Remove built-in cache_hit tracking

This was already only enabled in debug_assertions builds. Generally, it seems
like most use cases that would use this could also use the -Zself-profile flag
which also tracks cache hits (in all builds), and so the extra cfg's and such
are not really necessary.

This is largely just a small cleanup though, which primarily is intended to make
other changes easier by avoiding the need to deal with this field.

Author: Mark-Simulacrum

compiler/rustc_query_impl/src/stats.rs

@@ -5,8 +5,6 @@ use rustc_query_system::query::{QueryCache, QueryCacheStore};
 
 use std::any::type_name;
 use std::mem;
-#[cfg(debug_assertions)]
-use std::sync::atomic::Ordering;
 
 trait KeyStats {
     fn key_stats(&self, stats: &mut QueryStats);
@@ -27,7 +25,6 @@ impl KeyStats for DefId {
 #[derive(Clone)]
 struct QueryStats {
     name: &'static str,
-    cache_hits: usize,
     key_size: usize,
     key_type: &'static str,
     value_size: usize,
@@ -42,10 +39,6 @@ where
 {
     let mut stats = QueryStats {
         name,
-        #[cfg(debug_assertions)]
-        cache_hits: map.cache_hits.load(Ordering::Relaxed),
-        #[cfg(not(debug_assertions))]
-        cache_hits: 0,
         key_size: mem::size_of::<C::Key>(),
         key_type: type_name::<C::Key>(),
         value_size: mem::size_of::<C::Value>(),
@@ -63,12 +56,6 @@ where
 pub fn print_stats(tcx: TyCtxt<'_>) {
     let queries = query_stats(tcx);
 
-    if cfg!(debug_assertions) {
-        let hits: usize = queries.iter().map(|s| s.cache_hits).sum();
-        let results: usize = queries.iter().map(|s| s.entry_count).sum();
-        eprintln!("\nQuery cache hit rate: {}", hits as f64 / (hits + results) as f64);
-    }
-
     let mut query_key_sizes = queries.clone();
     query_key_sizes.sort_by_key(|q| q.key_size);
     eprintln!("\nLarge query keys:");
@@ -83,20 +70,6 @@ pub fn print_stats(tcx: TyCtxt<'_>) {
         eprintln!("   {} - {} x {} - {}", q.name, q.value_size, q.entry_count, q.value_type);
     }
 
-    if cfg!(debug_assertions) {
-        let mut query_cache_hits = queries.clone();
-        query_cache_hits.sort_by_key(|q| q.cache_hits);
-        eprintln!("\nQuery cache hits:");
-        for q in query_cache_hits.iter().rev() {
-            eprintln!(
-                "   {} - {} ({}%)",
-                q.name,
-                q.cache_hits,
-                q.cache_hits as f64 / (q.cache_hits + q.entry_count) as f64
-            );
-        }
-    }
-
     let mut query_value_count = queries.clone();
     query_value_count.sort_by_key(|q| q.entry_count);
     eprintln!("\nQuery value count:");

compiler/rustc_query_system/src/query/plumbing.rs

@@ -26,24 +26,15 @@ use std::hash::{Hash, Hasher};
 use std::mem;
 use std::num::NonZeroU32;
 use std::ptr;
-#[cfg(debug_assertions)]
-use std::sync::atomic::{AtomicUsize, Ordering};
 
 pub struct QueryCacheStore<C: QueryCache> {
     cache: C,
     shards: Sharded<C::Sharded>,
-    #[cfg(debug_assertions)]
-    pub cache_hits: AtomicUsize,
 }
 
 impl<C: QueryCache + Default> Default for QueryCacheStore<C> {
     fn default() -> Self {
-        Self {
-            cache: C::default(),
-            shards: Default::default(),
-            #[cfg(debug_assertions)]
-            cache_hits: AtomicUsize::new(0),
-        }
+        Self { cache: C::default(), shards: Default::default() }
     }
 }
 
@@ -377,10 +368,6 @@ where
         if unlikely!(tcx.profiler().enabled()) {
             tcx.profiler().query_cache_hit(index.into());
         }
-        #[cfg(debug_assertions)]
-        {
-            cache.cache_hits.fetch_add(1, Ordering::Relaxed);
-        }
         tcx.dep_graph().read_index(index);
         on_hit(value)
     })
@@ -429,10 +416,6 @@ where
             if unlikely!(tcx.dep_context().profiler().enabled()) {
                 tcx.dep_context().profiler().query_cache_hit(index.into());
             }
-            #[cfg(debug_assertions)]
-            {
-                cache.cache_hits.fetch_add(1, Ordering::Relaxed);
-            }
             query_blocked_prof_timer.finish_with_query_invocation_id(index.into());
 
             (v, Some(index))
@@ -705,10 +688,6 @@ where
         if unlikely!(tcx.dep_context().profiler().enabled()) {
             tcx.dep_context().profiler().query_cache_hit(index.into());
         }
-        #[cfg(debug_assertions)]
-        {
-            cache.cache_hits.fetch_add(1, Ordering::Relaxed);
-        }
     });
 
     let lookup = match cached {