1 files changed, 51 insertions, 12 deletions

diff --git a/compiler/rustc_query_system/src/dep_graph/graph.rs b/compiler/rustc_query_system/src/dep_graph/graph.rs
index 47b2fd8f8..59e0c3597 100644
--- a/compiler/rustc_query_system/src/dep_graph/graph.rs
+++ b/compiler/rustc_query_system/src/dep_graph/graph.rs
@@ -6,6 +6,7 @@ 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::OnDrop;
 use rustc_index::vec::IndexVec;
 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use smallvec::{smallvec, SmallVec};
@@ -47,7 +48,7 @@ impl DepNodeIndex {
 }
 
 impl From<DepNodeIndex> for QueryInvocationId {
-    #[inline]
+    #[inline(always)]
     fn from(dep_node_index: DepNodeIndex) -> Self {
         QueryInvocationId(dep_node_index.as_u32())
     }
@@ -278,6 +279,7 @@ impl<K: DepKind> DepGraph<K> {
     ///   `arg` parameter.
     ///
     /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/incremental-compilation.html
+    #[inline(always)]
     pub fn with_task<Ctxt: HasDepContext<DepKind = K>, A: Debug, R>(
         &self,
         key: DepNode<K>,
@@ -297,6 +299,7 @@ impl<K: DepKind> DepGraph<K> {
         }
     }
 
+    #[inline(always)]
     fn with_task_impl<Ctxt: HasDepContext<DepKind = K>, A: Debug, R>(
         &self,
         key: DepNode<K>,
@@ -597,6 +600,7 @@ impl<K: DepKind> DepGraph<K> {
         self.data.is_some() && self.dep_node_index_of_opt(dep_node).is_some()
     }
 
+    #[inline]
     pub fn prev_fingerprint_of(&self, dep_node: &DepNode<K>) -> Option<Fingerprint> {
         self.data.as_ref().unwrap().previous.fingerprint_of(dep_node)
     }
@@ -671,17 +675,24 @@ impl<K: DepKind> DepGraph<K> {
         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(qcx, data, prev_index, &dep_node)
-                    .map(|dep_node_index| (prev_index, dep_node_index))
-            }
+            Some(DepNodeColor::Green(dep_node_index)) => return Some((prev_index, dep_node_index)),
+            Some(DepNodeColor::Red) => return None,
+            None => {}
         }
+
+        let backtrace = backtrace_printer(qcx.dep_context().sess(), data, prev_index);
+
+        // 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.
+        let ret = self
+            .try_mark_previous_green(qcx, data, prev_index, &dep_node)
+            .map(|dep_node_index| (prev_index, dep_node_index));
+
+        // We succeeded, no backtrace.
+        backtrace.disable();
+        return ret;
     }
 
     #[instrument(skip(self, qcx, data, parent_dep_node_index), level = "debug")]
@@ -794,7 +805,10 @@ impl<K: DepKind> DepGraph<K> {
         let prev_deps = data.previous.edge_targets_from(prev_dep_node_index);
 
         for &dep_dep_node_index in prev_deps {
-            self.try_mark_parent_green(qcx, data, dep_dep_node_index, dep_node)?
+            let backtrace = backtrace_printer(qcx.dep_context().sess(), data, dep_dep_node_index);
+            let success = self.try_mark_parent_green(qcx, data, dep_dep_node_index, dep_node);
+            backtrace.disable();
+            success?;
         }
 
         // If we got here without hitting a `return` that means that all
@@ -1116,6 +1130,7 @@ impl<K: DepKind> CurrentDepGraph<K> {
 
     /// 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,
@@ -1354,6 +1369,7 @@ impl DepNodeColorMap {
         }
     }
 
+    #[inline]
     fn insert(&self, index: SerializedDepNodeIndex, color: DepNodeColor) {
         self.values[index].store(
             match color {
@@ -1364,3 +1380,26 @@ impl DepNodeColorMap {
         )
     }
 }
+
+fn backtrace_printer<'a, K: DepKind>(
+    sess: &'a rustc_session::Session,
+    graph: &'a DepGraphData<K>,
+    node: SerializedDepNodeIndex,
+) -> OnDrop<impl Fn() + 'a> {
+    OnDrop(
+        #[inline(never)]
+        #[cold]
+        move || {
+            let node = graph.previous.index_to_node(node);
+            // Do not try to rely on DepNode's Debug implementation, since it may panic.
+            let diag = rustc_errors::Diagnostic::new(
+                rustc_errors::Level::FailureNote,
+                &format!(
+                    "encountered while trying to mark dependency green: {:?}({})",
+                    node.kind, node.hash
+                ),
+            );
+            sess.diagnostic().force_print_diagnostic(diag);
+        },
+    )
+}