Differentiate between the availability of ctfe MIR and runtime MIR

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1160,9 +1160,12 @@ fn each_child_of_item<F>(&self, id: DefIndex, mut callback: F, sess: &Session)
         }
     }
 
+    fn is_ctfe_mir_available(&self, id: DefIndex) -> bool {
+        self.root.tables.mir_for_ctfe.get(self, id).is_some()
+    }
+
     fn is_item_mir_available(&self, id: DefIndex) -> bool {
         self.root.tables.mir.get(self, id).is_some()
-            || self.root.tables.mir_for_ctfe.get(self, id).is_some()
     }
 
     fn module_expansion(&self, id: DefIndex, sess: &Session) -> ExpnId {

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

@@ -146,6 +146,7 @@ fn into_args(self) -> (DefId, DefId) {
     impl_parent => { cdata.get_parent_impl(def_id.index) }
     trait_of_item => { cdata.get_trait_of_item(def_id.index) }
     is_mir_available => { cdata.is_item_mir_available(def_id.index) }
+    is_ctfe_mir_available => { cdata.is_ctfe_mir_available(def_id.index) }
 
     dylib_dependency_formats => { cdata.get_dylib_dependency_formats(tcx) }
     is_panic_runtime => { cdata.root.panic_runtime }

compiler/rustc_middle/src/mir/query.rs

@@ -444,7 +444,7 @@ pub fn optimized_mir_opt_const_arg(
         def: ty::WithOptConstParam<DefId>,
     ) -> &'tcx Body<'tcx> {
         if let Some((did, param_did)) = def.as_const_arg() {
-            self.optimized_mir_of_const_arg((did, param_did))
+            self.mir_for_ctfe_of_const_arg((did, param_did))
         } else {
             self.optimized_mir(def.did)
         }

compiler/rustc_middle/src/query/mod.rs

@@ -346,15 +346,6 @@ fn describe_as_module(def_id: LocalDefId, tcx: TyCtxt<'_>) -> String {
             cache_on_disk_if { key.is_local() }
         }
 
-        // FIXME: now that we have `mir_for_ctfe_of_const_arg` can we get
-        // rid of this query?
-        query optimized_mir_of_const_arg(key: (LocalDefId, DefId)) -> &'tcx mir::Body<'tcx> {
-            desc {
-                |tcx| "optimizing MIR for the const argument `{}`",
-                tcx.def_path_str(key.0.to_def_id())
-            }
-        }
-
         /// Returns coverage summary info for a function, after executing the `InstrumentCoverage`
         /// MIR pass (assuming the -Zinstrument-coverage option is enabled).
         query coverageinfo(key: DefId) -> mir::CoverageInfo {
@@ -944,6 +935,10 @@ fn describe_as_module(def_id: LocalDefId, tcx: TyCtxt<'_>) -> String {
     }
 
     Codegen {
+        // FIXME: remove after figuring out how to make miri able to detect non-Rust function calls
+        query is_ctfe_mir_available(key: DefId) -> bool {
+            desc { |tcx| "checking if item has ctfe mir available: `{}`", tcx.def_path_str(key) }
+        }
         query is_mir_available(key: DefId) -> bool {
             desc { |tcx| "checking if item has mir available: `{}`", tcx.def_path_str(key) }
         }

compiler/rustc_middle/src/ty/mod.rs

@@ -3010,7 +3010,16 @@ pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
     /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
     pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
         match instance {
-            ty::InstanceDef::Item(def) => self.optimized_mir_opt_const_arg(def),
+            ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
+                DefKind::Const
+                | DefKind::Static
+                | DefKind::AssocConst
+                | DefKind::Ctor(..)
+                | DefKind::AnonConst => self.mir_for_ctfe_opt_const_arg(def),
+                // If the caller wants `mir_for_ctfe` they should not be using `instance_mir`, so
+                // we'll assume const fn also wants the optimized version.
+                _ => self.optimized_mir_opt_const_arg(def),
+            },
             ty::InstanceDef::VtableShim(..)
             | ty::InstanceDef::ReifyShim(..)
             | ty::InstanceDef::Intrinsic(..)

compiler/rustc_mir/src/interpret/eval_context.rs

@@ -479,7 +479,7 @@ pub fn load_mir(
         }
         match instance {
             ty::InstanceDef::Item(def) => {
-                if self.tcx.is_mir_available(def.did) {
+                if self.tcx.is_ctfe_mir_available(def.did) {
                     Ok(self.tcx.mir_for_ctfe_opt_const_arg(def))
                 } else {
                     throw_unsup!(NoMirFor(def.did))

compiler/rustc_mir/src/monomorphize/polymorphize.rs

@@ -54,9 +54,17 @@ fn unused_generic_params(tcx: TyCtxt<'_>, def_id: DefId) -> FiniteBitSet<u32> {
     }
 
     // Exit early when there is no MIR available.
-    if !tcx.is_mir_available(def_id) {
-        debug!("unused_generic_params: (no mir available) def_id={:?}", def_id);
-        return FiniteBitSet::new_empty();
+    let context = tcx.hir().body_const_context(def_id.expect_local());
+    match context {
+        None if !tcx.is_mir_available(def_id) => {
+            debug!("unused_generic_params: (no mir available) def_id={:?}", def_id);
+            return FiniteBitSet::new_empty();
+        }
+        Some(_) if !tcx.is_ctfe_mir_available(def_id) => {
+            debug!("unused_generic_params: (no ctfe mir available) def_id={:?}", def_id);
+            return FiniteBitSet::new_empty();
+        }
+        _ => {}
     }
 
     // Create a bitset with N rightmost ones for each parameter.
@@ -69,8 +77,11 @@ fn unused_generic_params(tcx: TyCtxt<'_>, def_id: DefId) -> FiniteBitSet<u32> {
     debug!("unused_generic_params: (after default) unused_parameters={:?}", unused_parameters);
 
     // Visit MIR and accumululate used generic parameters.
-    let body = match tcx.hir().body_const_context(def_id.expect_local()) {
+    let body = match context {
         None => tcx.optimized_mir(def_id),
+        // FIXME(oli-obk): since this is solely used for codegen (I think?), should we keep using
+        // the optimized MIR for `const fn`? Need to adjust the above `is_mir_available` check
+        // in that case.
         Some(_) => tcx.mir_for_ctfe(def_id),
     };
     let mut vis = MarkUsedGenericParams { tcx, def_id, unused_parameters: &mut unused_parameters };

compiler/rustc_mir/src/transform/mod.rs

@@ -74,8 +74,8 @@ pub(crate) fn provide(providers: &mut Providers) {
         mir_for_ctfe,
         mir_for_ctfe_of_const_arg,
         optimized_mir,
-        optimized_mir_of_const_arg,
         is_mir_available,
+        is_ctfe_mir_available: |tcx, did| is_mir_available(tcx, did),
         promoted_mir: |tcx, def_id| {
             let def_id = def_id.expect_local();
             if let Some(def) = ty::WithOptConstParam::try_lookup(def_id, tcx) {
@@ -518,22 +518,12 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 fn optimized_mir<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx Body<'tcx> {
     let did = did.expect_local();
     if let Some(def) = ty::WithOptConstParam::try_lookup(did, tcx) {
-        tcx.optimized_mir_of_const_arg(def)
+        tcx.mir_for_ctfe_of_const_arg(def)
     } else {
         tcx.arena.alloc(inner_optimized_mir(tcx, ty::WithOptConstParam::unknown(did)))
     }
 }
 
-fn optimized_mir_of_const_arg<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    (did, param_did): (LocalDefId, DefId),
-) -> &'tcx Body<'tcx> {
-    tcx.arena.alloc(inner_optimized_mir(
-        tcx,
-        ty::WithOptConstParam { did, const_param_did: Some(param_did) },
-    ))
-}
-
 fn inner_optimized_mir(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_> {
     if tcx.is_constructor(def.did.to_def_id()) {
         // There's no reason to run all of the MIR passes on constructors when