Auto merge of #91743 - cjgillot:enable_mir_inlining_inline_all, r=oli-obk

Enable MIR inlining

Continuation of https://github.com/rust-lang/rust/pull/82280 by `@wesleywiser.`

#82280 has shown nice compile time wins could be obtained by enabling MIR inlining.
Most of the issues in https://github.com/rust-lang/rust/issues/81567 are now fixed,
except the interaction with polymorphization which is worked around specifically.

I believe we can proceed with enabling MIR inlining in the near future
(preferably just after beta branching, in case we discover new issues).

Steps before merging:
- [x] figure out the interaction with polymorphization;
- [x] figure out how miri should deal with extern types;
- [x] silence the extra arithmetic overflow warnings;
- [x] remove the codegen fulfilment ICE;
- [x] remove the type normalization ICEs while compiling nalgebra;
- [ ] tweak the inlining threshold.

2 files changed, 26 insertions, 5 deletions

diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs
index e8dd179eac1..0e10fe25c10 100644
--- a/compiler/rustc_middle/src/ty/instance.rs
+++ b/compiler/rustc_middle/src/ty/instance.rs
@@ -496,12 +496,12 @@ impl<'tcx> Instance<'tcx> {
         def_id: DefId,
         substs: ty::SubstsRef<'tcx>,
         requested_kind: ty::ClosureKind,
-    ) -> Instance<'tcx> {
+    ) -> Option<Instance<'tcx>> {
         let actual_kind = substs.as_closure().kind();
 
         match needs_fn_once_adapter_shim(actual_kind, requested_kind) {
             Ok(true) => Instance::fn_once_adapter_instance(tcx, def_id, substs),
-            _ => Instance::new(def_id, substs),
+            _ => Some(Instance::new(def_id, substs)),
         }
     }
 
@@ -515,7 +515,7 @@ impl<'tcx> Instance<'tcx> {
         tcx: TyCtxt<'tcx>,
         closure_did: DefId,
         substs: ty::SubstsRef<'tcx>,
-    ) -> Instance<'tcx> {
+    ) -> Option<Instance<'tcx>> {
         debug!("fn_once_adapter_shim({:?}, {:?})", closure_did, substs);
         let fn_once = tcx.require_lang_item(LangItem::FnOnce, None);
         let call_once = tcx
@@ -531,12 +531,13 @@ impl<'tcx> Instance<'tcx> {
         let self_ty = tcx.mk_closure(closure_did, substs);
 
         let sig = substs.as_closure().sig();
-        let sig = tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig);
+        let sig =
+            tcx.try_normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig).ok()?;
         assert_eq!(sig.inputs().len(), 1);
         let substs = tcx.mk_substs_trait(self_ty, &[sig.inputs()[0].into()]);
 
         debug!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty, sig);
-        Instance { def, substs }
+        Some(Instance { def, substs })
     }
 
     /// Depending on the kind of `InstanceDef`, the MIR body associated with an
diff --git a/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs b/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
index 66a0a192a87..9d8a8116594 100644
--- a/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
+++ b/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
@@ -112,6 +112,26 @@ impl<'tcx> TyCtxt<'tcx> {
         self.normalize_erasing_regions(param_env, value)
     }
 
+    /// If you have a `Binder<'tcx, T>`, you can do this to strip out the
+    /// late-bound regions and then normalize the result, yielding up
+    /// a `T` (with regions erased). This is appropriate when the
+    /// binder is being instantiated at the call site.
+    ///
+    /// N.B., currently, higher-ranked type bounds inhibit
+    /// normalization. Therefore, each time we erase them in
+    /// codegen, we need to normalize the contents.
+    pub fn try_normalize_erasing_late_bound_regions<T>(
+        self,
+        param_env: ty::ParamEnv<'tcx>,
+        value: ty::Binder<'tcx, T>,
+    ) -> Result<T, NormalizationError<'tcx>>
+    where
+        T: TypeFoldable<'tcx>,
+    {
+        let value = self.erase_late_bound_regions(value);
+        self.try_normalize_erasing_regions(param_env, value)
+    }
+
     /// Monomorphizes a type from the AST by first applying the
     /// in-scope substitutions and then normalizing any associated
     /// types.