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Auto merge of #94084 - Mark-Simulacrum:drop-sharded, r=cjgillot

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Avoid query cache sharding code in single-threaded mode

In non-parallel compilers, this is just adding needless overhead at compilation time (since there is only one shard statically anyway). This amounts to roughly ~10 seconds reduction in bootstrap time, with overall neutral (some wins, some losses) performance results.

Parallel compiler performance should be largely unaffected by this PR; sharding is kept there.
This commit is contained in:
bors 2022-02-27 14:04:07 +00:00
commit 3b1fe7e7c9
8 changed files with 167 additions and 204 deletions
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149
compiler/rustc_query_system/src/query/caches.rs
View file

@ -1,9 +1,12 @@
use crate::dep_graph::DepNodeIndex;
use crate::query::plumbing::{QueryCacheStore, QueryLookup};
use rustc_arena::TypedArena;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::sharded;
#[cfg(parallel_compiler)]
use rustc_data_structures::sharded::Sharded;
#[cfg(not(parallel_compiler))]
use rustc_data_structures::sync::Lock;
use rustc_data_structures::sync::WorkerLocal;
use std::default::Default;
use std::fmt::Debug;
@ -25,35 +28,23 @@ pub trait QueryStorage {
pub trait QueryCache: QueryStorage + Sized {
type Key: Hash + Eq + Clone + Debug;
type Sharded: Default;
/// Checks if the query is already computed and in the cache.
/// It returns the shard index and a lock guard to the shard,
/// which will be used if the query is not in the cache and we need
/// to compute it.
fn lookup<'s, R, OnHit>(
fn lookup<R, OnHit>(
&self,
state: &'s QueryCacheStore<Self>,
key: &Self::Key,
// `on_hit` can be called while holding a lock to the query state shard.
on_hit: OnHit,
) -> Result<R, QueryLookup>
) -> Result<R, ()>
where
OnHit: FnOnce(&Self::Stored, DepNodeIndex) -> R;
fn complete(
&self,
lock_sharded_storage: &mut Self::Sharded,
key: Self::Key,
value: Self::Value,
index: DepNodeIndex,
) -> Self::Stored;
fn complete(&self, key: Self::Key, value: Self::Value, index: DepNodeIndex) -> Self::Stored;
fn iter(
&self,
shards: &Sharded<Self::Sharded>,
f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex),
);
fn iter(&self, f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex));
}
pub struct DefaultCacheSelector;
@ -62,11 +53,16 @@ impl<K: Eq + Hash, V: Clone> CacheSelector<K, V> for DefaultCacheSelector {
type Cache = DefaultCache<K, V>;
}
pub struct DefaultCache<K, V>(PhantomData<(K, V)>);
pub struct DefaultCache<K, V> {
#[cfg(parallel_compiler)]
cache: Sharded<FxHashMap<K, (V, DepNodeIndex)>>,
#[cfg(not(parallel_compiler))]
cache: Lock<FxHashMap<K, (V, DepNodeIndex)>>,
}
impl<K, V> Default for DefaultCache<K, V> {
fn default() -> Self {
DefaultCache(PhantomData)
DefaultCache { cache: Default::default() }
}
}
@ -87,49 +83,51 @@ where
V: Clone + Debug,
{
type Key = K;
type Sharded = FxHashMap<K, (V, DepNodeIndex)>;
#[inline(always)]
fn lookup<'s, R, OnHit>(
&self,
state: &'s QueryCacheStore<Self>,
key: &K,
on_hit: OnHit,
) -> Result<R, QueryLookup>
fn lookup<R, OnHit>(&self, key: &K, on_hit: OnHit) -> Result<R, ()>
where
OnHit: FnOnce(&V, DepNodeIndex) -> R,
{
let (lookup, lock) = state.get_lookup(key);
let result = lock.raw_entry().from_key_hashed_nocheck(lookup.key_hash, key);
let key_hash = sharded::make_hash(key);
#[cfg(parallel_compiler)]
let lock = self.cache.get_shard_by_hash(key_hash).lock();
#[cfg(not(parallel_compiler))]
let lock = self.cache.lock();
let result = lock.raw_entry().from_key_hashed_nocheck(key_hash, key);
if let Some((_, value)) = result {
let hit_result = on_hit(&value.0, value.1);
Ok(hit_result)
} else {
Err(lookup)
Err(())
}
}
#[inline]
fn complete(
&self,
lock_sharded_storage: &mut Self::Sharded,
key: K,
value: V,
index: DepNodeIndex,
) -> Self::Stored {
lock_sharded_storage.insert(key, (value.clone(), index));
fn complete(&self, key: K, value: V, index: DepNodeIndex) -> Self::Stored {
#[cfg(parallel_compiler)]
let mut lock = self.cache.get_shard_by_value(&key).lock();
#[cfg(not(parallel_compiler))]
let mut lock = self.cache.lock();
lock.insert(key, (value.clone(), index));
value
}
fn iter(
&self,
shards: &Sharded<Self::Sharded>,
f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex),
) {
let shards = shards.lock_shards();
for shard in shards.iter() {
for (k, v) in shard.iter() {
fn iter(&self, f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex)) {
#[cfg(parallel_compiler)]
{
let shards = self.cache.lock_shards();
for shard in shards.iter() {
for (k, v) in shard.iter() {
f(k, &v.0, v.1);
}
}
}
#[cfg(not(parallel_compiler))]
{
let map = self.cache.lock();
for (k, v) in map.iter() {
f(k, &v.0, v.1);
}
}
@ -144,12 +142,15 @@ impl<'tcx, K: Eq + Hash, V: 'tcx> CacheSelector<K, V> for ArenaCacheSelector<'tc
pub struct ArenaCache<'tcx, K, V> {
arena: WorkerLocal<TypedArena<(V, DepNodeIndex)>>,
phantom: PhantomData<(K, &'tcx V)>,
#[cfg(parallel_compiler)]
cache: Sharded<FxHashMap<K, &'tcx (V, DepNodeIndex)>>,
#[cfg(not(parallel_compiler))]
cache: Lock<FxHashMap<K, &'tcx (V, DepNodeIndex)>>,
}
impl<'tcx, K, V> Default for ArenaCache<'tcx, K, V> {
fn default() -> Self {
ArenaCache { arena: WorkerLocal::new(|_| TypedArena::default()), phantom: PhantomData }
ArenaCache { arena: WorkerLocal::new(|_| TypedArena::default()), cache: Default::default() }
}
}
@ -171,51 +172,53 @@ where
V: Debug,
{
type Key = K;
type Sharded = FxHashMap<K, &'tcx (V, DepNodeIndex)>;
#[inline(always)]
fn lookup<'s, R, OnHit>(
&self,
state: &'s QueryCacheStore<Self>,
key: &K,
on_hit: OnHit,
) -> Result<R, QueryLookup>
fn lookup<R, OnHit>(&self, key: &K, on_hit: OnHit) -> Result<R, ()>
where
OnHit: FnOnce(&&'tcx V, DepNodeIndex) -> R,
{
let (lookup, lock) = state.get_lookup(key);
let result = lock.raw_entry().from_key_hashed_nocheck(lookup.key_hash, key);
let key_hash = sharded::make_hash(key);
#[cfg(parallel_compiler)]
let lock = self.cache.get_shard_by_hash(key_hash).lock();
#[cfg(not(parallel_compiler))]
let lock = self.cache.lock();
let result = lock.raw_entry().from_key_hashed_nocheck(key_hash, key);
if let Some((_, value)) = result {
let hit_result = on_hit(&&value.0, value.1);
Ok(hit_result)
} else {
Err(lookup)
Err(())
}
}
#[inline]
fn complete(
&self,
lock_sharded_storage: &mut Self::Sharded,
key: K,
value: V,
index: DepNodeIndex,
) -> Self::Stored {
fn complete(&self, key: K, value: V, index: DepNodeIndex) -> Self::Stored {
let value = self.arena.alloc((value, index));
let value = unsafe { &*(value as *const _) };
lock_sharded_storage.insert(key, value);
#[cfg(parallel_compiler)]
let mut lock = self.cache.get_shard_by_value(&key).lock();
#[cfg(not(parallel_compiler))]
let mut lock = self.cache.lock();
lock.insert(key, value);
&value.0
}
fn iter(
&self,
shards: &Sharded<Self::Sharded>,
f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex),
) {
let shards = shards.lock_shards();
for shard in shards.iter() {
for (k, v) in shard.iter() {
fn iter(&self, f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex)) {
#[cfg(parallel_compiler)]
{
let shards = self.cache.lock_shards();
for shard in shards.iter() {
for (k, v) in shard.iter() {
f(k, &v.0, v.1);
}
}
}
#[cfg(not(parallel_compiler))]
{
let map = self.cache.lock();
for (k, v) in map.iter() {
f(k, &v.0, v.1);
}
}

4
compiler/rustc_query_system/src/query/config.rs
View file

@ -4,7 +4,7 @@ use crate::dep_graph::DepNode;
use crate::dep_graph::SerializedDepNodeIndex;
use crate::ich::StableHashingContext;
use crate::query::caches::QueryCache;
use crate::query::{QueryCacheStore, QueryContext, QueryState};
use crate::query::{QueryContext, QueryState};
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_errors::{DiagnosticBuilder, ErrorReported};
@ -64,7 +64,7 @@ pub trait QueryDescription<CTX: QueryContext>: QueryConfig {
CTX: 'a;
// Don't use this method to access query results, instead use the methods on TyCtxt
fn query_cache<'a>(tcx: CTX) -> &'a QueryCacheStore<Self::Cache>
fn query_cache<'a>(tcx: CTX) -> &'a Self::Cache
where
CTX: 'a;

180
compiler/rustc_query_system/src/query/plumbing.rs
View file

@ -8,11 +8,12 @@ use crate::query::config::{QueryDescription, QueryVtable};
use crate::query::job::{report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo};
use crate::query::{QueryContext, QueryMap, QuerySideEffects, QueryStackFrame};
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxHasher};
use rustc_data_structures::fx::FxHashMap;
#[cfg(parallel_compiler)]
use rustc_data_structures::profiling::TimingGuard;
use rustc_data_structures::sharded::{get_shard_index_by_hash, Sharded};
use rustc_data_structures::sync::{Lock, LockGuard};
#[cfg(parallel_compiler)]
use rustc_data_structures::sharded::Sharded;
use rustc_data_structures::sync::Lock;
use rustc_data_structures::thin_vec::ThinVec;
use rustc_errors::{DiagnosticBuilder, ErrorReported, FatalError};
use rustc_session::Session;
@ -20,64 +21,15 @@ use rustc_span::{Span, DUMMY_SP};
use std::cell::Cell;
use std::collections::hash_map::Entry;
use std::fmt::Debug;
use std::hash::{Hash, Hasher};
use std::hash::Hash;
use std::mem;
use std::ptr;
pub struct QueryCacheStore<C: QueryCache> {
cache: C,
shards: Sharded<C::Sharded>,
}
impl<C: QueryCache + Default> Default for QueryCacheStore<C> {
fn default() -> Self {
Self { cache: C::default(), shards: Default::default() }
}
}
/// Values used when checking a query cache which can be reused on a cache-miss to execute the query.
pub struct QueryLookup {
pub(super) key_hash: u64,
shard: usize,
}
// We compute the key's hash once and then use it for both the
// shard lookup and the hashmap lookup. This relies on the fact
// that both of them use `FxHasher`.
fn hash_for_shard<K: Hash>(key: &K) -> u64 {
let mut hasher = FxHasher::default();
key.hash(&mut hasher);
hasher.finish()
}
impl<C: QueryCache> QueryCacheStore<C> {
pub(super) fn get_lookup<'tcx>(
&'tcx self,
key: &C::Key,
) -> (QueryLookup, LockGuard<'tcx, C::Sharded>) {
let key_hash = hash_for_shard(key);
let shard = get_shard_index_by_hash(key_hash);
let lock = self.shards.get_shard_by_index(shard).lock();
(QueryLookup { key_hash, shard }, lock)
}
pub fn iter_results(&self, f: &mut dyn FnMut(&C::Key, &C::Value, DepNodeIndex)) {
self.cache.iter(&self.shards, f)
}
}
struct QueryStateShard<K> {
active: FxHashMap<K, QueryResult>,
}
impl<K> Default for QueryStateShard<K> {
fn default() -> QueryStateShard<K> {
QueryStateShard { active: Default::default() }
}
}
pub struct QueryState<K> {
shards: Sharded<QueryStateShard<K>>,
#[cfg(parallel_compiler)]
active: Sharded<FxHashMap<K, QueryResult>>,
#[cfg(not(parallel_compiler))]
active: Lock<FxHashMap<K, QueryResult>>,
}
/// Indicates the state of a query for a given key in a query map.
@ -95,8 +47,15 @@ where
K: Eq + Hash + Clone + Debug,
{
pub fn all_inactive(&self) -> bool {
let shards = self.shards.lock_shards();
shards.iter().all(|shard| shard.active.is_empty())
#[cfg(parallel_compiler)]
{
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<CTX: Copy>(
@ -105,11 +64,27 @@ where
make_query: fn(CTX, K) -> QueryStackFrame,
jobs: &mut QueryMap,
) -> Option<()> {
// We use try_lock_shards here since we are called from the
// deadlock handler, and this shouldn't be locked.
let shards = self.shards.try_lock_shards()?;
for shard in shards.iter() {
for (k, v) in shard.active.iter() {
#[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 shards.iter() {
for (k, v) in shard.iter() {
if let QueryResult::Started(ref job) = *v {
let query = make_query(tcx, k.clone());
jobs.insert(job.id, QueryJobInfo { query, job: 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 {
let query = make_query(tcx, k.clone());
jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
@ -123,7 +98,7 @@ where
impl<K> Default for QueryState<K> {
fn default() -> QueryState<K> {
QueryState { shards: Default::default() }
QueryState { active: Default::default() }
}
}
@ -174,16 +149,17 @@ where
state: &'b QueryState<K>,
span: Span,
key: K,
lookup: QueryLookup,
) -> TryGetJob<'b, K>
where
CTX: QueryContext,
{
let shard = lookup.shard;
let mut state_lock = state.shards.get_shard_by_index(shard).lock();
#[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();
let lock = &mut *state_lock;
match lock.active.entry(key) {
match lock.entry(key) {
Entry::Vacant(entry) => {
let id = tcx.next_job_id();
let job = tcx.current_query_job();
@ -239,12 +215,7 @@ where
/// Completes the query by updating the query cache with the `result`,
/// signals the waiter and forgets the JobOwner, so it won't poison the query
fn complete<C>(
self,
cache: &QueryCacheStore<C>,
result: C::Value,
dep_node_index: DepNodeIndex,
) -> C::Stored
fn complete<C>(self, cache: &C, result: C::Value, dep_node_index: DepNodeIndex) -> C::Stored
where
C: QueryCache<Key = K>,
{
@ -256,19 +227,17 @@ where
mem::forget(self);
let (job, result) = {
let key_hash = hash_for_shard(&key);
let shard = get_shard_index_by_hash(key_hash);
let job = {
let mut lock = state.shards.get_shard_by_index(shard).lock();
match lock.active.remove(&key).unwrap() {
#[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!(),
}
};
let result = {
let mut lock = cache.shards.get_shard_by_index(shard).lock();
cache.cache.complete(&mut lock, key, result, dep_node_index)
};
let result = cache.complete(key, result, dep_node_index);
(job, result)
};
@ -286,14 +255,16 @@ where
fn drop(&mut self) {
// Poison the query so jobs waiting on it panic.
let state = self.state;
let shard = state.shards.get_shard_by_value(&self.key);
let job = {
let mut shard = shard.lock();
let job = match shard.active.remove(&self.key).unwrap() {
#[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!(),
};
shard.active.insert(self.key.clone(), QueryResult::Poisoned);
shard.insert(self.key.clone(), QueryResult::Poisoned);
job
};
// Also signal the completion of the job, so waiters
@ -334,17 +305,17 @@ where
#[inline]
pub fn try_get_cached<'a, CTX, C, R, OnHit>(
tcx: CTX,
cache: &'a QueryCacheStore<C>,
cache: &'a C,
key: &C::Key,
// `on_hit` can be called while holding a lock to the query cache
on_hit: OnHit,
) -> Result<R, QueryLookup>
) -> Result<R, ()>
where
C: QueryCache,
CTX: DepContext,
OnHit: FnOnce(&C::Stored) -> R,
{
cache.cache.lookup(cache, &key, |value, index| {
cache.lookup(&key, |value, index| {
if unlikely!(tcx.profiler().enabled()) {
tcx.profiler().query_cache_hit(index.into());
}
@ -356,10 +327,9 @@ where
fn try_execute_query<CTX, C>(
tcx: CTX,
state: &QueryState<C::Key>,
cache: &QueryCacheStore<C>,
cache: &C,
span: Span,
key: C::Key,
lookup: QueryLookup,
dep_node: Option<DepNode<CTX::DepKind>>,
query: &QueryVtable<CTX, C::Key, C::Value>,
) -> (C::Stored, Option<DepNodeIndex>)
@ -368,21 +338,20 @@ where
C::Key: Clone + DepNodeParams<CTX::DepContext>,
CTX: QueryContext,
{
match JobOwner::<'_, C::Key>::try_start(&tcx, state, span, key.clone(), lookup) {
match JobOwner::<'_, C::Key>::try_start(&tcx, state, span, key.clone()) {
TryGetJob::NotYetStarted(job) => {
let (result, dep_node_index) = execute_job(tcx, key, dep_node, query, job.id);
let result = job.complete(cache, result, dep_node_index);
(result, Some(dep_node_index))
}
TryGetJob::Cycle(error) => {
let result = mk_cycle(tcx, error, query.handle_cycle_error, &cache.cache);
let result = mk_cycle(tcx, error, query.handle_cycle_error, cache);
(result, None)
}
#[cfg(parallel_compiler)]
TryGetJob::JobCompleted(query_blocked_prof_timer) => {
let (v, index) = cache
.cache
.lookup(cache, &key, |value, index| (value.clone(), index))
.lookup(&key, |value, index| (value.clone(), index))
.unwrap_or_else(|_| panic!("value must be in cache after waiting"));
if unlikely!(tcx.dep_context().profiler().enabled()) {
@ -711,13 +680,7 @@ pub enum QueryMode {
Ensure,
}
pub fn get_query<Q, CTX>(
tcx: CTX,
span: Span,
key: Q::Key,
lookup: QueryLookup,
mode: QueryMode,
) -> Option<Q::Stored>
pub fn get_query<Q, CTX>(tcx: CTX, span: Span, key: Q::Key, mode: QueryMode) -> Option<Q::Stored>
where
Q: QueryDescription<CTX>,
Q::Key: DepNodeParams<CTX::DepContext>,
@ -741,7 +704,6 @@ where
Q::query_cache(tcx),
span,
key,
lookup,
dep_node,
&query,
);
@ -760,20 +722,20 @@ where
// We may be concurrently trying both execute and force a query.
// Ensure that only one of them runs the query.
let cache = Q::query_cache(tcx);
let cached = cache.cache.lookup(cache, &key, |_, index| {
let cached = cache.lookup(&key, |_, index| {
if unlikely!(tcx.dep_context().profiler().enabled()) {
tcx.dep_context().profiler().query_cache_hit(index.into());
}
});
let lookup = match cached {
match cached {
Ok(()) => return,
Err(lookup) => lookup,
};
Err(()) => {}
}
let query = Q::make_vtable(tcx, &key);
let state = Q::query_state(tcx);
debug_assert!(!query.anon);
try_execute_query(tcx, state, cache, DUMMY_SP, key, lookup, Some(dep_node), &query);
try_execute_query(tcx, state, cache, DUMMY_SP, key, Some(dep_node), &query);
}