Fix some mir eval/lowerings

crates/hir-ty/src/mir/eval/shim.rs

@@ -1,11 +1,12 @@
 //! Interpret intrinsics, lang items and `extern "C"` wellknown functions which their implementation
 //! is not available.
 //!
-use std::cmp;
+use std::cmp::{self, Ordering};
 
 use chalk_ir::TyKind;
 use hir_def::{
     builtin_type::{BuiltinInt, BuiltinUint},
+    lang_item::LangItemTarget,
     resolver::HasResolver,
 };
 use hir_expand::name::Name;
@@ -1317,6 +1318,82 @@ impl Evaluator<'_> {
                 self.write_memory_using_ref(dst, size)?.fill(val);
                 Ok(())
             }
+            "ptr_metadata" => {
+                let [ptr] = args else {
+                    return Err(MirEvalError::InternalError(
+                        "ptr_metadata args are not provided".into(),
+                    ));
+                };
+                let arg = ptr.interval.get(self)?.to_owned();
+                let metadata = &arg[self.ptr_size()..];
+                destination.write_from_bytes(self, metadata)?;
+                Ok(())
+            }
+            "three_way_compare" => {
+                let [lhs, rhs] = args else {
+                    return Err(MirEvalError::InternalError(
+                        "three_way_compare args are not provided".into(),
+                    ));
+                };
+                let Some(ty) =
+                    generic_args.as_slice(Interner).first().and_then(|it| it.ty(Interner))
+                else {
+                    return Err(MirEvalError::InternalError(
+                        "three_way_compare generic arg is not provided".into(),
+                    ));
+                };
+                let signed = match ty.as_builtin().unwrap() {
+                    BuiltinType::Int(_) => true,
+                    BuiltinType::Uint(_) => false,
+                    _ => {
+                        return Err(MirEvalError::InternalError(
+                            "three_way_compare expects an integral type".into(),
+                        ))
+                    }
+                };
+                let rhs = rhs.get(self)?;
+                let lhs = lhs.get(self)?;
+                let mut result = Ordering::Equal;
+                for (l, r) in lhs.iter().zip(rhs).rev() {
+                    let it = l.cmp(r);
+                    if it != Ordering::Equal {
+                        result = it;
+                        break;
+                    }
+                }
+                if signed {
+                    if let Some((&l, &r)) = lhs.iter().zip(rhs).next_back() {
+                        if l != r {
+                            result = (l as i8).cmp(&(r as i8));
+                        }
+                    }
+                }
+                if let Some(LangItemTarget::EnumId(e)) =
+                    self.db.lang_item(self.crate_id, LangItem::Ordering)
+                {
+                    let ty = self.db.ty(e.into());
+                    let r = self
+                        .compute_discriminant(ty.skip_binders().clone(), &[result as i8 as u8])?;
+                    destination.write_from_bytes(self, &r.to_le_bytes()[0..destination.size])?;
+                    Ok(())
+                } else {
+                    Err(MirEvalError::InternalError("Ordering enum not found".into()))
+                }
+            }
+            "aggregate_raw_ptr" => {
+                let [data, meta] = args else {
+                    return Err(MirEvalError::InternalError(
+                        "aggregate_raw_ptr args are not provided".into(),
+                    ));
+                };
+                destination.write_from_interval(self, data.interval)?;
+                Interval {
+                    addr: destination.addr.offset(data.interval.size),
+                    size: destination.size - data.interval.size,
+                }
+                .write_from_interval(self, meta.interval)?;
+                Ok(())
+            }
             _ if needs_override => not_supported!("intrinsic {name} is not implemented"),
             _ => return Ok(false),
         }