From 7208bdee33460b9915e6b389b236d231d2ca3ffc Mon Sep 17 00:00:00 2001
From: Joshua Nelson <jnelson@cloudflare.com>
Date: Thu, 1 Sep 2022 22:26:03 -0500
Subject: Remove `cache_on_disk` from `QueryVTable`

This is not only simpler, but removes a generic function and unwrap.
I have hope it will see compile time and bootstrap time improvements.
---
 compiler/rustc_query_system/src/query/config.rs   | 10 ++--------
 compiler/rustc_query_system/src/query/plumbing.rs |  6 +++---
 2 files changed, 5 insertions(+), 11 deletions(-)

(limited to 'compiler/rustc_query_system/src')

diff --git a/compiler/rustc_query_system/src/query/config.rs b/compiler/rustc_query_system/src/query/config.rs
index c63e110a62e..340deb88915 100644
--- a/compiler/rustc_query_system/src/query/config.rs
+++ b/compiler/rustc_query_system/src/query/config.rs
@@ -25,11 +25,12 @@ pub struct QueryVTable<CTX: QueryContext, K, V> {
     pub dep_kind: CTX::DepKind,
     pub eval_always: bool,
     pub depth_limit: bool,
-    pub cache_on_disk: bool,
 
     pub compute: fn(CTX::DepContext, K) -> V,
     pub hash_result: Option<fn(&mut StableHashingContext<'_>, &V) -> Fingerprint>,
     pub handle_cycle_error: HandleCycleError,
+    // NOTE: this is not quite the same as `Q::TRY_LOAD_FROM_DISK`; it can also be `None` if
+    // `cache_on_disk` returned false for this key.
     pub try_load_from_disk: Option<fn(CTX, SerializedDepNodeIndex) -> Option<V>>,
 }
 
@@ -44,13 +45,6 @@ impl<CTX: QueryContext, K, V> QueryVTable<CTX, K, V> {
     pub(crate) fn compute(&self, tcx: CTX::DepContext, key: K) -> V {
         (self.compute)(tcx, key)
     }
-
-    pub(crate) fn try_load_from_disk(&self, tcx: CTX, index: SerializedDepNodeIndex) -> Option<V> {
-        self.try_load_from_disk
-            .expect("QueryDescription::load_from_disk() called for an unsupported query.")(
-            tcx, index,
-        )
-    }
 }
 
 pub trait QueryDescription<CTX: QueryContext>: QueryConfig {
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index e39e39860cb..8179a674afa 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -488,14 +488,14 @@ where
 
     // First we try to load the result from the on-disk cache.
     // Some things are never cached on disk.
-    if query.cache_on_disk {
+    if let Some(try_load_from_disk) = query.try_load_from_disk {
         let prof_timer = tcx.dep_context().profiler().incr_cache_loading();
 
         // The call to `with_query_deserialization` enforces that no new `DepNodes`
         // are created during deserialization. See the docs of that method for more
         // details.
-        let result = dep_graph
-            .with_query_deserialization(|| query.try_load_from_disk(tcx, prev_dep_node_index));
+        let result =
+            dep_graph.with_query_deserialization(|| try_load_from_disk(tcx, prev_dep_node_index));
 
         prof_timer.finish_with_query_invocation_id(dep_node_index.into());
 
-- 
cgit 1.4.1-3-g733a5