Fix some mir eval/lowerings

.git-blame-ignore-revs

@@ -14,3 +14,4 @@ f247090558c9ba3c551566eae5882b7ca865225f
 b2f6fd4f961fc7e4fbfdb80cae2e6065f8436f15
 c48062fe2ab9a2d913d1985a6b0aec4bf936bfc1
 f532576ac53ddcc666bc8d59e0b6437065e2f599
+4704881b641884de50645637108b6b6f5b68aaf9

crates/hir-def/src/lang_item.rs

@@ -501,4 +501,5 @@ language_item_table! {
 
     String,                  sym::String,              string,                     Target::Struct,         GenericRequirement::None;
     CStr,                    sym::CStr,                c_str,                      Target::Struct,         GenericRequirement::None;
+    Ordering,                sym::Ordering,            ordering,                   Target::Enum,           GenericRequirement::None;
 }

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

@@ -1644,14 +1644,15 @@ impl Evaluator<'_> {
             Variants::Multiple { tag, tag_encoding, variants, .. } => {
                 let size = tag.size(&*self.target_data_layout).bytes_usize();
                 let offset = layout.fields.offset(0).bytes_usize(); // The only field on enum variants is the tag field
+                let is_signed = tag.is_signed();
                 match tag_encoding {
                     TagEncoding::Direct => {
                         let tag = &bytes[offset..offset + size];
-                        Ok(i128::from_le_bytes(pad16(tag, false)))
+                        Ok(i128::from_le_bytes(pad16(tag, is_signed)))
                     }
                     TagEncoding::Niche { untagged_variant, niche_start, .. } => {
                         let tag = &bytes[offset..offset + size];
-                        let candidate_tag = i128::from_le_bytes(pad16(tag, false))
+                        let candidate_tag = i128::from_le_bytes(pad16(tag, is_signed))
                             .wrapping_sub(*niche_start as i128)
                             as usize;
                         let idx = variants
@@ -2943,10 +2944,10 @@ pub fn render_const_using_debug_impl(
     // a3 = ::core::fmt::Arguments::new_v1(a1, a2)
     // FIXME: similarly, we should call function here, not directly working with memory.
     let a3 = evaluator.heap_allocate(evaluator.ptr_size() * 6, evaluator.ptr_size())?;
-    evaluator.write_memory(a3.offset(2 * evaluator.ptr_size()), &a1.to_bytes())?;
+    evaluator.write_memory(a3, &a1.to_bytes())?;
+    evaluator.write_memory(a3.offset(evaluator.ptr_size()), &[1])?;
+    evaluator.write_memory(a3.offset(2 * evaluator.ptr_size()), &a2.to_bytes())?;
     evaluator.write_memory(a3.offset(3 * evaluator.ptr_size()), &[1])?;
-    evaluator.write_memory(a3.offset(4 * evaluator.ptr_size()), &a2.to_bytes())?;
-    evaluator.write_memory(a3.offset(5 * evaluator.ptr_size()), &[1])?;
     let Some(ValueNs::FunctionId(format_fn)) = resolver.resolve_path_in_value_ns_fully(
         db.upcast(),
         &hir_def::path::Path::from_known_path_with_no_generic(path![std::fmt::format]),

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),
         }

crates/intern/src/symbol/symbols.rs

@@ -347,6 +347,7 @@ define_symbols! {
     option,
     Option,
     Ord,
+    Ordering,
     Output,
     CallRefFuture,
     CallOnceFuture,