasDepContext, WorkProductId};
use crate::query::QueryContext;
#[derive(Clone)]
pub struct DepGraph<K: DepKind> {
data: Option<Lrc<DepGraphData<K>>>,
/// This field is used for assigning DepNodeIndices when running in
/// non-incremental mode. Even in non-incremental mode we make sure that
/// each task has a `DepNodeIndex` that uniquely identifies it. This unique
/// ID is used for self-profiling.
virtual_dep_node_index: Lrc<AtomicU32>,
}
rustc_index::newtype_index! {
pub struct DepNodeIndex { .. }
}
impl DepNodeIndex {
pub const INVALID: DepNodeIndex = DepNodeIndex::MAX;
}
impl std::convert::From<DepNodeIndex> for QueryInvocationId {
#[inline]
fn from(dep_node_index: DepNodeIndex) -> Self {
QueryInvocationId(dep_node_index.as_u32())
}
}
#[derive(PartialEq)]
pub enum DepNodeColor {
Red,
Green(DepNodeIndex),
}
impl DepNodeColor {
pub fn is_green(self) -> bool {
match self {
DepNodeColor::Red => false,
DepNodeColor::Green(_) => true,
}
}
}
struct DepGraphData<K: DepKind> {
/// The new encoding of the dependency graph, optimized for red/green
/// tracking. The `current` field is the dependency graph of only the
/// current compilation session: We don't merge the previous dep-graph into
/// current one anymore, but we do reference shared data to save space.
current: CurrentDepGraph<K>,
/// The dep-graph from the previous compilation session. It contains all
/// nodes and edges as well as all fingerprints of nodes that have them.
previous: PreviousDepGraph<K>,
colors: DepNodeColorMap,
/// A set of loaded diagnostics that is in the progress of being emitted.
emitting_diagnostics: Mutex<FxHashSet<DepNodeIndex>>,
/// Used to wait for diagnostics to be emitted.
emitting_diagnostics_cond_var: Condvar,
/// When we load, there may be `.o` files, cached MIR, or other such
/// things available to us. If we find that they are not dirty, we
/// load the path to the file storing those work-products here into
/// this map. We can later look for and extract that data.
previous_work_products: FxHashMap<WorkProductId, WorkProduct>,
dep_node_debug: Lock<FxHashMap<DepNode<K>, String>>,
}
pub fn hash_result<HashCtxt, R>(hcx: &mut HashCtxt, result: &R) -> Option<Fingerprint>
where
R: HashStable<HashCtxt>,
{
let mut stable_hasher = StableHasher::new();
result.hash_stable(hcx, &mut stable_hasher);
Some(stable_hasher.finish())
}
impl<K: DepKind> DepGraph<K> {
pub fn new(
prev_graph: PreviousDepGraph<K>,
prev_work_products: FxHashMap<WorkProductId, WorkProduct>,
) -> DepGraph<K> {
let prev_graph_node_count = prev_graph.node_count();
DepGraph {
data: Some(Lrc::new(DepGraphData {
previous_work_products: prev_work_products,
dep_node_debug: Default::default(),
current: CurrentDepGraph::new(prev_graph_node_count),
emitting_diagnostics: Default::default(),
emitting_diagnostics_cond_var: Condvar::new(),
previous: prev_graph,
colors: DepNodeColorMap::new(prev_graph_node_count),
})),
virtual_dep_node_index: Lrc::new(AtomicU32::new(0)),
}
}
pub fn new_disabled() -> DepGraph<K> {
DepGraph { data: None, virtual_dep_node_index: Lrc::new(AtomicU32::new(0)) }
}
/// Returns `true` if we are actually building the full dep-graph, and `false` otherwise.
#[inline]
pub fn is_fully_enabled(&self) -> bool {
self.data.is_some()
}
pub fn query(&self) -> DepGraphQuery<K> {
let data = self.data.as_ref().unwrap();
let previous = &data.previous;
// Note locking order: `prev_index_to_index`, then `data`.
let prev_index_to_index = data.current.prev_index_to_index.lock();
let data = data.current.data.lock();
let node_count = data.hybrid_indices.len();
let edge_count = self.edge_count(&data);
let mut nodes = Vec::with_capacity(node_count);
let mut edge_list_indices = Vec::with_capacity(node_count);
let mut edge_list_data = Vec::with_capacity(edge_count);
// See `DepGraph`'s `Encodable` implementation for notes on the approach used here.
edge_list_data.extend(data.unshared_edges.iter().map(|i| i.index()));
for &hybrid_index in data.hybrid_indices.iter() {
match hybrid_index.into() {
HybridIndex::New(new_index) => {
nodes.push(data.new.nodes[new_index]);
let edges = &data.new.edges[new_index];
edge_list_indices.push((edges.start.index(), edges.end.index()));
}
HybridIndex::Red(red_index) => {
nodes.push(previous.index_to_node(data.red.node_indices[red_index]));
let edges = &data.red.edges[red_index];
edge_list_indices.push((edges.start.index(), edges.end.index()));
}
HybridIndex::LightGreen(lg_index) => {
nodes.push(previous.index_to_node(data.light_green.node_indices[lg_index]));
let edges = &data.light_green.edges[lg_index];
edge_list_indices.push((edges.start.index(), edges.end.index()));
}
HybridIndex::DarkGreen(prev_index) => {
nodes.push(previous.index_to_node(prev_index));
let edges_iter = previous
.edge_targets_from(prev_index)
.iter()
.map(|&dst| prev_index_to_index[dst].unwrap().index());
let start = edge_list_data.len();
edge_list_data.extend(edges_iter);
let end = edge_list_data.len();
edge_list_indices.push((start, end));
}
}
}
debug_assert_eq!(nodes.len(), node_count);
debug_assert_eq!(edge_list_indices.len(), node_count);
debug_assert_eq!(edge_list_data.len(), edge_count);
DepGraphQuery::new(&nodes[..], &edge_list_indices[..], &edge_list_data[..])
}
pub fn assert_ignored(&self) {
if let Some(..) = self.data {
K::read_deps(|task_deps| {
assert!(task_deps.is_none(), "expected no task dependency tracking");
})
}
}
pub fn with_ignore<OP, R>(&self, op: OP) -> R
where
OP: FnOnce() -> R,
{
K::with_deps(None, op)
}
/// Starts a new dep-graph task. Dep-graph tasks are specified
/// using a free function (`task`) and **not** a closure -- this
/// is intentional because we want to exercise tight control over
/// what state they have access to. In particular, we want to
/// prevent implicit 'leaks' of tracked state into the task (which
/// could then be read without generating correct edges in the
/// dep-graph -- see the [rustc dev guide] for more details on
/// the dep-graph). To this end, the task function gets exactly two
/// pieces of state: the context `cx` and an argument `arg`. Both
/// of these bits of state must be of some type that implements
/// `DepGraphSafe` and hence does not leak.
///
/// The choice of two arguments is not fundamental. One argument
/// would work just as well, since multiple values can be
/// collected using tuples. However, using two arguments works out
/// to be quite convenient, since it is common to need a context
/// (`cx`) and some argument (e.g., a `DefId` identifying what
/// item to process).
///
/// For cases where you need some other number of arguments:
///
/// - If you only need one argument, just use `()` for the `arg`
/// parameter.
/// - If you need 3+ arguments, use a tuple for the
/// `arg` parameter.
///
/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/incremental-compilation.html
pub fn with_task<Ctxt: HasDepContext<DepKind = K>, A, R>(
&self,
key: DepNode<K>,
cx: Ctxt,
arg: A,
task: fn(Ctxt, A) -> R,
hash_result: impl FnOnce(&mut Ctxt::StableHashingContext, &R) -> Option<Fingerprint>,
) -> (R, DepNodeIndex) {
self.with_task_impl(
key,
cx,
arg,
task,
|_key| {
Some(TaskDeps {
#[cfg(debug_assertions)]
node: Some(_key),
reads: SmallVec::new(),
read_set: Default::default(),
phantom_data: PhantomData,
})
},
hash_result,
)
}
fn with_task_impl<Ctxt: HasDepContext<DepKind = K>, A, R>(
&self,
key: DepNode<K>,
cx: Ctxt,
arg: A,
task: fn(Ctxt, A) -> R,
create_task: fn(DepNode<K>) -> Option<TaskDeps<K>>,
hash_result: impl FnOnce(&mut Ctxt::StableHashingContext, &R) -> Option<Fingerprint>,
) -> (R, DepNodeIndex) {
if let Some(ref data) = self.data {
let dcx = cx.dep_context();
let task_deps = create_task(key).map(Lock::new);
let result = K::with_deps(task_deps.as_ref(), || task(cx, arg));
let edges = task_deps.map_or_else(|| smallvec![], |lock| lock.into_inner().reads);
let mut hcx = dcx.create_stable_hashing_context();
let current_fingerprint = hash_result(&mut hcx, &result);
let print_status = cfg!(debug_assertions) && dcx.sess().opts.debugging_opts.dep_tasks;
// Intern the new `DepNode`.
let dep_node_index = if let Some(prev_index) = data.previous.node_to_index_opt(&key) {
// Determine the color and index of the new `DepNode`.
let (color, dep_node_index) = if let Some(current_fingerprint) = current_fingerprint
{
if current_fingerprint == data.previous.fingerprint_by_index(prev_index) {
if print_status {
eprintln!("[task::green] {:?}", key);
}
// This is a light green node: it existed in the previous compilation,
// its query was re-executed, and it has the same result as before.
let dep_node_index =
data.current.intern_light_green_node(&data.previous, prev_index, edges);
(DepNodeColor::Green(dep_node_index), dep_node_index)
} else {
if print_status {
eprintln!("[task::red] {:?}", key);
}
// This is a red node: it existed in the previous compilation, its query
// was re-executed, but it has a different result from before.
let dep_node_index = data.current.intern_red_node(
&data.previous,
prev_index,
edges,
current_fingerprint,
);
(DepNodeColor::Red, dep_node_index)
}
} else {
if print_status {
eprintln!("[task::unknown] {:?}", key);
}
// This is a red node, effectively: it existed in the previous compilation
// session, its query was re-executed, but it doesn't compute a result hash
// (i.e. it represents a `no_hash` query), so we have no way of determining
// whether or not the result was the same as before.
let dep_node_index = data.current.intern_red_node(
&data.previous,
prev_index,
edges,
Fingerprint::ZERO,
);
(DepNodeColor::Red, dep_node_index)
};
debug_assert!(
data.colors.get(prev_index).is_none(),
"DepGraph::with_task() - Duplicate DepNodeColor \
insertion for {:?}",
key
);
data.colors.insert(prev_index, color);
dep_node_index
} else {
if print_status {
eprintln!("[task::new] {:?}", key);
}
// This is a new node: it didn't exist in the previous compilation session.
data.current.intern_new_node(
&data.previous,
key,
edges,
current_fingerprint.unwrap_or(Fingerprint::ZERO),
)
};
(result, dep_node_index)
} else {
// Incremental compilation is turned off. We just execute the task
// without tracking. We still provide a dep-node index that uniquely
// identifies the task so that we have a cheap way of referring to
// the query for self-profiling.
(task(cx, arg), self.next_virtual_depnode_index())
}
}
/// Executes something within an "anonymous" task, that is, a task the
/// `DepNode` of which is determined by the list of inputs it read from.
pub fn with_anon_task<OP, R>(&self, dep_kind: K, op: OP) -> (R, DepNodeIndex)
where
OP: FnOnce() -> R,
{
debug_assert!(!dep_kind.is_eval_always());
if let Some(ref data) = self.data {
let task_deps = Lock::new(TaskDeps::default());
let result = K::with_deps(Some(&task_deps), op);
let task_deps = task_deps.into_inner();
// The dep node indices are hashed here instead of hashing the dep nodes of the
// dependencies. These indices may refer to different nodes per session, but this isn't
// a problem here because we that ensure the final dep node hash is per session only by
// combining it with the per session random number `anon_id_seed`. This hash only need
// to map the dependencies to a single value on a per session basis.
let mut hasher = StableHasher::new();
task_deps.reads.hash(&mut hasher);
let target_dep_node = DepNode {
kind: dep_kind,
// Fingerprint::combine() is faster than sending Fingerprint
// through the StableHasher (at least as long as StableHasher
// is so slow).
hash: data.current.anon_id_seed.combine(hasher.finish()).into(),
};
let dep_node_index = data.current.intern_new_node(
&data.previous,
target_dep_node,
task_deps.reads,
Fingerprint::ZERO,
);
(result, dep_node_index)
} else {
(op(), self.next_virtual_depnode_index())
}
}
/// Executes something within an "eval-always" task which is a task
/// that runs whenever anything changes.
pub fn with_eval_always_task<Ctxt: HasDepContext<DepKind = K>, A, R>(
&self,
key: DepNode<K>,
cx: Ctxt,
arg: A,
task: fn(Ctxt, A) -> R,
hash_result: impl FnOnce(&mut Ctxt::StableHashingContext, &R) -> Option<Fingerprint>,
) -> (R, DepNodeIndex) {
self.with_task_impl(key, cx, arg, task, |_| None, hash_result)
}
#[inline]
pub fn read_index(&self, dep_node_index: DepNodeIndex) {
if let Some(ref data) = self.data {
K::read_deps(|task_deps| {
if let Some(task_deps) = task_deps {
let mut task_deps = task_deps.lock();
let task_deps = &mut *task_deps;
if cfg!(debug_assertions) {
data.current.total_read_count.fetch_add(1, Relaxed);
}
// As long as we only have a low number of reads we can avoid doing a hash
// insert and potentially allocating/reallocating the hashmap
let new_read = if task_deps.reads.len() < TASK_DEPS_READS_CAP {
task_deps.reads.iter().all(|other| *other != dep_node_index)
} else {
task_deps.read_set.insert(dep_node_index)
};
if new_read {
task_deps.reads.push(dep_node_index);
if task_deps.reads.len() == TASK_DEPS_READS_CAP {
// Fill `read_set` with what we have so far so we can use the hashset
// next time
task_deps.read_set.extend(task_deps.reads.iter().copied());
}
#[cfg(debug_assertions)]
{
if let Some(target) = task_deps.node {
if let Some(ref forbidden_edge) = data.current.forbidden_edge {
let src = self.dep_node_of(dep_node_index);
if forbidden_edge.test(&src, &target) {
panic!("forbidden edge {:?} -> {:?} created", src, target)
}
}
}
}
} else if cfg!(debug_assertions) {
data.current.total_duplicate_read_count.fetch_add(1, Relaxed);
}
}
})
}
}
#[inline]
pub fn dep_node_index_of(&self, dep_node: &DepNode<K>) -> DepNodeIndex {
self.dep_node_index_of_opt(dep_node).unwrap()
}
#[inline]
pub fn dep_node_index_of_opt(&self, dep_node: &DepNode<K>) -> Option<DepNodeIndex> {
let data = self.data.as_ref().unwrap();
let current = &data.current;
if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
current.prev_index_to_index.lock()[prev_index]
} else {
current.new_node_to_index.get_shard_by_value(dep_node).lock().get(dep_node).copied()
}
}
#[inline]
pub fn dep_node_exists(&self, dep_node: &DepNode<K>) -> bool {
self.data.is_some() && self.dep_node_index_of_opt(dep_node).is_some()
}
#[inline]
pub fn dep_node_of(&self, dep_node_index: DepNodeIndex) -> DepNode<K> {
let data = self.data.as_ref().unwrap();
let previous = &data.previous;
let data = data.current.data.lock();
match data.hybrid_indices[dep_node_index].into() {
HybridIndex::New(new_index) => data.new.nodes[new_index],
HybridIndex::Red(red_index) => previous.index_to_node(data.red.node_indices[red_index]),
HybridIndex::LightGreen(light_green_index) => {
previous.index_to_node(data.light_green.node_indices[light_green_index])
}
HybridIndex::DarkGreen(prev_index) => previous.index_to_node(prev_index),
}
}
#[inline]
pub fn fingerprint_of(&self, dep_node_index: DepNodeIndex) -> Fingerprint {
let data = self.data.as_ref().unwrap();
let previous = &data.previous;
let data = data.current.data.lock();
match data.hybrid_indices[dep_node_index].into() {
HybridIndex::New(new_index) => data.new.fingerprints[new_index],
HybridIndex::Red(red_index) => data.red.fingerprints[red_index],
HybridIndex::LightGreen(light_green_index) => {
previous.fingerprint_by_index(data.light_green.node_indices[light_green_index])
}
HybridIndex::DarkGreen(prev_index) => previous.fingerprint_by_index(prev_index),
}
}
pub fn prev_fingerprint_of(&self, dep_node: &DepNode<K>) -> Option<Fingerprint> {
self.data.as_ref().unwrap().previous.fingerprint_of(dep_node)
}
/// Checks whether a previous work product exists for `v` and, if
/// so, return the path that leads to it. Used to skip doing work.
pub fn previous_work_product(&self, v: &WorkProductId) -> Option<WorkProduct> {
self.data.as_ref().and_then(|data| data.previous_work_products.get(v).cloned())
}
/// Access the map of work-products created during the cached run. Only
/// used during saving of the dep-graph.
pub fn previous_work_products(&self) -> &FxHashMap<WorkProductId, WorkProduct> {
&self.data.as_ref().unwrap().previous_work_products
}
#[inline(always)]
pub fn register_dep_node_debug_str<F>(&self, dep_node: DepNode<K>, debug_str_gen: F)
where
F: FnOnce() -> String,
{
let dep_node_debug = &self.data.as_ref().unwrap().dep_node_debug;
if dep_node_debug.borrow().contains_key(&dep_node) {
return;
}
let debug_str = debug_str_gen();
dep_node_debug.borrow_mut().insert(dep_node, debug_str);
}
pub fn dep_node_debug_str(&self, dep_node: DepNode<K>) -> Option<String> {
self.data.as_ref()?.dep_node_debug.borrow().get(&dep_node).cloned()
}
fn edge_count(&self, node_data: &LockGuard<'_, DepNodeData<K>>) -> usize {
let data = self.data.as_ref().unwrap();
let previous = &data.previous;
let mut edge_count = node_data.unshared_edges.len();
for &hybrid_index in node_data.hybrid_indices.iter() {
if let HybridIndex::DarkGreen(prev_index) = hybrid_index.into() {
edge_count += previous.edge_targets_from(prev_index).len()
}
}
edge_count
}
pub fn node_color(&self, dep_node: &DepNode<K>) -> Option<DepNodeColor> {
if let Some(ref data) = self.data {
if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
return data.colors.get(prev_index);
} else {
// This is a node that did not exist in the previous compilation
// session, so we consider it to be red.
return Some(DepNodeColor::Red);
}
}
None
}
/// Try to read a node index for the node dep_node.
/// A node will have an index, when it's already been marked green, or when we can mark it
/// green. This function will mark the current task as a reader of the specified node, when
/// a node index can be found for that node.
pub fn try_mark_green_and_read<Ctxt: QueryContext<DepKind = K>>(
&self,
tcx: Ctxt,
dep_node: &DepNode<K>,
) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
self.try_mark_green(tcx, dep_node).map(|(prev_index, dep_node_index)| {
debug_assert!(self.is_green(&dep_node));
self.read_index(dep_node_index);
(prev_index, dep_node_index)
})
}
pub fn try_mark_green<Ctxt: QueryContext<DepKind = K>>(
&self,
tcx: Ctxt,
dep_node: &DepNode<K>,
) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
debug_assert!(!dep_node.kind.is_eval_always());
// Return None if the dep graph is disabled
let data = self.data.as_ref()?;
// Return None if the dep node didn't exist in the previous session
let prev_index = data.previous.node_to_index_opt(dep_node)?;
match data.colors.get(prev_index) {
Some(DepNodeColor::Green(dep_node_index)) => Some((prev_index, dep_node_index)),
Some(DepNodeColor::Red) => None,
None => {
// This DepNode and the corresponding query invocation existed
// in the previous compilation session too, so we can try to
// mark it as green by recursively marking all of its
// dependencies green.
self.try_mark_previous_green(tcx, data, prev_index, &dep_node)
.map(|dep_node_index| (prev_index, dep_node_index))
}
}
}
/// Try to mark a dep-node which existed in the previous compilation session as green.
fn try_mark_previous_green<Ctxt: QueryContext<DepKind = K>>(
&self,
tcx: Ctxt,
data: &DepGraphData<K>,
prev_dep_node_index: SerializedDepNodeIndex,
dep_node: &DepNode<K>,
) -> Option<DepNodeIndex> {
debug!("try_mark_previous_green({:?}) - BEGIN", dep_node);
#[cfg(not(parallel_compiler))]
{
debug_assert!(!self.dep_node_exists(dep_node));
debug_assert!(data.colors.get(prev_dep_node_index).is_none());
}
// We never try to mark eval_always nodes as green
debug_assert!(!dep_node.kind.is_eval_always());
debug_assert_eq!(data.previous.index_to_node(prev_dep_node_index), *dep_node);
let prev_deps = data.previous.edge_targets_from(prev_dep_node_index);
for &dep_dep_node_index in prev_deps {
let dep_dep_node_color = data.colors.get(dep_dep_node_index);
match dep_dep_node_color {
Some(DepNodeColor::Green(_)) => {
// This dependency has been marked as green before, we are
// still fine and can continue with checking the other
// dependencies.
debug!(
"try_mark_previous_green({:?}) --- found dependency {:?} to \
be immediately green",
dep_node,
data.previous.index_to_node(dep_dep_node_index)
);
}
Some(DepNodeColor::Red) => {
// We found a dependency the value of which has changed
// compared to the previous compilation session. We cannot
// mark the DepNode as green and also don't need to bother
// with checking any of the other dependencies.
debug!(
"try_mark_previous_green({:?}) - END - dependency {:?} was \
immediately red",
dep_node,
data.previous.index_to_node(dep_dep_node_index)
);
return None;
}
None => {
let dep_dep_node = &data.previous.index_to_node(dep_dep_node_index);
// We don't know the state of this dependency. If it isn't
// an eval_always node, let's try to mark it green recursively.
if !dep_dep_node.kind.is_eval_always() {
debug!(
"try_mark_previous_green({:?}) --- state of dependency {:?} ({}) \
is unknown, trying to mark it green",
dep_node, dep_dep_node, dep_dep_node.hash,
);
let node_index = self.try_mark_previous_green(
tcx,
data,
dep_dep_node_index,
dep_dep_node,
);
if node_index.is_some() {
debug!(
"try_mark_previous_green({:?}) --- managed to MARK \
dependency {:?} as green",
dep_node, dep_dep_node
);
continue;
}
}
// We failed to mark it green, so we try to force the query.
debug!(
"try_mark_previous_green({:?}) --- trying to force \
dependency {:?}",
dep_node, dep_dep_node
);
if tcx.try_force_from_dep_node(dep_dep_node) {
let dep_dep_node_color = data.colors.get(dep_dep_node_index);
match dep_dep_node_color {
Some(DepNodeColor::Green(_)) => {
debug!(
"try_mark_previous_green({:?}) --- managed to \
FORCE dependency {:?} to green",
dep_node, dep_dep_node
);
}
Some(DepNodeColor::Red) => {
debug!(
"try_mark_previous_green({:?}) - END - \
dependency {:?} was red after forcing",
dep_node, dep_dep_node
);
return None;
}
None => {
if !tcx.dep_context().sess().has_errors_or_delayed_span_bugs() {
panic!(
"try_mark_previous_green() - Forcing the DepNode \
should have set its color"
)
} else {
// If the query we just forced has resulted in
// some kind of compilation error, we cannot rely on
// the dep-node color having been properly updated.
// This means that the query system has reached an
// invalid state. We let the compiler continue (by
// returning `None`) so it can emit error messages
// and wind down, but rely on the fact that this
// invalid state will not be persisted to the
// incremental compilation cache because of
// compilation errors being present.
debug!(
"try_mark_previous_green({:?}) - END - \
dependency {:?} resulted in compilation error",
dep_node, dep_dep_node
);
return None;
}
}
}
} else {
// The DepNode could not be forced.
debug!(
"try_mark_previous_green({:?}) - END - dependency {:?} \
could not be forced",
dep_node, dep_dep_node
);
return None;
}
}
}
}
// If we got here without hitting a `return` that means that all
// dependencies of this DepNode could be marked as green. Therefore we
// can also mark this DepNode as green.
// There may be multiple threads trying to mark the same dep node green concurrently
let dep_node_index = {
// We allocating an entry for the node in the current dependency graph and
// adding all the appropriate edges imported from the previous graph
data.current.intern_dark_green_node(&data.previous, prev_dep_node_index)
};
// ... emitting any stored diagnostic ...
// FIXME: Store the fact that a node has diagnostics in a bit in the dep graph somewhere
// Maybe store a list on disk and encode this fact in the DepNodeState
let diagnostics = tcx.load_diagnostics(prev_dep_node_index);
#[cfg(not(parallel_compiler))]
debug_assert!(
data.colors.get(prev_dep_node_index).is_none(),
"DepGraph::try_mark_previous_green() - Duplicate DepNodeColor \
insertion for {:?}",
dep_node
);
if unlikely!(!diagnostics.is_empty()) {
self.emit_diagnostics(tcx, data, dep_node_index, prev_dep_node_index, diagnostics);
}
// ... and finally storing a "Green" entry in the color map.
// Multiple threads can all write the same color here
data.colors.insert(prev_dep_node_index, DepNodeColor::Green(dep_node_index));
debug!("try_mark_previous_green({:?}) - END - successfully marked as green", dep_node);
Some(dep_node_index)
}
/// Atomically emits some loaded diagnostics.
/// This may be called concurrently on multiple threads for the same dep node.
#[cold]
#[inline(never)]
fn emit_diagnostics<Ctxt: QueryContext<DepKind = K>>(
&self,
tcx: Ctxt,
data: &DepGraphData<K>,
dep_node_index: DepNodeIndex,
prev_dep_node_index: SerializedDepNodeIndex,
diagnostics: Vec<Diagnostic>,
) {
let mut emitting = data.emitting_diagnostics.lock();
if data.colors.get(prev_dep_node_index) == Some(DepNodeColor::Green(dep_node_index)) {
// The node is already green so diagnostics must have been emitted already
return;
}
if emitting.insert(dep_node_index) {
// We were the first to insert the node in the set so this thread
// must emit the diagnostics and signal other potentially waiting
// threads after.
mem::drop(emitting);
// Promote the previous diagnostics to the current session.
tcx.store_diagnostics(dep_node_index, diagnostics.clone().into());
let handle = tcx.dep_context().sess().diagnostic();
for diagnostic in diagnostics {
handle.emit_diagnostic(&diagnostic);
}
// Mark the node as green now that diagnostics are emitted
data.colors.insert(prev_dep_node_index, DepNodeColor::Green(dep_node_index));
// Remove the node from the set
data.emitting_diagnostics.lock().remove(&dep_node_index);
// Wake up waiters
data.emitting_diagnostics_cond_var.notify_all();
} else {
// We must wait for the other thread to finish emitting the diagnostic
loop {
data.emitting_diagnostics_cond_var.wait(&mut emitting);
if data.colors.get(prev_dep_node_index) == Some(DepNodeColor::Green(dep_node_index))
{
break;
}
}
}
}
// Returns true if the given node has been marked as green during the
// current compilation session. Used in various assertions
pub fn is_green(&self, dep_node: &DepNode<K>) -> bool {
self.node_color(dep_node).map_or(false, |c| c.is_green())
}
// This method loads all on-disk cacheable query results into memory, so
// they can be written out to the new cache file again. Most query results
// will already be in memory but in the case where we marked something as
// green but then did not need the value, that value will never have been
// loaded from disk.
//
// This method will only load queries that will end up in the disk cache.
// Other queries will not be executed.
pub fn exec_cache_promotions<Ctxt: QueryContext<DepKind = K>>(&self, qcx: Ctxt) {
let tcx = qcx.dep_context();
let _prof_timer = tcx.profiler().generic_activity("incr_comp_query_cache_promotion");
let data = self.data.as_ref().unwrap();
for prev_index in data.colors.values.indices() {
match data.colors.get(prev_index) {
Some(DepNodeColor::Green(_)) => {
let dep_node = data.previous.index_to_node(prev_index);
qcx.try_load_from_on_disk_cache(&dep_node);
}
None | Some(DepNodeColor::Red) => {
// We can skip red nodes because a node can only be marked
// as red if the query result was recomputed and thus is
// already in memory.
}
}
}
}
// Register reused dep nodes (i.e. nodes we've marked red or green) with the context.
pub fn register_reused_dep_nodes<Ctxt: DepContext<DepKind = K>>(&self, tcx: Ctxt) {
let data = self.data.as_ref().unwrap();
for prev_index in data.colors.values.indices() {
match data.colors.get(prev_index) {
Some(DepNodeColor::Red) | Some(DepNodeColor::Green(_)) => {
let dep_node = data.previous.index_to_node(prev_index);
tcx.register_reused_dep_node(&dep_node);
}
None => {}
}
}
}
pub fn print_incremental_info(&self) {
#[derive(Clone)]
struct Stat<Kind: DepKind> {
kind: Kind,
node_counter: u64,
edge_counter: u64,
}
let data = self.data.as_ref().unwrap();
let prev = &data.previous;
let current = &data.current;
let data = current.data.lock();
let mut stats: FxHashMap<_, Stat<K>> = FxHashMap::with_hasher(Default::default());
for &hybrid_index in data.hybrid_indices.iter() {
let (kind, edge_count) = match hybrid_index.into() {
HybridIndex::New(new_index) => {
let kind = data.new.nodes[new_index].kind;
let edge_range = &data.new.edges[new_index];
(kind, edge_range.end.as_usize() - edge_range.start.as_usize())
}
HybridIndex::Red(red_index) => {
let kind = prev.index_to_node(data.red.node_indices[red_index]).kind;
let edge_range = &data.red.edges[red_index];
(kind, edge_range.end.as_usize() - edge_range.start.as_usize())
}
HybridIndex::LightGreen(lg_index) => {
let kind = prev.index_to_node(data.light_green.node_indices[lg_index]).kind;
let edge_range = &data.light_green.edges[lg_index];
(kind, edge_range.end.as_usize() - edge_range.start.as_usize())
}
HybridIndex::DarkGreen(prev_index) => {
let kind = prev.index_to_node(prev_index).kind;
let edge_count = prev.edge_targets_from(prev_index).len();
(kind, edge_count)
}
};
let stat = stats.entry(kind).or_insert(Stat { kind, node_counter: 0, edge_counter: 0 });
stat.node_counter += 1;
stat.edge_counter += edge_count as u64;
}
let total_node_count = data.hybrid_indices.len();
let total_edge_count = self.edge_count(&data);
// Drop the lock guard.
std::mem::drop(data);
let mut stats: Vec<_> = stats.values().cloned().collect();
stats.sort_by_key(|s| -(s.node_counter as i64));
const SEPARATOR: &str = "[incremental] --------------------------------\
----------------------------------------------\
------------";
eprintln!("[incremental]");
eprintln!("[incremental] DepGraph Statistics");
eprintln!("{}", SEPARATOR);
eprintln!("[incremental]");
eprintln!("[incremental] Total Node Count: {}", total_node_count);
eprintln!("[incremental] Total Edge Count: {}", total_edge_count);
if cfg!(debug_assertions) {
let total_edge_reads = current.total_read_count.load(Relaxed);
let total_duplicate_edge_reads = current.total_duplicate_read_count.load(Relaxed);
eprintln!("[incremental] Total Edge Reads: {}", total_edge_reads);
eprintln!("[incremental] Total Duplicate Edge Reads: {}", total_duplicate_edge_reads);
}
eprintln!("[incremental]");
eprintln!(
"[incremental] {:<36}| {:<17}| {:<12}| {:<17}|",
"Node Kind", "Node Frequency", "Node Count", "Avg. Edge Count"
);
eprintln!(
"[incremental] -------------------------------------\
|------------------\
|-------------\
|------------------|"
);
for stat in stats {
let node_kind_ratio = (100.0 * (stat.node_counter as f64)) / (total_node_count as f64);
let node_kind_avg_edges = (stat.edge_counter as f64) / (stat.node_counter as f64);
eprintln!(
"[incremental] {:<36}|{:>16.1}% |{:>12} |{:>17.1} |",
format!("{:?}", stat.kind),
node_kind_ratio,
stat.node_counter,
node_kind_avg_edges,
);
}
eprintln!("{}", SEPARATOR);
eprintln!("[incremental]");
}
fn next_virtual_depnode_index(&self) -> DepNodeIndex {
let index = self.virtual_dep_node_index.fetch_add(1, Relaxed);
DepNodeIndex::from_u32(index)
}
}
impl<E: Encoder, K: DepKind + Encodable<E>> Encodable<E> for DepGraph<K> {
fn encode(&self, e: &mut E) -> Result<(), E::Error> {
// We used to serialize the dep graph by creating and serializing a `SerializedDepGraph`
// using data copied from the `DepGraph`. But copying created a large memory spike, so we
// now serialize directly from the `DepGraph` as if it's a `SerializedDepGraph`. Because we
// deserialize that data into a `SerializedDepGraph` in the next compilation session, we
// need `DepGraph`'s `Encodable` and `SerializedDepGraph`'s `Decodable` implementations to
// be in sync. If you update this encoding, be sure to update the decoding, and vice-versa.
let data = self.data.as_ref().unwrap();
let prev = &data.previous;
// Note locking order: `prev_index_to_index`, then `data`.
let prev_index_to_index = data.current.prev_index_to_index.lock();
let data = data.current.data.lock();
let new = &data.new;
let red = &data.red;
let lg = &data.light_green;
let node_count = data.hybrid_indices.len();
let edge_count = self.edge_count(&data);
// `rustc_middle::ty::query::OnDiskCache` expects nodes to be encoded in `DepNodeIndex`
// order. The edges in `edge_list_data` don't need to be in a particular order, as long as
// each node references its edges as a contiguous range within it. Therefore, we can encode
// `edge_list_data` directly from `unshared_edges`. It meets the above requirements, as
// each non-dark-green node already knows the range of edges to reference within it, which
// they'll encode in `edge_list_indices`. Dark green nodes, however, don't have their edges
// in `unshared_edges`, so need to add them to `edge_list_data`.
use HybridIndex::*;
// Encoded values (nodes, etc.) are explicitly typed below to avoid inadvertently
// serializing data in the wrong format (i.e. one incompatible with `SerializedDepGraph`).
e.emit_struct("SerializedDepGraph", 4, |e| {
e.emit_struct_field("nodes", 0, |e| {
// `SerializedDepGraph` expects this to be encoded as a sequence of `DepNode`s.
e.emit_seq(node_count, |e| {
for (seq_index, &hybrid_index) in data.hybrid_indices.iter().enumerate() {
let node: DepNode<K> = match hybrid_index.into() {
New(i) => new.nodes[i],
Red(i) => prev.index_to_node(red.node_indices[i]),
LightGreen(i) => prev.index_to_node(lg.node_indices[i]),
DarkGreen(prev_index) => prev.index_to_node(prev_index),
};
e.emit_seq_elt(seq_index, |e| node.encode(e))?;
}
Ok(())
})
})?;
e.emit_struct_field("fingerprints", 1, |e| {
// `SerializedDepGraph` expects this to be encoded as a sequence of `Fingerprints`s.
e.emit_seq(node_count, |e| {
for (seq_index, &hybrid_index) in data.hybrid_indices.iter().enumerate() {
let fingerprint: Fingerprint = match hybrid_index.into() {
New(i) => new.fingerprints[i],
Red(i) => red.fingerprints[i],
LightGreen(i) => prev.fingerprint_by_index(lg.node_indices[i]),
DarkGreen(prev_index) => prev.fingerprint_by_index(prev_index),
};
e.emit_seq_elt(seq_index, |e| fingerprint.encode(e))?;
}
Ok(())
})
})?;
e.emit_struct_field("edge_list_indices", 2, |e| {
// `SerializedDepGraph` expects this to be encoded as a sequence of `(u32, u32)`s.
e.emit_seq(node_count, |e| {
// Dark green node edges start after the unshared (all other nodes') edges.
let mut dark_green_edge_index = data.unshared_edges.len();
for (seq_index, &hybrid_index) in data.hybrid_indices.iter().enumerate() {
let edge_indices: (u32, u32) = match hybrid_index.into() {
New(i) => (new.edges[i].start.as_u32(), new.edges[i].end.as_u32()),
Red(i) => (red.edges[i].start.as_u32(), red.edges[i].end.as_u32()),
LightGreen(i) => (lg.edges[i].start.as_u32(), lg.edges[i].end.as_u32()),
DarkGreen(prev_index) => {
let edge_count = prev.edge_targets_from(prev_index).len();
let start = dark_green_edge_index as u32;
dark_green_edge_index += edge_count;
let end = dark_green_edge_index as u32;
(start, end)
}
};
e.emit_seq_elt(seq_index, |e| edge_indices.encode(e))?;
}
assert_eq!(dark_green_edge_index, edge_count);
Ok(())
})
})?;
e.emit_struct_field("edge_list_data", 3, |e| {
// `SerializedDepGraph` expects this to be encoded as a sequence of
// `SerializedDepNodeIndex`.
e.emit_seq(edge_count, |e| {
for (seq_index, &edge) in data.unshared_edges.iter().enumerate() {
let serialized_edge = SerializedDepNodeIndex::new(edge.index());
e.emit_seq_elt(seq_index, |e| serialized_edge.encode(e))?;
}
let mut seq_index = data.unshared_edges.len();
for &hybrid_index in data.hybrid_indices.iter() {
if let DarkGreen(prev_index) = hybrid_index.into() {
for &edge in prev.edge_targets_from(prev_index) {
// Dark green node edges are stored in the previous graph
// and must be converted to edges in the current graph,
// and then serialized as `SerializedDepNodeIndex`.
let serialized_edge = SerializedDepNodeIndex::new(
prev_index_to_index[edge].as_ref().unwrap().index(),
);
e.emit_seq_elt(seq_index, |e| serialized_edge.encode(e))?;
seq_index += 1;
}
}
}
assert_eq!(seq_index, edge_count);
Ok(())
})
})
})
}
}
/// A "work product" is an intermediate result that we save into the
/// incremental directory for later re-use. The primary example are
/// the object files that we save for each partition at code
/// generation time.
///
/// Each work product is associated with a dep-node, representing the
/// process that produced the work-product. If that dep-node is found
/// to be dirty when we load up, then we will delete the work-product
/// at load time. If the work-product is found to be clean, then we
/// will keep a record in the `previous_work_products` list.
///
/// In addition, work products have an associated hash. This hash is
/// an extra hash that can be used to decide if the work-product from
/// a previous compilation can be re-used (in addition to the dirty
/// edges check).
///
/// As the primary example, consider the object files we generate for
/// each partition. In the first run, we create partitions based on
/// the symbols that need to be compiled. For each partition P, we
/// hash the symbols in P and create a `WorkProduct` record associated
/// with `DepNode::CodegenUnit(P)`; the hash is the set of symbols
/// in P.
///
/// The next time we compile, if the `DepNode::CodegenUnit(P)` is
/// judged to be clean (which means none of the things we read to
/// generate the partition were found to be dirty), it will be loaded
/// into previous work products. We will then regenerate the set of
/// symbols in the partition P and hash them (note that new symbols
/// may be added -- for example, new monomorphizations -- even if
/// nothing in P changed!). We will compare that hash against the
/// previous hash. If it matches up, we can reuse the object file.
#[derive(Clone, Debug, Encodable, Decodable)]
pub struct WorkProduct {
pub cgu_name: String,
/// Saved file associated with this CGU.
pub saved_file: Option<String>,
}
// The maximum value of the follow index types leaves the upper two bits unused
// so that we can store multiple index types in `CompressedHybridIndex`, and use
// those bits to encode which index type it contains.
// Index type for `NewDepNodeData`.
rustc_index::newtype_index! {
struct NewDepNodeIndex {
MAX = 0x7FFF_FFFF
}
}
// Index type for `RedDepNodeData`.
rustc_index::newtype_index! {
struct RedDepNodeIndex {
MAX = 0x7FFF_FFFF
}
}
// Index type for `LightGreenDepNodeData`.
rustc_index::newtype_index! {
struct LightGreenDepNodeIndex {
MAX = 0x7FFF_FFFF
}
}
/// Compressed representation of `HybridIndex` enum. Bits unused by the
/// contained index types are used to encode which index type it contains.
#[derive(Copy, Clone)]
struct CompressedHybridIndex(u32);
impl CompressedHybridIndex {
const NEW_TAG: u32 = 0b0000_0000_0000_0000_0000_0000_0000_0000;
const RED_TAG: u32 = 0b0100_0000_0000_0000_0000_0000_0000_0000;
const LIGHT_GREEN_TAG: u32 = 0b1000_0000_0000_0000_0000_0000_0000_0000;
const DARK_GREEN_TAG: u32 = 0b1100_0000_0000_0000_0000_0000_0000_0000;
const TAG_MASK: u32 = 0b1100_0000_0000_0000_0000_0000_0000_0000;
const INDEX_MASK: u32 = !Self::TAG_MASK;
}
impl From<NewDepNodeIndex> for CompressedHybridIndex {
#[inline]
fn from(index: NewDepNodeIndex) -> Self {
CompressedHybridIndex(Self::NEW_TAG | index.as_u32())
}
}
impl From<RedDepNodeIndex> for CompressedHybridIndex {
#[inline]
fn from(index: RedDepNodeIndex) -> Self {
CompressedHybridIndex(Self::RED_TAG | index.as_u32())
}
}
impl From<LightGreenDepNodeIndex> for CompressedHybridIndex {
#[inline]
fn from(index: LightGreenDepNodeIndex) -> Self {
CompressedHybridIndex(Self::LIGHT_GREEN_TAG | index.as_u32())
}
}
impl From<SerializedDepNodeIndex> for CompressedHybridIndex {
#[inline]
fn from(index: SerializedDepNodeIndex) -> Self {
CompressedHybridIndex(Self::DARK_GREEN_TAG | index.as_u32())
}
}
/// Contains an index into one of several node data collections. Elsewhere, we
/// store `CompressedHyridIndex` instead of this to save space, but convert to
/// this type during processing to take advantage of the enum match ergonomics.
enum HybridIndex {
New(NewDepNodeIndex),
Red(RedDepNodeIndex),
LightGreen(LightGreenDepNodeIndex),
DarkGreen(SerializedDepNodeIndex),
}
impl From<CompressedHybridIndex> for HybridIndex {
#[inline]
fn from(hybrid_index: CompressedHybridIndex) -> Self {
let index = hybrid_index.0 & CompressedHybridIndex::INDEX_MASK;
match hybrid_index.0 & CompressedHybridIndex::TAG_MASK {
CompressedHybridIndex::NEW_TAG => HybridIndex::New(NewDepNodeIndex::from_u32(index)),
CompressedHybridIndex::RED_TAG => HybridIndex::Red(RedDepNodeIndex::from_u32(index)),
CompressedHybridIndex::LIGHT_GREEN_TAG => {
HybridIndex::LightGreen(LightGreenDepNodeIndex::from_u32(index))
}
CompressedHybridIndex::DARK_GREEN_TAG => {
HybridIndex::DarkGreen(SerializedDepNodeIndex::from_u32(index))
}
_ => unreachable!(),
}
}
}
// Index type for `DepNodeData`'s edges.
rustc_index::newtype_index! {
struct EdgeIndex { .. }
}
/// Data for nodes in the current graph, divided into different collections
/// based on their presence in the previous graph, and if present, their color.
/// We divide nodes this way because different types of nodes are able to share
/// more or less data with the previous graph.
///
/// To enable more sharing, we distinguish between two kinds of green nodes.
/// Light green nodes are nodes in the previous graph that have been marked
/// green because we re-executed their queries and the results were the same as
/// in the previous session. Dark green nodes are nodes in the previous graph
/// that have been marked green because we were able to mark all of their
/// dependencies green.
///
/// Both light and dark green nodes can share the dep node and fingerprint with
/// the previous graph, but for light green nodes, we can't be sure that the
/// edges may be shared without comparing them against the previous edges, so we
/// store them directly (an approach in which we compare edges with the previous
/// edges to see if they can be shared was evaluated, but was not found to be
/// very profitable).
///
/// For dark green nodes, we can share everything with the previous graph, which
/// is why the `HybridIndex::DarkGreen` enum variant contains the index of the
/// node in the previous graph, and why we don't have a separate collection for
/// dark green node data--the collection is the `PreviousDepGraph` itself.
///
/// (Note that for dark green nodes, the edges in the previous graph
/// (`SerializedDepNodeIndex`s) must be converted to edges in the current graph
/// (`DepNodeIndex`s). `CurrentDepGraph` contains `prev_index_to_index`, which
/// can perform this conversion. It should always be possible, as by definition,
/// a dark green node is one whose dependencies from the previous session have
/// all been marked green--which means `prev_index_to_index` contains them.)
///
/// Node data is stored in parallel vectors to eliminate the padding between
/// elements that would be needed to satisfy alignment requirements of the
/// structure that would contain all of a node's data. We could group tightly
/// packing subsets of node data together and use fewer vectors, but for
/// consistency's sake, we use separate vectors for each piece of data.
struct DepNodeData<K> {
/// Data for nodes not in previous graph.
new: NewDepNodeData<K>,
/// Data for nodes in previous graph that have been marked red.
red: RedDepNodeData,
/// Data for nodes in previous graph that have been marked light green.
light_green: LightGreenDepNodeData,
// Edges for all nodes other than dark-green ones. Edges for each node
// occupy a contiguous region of this collection, which a node can reference
// using two indices. Storing edges this way rather than using an `EdgesVec`
// for each node reduces memory consumption by a not insignificant amount
// when compiling large crates. The downside is that we have to copy into
// this collection the edges from the `EdgesVec`s that are built up during
// query execution. But this is mostly balanced out by the more efficient
// implementation of `DepGraph::serialize` enabled by this representation.
unshared_edges: IndexVec<EdgeIndex, DepNodeIndex>,
/// Mapping from `DepNodeIndex` to an index into a collection above.
/// Indicates which of the above collections contains a node's data.
///
/// This collection is wasteful in time and space during incr-full builds,
/// because for those, all nodes are new. However, the waste is relatively
/// small, and the maintenance cost of avoiding using this for incr-full
/// builds is somewhat high and prone to bugginess. It does not seem worth
/// it at the time of this writing, but we may want to revisit the idea.
hybrid_indices: IndexVec<DepNodeIndex, CompressedHybridIndex>,
}
/// Data for nodes not in previous graph. Since we cannot share any data with
/// the previous graph, so we must store all of such a node's data here.
struct NewDepNodeData<K> {
nodes: IndexVec<NewDepNodeIndex, DepNode<K>>,
edges: IndexVec<NewDepNodeIndex, Range<EdgeIndex>>,
fingerprints: IndexVec<NewDepNodeIndex, Fingerprint>,
}
/// Data for nodes in previous graph that have been marked red. We can share the
/// dep node with the previous graph, but the edges may be different, and the
/// fingerprint is known to be different, so we store the latter two directly.
struct RedDepNodeData {
node_indices: IndexVec<RedDepNodeIndex, SerializedDepNodeIndex>,
edges: IndexVec<RedDepNodeIndex, Range<EdgeIndex>>,
fingerprints: IndexVec<RedDepNodeIndex, Fingerprint>,
}
/// Data for nodes in previous graph that have been marked green because we
/// re-executed their queries and the results were the same as in the previous
/// session. We can share the dep node and the fingerprint with the previous
/// graph, but the edges may be different, so we store them directly.
struct LightGreenDepNodeData {
node_indices: IndexVec<LightGreenDepNodeIndex, SerializedDepNodeIndex>,
edges: IndexVec<LightGreenDepNodeIndex, Range<EdgeIndex>>,
}
/// `CurrentDepGraph` stores the dependency graph for the current session. It
/// will be populated as we run queries or tasks. We never remove nodes from the
/// graph: they are only added.
///
/// The nodes in it are identified by a `DepNodeIndex`. Internally, this maps to
/// a `HybridIndex`, which identifies which collection in the `data` field
/// contains a node's data. Which collection is used for a node depends on
/// whether the node was present in the `PreviousDepGraph`, and if so, the color
/// of the node. Each type of node can share more or less data with the previous
/// graph. When possible, we can store just the index of the node in the
/// previous graph, rather than duplicating its data in our own collections.
/// This is important, because these graph structures are some of the largest in
/// the compiler.
///
/// For the same reason, we also avoid storing `DepNode`s more than once as map
/// keys. The `new_node_to_index` map only contains nodes not in the previous
/// graph, and we map nodes in the previous graph to indices via a two-step
/// mapping. `PreviousDepGraph` maps from `DepNode` to `SerializedDepNodeIndex`,
/// and the `prev_index_to_index` vector (which is more compact and faster than
/// using a map) maps from `SerializedDepNodeIndex` to `DepNodeIndex`.
///
/// This struct uses three locks internally. The `data`, `new_node_to_index`,
/// and `prev_index_to_index` fields are locked separately. Operations that take
/// a `DepNodeIndex` typically just access the `data` field.
///
/// We only need to manipulate at most two locks simultaneously:
/// `new_node_to_index` and `data`, or `prev_index_to_index` and `data`. When
/// manipulating both, we acquire `new_node_to_index` or `prev_index_to_index`
/// first, and `data` second.
pub(super) struct CurrentDepGraph<K> {
data: Lock<DepNodeData<K>>,
new_node_to_index: Sharded<FxHashMap<DepNode<K>, DepNodeIndex>>,
prev_index_to_index: Lock<IndexVec<SerializedDepNodeIndex, Option<DepNodeIndex>>>,
/// Used to trap when a specific edge is added to the graph.
/// This is used for debug purposes and is only active with `debug_assertions`.
#[allow(dead_code)]
forbidden_edge: Option<EdgeFilter>,
/// Anonymous `DepNode`s are nodes whose IDs we compute from the list of
/// their edges. This has the beneficial side-effect that multiple anonymous
/// nodes can be coalesced into one without changing the semantics of the
/// dependency graph. However, the merging of nodes can lead to a subtle
/// problem during red-green marking: The color of an anonymous node from
/// the current session might "shadow" the color of the node with the same
/// ID from the previous session. In order to side-step this problem, we make
/// sure that anonymous `NodeId`s allocated in different sessions don't overlap.
/// This is implemented by mixing a session-key into the ID fingerprint of
/// each anon node. The session-key is just a random number generated when
/// the `DepGraph` is created.
anon_id_seed: Fingerprint,
/// These are simple counters that are for profiling and
/// debugging and only active with `debug_assertions`.
total_read_count: AtomicU64,
total_duplicate_read_count: AtomicU64,
}
impl<K: DepKind> CurrentDepGraph<K> {
fn new(prev_graph_node_count: usize) -> CurrentDepGraph<K> {
use std::time::{SystemTime, UNIX_EPOCH};
let duration = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
let nanos = duration.as_secs() * 1_000_000_000 + duration.subsec_nanos() as u64;
let mut stable_hasher = StableHasher::new();
nanos.hash(&mut stable_hasher);
let forbidden_edge = if cfg!(debug_assertions) {
match env::var("RUST_FORBID_DEP_GRAPH_EDGE") {
Ok(s) => match EdgeFilter::new(&s) {
Ok(f) => Some(f),
Err(err) => panic!("RUST_FORBID_DEP_GRAPH_EDGE invalid: {}", err),
},
Err(_) => None,
}
} else {
None
};
// Pre-allocate the dep node structures. We over-allocate a little so
// that we hopefully don't have to re-allocate during this compilation
// session. The over-allocation for new nodes is 2% plus a small
// constant to account for the fact that in very small crates 2% might
// not be enough. The allocation for red and green node data doesn't
// include a constant, as we don't want to allocate anything for these
// structures during full incremental builds, where they aren't used.
//
// These estimates are based on the distribution of node and edge counts
// seen in rustc-perf benchmarks, adjusted somewhat to account for the
// fact that these benchmarks aren't perfectly representative.
//
// FIXME Use a collection type that doesn't copy node and edge data and
// grow multiplicatively on reallocation. Without such a collection or
// solution having the same effect, there is a performance hazard here
// in both time and space, as growing these collections means copying a
// large amount of data and doubling already large buffer capacities. A
// solution for this will also mean that it's less important to get
// these estimates right.
let new_node_count_estimate = (prev_graph_node_count * 2) / 100 + 200;
let red_node_count_estimate = (prev_graph_node_count * 3) / 100;
let light_green_node_count_estimate = (prev_graph_node_count * 25) / 100;
let total_node_count_estimate = prev_graph_node_count + new_node_count_estimate;
let average_edges_per_node_estimate = 6;
let unshared_edge_count_estimate = average_edges_per_node_estimate
* (new_node_count_estimate + red_node_count_estimate + light_green_node_count_estimate);
// We store a large collection of these in `prev_index_to_index` during
// non-full incremental builds, and want to ensure that the element size
// doesn't inadvertently increase.
static_assert_size!(Option<DepNodeIndex>, 4);
CurrentDepGraph {
data: Lock::new(DepNodeData {
new: NewDepNodeData {
nodes: IndexVec::with_capacity(new_node_count_estimate),
edges: IndexVec::with_capacity(new_node_count_estimate),
fingerprints: IndexVec::with_capacity(new_node_count_estimate),
},
red: RedDepNodeData {
node_indices: IndexVec::with_capacity(red_node_count_estimate),
edges: IndexVec::with_capacity(red_node_count_estimate),
fingerprints: IndexVec::with_capacity(red_node_count_estimate),
},
light_green: LightGreenDepNodeData {
node_indices: IndexVec::with_capacity(light_green_node_count_estimate),
edges: IndexVec::with_capacity(light_green_node_count_estimate),
},
unshared_edges: IndexVec::with_capacity(unshared_edge_count_estimate),
hybrid_indices: IndexVec::with_capacity(total_node_count_estimate),
}),
new_node_to_index: Sharded::new(|| {
FxHashMap::with_capacity_and_hasher(
new_node_count_estimate / sharded::SHARDS,
Default::default(),
)
}),
prev_index_to_index: Lock::new(IndexVec::from_elem_n(None, prev_graph_node_count)),
anon_id_seed: stable_hasher.finish(),
forbidden_edge,
total_read_count: AtomicU64::new(0),
total_duplicate_read_count: AtomicU64::new(0),
}
}
fn intern_new_node(
&self,
prev_graph: &PreviousDepGraph<K>,
dep_node: DepNode<K>,
edges: EdgesVec,
fingerprint: Fingerprint,
) -> DepNodeIndex {
debug_assert!(
prev_graph.node_to_index_opt(&dep_node).is_none(),
"node in previous graph should be interned using one \
of `intern_red_node`, `intern_light_green_node`, etc."
);
match self.new_node_to_index.get_shard_by_value(&dep_node).lock().entry(dep_node) {
Entry::Occupied(entry) => *entry.get(),
Entry::Vacant(entry) => {
let data = &mut *self.data.lock();
let new_index = data.new.nodes.push(dep_node);
add_edges(&mut data.unshared_edges, &mut data.new.edges, edges);
data.new.fingerprints.push(fingerprint);
let dep_node_index = data.hybrid_indices.push(new_index.into());
entry.insert(dep_node_index);
dep_node_index
}
}
}
fn intern_red_node(
&self,
prev_graph: &PreviousDepGraph<K>,
prev_index: SerializedDepNodeIndex,
edges: EdgesVec,
fingerprint: Fingerprint,
) -> DepNodeIndex {
self.debug_assert_not_in_new_nodes(prev_graph, prev_index);
let mut prev_index_to_index = self.prev_index_to_index.lock();
match prev_index_to_index[prev_index] {
Some(dep_node_index) => dep_node_index,
None => {
let data = &mut *self.data.lock();
let red_index = data.red.node_indices.push(prev_index);
add_edges(&mut data.unshared_edges, &mut data.red.edges, edges);
data.red.fingerprints.push(fingerprint);
let dep_node_index = data.hybrid_indices.push(red_index.into());
prev_index_to_index[prev_index] = Some(dep_node_index);
dep_node_index
}
}
}
fn intern_light_green_node(
&self,
prev_graph: &PreviousDepGraph<K>,
prev_index: SerializedDepNodeIndex,
edges: EdgesVec,
) -> DepNodeIndex {
self.debug_assert_not_in_new_nodes(prev_graph, prev_index);
let mut prev_index_to_index = self.prev_index_to_index.lock();
match prev_index_to_index[prev_index] {
Some(dep_node_index) => dep_node_index,
None => {
let data = &mut *self.data.lock();
let light_green_index = data.light_green.node_indices.push(prev_index);
add_edges(&mut data.unshared_edges, &mut data.light_green.edges, edges);
let dep_node_index = data.hybrid_indices.push(light_green_index.into());
prev_index_to_index[prev_index] = Some(dep_node_index);
dep_node_index
}
}
}
fn intern_dark_green_node(
&self,
prev_graph: &PreviousDepGraph<K>,
prev_index: SerializedDepNodeIndex,
) -> DepNodeIndex {
self.debug_assert_not_in_new_nodes(prev_graph, prev_index);
let mut prev_index_to_index = self.prev_index_to_index.lock();
match prev_index_to_index[prev_index] {
Some(dep_node_index) => dep_node_index,
None => {
let mut data = self.data.lock();
let dep_node_index = data.hybrid_indices.push(prev_index.into());
prev_index_to_index[prev_index] = Some(dep_node_index);
dep_node_index
}
}
}
#[inline]
fn debug_assert_not_in_new_nodes(
&self,
prev_graph: &PreviousDepGraph<K>,
prev_index: SerializedDepNodeIndex,
) {
let node = &prev_graph.index_to_node(prev_index);
debug_assert!(
!self.new_node_to_index.get_shard_by_value(node).lock().contains_key(node),
"node from previous graph present in new node collection"
);
}
}
#[inline]
fn add_edges<I: Idx>(
edges: &mut IndexVec<EdgeIndex, DepNodeIndex>,
edge_indices: &mut IndexVec<I, Range<EdgeIndex>>,
new_edges: EdgesVec,
) {
let start = edges.next_index();
edges.extend(new_edges);
let end = edges.next_index();
edge_indices.push(start..end);
}
/// The capacity of the `reads` field `SmallVec`
const TASK_DEPS_READS_CAP: usize = 8;
type EdgesVec = SmallVec<[DepNodeIndex; TASK_DEPS_READS_CAP]>;
pub struct TaskDeps<K> {
#[cfg(debug_assertions)]
node: Option<DepNode<K>>,
reads: EdgesVec,
read_set: FxHashSet<DepNodeIndex>,
phantom_data: PhantomData<DepNode<K>>,
}
impl<K> Default for TaskDeps<K> {
fn default() -> Self {
Self {
#[cfg(debug_assertions)]
node: None,
reads: EdgesVec::new(),
read_set: FxHashSet::default(),
phantom_data: PhantomData,
}
}
}
// A data structure that stores Option<DepNodeColor> values as a contiguous
// array, using one u32 per entry.
struct DepNodeColorMap {
values: IndexVec<SerializedDepNodeIndex, AtomicU32>,
}
const COMPRESSED_NONE: u32 = 0;
const COMPRESSED_RED: u32 = 1;
const COMPRESSED_FIRST_GREEN: u32 = 2;
impl DepNodeColorMap {
fn new(size: usize) -> DepNodeColorMap {
DepNodeColorMap { values: (0..size).map(|_| AtomicU32::new(COMPRESSED_NONE)).collect() }
}
#[inline]
fn get(&self, index: SerializedDepNodeIndex) -> Option<DepNodeColor> {
match self.values[index].load(Ordering::Acquire) {
COMPRESSED_NONE => None,
COMPRESSED_RED => Some(DepNodeColor::Red),
value => {
Some(DepNodeColor::Green(DepNodeIndex::from_u32(value - COMPRESSED_FIRST_GREEN)))
}
}
}
fn insert(&self, index: SerializedDepNodeIndex, color: DepNodeColor) {
self.values[index].store(
match color {
DepNodeColor::Red => COMPRESSED_RED,
DepNodeColor::Green(index) => index.as_u32() + COMPRESSED_FIRST_GREEN,
},
Ordering::Release,
)
}
}