Auto merge of #114894 - Zoxc:sharded-cfg-cleanup2, r=cjgillot

Remove conditional use of `Sharded` from query state

`Sharded` is already a zero cost abstraction, so it shouldn't affect the performance of the single thread compiler if LLVM does its job.

r? `@cjgillot`

compiler/rustc_data_structures/src/sharded.rs

@@ -2,9 +2,12 @@ use crate::fx::{FxHashMap, FxHasher};
 #[cfg(parallel_compiler)]
 use crate::sync::{is_dyn_thread_safe, CacheAligned};
 use crate::sync::{Lock, LockGuard};
+#[cfg(parallel_compiler)]
+use itertools::Either;
 use std::borrow::Borrow;
 use std::collections::hash_map::RawEntryMut;
 use std::hash::{Hash, Hasher};
+use std::iter;
 use std::mem;
 
 // 32 shards is sufficient to reduce contention on an 8-core Ryzen 7 1700,
@@ -70,19 +73,27 @@ impl<T> Sharded<T> {
         }
     }
 
-    pub fn lock_shards(&self) -> Vec<LockGuard<'_, T>> {
+    #[inline]
+    pub fn lock_shards(&self) -> impl Iterator<Item = LockGuard<'_, T>> {
         match self {
-            Self::Single(single) => vec![single.lock()],
+            #[cfg(not(parallel_compiler))]
+            Self::Single(single) => iter::once(single.lock()),
             #[cfg(parallel_compiler)]
-            Self::Shards(shards) => shards.iter().map(|shard| shard.0.lock()).collect(),
+            Self::Single(single) => Either::Left(iter::once(single.lock())),
+            #[cfg(parallel_compiler)]
+            Self::Shards(shards) => Either::Right(shards.iter().map(|shard| shard.0.lock())),
         }
     }
 
-    pub fn try_lock_shards(&self) -> Option<Vec<LockGuard<'_, T>>> {
+    #[inline]
+    pub fn try_lock_shards(&self) -> impl Iterator<Item = Option<LockGuard<'_, T>>> {
         match self {
-            Self::Single(single) => Some(vec![single.try_lock()?]),
+            #[cfg(not(parallel_compiler))]
+            Self::Single(single) => iter::once(single.try_lock()),
             #[cfg(parallel_compiler)]
-            Self::Shards(shards) => shards.iter().map(|shard| shard.0.try_lock()).collect(),
+            Self::Single(single) => Either::Left(iter::once(single.try_lock())),
+            #[cfg(parallel_compiler)]
+            Self::Shards(shards) => Either::Right(shards.iter().map(|shard| shard.0.try_lock())),
         }
     }
 }
@@ -101,7 +112,7 @@ pub type ShardedHashMap<K, V> = Sharded<FxHashMap<K, V>>;
 
 impl<K: Eq, V> ShardedHashMap<K, V> {
     pub fn len(&self) -> usize {
-        self.lock_shards().iter().map(|shard| shard.len()).sum()
+        self.lock_shards().map(|shard| shard.len()).sum()
     }
 }
 

compiler/rustc_middle/src/ty/context.rs

@@ -1296,8 +1296,8 @@ macro_rules! sty_debug_print {
                 };
                 $(let mut $variant = total;)*
 
-                let shards = tcx.interners.type_.lock_shards();
+                for shard in tcx.interners.type_.lock_shards() {
-                let types = shards.iter().flat_map(|shard| shard.keys());
+                    let types = shard.keys();
                     for &InternedInSet(t) in types {
                         let variant = match t.internee {
                             ty::Bool | ty::Char | ty::Int(..) | ty::Uint(..) |
@@ -1316,6 +1316,7 @@ macro_rules! sty_debug_print {
                         if ct { total.ct_infer += 1; variant.ct_infer += 1 }
                         if lt && ty && ct { total.all_infer += 1; variant.all_infer += 1 }
                     }
+                }
                 writeln!(fmt, "Ty interner             total           ty lt ct all")?;
                 $(writeln!(fmt, "    {:18}: {uses:6} {usespc:4.1}%, \
                             {ty:4.1}% {lt:5.1}% {ct:4.1}% {all:4.1}%",

compiler/rustc_query_system/src/query/caches.rs

@@ -70,8 +70,7 @@ where
     }
 
     fn iter(&self, f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex)) {
-        let shards = self.cache.lock_shards();
+        for shard in self.cache.lock_shards() {
-        for shard in shards.iter() {
             for (k, v) in shard.iter() {
                 f(k, &v.0, v.1);
             }
@@ -160,8 +159,7 @@ where
     }
 
     fn iter(&self, f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex)) {
-        let shards = self.cache.lock_shards();
+        for shard in self.cache.lock_shards() {
-        for shard in shards.iter() {
             for (k, v) in shard.iter_enumerated() {
                 if let Some(v) = v {
                     f(&k, &v.0, v.1);

compiler/rustc_query_system/src/query/plumbing.rs

@@ -12,12 +12,13 @@ use crate::query::job::{report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobI
 use crate::query::SerializedDepNodeIndex;
 use crate::query::{QueryContext, QueryMap, QuerySideEffects, QueryStackFrame};
 use crate::HandleCycleError;
+#[cfg(parallel_compiler)]
+use rustc_data_structures::cold_path;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::sharded::Sharded;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::sync::Lock;
-#[cfg(parallel_compiler)]
-use rustc_data_structures::{cold_path, sharded::Sharded};
 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed, FatalError};
 use rustc_span::{Span, DUMMY_SP};
 use std::cell::Cell;
@@ -30,10 +31,7 @@ use thin_vec::ThinVec;
 use super::QueryConfig;
 
 pub struct QueryState<K, D: DepKind> {
-    #[cfg(parallel_compiler)]
     active: Sharded<FxHashMap<K, QueryResult<D>>>,
-    #[cfg(not(parallel_compiler))]
-    active: Lock<FxHashMap<K, QueryResult<D>>>,
 }
 
 /// Indicates the state of a query for a given key in a query map.
@@ -52,15 +50,7 @@ where
     D: DepKind,
 {
     pub fn all_inactive(&self) -> bool {
-        #[cfg(parallel_compiler)]
+        self.active.lock_shards().all(|shard| shard.is_empty())
-        {
-            let shards = self.active.lock_shards();
-            shards.iter().all(|shard| shard.is_empty())
-        }
-        #[cfg(not(parallel_compiler))]
-        {
-            self.active.lock().is_empty()
-        }
     }
 
     pub fn try_collect_active_jobs<Qcx: Copy>(
@@ -71,26 +61,10 @@ where
     ) -> Option<()> {
         let mut active = Vec::new();
 
-        #[cfg(parallel_compiler)]
-        {
         // We use try_lock_shards here since we are called from the
         // deadlock handler, and this shouldn't be locked.
-            let shards = self.active.try_lock_shards()?;
+        for shard in self.active.try_lock_shards() {
-            for shard in shards.iter() {
+            for (k, v) in shard?.iter() {
-                for (k, v) in shard.iter() {
-                    if let QueryResult::Started(ref job) = *v {
-                        active.push((*k, job.clone()));
-                    }
-                }
-            }
-        }
-        #[cfg(not(parallel_compiler))]
-        {
-            // We use try_lock here since we are called from the
-            // deadlock handler, and this shouldn't be locked.
-            // (FIXME: Is this relevant for non-parallel compilers? It doesn't
-            // really hurt much.)
-            for (k, v) in self.active.try_lock()?.iter() {
                 if let QueryResult::Started(ref job) = *v {
                     active.push((*k, job.clone()));
                 }
@@ -184,10 +158,7 @@ where
         cache.complete(key, result, dep_node_index);
 
         let job = {
-            #[cfg(parallel_compiler)]
             let mut lock = state.active.get_shard_by_value(&key).lock();
-            #[cfg(not(parallel_compiler))]
-            let mut lock = state.active.lock();
             match lock.remove(&key).unwrap() {
                 QueryResult::Started(job) => job,
                 QueryResult::Poisoned => panic!(),
@@ -209,10 +180,7 @@ where
         // Poison the query so jobs waiting on it panic.
         let state = self.state;
         let job = {
-            #[cfg(parallel_compiler)]
             let mut shard = state.active.get_shard_by_value(&self.key).lock();
-            #[cfg(not(parallel_compiler))]
-            let mut shard = state.active.lock();
             let job = match shard.remove(&self.key).unwrap() {
                 QueryResult::Started(job) => job,
                 QueryResult::Poisoned => panic!(),
@@ -336,10 +304,7 @@ where
     Qcx: QueryContext,
 {
     let state = query.query_state(qcx);
-    #[cfg(parallel_compiler)]
     let mut state_lock = state.active.get_shard_by_value(&key).lock();
-    #[cfg(not(parallel_compiler))]
-    let mut state_lock = state.active.lock();
 
     // For the parallel compiler we need to check both the query cache and query state structures
     // while holding the state lock to ensure that 1) the query has not yet completed and 2) the