Auto merge of #139758 - Zoxc:thread-local-graph, r=oli-obk

Use thread local dep graph encoding

This adds thread local encoding of dep graph nodes. Each thread has a `MemEncoder` that gets flushed to the global `FileEncoder` when it exceeds 64 kB. Each thread also has a local cache of dep indices. This means there can now be empty gaps in `SerializedDepGraph`.

Indices are marked green and also allocated by the new atomic operation `DepNodeColorMap::try_mark_green` as the encoder lock is removed.

2 files changed, 11 insertions, 1 deletions

diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 80d49effbf8..b28c333d860 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -43,7 +43,7 @@ pub use self::freeze::{FreezeLock, FreezeReadGuard, FreezeWriteGuard};
 pub use self::lock::{Lock, LockGuard, Mode};
 pub use self::mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode};
 pub use self::parallel::{
-    join, par_for_each_in, par_map, parallel_guard, scope, spawn, try_par_for_each_in,
+    broadcast, join, par_for_each_in, par_map, parallel_guard, scope, spawn, try_par_for_each_in,
 };
 pub use self::vec::{AppendOnlyIndexVec, AppendOnlyVec};
 pub use self::worker_local::{Registry, WorkerLocal};
diff --git a/compiler/rustc_data_structures/src/sync/parallel.rs b/compiler/rustc_data_structures/src/sync/parallel.rs
index 64db39cc4c6..ab65c7f3a6b 100644
--- a/compiler/rustc_data_structures/src/sync/parallel.rs
+++ b/compiler/rustc_data_structures/src/sync/parallel.rs
@@ -237,3 +237,13 @@ pub fn par_map<I: DynSend, T: IntoIterator<Item = I>, R: DynSend, C: FromIterato
         }
     })
 }
+
+pub fn broadcast<R: DynSend>(op: impl Fn(usize) -> R + DynSync) -> Vec<R> {
+    if mode::is_dyn_thread_safe() {
+        let op = FromDyn::from(op);
+        let results = rayon_core::broadcast(|context| op.derive(op(context.index())));
+        results.into_iter().map(|r| r.into_inner()).collect()
+    } else {
+        vec![op(0)]
+    }
+}