Rollup merge of #75452 - michaelwoerister:sp-cache-more-query-keys, r=lcnr

self-profile: Cache more query key strings when doing self-profiling.

This PR adds optimized `SpecIntoSelfProfilingString` implementations for two common query key types (`LocalDefId` and `WithOptConstParam`). This makes raw self-profiling data on disk 8-9% smaller for my two test cases (`regex` and `cargo`).

The on-disk format is not affected, so no tooling updates need to happen.

I also tried adding an impl for `Ty<'tcx>` (which should reduce size quite a bit) but the compiler did not allow me to add a specialized impl parameterized with `'tcx`. I don't know if there is an actual problem with that or if the implementation of specialization just doesn't support it yet.

cc @wesleywiser @Mark-Simulacrum

Author: tmandry

src/librustc_middle/ty/query/profiling_support.rs

@@ -1,8 +1,9 @@
 use crate::ty::context::TyCtxt;
+use crate::ty::WithOptConstParam;
 use measureme::{StringComponent, StringId};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::profiling::SelfProfiler;
-use rustc_hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::definitions::DefPathData;
 use rustc_query_system::query::QueryCache;
 use rustc_query_system::query::QueryState;
@@ -154,6 +155,49 @@ impl SpecIntoSelfProfilingString for DefIndex {
     }
 }
 
+impl SpecIntoSelfProfilingString for LocalDefId {
+    fn spec_to_self_profile_string(
+        &self,
+        builder: &mut QueryKeyStringBuilder<'_, '_, '_>,
+    ) -> StringId {
+        builder.def_id_to_string_id(DefId { krate: LOCAL_CRATE, index: self.local_def_index })
+    }
+}
+
+impl<T: SpecIntoSelfProfilingString> SpecIntoSelfProfilingString for WithOptConstParam<T> {
+    fn spec_to_self_profile_string(
+        &self,
+        builder: &mut QueryKeyStringBuilder<'_, '_, '_>,
+    ) -> StringId {
+        // We print `WithOptConstParam` values as tuples to make them shorter
+        // and more readable, without losing information:
+        //
+        // "WithOptConstParam { did: foo::bar, const_param_did: Some(foo::baz) }"
+        // becomes "(foo::bar, foo::baz)" and
+        // "WithOptConstParam { did: foo::bar, const_param_did: None }"
+        // becomes "(foo::bar, _)".
+
+        let did = StringComponent::Ref(self.did.to_self_profile_string(builder));
+
+        let const_param_did = if let Some(const_param_did) = self.const_param_did {
+            let const_param_did = builder.def_id_to_string_id(const_param_did);
+            StringComponent::Ref(const_param_did)
+        } else {
+            StringComponent::Value("_")
+        };
+
+        let components = [
+            StringComponent::Value("("),
+            did,
+            StringComponent::Value(", "),
+            const_param_did,
+            StringComponent::Value(")"),
+        ];
+
+        builder.profiler.alloc_string(&components[..])
+    }
+}
+
 impl<T0, T1> SpecIntoSelfProfilingString for (T0, T1)
 where
     T0: SpecIntoSelfProfilingString,