Avoid a branch on key being local for queries that use the same local and extern providers

compiler/rustc_codegen_ssa/src/back/symbol_export.rs

@@ -11,7 +11,7 @@ use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::middle::exported_symbols::{
     metadata_symbol_name, ExportedSymbol, SymbolExportLevel,
 };
-use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::query::{ExternProviders, Providers};
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::{SymbolName, TyCtxt};
@@ -363,7 +363,7 @@ pub fn provide(providers: &mut Providers) {
     providers.wasm_import_module_map = wasm_import_module_map;
 }
 
-pub fn provide_extern(providers: &mut Providers) {
+pub fn provide_extern(providers: &mut ExternProviders) {
     providers.is_reachable_non_generic = is_reachable_non_generic_provider_extern;
     providers.upstream_monomorphizations_for = upstream_monomorphizations_for_provider;
 }

compiler/rustc_codegen_ssa/src/lib.rs

@@ -28,7 +28,7 @@ use rustc_hir::def_id::CrateNum;
 use rustc_hir::LangItem;
 use rustc_middle::dep_graph::WorkProduct;
 use rustc_middle::middle::dependency_format::Dependencies;
-use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::query::{ExternProviders, Providers};
 use rustc_session::config::{CrateType, OutputFilenames, OutputType, RUST_CGU_EXT};
 use rustc_session::cstore::{self, CrateSource};
 use rustc_session::utils::NativeLibKind;
@@ -170,7 +170,7 @@ pub fn provide(providers: &mut Providers) {
     crate::target_features::provide(providers);
 }
 
-pub fn provide_extern(providers: &mut Providers) {
+pub fn provide_extern(providers: &mut ExternProviders) {
     crate::back::symbol_export::provide_extern(providers);
 }
 

compiler/rustc_codegen_ssa/src/traits/backend.rs

@@ -9,7 +9,7 @@ use rustc_errors::ErrorReported;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf, TyAndLayout};
-use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::query::{ExternProviders, Providers};
 use rustc_middle::ty::{Ty, TyCtxt};
 use rustc_session::{
     config::{self, OutputFilenames, PrintRequest},
@@ -80,7 +80,7 @@ pub trait CodegenBackend {
     }
 
     fn provide(&self, _providers: &mut Providers) {}
-    fn provide_extern(&self, _providers: &mut Providers) {}
+    fn provide_extern(&self, _providers: &mut ExternProviders) {}
     fn codegen_crate<'tcx>(
         &self,
         tcx: TyCtxt<'tcx>,

compiler/rustc_interface/src/interface.rs

@@ -38,7 +38,7 @@ pub struct Compiler {
     pub(crate) output_file: Option<PathBuf>,
     pub(crate) register_lints: Option<Box<dyn Fn(&Session, &mut LintStore) + Send + Sync>>,
     pub(crate) override_queries:
-        Option<fn(&Session, &mut ty::query::Providers, &mut ty::query::Providers)>,
+        Option<fn(&Session, &mut ty::query::Providers, &mut ty::query::ExternProviders)>,
 }
 
 impl Compiler {
@@ -155,7 +155,7 @@ pub struct Config {
     ///
     /// The second parameter is local providers and the third parameter is external providers.
     pub override_queries:
-        Option<fn(&Session, &mut ty::query::Providers, &mut ty::query::Providers)>,
+        Option<fn(&Session, &mut ty::query::Providers, &mut ty::query::ExternProviders)>,
 
     /// This is a callback from the driver that is called to create a codegen backend.
     pub make_codegen_backend:

compiler/rustc_interface/src/passes.rs

@@ -19,7 +19,7 @@ use rustc_metadata::creader::CStore;
 use rustc_metadata::{encode_metadata, EncodedMetadata};
 use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::DepGraph;
-use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::query::{ExternProviders, Providers};
 use rustc_middle::ty::{self, GlobalCtxt, ResolverOutputs, TyCtxt};
 use rustc_mir_build as mir_build;
 use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str, validate_attr};
@@ -764,8 +764,8 @@ pub static DEFAULT_QUERY_PROVIDERS: SyncLazy<Providers> = SyncLazy::new(|| {
     *providers
 });
 
-pub static DEFAULT_EXTERN_QUERY_PROVIDERS: SyncLazy<Providers> = SyncLazy::new(|| {
-    let mut extern_providers = *DEFAULT_QUERY_PROVIDERS;
+pub static DEFAULT_EXTERN_QUERY_PROVIDERS: SyncLazy<ExternProviders> = SyncLazy::new(|| {
+    let mut extern_providers = ExternProviders::default();
     rustc_metadata::provide_extern(&mut extern_providers);
     rustc_codegen_ssa::provide_extern(&mut extern_providers);
     extern_providers
@@ -816,7 +816,6 @@ pub fn create_global_ctxt<'tcx>(
     codegen_backend.provide(&mut local_providers);
 
     let mut extern_providers = *DEFAULT_EXTERN_QUERY_PROVIDERS;
-    codegen_backend.provide(&mut extern_providers);
     codegen_backend.provide_extern(&mut extern_providers);
 
     if let Some(callback) = compiler.override_queries {

compiler/rustc_macros/src/query.rs

@@ -55,6 +55,9 @@ enum QueryModifier {
 
     /// Always evaluate the query, ignoring its dependencies
     EvalAlways(Ident),
+
+    /// Use a separate query provider for local and extern crates
+    SeparateProvideExtern(Ident),
 }
 
 impl Parse for QueryModifier {
@@ -118,6 +121,8 @@ impl Parse for QueryModifier {
             Ok(QueryModifier::Anon(modifier))
         } else if modifier == "eval_always" {
             Ok(QueryModifier::EvalAlways(modifier))
+        } else if modifier == "separate_provide_extern" {
+            Ok(QueryModifier::SeparateProvideExtern(modifier))
         } else {
             Err(Error::new(modifier.span(), "unknown query modifier"))
         }
@@ -214,6 +219,9 @@ struct QueryModifiers {
 
     // Always evaluate the query, ignoring its dependencies
     eval_always: Option<Ident>,
+
+    /// Use a separate query provider for local and extern crates
+    separate_provide_extern: Option<Ident>,
 }
 
 /// Process query modifiers into a struct, erroring on duplicates
@@ -227,6 +235,7 @@ fn process_modifiers(query: &mut Query) -> QueryModifiers {
     let mut no_hash = None;
     let mut anon = None;
     let mut eval_always = None;
+    let mut separate_provide_extern = None;
     for modifier in query.modifiers.0.drain(..) {
         match modifier {
             QueryModifier::LoadCached(tcx, id, block) => {
@@ -317,6 +326,15 @@ fn process_modifiers(query: &mut Query) -> QueryModifiers {
                 }
                 eval_always = Some(ident);
             }
+            QueryModifier::SeparateProvideExtern(ident) => {
+                if separate_provide_extern.is_some() {
+                    panic!(
+                        "duplicate modifier `separate_provide_extern` for query `{}`",
+                        query.name
+                    );
+                }
+                separate_provide_extern = Some(ident);
+            }
         }
     }
     let desc = desc.unwrap_or_else(|| {
@@ -332,6 +350,7 @@ fn process_modifiers(query: &mut Query) -> QueryModifiers {
         no_hash,
         anon,
         eval_always,
+        separate_provide_extern,
     }
 }
 
@@ -462,6 +481,10 @@ pub fn rustc_queries(input: TokenStream) -> TokenStream {
         if let Some(eval_always) = &modifiers.eval_always {
             attributes.push(quote! { (#eval_always) });
         };
+        // Pass on the separate_provide_extern modifier
+        if let Some(separate_provide_extern) = &modifiers.separate_provide_extern {
+            attributes.push(quote! { (#separate_provide_extern) });
+        }
 
         // This uses the span of the query definition for the commas,
         // which can be important if we later encounter any ambiguity

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -10,7 +10,7 @@ use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
 use rustc_middle::hir::exports::Export;
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
 use rustc_middle::middle::stability::DeprecationEntry;
-use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::query::{ExternProviders, Providers};
 use rustc_middle::ty::{self, TyCtxt, Visibility};
 use rustc_session::cstore::{CrateSource, CrateStore, ForeignModule};
 use rustc_session::utils::NativeLibKind;
@@ -26,7 +26,7 @@ use std::any::Any;
 macro_rules! provide {
     (<$lt:tt> $tcx:ident, $def_id:ident, $other:ident, $cdata:ident,
       $($name:ident => $compute:block)*) => {
-        pub fn provide_extern(providers: &mut Providers) {
+        pub fn provide_extern(providers: &mut ExternProviders) {
             $(fn $name<$lt>(
                 $tcx: TyCtxt<$lt>,
                 def_id_arg: ty::query::query_keys::$name<$lt>,
@@ -51,7 +51,7 @@ macro_rules! provide {
                 $compute
             })*
 
-            *providers = Providers {
+            *providers = ExternProviders {
                 $($name,)*
                 ..*providers
             };