WIP wasm gc instructions in wasm-smith

crates/wasm-smith/src/core.rs

@@ -392,6 +392,24 @@ impl Module {
         Ok(())
     }
 
+    fn val_type_is_sub_type(&self, a: ValType, b: ValType) -> bool {
+        match (a, b) {
+            (a, b) if a == b => true,
+            (ValType::Ref(a), ValType::Ref(b)) => self.ref_type_is_sub_type(a, b),
+            _ => false,
+        }
+    }
+
+    /// Is `a` a subtype of `b`?
+    fn ref_type_is_sub_type(&self, a: RefType, b: RefType) -> bool {
+        if a == b {
+            return true;
+        }
+
+        // TODO FITZGEN: do proper subtype checking
+        false
+    }
+
     fn arbitrary_types(&mut self, u: &mut Unstructured) -> Result<()> {
         assert!(self.config.min_types <= self.config.max_types);
         while self.types.len() < self.config.min_types {
@@ -601,28 +619,14 @@ impl Module {
         }
     }
 
-    fn arbitrary_matching_ref_type(
-        &mut self,
-        u: &mut Unstructured,
-        ty: RefType,
-    ) -> Result<RefType> {
+    fn arbitrary_matching_ref_type(&self, u: &mut Unstructured, ty: RefType) -> Result<RefType> {
         Ok(RefType {
-            // TODO: For now, only create allow nullable reference
-            // types. Eventually we should support non-nullable reference types,
-            // but this means that we will also need to recognize when it is
-            // impossible to create an instance of the reference (eg `(ref
-            // nofunc)` has no instances, and self-referential types that
-            // contain a non-null self-reference are also impossible to create).
-            nullable: true,
+            nullable: ty.nullable,
             heap_type: self.arbitrary_matching_heap_type(u, ty.heap_type)?,
         })
     }
 
-    fn arbitrary_matching_heap_type(
-        &mut self,
-        u: &mut Unstructured,
-        ty: HeapType,
-    ) -> Result<HeapType> {
+    fn arbitrary_matching_heap_type(&self, u: &mut Unstructured, ty: HeapType) -> Result<HeapType> {
         use HeapType as HT;
         let mut choices = vec![ty];
         match ty {
@@ -716,7 +720,7 @@ impl Module {
     }
 
     fn arbitrary_super_type_of_ref_type(
-        &mut self,
+        &self,
         u: &mut Unstructured,
         ty: RefType,
     ) -> Result<RefType> {
@@ -733,7 +737,7 @@ impl Module {
     }
 
     fn arbitrary_super_type_of_heap_type(
-        &mut self,
+        &self,
         u: &mut Unstructured,
         ty: HeapType,
     ) -> Result<HeapType> {
@@ -860,6 +864,45 @@ impl Module {
         }
     }
 
+    fn arbitrary_ref_type(&self, u: &mut Unstructured) -> Result<RefType> {
+        Ok(RefType {
+            nullable: true,
+            heap_type: self.arbitrary_heap_type(u)?,
+        })
+    }
+
+    fn arbitrary_heap_type(&self, u: &mut Unstructured) -> Result<HeapType> {
+        assert!(self.config.reference_types_enabled);
+
+        if self.config.gc_enabled && !self.types.is_empty() && u.arbitrary()? {
+            let type_ref_limit = u32::try_from(self.types.len()).unwrap();
+            let idx = u.int_in_range(0..=type_ref_limit)?;
+            return Ok(HeapType::Concrete(idx));
+        }
+
+        let mut choices = vec![HeapType::Func, HeapType::Extern];
+        if self.config.exceptions_enabled {
+            choices.push(HeapType::Exn);
+        }
+        if self.config.gc_enabled {
+            choices.extend(
+                [
+                    HeapType::Any,
+                    HeapType::None,
+                    HeapType::NoExtern,
+                    HeapType::NoFunc,
+                    HeapType::Eq,
+                    HeapType::Struct,
+                    HeapType::Array,
+                    HeapType::I31,
+                ]
+                .iter()
+                .copied(),
+            );
+        }
+        u.choose(&choices).copied()
+    }
+
     fn arbitrary_func_type(
         &mut self,
         u: &mut Unstructured,
@@ -2212,6 +2255,7 @@ flags! {
         Table,
         Memory,
         Control,
+        Aggregate,
     }
 }