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use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::profiling::{EventId, QueryInvocationId, SelfProfilerRef};
use rustc_data_structures::sharded::{self, Sharded};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::steal::Steal;
use rustc_data_structures::sync::{AtomicU32, AtomicU64, Lock, Lrc, Ordering};
use rustc_data_structures::unord::UnordMap;
use rustc_index::IndexVec;
use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
use std::assert_matches::assert_matches;
use std::collections::hash_map::Entry;
use std::fmt::Debug;
use std::hash::Hash;
use std::marker::PhantomData;
use std::sync::atomic::Ordering::Relaxed;
use super::query::DepGraphQuery;
use super::serialized::{GraphEncoder, SerializedDepGraph, SerializedDepNodeIndex};
use super::{DepContext, DepKind, DepNode, Deps, HasDepContext, WorkProductId};
use crate::dep_graph::EdgesVec;
use crate::ich::StableHashingContext;
use crate::query::{QueryContext, QuerySideEffects};
#[cfg(debug_assertions)]
use {super::debug::EdgeFilter, std::env};
#[derive(Clone)]
pub struct DepGraph<D: Deps> {
data: Option<Lrc<DepGraphData<D>>>,
/// 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;
pub const SINGLETON_DEPENDENCYLESS_ANON_NODE: DepNodeIndex = DepNodeIndex::from_u32(0);
pub const FOREVER_RED_NODE: DepNodeIndex = DepNodeIndex::from_u32(1);
}
impl From<DepNodeIndex> for QueryInvocationId {
#[inline(always)]
fn from(dep_node_index: DepNodeIndex) -> Self {
QueryInvocationId(dep_node_index.as_u32())
}
}
pub struct MarkFrame<'a> {
index: SerializedDepNodeIndex,
parent: Option<&'a MarkFrame<'a>>,
}
#[derive(PartialEq)]
pub enum DepNodeColor {
Red,
Green(DepNodeIndex),
}
impl DepNodeColor {
#[inline]
pub fn is_green(self) -> bool {
match self {
DepNodeColor::Red => false,
DepNodeColor::Green(_) => true,
}
}
}
pub struct DepGraphData<D: Deps> {
/// 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<D>,
/// 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: SerializedDepGraph,
colors: DepNodeColorMap,
processed_side_effects: Lock<FxHashSet<DepNodeIndex>>,
/// 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: WorkProductMap,
dep_node_debug: Lock<FxHashMap<DepNode, String>>,
/// Used by incremental compilation tests to assert that
/// a particular query result was decoded from disk
/// (not just marked green)
debug_loaded_from_disk: Lock<FxHashSet<DepNode>>,
}
pub fn hash_result<R>(hcx: &mut StableHashingContext<'_>, result: &R) -> Fingerprint
where
R: for<'a> HashStable<StableHashingContext<'a>>,
{
let mut stable_hasher = StableHasher::new();
result.hash_stable(hcx, &mut stable_hasher);
stable_hasher.finish()
}
impl<D: Deps> DepGraph<D> {
pub fn new(
profiler: &SelfProfilerRef,
prev_graph: SerializedDepGraph,
prev_work_products: WorkProductMap,
encoder: FileEncoder,
record_graph: bool,
record_stats: bool,
) -> DepGraph<D> {
let prev_graph_node_count = prev_graph.node_count();
let current = CurrentDepGraph::new(
profiler,
prev_graph_node_count,
encoder,
record_graph,
record_stats,
);
let colors = DepNodeColorMap::new(prev_graph_node_count);
// Instantiate a dependy-less node only once for anonymous queries.
let _green_node_index = current.intern_new_node(
profiler,
DepNode { kind: D::DEP_KIND_NULL, hash: current.anon_id_seed.into() },
EdgesVec::new(),
Fingerprint::ZERO,
);
assert_eq!(_green_node_index, DepNodeIndex::SINGLETON_DEPENDENCYLESS_ANON_NODE);
// Instantiate a dependy-less red node only once for anonymous queries.
let (red_node_index, red_node_prev_index_and_color) = current.intern_node(
profiler,
&prev_graph,
DepNode { kind: D::DEP_KIND_RED, hash: Fingerprint::ZERO.into() },
EdgesVec::new(),
None,
false,
);
assert_eq!(red_node_index, DepNodeIndex::FOREVER_RED_NODE);
match red_node_prev_index_and_color {
None => {
// This is expected when we have no previous compilation session.
assert!(prev_graph_node_count == 0);
}
Some((prev_red_node_index, DepNodeColor::Red)) => {
assert_eq!(prev_red_node_index.as_usize(), red_node_index.as_usize());
colors.insert(prev_red_node_index, DepNodeColor::Red);
}
Some((_, DepNodeColor::Green(_))) => {
// There must be a logic error somewhere if we hit this branch.
panic!("DepNodeIndex::FOREVER_RED_NODE evaluated to DepNodeColor::Green")
}
}
DepGraph {
data: Some(Lrc::new(DepGraphData {
previous_work_products: prev_work_products,
dep_node_debug: Default::default(),
current,
processed_side_effects: Default::default(),
previous: prev_graph,
colors,
debug_loaded_from_disk: Default::default(),
})),
virtual_dep_node_index: Lrc::new(AtomicU32::new(0)),
}
}
pub fn new_disabled() -> DepGraph<D> {
DepGraph { data: None, virtual_dep_node_index: Lrc::new(AtomicU32::new(0)) }
}
#[inline]
pub fn data(&self) -> Option<&DepGraphData<D>> {
self.data.as_deref()
}
/// 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 with_query(&self, f: impl Fn(&DepGraphQuery)) {
if let Some(data) = &self.data {
data.current.encoder.borrow().with_query(f)
}
}
pub fn assert_ignored(&self) {
if let Some(..) = self.data {
D::read_deps(|task_deps| {
assert_matches!(
task_deps,
TaskDepsRef::Ignore,
"expected no task dependency tracking"
);
})
}
}
pub fn with_ignore<OP, R>(&self, op: OP) -> R
where
OP: FnOnce() -> R,
{
D::with_deps(TaskDepsRef::Ignore, op)
}
/// Used to wrap the deserialization of a query result from disk,
/// This method enforces that no new `DepNodes` are created during
/// query result deserialization.
///
/// Enforcing this makes the query dep graph simpler - all nodes
/// must be created during the query execution, and should be
/// created from inside the 'body' of a query (the implementation
/// provided by a particular compiler crate).
///
/// Consider the case of three queries `A`, `B`, and `C`, where
/// `A` invokes `B` and `B` invokes `C`:
///
/// `A -> B -> C`
///
/// Suppose that decoding the result of query `B` required re-computing
/// the query `C`. If we did not create a fresh `TaskDeps` when
/// decoding `B`, we would still be using the `TaskDeps` for query `A`
/// (if we needed to re-execute `A`). This would cause us to create
/// a new edge `A -> C`. If this edge did not previously
/// exist in the `DepGraph`, then we could end up with a different
/// `DepGraph` at the end of compilation, even if there were no
/// meaningful changes to the overall program (e.g. a newline was added).
/// In addition, this edge might cause a subsequent compilation run
/// to try to force `C` before marking other necessary nodes green. If
/// `C` did not exist in the new compilation session, then we could
/// get an ICE. Normally, we would have tried (and failed) to mark
/// some other query green (e.g. `item_children`) which was used
/// to obtain `C`, which would prevent us from ever trying to force
/// a nonexistent `D`.
///
/// It might be possible to enforce that all `DepNode`s read during
/// deserialization already exist in the previous `DepGraph`. In
/// the above example, we would invoke `D` during the deserialization
/// of `B`. Since we correctly create a new `TaskDeps` from the decoding
/// of `B`, this would result in an edge `B -> D`. If that edge already
/// existed (with the same `DepPathHash`es), then it should be correct
/// to allow the invocation of the query to proceed during deserialization
/// of a query result. We would merely assert that the dep-graph fragment
/// that would have been added by invoking `C` while decoding `B`
/// is equivalent to the dep-graph fragment that we already instantiated for B
/// (at the point where we successfully marked B as green).
///
/// However, this would require additional complexity
/// in the query infrastructure, and is not currently needed by the
/// decoding of any query results. Should the need arise in the future,
/// we should consider extending the query system with this functionality.
pub fn with_query_deserialization<OP, R>(&self, op: OP) -> R
where
OP: FnOnce() -> R,
{
D::with_deps(TaskDepsRef::Forbid, op)
}
#[inline(always)]
pub fn with_task<Ctxt: HasDepContext<Deps = D>, A: Debug, R>(
&self,
key: DepNode,
cx: Ctxt,
arg: A,
task: fn(Ctxt, A) -> R,
hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
) -> (R, DepNodeIndex) {
match self.data() {
Some(data) => data.with_task(key, cx, arg, task, hash_result),
None => (task(cx, arg), self.next_virtual_depnode_index()),
}
}
pub fn with_anon_task<Tcx: DepContext<Deps = D>, OP, R>(
&self,
cx: Tcx,
dep_kind: DepKind,
op: OP,
) -> (R, DepNodeIndex)
where
OP: FnOnce() -> R,
{
match self.data() {
Some(data) => data.with_anon_task(cx, dep_kind, op),
None => (op(), self.next_virtual_depnode_index()),
}
}
}
impl<D: Deps> DepGraphData<D> {
/// 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
#[inline(always)]
pub fn with_task<Ctxt: HasDepContext<Deps = D>, A: Debug, R>(
&self,
key: DepNode,
cx: Ctxt,
arg: A,
task: fn(Ctxt, A) -> R,
hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
) -> (R, DepNodeIndex) {
// If the following assertion triggers, it can have two reasons:
// 1. Something is wrong with DepNode creation, either here or
// in `DepGraph::try_mark_green()`.
// 2. Two distinct query keys get mapped to the same `DepNode`
// (see for example #48923).
assert!(
!self.dep_node_exists(&key),
"forcing query with already existing `DepNode`\n\
- query-key: {arg:?}\n\
- dep-node: {key:?}"
);
let with_deps = |task_deps| D::with_deps(task_deps, || task(cx, arg));
let (result, edges) = if cx.dep_context().is_eval_always(key.kind) {
(with_deps(TaskDepsRef::EvalAlways), EdgesVec::new())
} else {
let task_deps = Lock::new(TaskDeps {
#[cfg(debug_assertions)]
node: Some(key),
reads: EdgesVec::new(),
read_set: Default::default(),
phantom_data: PhantomData,
});
(with_deps(TaskDepsRef::Allow(&task_deps)), task_deps.into_inner().reads)
};
let dcx = cx.dep_context();
let hashing_timer = dcx.profiler().incr_result_hashing();
let current_fingerprint =
hash_result.map(|f| dcx.with_stable_hashing_context(|mut hcx| f(&mut hcx, &result)));
let print_status = cfg!(debug_assertions) && dcx.sess().opts.unstable_opts.dep_tasks;
// Intern the new `DepNode`.
let (dep_node_index, prev_and_color) = self.current.intern_node(
dcx.profiler(),
&self.previous,
key,
edges,
current_fingerprint,
print_status,
);
hashing_timer.finish_with_query_invocation_id(dep_node_index.into());
if let Some((prev_index, color)) = prev_and_color {
debug_assert!(
self.colors.get(prev_index).is_none(),
"DepGraph::with_task() - Duplicate DepNodeColor \
insertion for {key:?}"
);
self.colors.insert(prev_index, color);
}
(result, dep_node_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<Tcx: DepContext<Deps = D>, OP, R>(
&self,
cx: Tcx,
dep_kind: DepKind,
op: OP,
) -> (R, DepNodeIndex)
where
OP: FnOnce() -> R,
{
debug_assert!(!cx.is_eval_always(dep_kind));
let task_deps = Lock::new(TaskDeps::default());
let result = D::with_deps(TaskDepsRef::Allow(&task_deps), op);
let task_deps = task_deps.into_inner();
let task_deps = task_deps.reads;
let dep_node_index = match task_deps.len() {
0 => {
// Because the dep-node id of anon nodes is computed from the sets of its
// dependencies we already know what the ID of this dependency-less node is
// going to be (i.e. equal to the precomputed
// `SINGLETON_DEPENDENCYLESS_ANON_NODE`). As a consequence we can skip creating
// a `StableHasher` and sending the node through interning.
DepNodeIndex::SINGLETON_DEPENDENCYLESS_ANON_NODE
}
1 => {
// When there is only one dependency, don't bother creating a node.
task_deps[0]
}
_ => {
// 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.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: self.current.anon_id_seed.combine(hasher.finish()).into(),
};
self.current.intern_new_node(
cx.profiler(),
target_dep_node,
task_deps,
Fingerprint::ZERO,
)
}
};
(result, dep_node_index)
}
}
impl<D: Deps> DepGraph<D> {
#[inline]
pub fn read_index(&self, dep_node_index: DepNodeIndex) {
if let Some(ref data) = self.data {
D::read_deps(|task_deps| {
let mut task_deps = match task_deps {
TaskDepsRef::Allow(deps) => deps.lock(),
TaskDepsRef::EvalAlways => {
// We don't need to record dependencies of eval_always
// queries. They are re-evaluated unconditionally anyway.
return;
}
TaskDepsRef::Ignore => return,
TaskDepsRef::Forbid => {
panic!("Illegal read of: {dep_node_index:?}")
}
};
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() < EdgesVec::INLINE_CAPACITY {
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() == EdgesVec::INLINE_CAPACITY {
// 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 = forbidden_edge.index_to_node.lock()[&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);
}
})
}
}
/// Create a node when we force-feed a value into the query cache.
/// This is used to remove cycles during type-checking const generic parameters.
///
/// As usual in the query system, we consider the current state of the calling query
/// only depends on the list of dependencies up to now. As a consequence, the value
/// that this query gives us can only depend on those dependencies too. Therefore,
/// it is sound to use the current dependency set for the created node.
///
/// During replay, the order of the nodes is relevant in the dependency graph.
/// So the unchanged replay will mark the caller query before trying to mark this one.
/// If there is a change to report, the caller query will be re-executed before this one.
///
/// FIXME: If the code is changed enough for this node to be marked before requiring the
/// caller's node, we suppose that those changes will be enough to mark this node red and
/// force a recomputation using the "normal" way.
pub fn with_feed_task<Ctxt: DepContext<Deps = D>, A: Debug, R: Debug>(
&self,
node: DepNode,
cx: Ctxt,
key: A,
result: &R,
hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
) -> DepNodeIndex {
if let Some(data) = self.data.as_ref() {
// The caller query has more dependencies than the node we are creating. We may
// encounter a case where this created node is marked as green, but the caller query is
// subsequently marked as red or recomputed. In this case, we will end up feeding a
// value to an existing node.
//
// For sanity, we still check that the loaded stable hash and the new one match.
if let Some(prev_index) = data.previous.node_to_index_opt(&node) {
let dep_node_index = data.current.prev_index_to_index.lock()[prev_index];
if let Some(dep_node_index) = dep_node_index {
crate::query::incremental_verify_ich(
cx,
data,
result,
prev_index,
hash_result,
|value| format!("{value:?}"),
);
#[cfg(debug_assertions)]
if hash_result.is_some() {
data.current.record_edge(
dep_node_index,
node,
data.prev_fingerprint_of(prev_index),
);
}
return dep_node_index;
}
}
let mut edges = EdgesVec::new();
D::read_deps(|task_deps| match task_deps {
TaskDepsRef::Allow(deps) => edges.extend(deps.lock().reads.iter().copied()),
TaskDepsRef::EvalAlways => {
edges.push(DepNodeIndex::FOREVER_RED_NODE);
}
TaskDepsRef::Ignore => {}
TaskDepsRef::Forbid => {
panic!("Cannot summarize when dependencies are not recorded.")
}
});
let hashing_timer = cx.profiler().incr_result_hashing();
let current_fingerprint = hash_result.map(|hash_result| {
cx.with_stable_hashing_context(|mut hcx| hash_result(&mut hcx, result))
});
let print_status = cfg!(debug_assertions) && cx.sess().opts.unstable_opts.dep_tasks;
// Intern the new `DepNode` with the dependencies up-to-now.
let (dep_node_index, prev_and_color) = data.current.intern_node(
cx.profiler(),
&data.previous,
node,
edges,
current_fingerprint,
print_status,
);
hashing_timer.finish_with_query_invocation_id(dep_node_index.into());
if let Some((prev_index, color)) = prev_and_color {
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 {
// 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.
self.next_virtual_depnode_index()
}
}
}
impl<D: Deps> DepGraphData<D> {
#[inline]
pub fn dep_node_index_of_opt(&self, dep_node: &DepNode) -> Option<DepNodeIndex> {
if let Some(prev_index) = self.previous.node_to_index_opt(dep_node) {
self.current.prev_index_to_index.lock()[prev_index]
} else {
self.current.new_node_to_index.lock_shard_by_value(dep_node).get(dep_node).copied()
}
}
#[inline]
pub fn dep_node_exists(&self, dep_node: &DepNode) -> bool {
self.dep_node_index_of_opt(dep_node).is_some()
}
fn node_color(&self, dep_node: &DepNode) -> Option<DepNodeColor> {
if let Some(prev_index) = self.previous.node_to_index_opt(dep_node) {
self.colors.get(prev_index)
} else {
// This is a node that did not exist in the previous compilation session.
None
}
}
/// Returns true if the given node has been marked as green during the
/// current compilation session. Used in various assertions
#[inline]
pub fn is_index_green(&self, prev_index: SerializedDepNodeIndex) -> bool {
self.colors.get(prev_index).is_some_and(|c| c.is_green())
}
#[inline]
pub fn prev_fingerprint_of(&self, prev_index: SerializedDepNodeIndex) -> Fingerprint {
self.previous.fingerprint_by_index(prev_index)
}
#[inline]
pub fn prev_node_of(&self, prev_index: SerializedDepNodeIndex) -> DepNode {
self.previous.index_to_node(prev_index)
}
pub fn mark_debug_loaded_from_disk(&self, dep_node: DepNode) {
self.debug_loaded_from_disk.lock().insert(dep_node);
}
}
impl<D: Deps> DepGraph<D> {
#[inline]
pub fn dep_node_exists(&self, dep_node: &DepNode) -> bool {
self.data.as_ref().is_some_and(|data| data.dep_node_exists(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) -> &WorkProductMap {
&self.data.as_ref().unwrap().previous_work_products
}
pub fn debug_was_loaded_from_disk(&self, dep_node: DepNode) -> bool {
self.data.as_ref().unwrap().debug_loaded_from_disk.lock().contains(&dep_node)
}
#[inline(always)]
pub fn register_dep_node_debug_str<F>(&self, dep_node: DepNode, 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 = self.with_ignore(debug_str_gen);
dep_node_debug.borrow_mut().insert(dep_node, debug_str);
}
pub fn dep_node_debug_str(&self, dep_node: DepNode) -> Option<String> {
self.data.as_ref()?.dep_node_debug.borrow().get(&dep_node).cloned()
}
fn node_color(&self, dep_node: &DepNode) -> Option<DepNodeColor> {
if let Some(ref data) = self.data {
return data.node_color(dep_node);
}
None
}
pub fn try_mark_green<Qcx: QueryContext<Deps = D>>(
&self,
qcx: Qcx,
dep_node: &DepNode,
) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
self.data().and_then(|data| data.try_mark_green(qcx, dep_node))
}
}
impl<D: Deps> DepGraphData<D> {
/// Try to mark 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<Qcx: QueryContext<Deps = D>>(
&self,
qcx: Qcx,
dep_node: &DepNode,
) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
debug_assert!(!qcx.dep_context().is_eval_always(dep_node.kind));
// Return None if the dep node didn't exist in the previous session
let prev_index = self.previous.node_to_index_opt(dep_node)?;
match self.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(qcx, prev_index, &dep_node, None)
.map(|dep_node_index| (prev_index, dep_node_index))
}
}
}
#[instrument(skip(self, qcx, parent_dep_node_index, frame), level = "debug")]
fn try_mark_parent_green<Qcx: QueryContext<Deps = D>>(
&self,
qcx: Qcx,
parent_dep_node_index: SerializedDepNodeIndex,
dep_node: &DepNode,
frame: Option<&MarkFrame<'_>>,
) -> Option<()> {
let dep_dep_node_color = self.colors.get(parent_dep_node_index);
let dep_dep_node = &self.previous.index_to_node(parent_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!("dependency {dep_dep_node:?} was immediately green");
return Some(());
}
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!("dependency {dep_dep_node:?} was immediately red");
return None;
}
None => {}
}
// 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 !qcx.dep_context().is_eval_always(dep_dep_node.kind) {
debug!(
"state of dependency {:?} ({}) is unknown, trying to mark it green",
dep_dep_node, dep_dep_node.hash,
);
let node_index =
self.try_mark_previous_green(qcx, parent_dep_node_index, dep_dep_node, frame);
if node_index.is_some() {
debug!("managed to MARK dependency {dep_dep_node:?} as green",);
return Some(());
}
}
// We failed to mark it green, so we try to force the query.
debug!("trying to force dependency {dep_dep_node:?}");
if !qcx.dep_context().try_force_from_dep_node(*dep_dep_node, frame) {
// The DepNode could not be forced.
debug!("dependency {dep_dep_node:?} could not be forced");
return None;
}
let dep_dep_node_color = self.colors.get(parent_dep_node_index);
match dep_dep_node_color {
Some(DepNodeColor::Green(_)) => {
debug!("managed to FORCE dependency {dep_dep_node:?} to green");
return Some(());
}
Some(DepNodeColor::Red) => {
debug!("dependency {dep_dep_node:?} was red after forcing",);
return None;
}
None => {}
}
if let None = qcx.dep_context().sess().has_errors_or_delayed_span_bugs() {
panic!("try_mark_previous_green() - Forcing the DepNode should have set its color")
}
// 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!("dependency {dep_dep_node:?} resulted in compilation error",);
return None;
}
/// Try to mark a dep-node which existed in the previous compilation session as green.
#[instrument(skip(self, qcx, prev_dep_node_index, frame), level = "debug")]
fn try_mark_previous_green<Qcx: QueryContext<Deps = D>>(
&self,
qcx: Qcx,
prev_dep_node_index: SerializedDepNodeIndex,
dep_node: &DepNode,
frame: Option<&MarkFrame<'_>>,
) -> Option<DepNodeIndex> {
let frame = MarkFrame { index: prev_dep_node_index, parent: frame };
#[cfg(not(parallel_compiler))]
{
debug_assert!(!self.dep_node_exists(dep_node));
debug_assert!(self.colors.get(prev_dep_node_index).is_none());
}
// We never try to mark eval_always nodes as green
debug_assert!(!qcx.dep_context().is_eval_always(dep_node.kind));
debug_assert_eq!(self.previous.index_to_node(prev_dep_node_index), *dep_node);
let prev_deps = self.previous.edge_targets_from(prev_dep_node_index);
for dep_dep_node_index in prev_deps {
self.try_mark_parent_green(qcx, dep_dep_node_index, dep_node, Some(&frame))?;
}
// 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
// We allocating an entry for the node in the current dependency graph and
// adding all the appropriate edges imported from the previous graph
let dep_node_index = self.current.promote_node_and_deps_to_current(
qcx.dep_context().profiler(),
&self.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 side_effects = qcx.load_side_effects(prev_dep_node_index);
#[cfg(not(parallel_compiler))]
debug_assert!(
self.colors.get(prev_dep_node_index).is_none(),
"DepGraph::try_mark_previous_green() - Duplicate DepNodeColor \
insertion for {dep_node:?}"
);
if !side_effects.is_empty() {
qcx.dep_context().dep_graph().with_query_deserialization(|| {
self.emit_side_effects(qcx, dep_node_index, side_effects)
});
}
// ... and finally storing a "Green" entry in the color map.
// Multiple threads can all write the same color here
self.colors.insert(prev_dep_node_index, DepNodeColor::Green(dep_node_index));
debug!("successfully marked {dep_node:?} as green");
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_side_effects<Qcx: QueryContext<Deps = D>>(
&self,
qcx: Qcx,
dep_node_index: DepNodeIndex,
side_effects: QuerySideEffects,
) {
let mut processed = self.processed_side_effects.lock();
if processed.insert(dep_node_index) {
// We were the first to insert the node in the set so this thread
// must process side effects
// Promote the previous diagnostics to the current session.
qcx.store_side_effects(dep_node_index, side_effects.clone());
let handle = qcx.dep_context().sess().diagnostic();
for mut diagnostic in side_effects.diagnostics {
handle.emit_diagnostic(&mut diagnostic);
}
}
}
}
impl<D: Deps> DepGraph<D> {
/// Returns true if the given node has been marked as red during the
/// current compilation session. Used in various assertions
pub fn is_red(&self, dep_node: &DepNode) -> bool {
self.node_color(dep_node) == Some(DepNodeColor::Red)
}
/// 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) -> bool {
self.node_color(dep_node).is_some_and(|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<Tcx: DepContext>(&self, tcx: Tcx) {
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);
tcx.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.
}
}
}
}
pub fn print_incremental_info(&self) {
if let Some(data) = &self.data {
data.current.encoder.borrow().print_incremental_info(
data.current.total_read_count.load(Relaxed),
data.current.total_duplicate_read_count.load(Relaxed),
)
}
}
pub fn encode(&self, profiler: &SelfProfilerRef) -> FileEncodeResult {
if let Some(data) = &self.data {
data.current.encoder.steal().finish(profiler)
} else {
Ok(0)
}
}
pub(crate) fn next_virtual_depnode_index(&self) -> DepNodeIndex {
debug_assert!(self.data.is_none());
let index = self.virtual_dep_node_index.fetch_add(1, Relaxed);
DepNodeIndex::from_u32(index)
}
}
/// 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 files associated with this CGU. In each key/value pair, the value is the path to the
/// saved file and the key is some identifier for the type of file being saved.
///
/// By convention, file extensions are currently used as identifiers, i.e. the key "o" maps to
/// the object file's path, and "dwo" to the dwarf object file's path.
pub saved_files: UnordMap<String, String>,
}
pub type WorkProductMap = UnordMap<WorkProductId, WorkProduct>;
// Index type for `DepNodeData`'s edges.
rustc_index::newtype_index! {
struct 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`. We avoid keeping the nodes
/// in memory. This is important, because these graph structures are some of the
/// largest in the compiler.
///
/// For this reason, we 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. `SerializedDepGraph` 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<D: Deps> {
encoder: Steal<GraphEncoder<D>>,
new_node_to_index: Sharded<FxHashMap<DepNode, DepNodeIndex>>,
prev_index_to_index: Lock<IndexVec<SerializedDepNodeIndex, Option<DepNodeIndex>>>,
/// This is used to verify that fingerprints do not change between the creation of a node
/// and its recomputation.
#[cfg(debug_assertions)]
fingerprints: Lock<IndexVec<DepNodeIndex, Option<Fingerprint>>>,
/// 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`.
#[cfg(debug_assertions)]
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,
/// The cached event id for profiling node interning. This saves us
/// from having to look up the event id every time we intern a node
/// which may incur too much overhead.
/// This will be None if self-profiling is disabled.
node_intern_event_id: Option<EventId>,
}
impl<D: Deps> CurrentDepGraph<D> {
fn new(
profiler: &SelfProfilerRef,
prev_graph_node_count: usize,
encoder: FileEncoder,
record_graph: bool,
record_stats: bool,
) -> Self {
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 anon_id_seed = stable_hasher.finish();
#[cfg(debug_assertions)]
let forbidden_edge = 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,
};
// 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);
let new_node_count_estimate = 102 * prev_graph_node_count / 100 + 200;
let node_intern_event_id = profiler
.get_or_alloc_cached_string("incr_comp_intern_dep_graph_node")
.map(EventId::from_label);
CurrentDepGraph {
encoder: Steal::new(GraphEncoder::new(
encoder,
prev_graph_node_count,
record_graph,
record_stats,
)),
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,
#[cfg(debug_assertions)]
forbidden_edge,
#[cfg(debug_assertions)]
fingerprints: Lock::new(IndexVec::from_elem_n(None, new_node_count_estimate)),
total_read_count: AtomicU64::new(0),
total_duplicate_read_count: AtomicU64::new(0),
node_intern_event_id,
}
}
#[cfg(debug_assertions)]
fn record_edge(&self, dep_node_index: DepNodeIndex, key: DepNode, fingerprint: Fingerprint) {
if let Some(forbidden_edge) = &self.forbidden_edge {
forbidden_edge.index_to_node.lock().insert(dep_node_index, key);
}
let previous = *self.fingerprints.lock().get_or_insert_with(dep_node_index, || fingerprint);
assert_eq!(previous, fingerprint, "Unstable fingerprints for {:?}", key);
}
/// Writes the node to the current dep-graph and allocates a `DepNodeIndex` for it.
/// Assumes that this is a node that has no equivalent in the previous dep-graph.
#[inline(always)]
fn intern_new_node(
&self,
profiler: &SelfProfilerRef,
key: DepNode,
edges: EdgesVec,
current_fingerprint: Fingerprint,
) -> DepNodeIndex {
let dep_node_index = match self.new_node_to_index.lock_shard_by_value(&key).entry(key) {
Entry::Occupied(entry) => *entry.get(),
Entry::Vacant(entry) => {
let dep_node_index =
self.encoder.borrow().send(profiler, key, current_fingerprint, edges);
entry.insert(dep_node_index);
dep_node_index
}
};
#[cfg(debug_assertions)]
self.record_edge(dep_node_index, key, current_fingerprint);
dep_node_index
}
fn intern_node(
&self,
profiler: &SelfProfilerRef,
prev_graph: &SerializedDepGraph,
key: DepNode,
edges: EdgesVec,
fingerprint: Option<Fingerprint>,
print_status: bool,
) -> (DepNodeIndex, Option<(SerializedDepNodeIndex, DepNodeColor)>) {
let print_status = cfg!(debug_assertions) && print_status;
// Get timer for profiling `DepNode` interning
let _node_intern_timer =
self.node_intern_event_id.map(|eid| profiler.generic_activity_with_event_id(eid));
if let Some(prev_index) = prev_graph.node_to_index_opt(&key) {
let get_dep_node_index = |color, fingerprint| {
if print_status {
eprintln!("[task::{color:}] {key:?}");
}
let mut prev_index_to_index = self.prev_index_to_index.lock();
let dep_node_index = match prev_index_to_index[prev_index] {
Some(dep_node_index) => dep_node_index,
None => {
let dep_node_index =
self.encoder.borrow().send(profiler, key, fingerprint, edges);
prev_index_to_index[prev_index] = Some(dep_node_index);
dep_node_index
}
};
#[cfg(debug_assertions)]
self.record_edge(dep_node_index, key, fingerprint);
dep_node_index
};
// Determine the color and index of the new `DepNode`.
if let Some(fingerprint) = fingerprint {
if fingerprint == prev_graph.fingerprint_by_index(prev_index) {
// This is a 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 = get_dep_node_index("green", fingerprint);
(dep_node_index, Some((prev_index, DepNodeColor::Green(dep_node_index))))
} else {
// 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 = get_dep_node_index("red", fingerprint);
(dep_node_index, Some((prev_index, DepNodeColor::Red)))
}
} else {
// 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 = get_dep_node_index("unknown", Fingerprint::ZERO);
(dep_node_index, Some((prev_index, DepNodeColor::Red)))
}
} else {
if print_status {
eprintln!("[task::new] {key:?}");
}
let fingerprint = fingerprint.unwrap_or(Fingerprint::ZERO);
// This is a new node: it didn't exist in the previous compilation session.
let dep_node_index = self.intern_new_node(profiler, key, edges, fingerprint);
(dep_node_index, None)
}
}
fn promote_node_and_deps_to_current(
&self,
profiler: &SelfProfilerRef,
prev_graph: &SerializedDepGraph,
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 key = prev_graph.index_to_node(prev_index);
let edges = prev_graph
.edge_targets_from(prev_index)
.map(|i| prev_index_to_index[i].unwrap())
.collect();
let fingerprint = prev_graph.fingerprint_by_index(prev_index);
let dep_node_index = self.encoder.borrow().send(profiler, key, fingerprint, edges);
prev_index_to_index[prev_index] = Some(dep_node_index);
#[cfg(debug_assertions)]
self.record_edge(dep_node_index, key, fingerprint);
dep_node_index
}
}
}
#[inline]
fn debug_assert_not_in_new_nodes(
&self,
prev_graph: &SerializedDepGraph,
prev_index: SerializedDepNodeIndex,
) {
let node = &prev_graph.index_to_node(prev_index);
debug_assert!(
!self.new_node_to_index.lock_shard_by_value(node).contains_key(node),
"node from previous graph present in new node collection"
);
}
}
#[derive(Debug, Clone, Copy)]
pub enum TaskDepsRef<'a> {
/// New dependencies can be added to the
/// `TaskDeps`. This is used when executing a 'normal' query
/// (no `eval_always` modifier)
Allow(&'a Lock<TaskDeps>),
/// This is used when executing an `eval_always` query. We don't
/// need to track dependencies for a query that's always
/// re-executed -- but we need to know that this is an `eval_always`
/// query in order to emit dependencies to `DepNodeIndex::FOREVER_RED_NODE`
/// when directly feeding other queries.
EvalAlways,
/// New dependencies are ignored. This is also used for `dep_graph.with_ignore`.
Ignore,
/// Any attempt to add new dependencies will cause a panic.
/// This is used when decoding a query result from disk,
/// to ensure that the decoding process doesn't itself
/// require the execution of any queries.
Forbid,
}
#[derive(Debug)]
pub struct TaskDeps {
#[cfg(debug_assertions)]
node: Option<DepNode>,
reads: EdgesVec,
read_set: FxHashSet<DepNodeIndex>,
phantom_data: PhantomData<DepNode>,
}
impl Default for TaskDeps {
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)))
}
}
}
#[inline]
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,
)
}
}
#[inline(never)]
#[cold]
pub(crate) fn print_markframe_trace<D: Deps>(graph: &DepGraph<D>, frame: Option<&MarkFrame<'_>>) {
let data = graph.data.as_ref().unwrap();
eprintln!("there was a panic while trying to force a dep node");
eprintln!("try_mark_green dep node stack:");
let mut i = 0;
let mut current = frame;
while let Some(frame) = current {
let node = data.previous.index_to_node(frame.index);
eprintln!("#{i} {node:?}");
current = frame.parent;
i += 1;
}
eprintln!("end of try_mark_green dep node stack");
}