Auto merge of #109611 - Zoxc:query-engine-rem, r=cjgillot

Remove `QueryEngine` trait

This removes the `QueryEngine` trait and `Queries` from `rustc_query_impl` and replaced them with function pointers and fields in `QuerySystem`. As a side effect `OnDiskCache` is moved back into `rustc_middle` and the `OnDiskCache` trait is also removed.

This has a couple of benefits.
- `TyCtxt` is used in the query system instead of the removed `QueryCtxt` which is larger.
- Function pointers are more flexible to work with. A variant of #107802 is included which avoids the double indirection. For #108938 we can name entry point `__rust_end_short_backtrace` to avoid some overhead. For #108062 it avoids the duplicate `QueryEngine` structs.
- `QueryContext` now implements `DepContext` which avoids many `dep_context()` calls in `rustc_query_system`.
- The `rustc_driver` size is reduced by 0.33%, hopefully that means some bootstrap improvements.
- This avoids the unsafe code around the `QueryEngine` trait.

r? `@cjgillot`

Author: bors

Diff for: Cargo.lock

@@ -3641,6 +3641,7 @@ dependencies = [
  "rustc_plugin_impl",
  "rustc_privacy",
  "rustc_query_impl",
+ "rustc_query_system",
  "rustc_resolve",
  "rustc_session",
  "rustc_span",
@@ -3770,6 +3771,7 @@ dependencies = [
  "derive_more",
  "either",
  "gsgdt",
+ "measureme",
  "polonius-engine",
  "rustc-rayon",
  "rustc-rayon-core",

Diff for: compiler/rustc_incremental/src/persist/load.rs

@@ -4,7 +4,7 @@ use crate::errors;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::memmap::Mmap;
 use rustc_middle::dep_graph::{SerializedDepGraph, WorkProduct, WorkProductId};
-use rustc_middle::ty::OnDiskCache;
+use rustc_middle::query::on_disk_cache::OnDiskCache;
 use rustc_serialize::opaque::MemDecoder;
 use rustc_serialize::Decodable;
 use rustc_session::config::IncrementalStateAssertion;
@@ -211,7 +211,7 @@ pub fn load_dep_graph(sess: &Session) -> DepGraphFuture {
 /// If we are not in incremental compilation mode, returns `None`.
 /// Otherwise, tries to load the query result cache from disk,
 /// creating an empty cache if it could not be loaded.
-pub fn load_query_result_cache<'a, C: OnDiskCache<'a>>(sess: &'a Session) -> Option<C> {
+pub fn load_query_result_cache(sess: &Session) -> Option<OnDiskCache<'_>> {
     if sess.opts.incremental.is_none() {
         return None;
     }
@@ -223,7 +223,9 @@ pub fn load_query_result_cache<'a, C: OnDiskCache<'a>>(sess: &'a Session) -> Opt
         &query_cache_path(sess),
         sess.is_nightly_build(),
     ) {
-        LoadResult::Ok { data: (bytes, start_pos) } => Some(C::new(sess, bytes, start_pos)),
-        _ => Some(C::new_empty(sess.source_map())),
+        LoadResult::Ok { data: (bytes, start_pos) } => {
+            Some(OnDiskCache::new(sess, bytes, start_pos))
+        }
+        _ => Some(OnDiskCache::new_empty(sess.source_map())),
     }
 }

Diff for: compiler/rustc_incremental/src/persist/save.rs

@@ -48,7 +48,7 @@ pub fn save_dep_graph(tcx: TyCtxt<'_>) {
             move || {
                 sess.time("incr_comp_persist_result_cache", || {
                     // Drop the memory map so that we can remove the file and write to it.
-                    if let Some(odc) = &tcx.on_disk_cache {
+                    if let Some(odc) = &tcx.query_system.on_disk_cache {
                         odc.drop_serialized_data(tcx);
                     }
 

Diff for: compiler/rustc_interface/Cargo.toml

@@ -44,6 +44,7 @@ rustc_lint = { path = "../rustc_lint" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_plugin_impl = { path = "../rustc_plugin_impl" }
 rustc_privacy = { path = "../rustc_privacy" }
+rustc_query_system = { path = "../rustc_query_system" }
 rustc_query_impl = { path = "../rustc_query_impl" }
 rustc_resolve = { path = "../rustc_resolve" }
 rustc_target = { path = "../rustc_target" }

Diff for: compiler/rustc_interface/src/interface.rs

@@ -12,6 +12,7 @@ use rustc_lint::LintStore;
 use rustc_middle::ty;
 use rustc_parse::maybe_new_parser_from_source_str;
 use rustc_query_impl::QueryCtxt;
+use rustc_query_system::query::print_query_stack;
 use rustc_session::config::{self, CheckCfg, ErrorOutputType, Input, OutputFilenames};
 use rustc_session::lint;
 use rustc_session::parse::{CrateConfig, ParseSess};
@@ -317,7 +318,7 @@ pub fn try_print_query_stack(handler: &Handler, num_frames: Option<usize>) {
     // state if it was responsible for triggering the panic.
     let i = ty::tls::with_context_opt(|icx| {
         if let Some(icx) = icx {
-            QueryCtxt::from_tcx(icx.tcx).try_print_query_stack(icx.query, handler, num_frames)
+            print_query_stack(QueryCtxt { tcx: icx.tcx }, icx.query, handler, num_frames)
         } else {
             0
         }

Diff for: compiler/rustc_interface/src/passes.rs

@@ -23,7 +23,6 @@ use rustc_mir_build as mir_build;
 use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str, validate_attr};
 use rustc_passes::{self, hir_stats, layout_test};
 use rustc_plugin_impl as plugin;
-use rustc_query_impl::{OnDiskCache, Queries as TcxQueries};
 use rustc_resolve::Resolver;
 use rustc_session::config::{CrateType, Input, OutputFilenames, OutputType};
 use rustc_session::cstore::{MetadataLoader, Untracked};
@@ -669,7 +668,6 @@ pub fn create_global_ctxt<'tcx>(
     lint_store: Lrc<LintStore>,
     dep_graph: DepGraph,
     untracked: Untracked,
-    queries: &'tcx OnceCell<TcxQueries<'tcx>>,
     gcx_cell: &'tcx OnceCell<GlobalCtxt<'tcx>>,
     arena: &'tcx WorkerLocal<Arena<'tcx>>,
     hir_arena: &'tcx WorkerLocal<rustc_hir::Arena<'tcx>>,
@@ -693,10 +691,6 @@ pub fn create_global_ctxt<'tcx>(
         callback(sess, &mut local_providers, &mut extern_providers);
     }
 
-    let queries = queries.get_or_init(|| {
-        TcxQueries::new(local_providers, extern_providers, query_result_on_disk_cache)
-    });
-
     sess.time("setup_global_ctxt", || {
         gcx_cell.get_or_init(move || {
             TyCtxt::create_global_ctxt(
@@ -706,9 +700,9 @@ pub fn create_global_ctxt<'tcx>(
                 hir_arena,
                 untracked,
                 dep_graph,
-                queries.on_disk_cache.as_ref().map(OnDiskCache::as_dyn),
-                queries.as_dyn(),
+                query_result_on_disk_cache,
                 rustc_query_impl::query_callbacks(arena),
+                rustc_query_impl::query_system_fns(local_providers, extern_providers),
             )
         })
     })

Diff for: compiler/rustc_interface/src/queries.rs

@@ -16,7 +16,6 @@ use rustc_metadata::creader::CStore;
 use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::DepGraph;
 use rustc_middle::ty::{GlobalCtxt, TyCtxt};
-use rustc_query_impl::Queries as TcxQueries;
 use rustc_session::config::{self, OutputFilenames, OutputType};
 use rustc_session::cstore::Untracked;
 use rustc_session::{output::find_crate_name, Session};
@@ -81,7 +80,6 @@ impl<T> Default for Query<T> {
 pub struct Queries<'tcx> {
     compiler: &'tcx Compiler,
     gcx_cell: OnceCell<GlobalCtxt<'tcx>>,
-    queries: OnceCell<TcxQueries<'tcx>>,
 
     arena: WorkerLocal<Arena<'tcx>>,
     hir_arena: WorkerLocal<rustc_hir::Arena<'tcx>>,
@@ -102,7 +100,6 @@ impl<'tcx> Queries<'tcx> {
         Queries {
             compiler,
             gcx_cell: OnceCell::new(),
-            queries: OnceCell::new(),
             arena: WorkerLocal::new(|_| Arena::default()),
             hir_arena: WorkerLocal::new(|_| rustc_hir::Arena::default()),
             dep_graph_future: Default::default(),
@@ -225,7 +222,6 @@ impl<'tcx> Queries<'tcx> {
                 lint_store,
                 self.dep_graph()?.steal(),
                 untracked,
-                &self.queries,
                 &self.gcx_cell,
                 &self.arena,
                 &self.hir_arena,

Diff for: compiler/rustc_interface/src/util.rs

@@ -170,7 +170,8 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
 ) -> R {
     use rustc_data_structures::jobserver;
     use rustc_middle::ty::tls;
-    use rustc_query_impl::{deadlock, QueryContext, QueryCtxt};
+    use rustc_query_impl::QueryCtxt;
+    use rustc_query_system::query::{deadlock, QueryContext};
 
     let registry = sync::Registry::new(threads);
     let mut builder = rayon::ThreadPoolBuilder::new()
@@ -182,7 +183,7 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
             // On deadlock, creates a new thread and forwards information in thread
             // locals to it. The new thread runs the deadlock handler.
             let query_map = tls::with(|tcx| {
-                QueryCtxt::from_tcx(tcx)
+                QueryCtxt::new(tcx)
                     .try_collect_active_jobs()
                     .expect("active jobs shouldn't be locked in deadlock handler")
             });

Diff for: compiler/rustc_middle/Cargo.toml

@@ -11,6 +11,7 @@ chalk-ir = "0.87.0"
 derive_more = "0.99.17"
 either = "1.5.0"
 gsgdt = "0.1.2"
+measureme = "10.0.0"
 polonius-engine = "0.13.0"
 rustc_apfloat = { path = "../rustc_apfloat" }
 rustc_arena = { path = "../rustc_arena" }

Diff for: compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -227,7 +227,9 @@ pub fn specialized_encode_alloc_id<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>>(
             // References to statics doesn't need to know about their allocations,
             // just about its `DefId`.
             AllocDiscriminant::Static.encode(encoder);
-            did.encode(encoder);
+            // Cannot use `did.encode(encoder)` because of a bug around
+            // specializations and method calls.
+            Encodable::<E>::encode(&did, encoder);
         }
     }
 }

Diff for: compiler/rustc_middle/src/query/mod.rs

@@ -9,6 +9,7 @@ use rustc_span::def_id::LOCAL_CRATE;
 
 pub mod erase;
 mod keys;
+pub mod on_disk_cache;
 pub use keys::{AsLocalKey, Key, LocalCrate};
 
 // Each of these queries corresponds to a function pointer field in the