Auto merge of #105582 - saethlin:instcombine-assert-inhabited, r=cjgillot

InstCombine away intrinsic validity assertions

This optimization (currently) fires 246 times on the standard library. It seems to fire hardly at all on the big crates in the benchmark suite. Interesting.

compiler/rustc_middle/src/ty/structural_impls.rs

@@ -11,6 +11,7 @@ use crate::ty::{self, AliasTy, InferConst, Lift, Term, TermKind, Ty, TyCtxt};
 use rustc_data_structures::functor::IdFunctor;
 use rustc_hir::def::Namespace;
 use rustc_index::vec::{Idx, IndexVec};
+use rustc_target::abi::TyAndLayout;
 
 use std::fmt;
 use std::mem::ManuallyDrop;
@@ -853,3 +854,9 @@ impl<'tcx> TypeSuperVisitable<'tcx> for ty::UnevaluatedConst<'tcx> {
         self.substs.visit_with(visitor)
     }
 }
+
+impl<'tcx> TypeVisitable<'tcx> for TyAndLayout<'tcx, Ty<'tcx>> {
+    fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+        visitor.visit_ty(self.ty)
+    }
+}