Replace mir_built query with a hook and use mir_const everywhere instead

Author: oli-obk

compiler/rustc_incremental/src/persist/dirty_clean.rs

@@ -65,7 +65,7 @@ const BASE_HIR: &[&str] = &[
 const BASE_IMPL: &[&str] =
     &[label_strs::associated_item_def_ids, label_strs::generics_of, label_strs::impl_trait_header];
 
-/// DepNodes for mir_built/Optimized, which is relevant in "executable"
+/// DepNodes for exported mir bodies, which is relevant in "executable"
 /// code, i.e., functions+methods
 const BASE_MIR: &[&str] = &[label_strs::optimized_mir, label_strs::promoted_mir];
 

compiler/rustc_middle/src/hooks/mod.rs

@@ -77,4 +77,10 @@ declare_hooks! {
     ///
     /// (Eligible functions might nevertheless be skipped for other reasons.)
     hook is_eligible_for_coverage(key: LocalDefId) -> bool;
+
+    /// Create the MIR for a given `DefId` - this includes
+    /// unreachable code.
+    /// You do not want to call this yourself, instead use the cached version
+    /// via `mir_const`
+    hook build_mir(key: LocalDefId) -> mir::Body<'tcx>;
 }

compiler/rustc_middle/src/query/mod.rs

@@ -485,19 +485,12 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    /// Fetch the MIR for a given `DefId` right after it's built - this includes
-    /// unreachable code.
-    query mir_built(key: LocalDefId) -> &'tcx Steal<mir::Body<'tcx>> {
-        desc { |tcx| "building MIR for `{}`", tcx.def_path_str(key) }
-    }
-
     /// Fetch the MIR for a given `DefId` up till the point where it is
     /// ready for const qualification.
     ///
     /// See the README for the `mir` module for details.
     query mir_const(key: LocalDefId) -> &'tcx Steal<mir::Body<'tcx>> {
         desc { |tcx| "preparing `{}` for borrow checking", tcx.def_path_str(key) }
-        no_hash
     }
 
     /// Try to build an abstract representation of the given constant.

compiler/rustc_mir_build/src/build/custom/mod.rs

@@ -6,7 +6,7 @@
 //! present, and if so we branch off into this module, which implements the attribute by
 //! implementing a custom lowering from THIR to MIR.
 //!
-//! The result of this lowering is returned "normally" from the `mir_built` query, with the only
+//! The result of this lowering is returned "normally" from the `build_mir` hook, with the only
 //! notable difference being that the `injected` field in the body is set. Various components of the
 //! MIR pipeline, like borrowck and the pass manager will then consult this field (via
 //! `body.should_skip()`) to skip the parts of the MIR pipeline that precede the MIR phase the user

compiler/rustc_mir_build/src/build/mod.rs

@@ -18,6 +18,7 @@ use rustc_middle::hir::place::PlaceBase as HirPlaceBase;
 use rustc_middle::middle::region;
 use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::mir::*;
+use rustc_middle::query::TyCtxtAt;
 use rustc_middle::thir::{
     self, BindingMode, ExprId, LintLevel, LocalVarId, Param, ParamId, PatKind, Thir,
 };
@@ -30,13 +31,6 @@ use rustc_target::spec::abi::Abi;
 
 use super::lints;
 
-pub(crate) fn mir_built(
-    tcx: TyCtxt<'_>,
-    def: LocalDefId,
-) -> &rustc_data_structures::steal::Steal<Body<'_>> {
-    tcx.alloc_steal_mir(mir_build(tcx, def))
-}
-
 pub(crate) fn closure_saved_names_of_captured_variables<'tcx>(
     tcx: TyCtxt<'tcx>,
     def_id: LocalDefId,
@@ -54,7 +48,8 @@ pub(crate) fn closure_saved_names_of_captured_variables<'tcx>(
 }
 
 /// Construct the MIR for a given `DefId`.
-fn mir_build<'tcx>(tcx: TyCtxt<'tcx>, def: LocalDefId) -> Body<'tcx> {
+pub(crate) fn mir_build<'tcx>(tcx: TyCtxtAt<'tcx>, def: LocalDefId) -> Body<'tcx> {
+    let tcx = tcx.tcx;
     tcx.ensure_with_value().thir_abstract_const(def);
     if let Err(e) = tcx.check_match(def) {
         return construct_error(tcx, def, e);

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -139,7 +139,7 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
     fn visit_inner_body(&mut self, def: LocalDefId) {
         if let Ok((inner_thir, expr)) = self.tcx.thir_body(def) {
             // Runs all other queries that depend on THIR.
-            self.tcx.ensure_with_value().mir_built(def);
+            self.tcx.ensure_with_value().mir_const(def);
             let inner_thir = &inner_thir.steal();
             let hir_context = self.tcx.local_def_id_to_hir_id(def);
             let safety_context = mem::replace(&mut self.safety_context, SafetyContext::Safe);
@@ -921,7 +921,7 @@ pub fn check_unsafety(tcx: TyCtxt<'_>, def: LocalDefId) {
 
     let Ok((thir, expr)) = tcx.thir_body(def) else { return };
     // Runs all other queries that depend on THIR.
-    tcx.ensure_with_value().mir_built(def);
+    tcx.ensure_with_value().mir_const(def);
     let thir = &thir.steal();
     // If `thir` is empty, a type error occurred, skip this body.
     if thir.exprs.is_empty() {

compiler/rustc_mir_build/src/lib.rs

@@ -23,14 +23,14 @@ mod errors;
 pub mod lints;
 mod thir;
 
-use rustc_middle::query::Providers;
+use rustc_middle::util::Providers;
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
 pub fn provide(providers: &mut Providers) {
     providers.check_match = thir::pattern::check_match;
     providers.lit_to_const = thir::constant::lit_to_const;
-    providers.mir_built = build::mir_built;
+    providers.hooks.build_mir = build::mir_build;
     providers.closure_saved_names_of_captured_variables =
         build::closure_saved_names_of_captured_variables;
     providers.check_unsafety = check_unsafety::check_unsafety;

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -497,8 +497,8 @@ fn mir_unsafety_check_result(tcx: TyCtxt<'_>, def: LocalDefId) -> &UnsafetyCheck
     debug!("unsafety_violations({:?})", def);
 
     // N.B., this borrow is valid because all the consumers of
-    // `mir_built` force this.
-    let body = &tcx.mir_built(def).borrow();
+    // `mir_const` force this.
+    let body = &tcx.mir_const(def).borrow();
 
     if body.is_custom_mir() || body.tainted_by_errors.is_some() {
         return tcx.arena.alloc(UnsafetyCheckResult {

compiler/rustc_mir_transform/src/ffi_unwind_calls.rs

@@ -53,7 +53,7 @@ fn has_ffi_unwind_calls(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> bool {
         return false;
     }
 
-    let body = &*tcx.mir_built(local_def_id).borrow();
+    let body = &*tcx.mir_const(local_def_id).borrow();
 
     let body_ty = tcx.type_of(def_id).skip_binder();
     let body_abi = match body_ty.kind() {

compiler/rustc_mir_transform/src/lib.rs

@@ -288,10 +288,7 @@ fn mir_const(tcx: TyCtxt<'_>, def: LocalDefId) -> &Steal<Body<'_>> {
         tcx.ensure_with_value().mir_unsafety_check_result(def);
     }
 
-    // has_ffi_unwind_calls query uses the raw mir, so make sure it is run.
-    tcx.ensure_with_value().has_ffi_unwind_calls(def);
-
-    let mut body = tcx.mir_built(def).steal();
+    let mut body = tcx.build_mir(def);
 
     pass_manager::dump_mir_for_phase_change(tcx, &body);
 
@@ -339,6 +336,8 @@ fn mir_promoted(
         | DefKind::AnonConst => tcx.mir_const_qualif(def),
         _ => ConstQualifs::default(),
     };
+    // has_ffi_unwind_calls query uses the raw mir, so make sure it is run.
+    tcx.ensure_with_value().has_ffi_unwind_calls(def);
     let mut body = tcx.mir_const(def).steal();
     if let Some(error_reported) = const_qualifs.tainted_by_errors {
         body.tainted_by_errors = Some(error_reported);