Update reference types (#3084)

Align with the current state of the reference types proposal:
* Remove `nullref`
* Remove `externref` and `funcref` subtyping
* A `Literal` of a nullable reference type can now represent `null` (previously was type `nullref`)
* Update the tests and temporarily comment out those tests relying on subtyping

87 files changed, 2060 insertions, 1864 deletions

diff --git a/scripts/gen-s-parser.py b/scripts/gen-s-parser.py
index 2d22c2cbd..f105e6407 100755
--- a/scripts/gen-s-parser.py
+++ b/scripts/gen-s-parser.py
@@ -50,7 +50,6 @@ instructions = [
     ("v128.pop",       "makePop(Type::v128)"),
     ("funcref.pop",    "makePop(Type::funcref)"),
     ("externref.pop",  "makePop(Type::externref)"),
-    ("nullref.pop",    "makePop(Type::nullref)"),
     ("exnref.pop",     "makePop(Type::exnref)"),
     ("i32.load",       "makeLoad(s, Type::i32, /*isAtomic=*/false)"),
     ("i64.load",       "makeLoad(s, Type::i64, /*isAtomic=*/false)"),
diff --git a/src/asmjs/asm_v_wasm.cpp b/src/asmjs/asm_v_wasm.cpp
index 4a79d9caf..ddcb27d3d 100644
--- a/src/asmjs/asm_v_wasm.cpp
+++ b/src/asmjs/asm_v_wasm.cpp
@@ -56,7 +56,6 @@ AsmType wasmToAsmType(Type type) {
       assert(false && "v128 not implemented yet");
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
       assert(false && "reference types are not supported by asm2wasm");
     case Type::none:
@@ -84,8 +83,6 @@ char getSig(Type type) {
       return 'F';
     case Type::externref:
       return 'X';
-    case Type::nullref:
-      return 'N';
     case Type::exnref:
       return 'E';
     case Type::none:
diff --git a/src/binaryen-c.cpp b/src/binaryen-c.cpp
index 4c5063114..a3aa0cd94 100644
--- a/src/binaryen-c.cpp
+++ b/src/binaryen-c.cpp
@@ -69,12 +69,12 @@ BinaryenLiteral toBinaryenLiteral(Literal x) {
       memcpy(&ret.v128, x.getv128Ptr(), 16);
       break;
     case Type::funcref:
-      ret.func = x.getFunc().c_str();
-      break;
-    case Type::nullref:
+      ret.func = x.isNull() ? nullptr : x.getFunc().c_str();
       break;
     case Type::externref:
     case Type::exnref:
+      assert(x.isNull());
+      break;
     case Type::none:
     case Type::unreachable:
       WASM_UNREACHABLE("unexpected type");
@@ -95,11 +95,10 @@ Literal fromBinaryenLiteral(BinaryenLiteral x) {
     case Type::v128:
       return Literal(x.v128);
     case Type::funcref:
-      return Literal::makeFuncref(x.func);
-    case Type::nullref:
-      return Literal::makeNullref();
+      return Literal::makeFunc(x.func);
     case Type::externref:
     case Type::exnref:
+      return Literal::makeNull(Type(x.type));
     case Type::none:
     case Type::unreachable:
       WASM_UNREACHABLE("unexpected type");
@@ -133,7 +132,6 @@ BinaryenType BinaryenTypeFloat64(void) { return Type::f64; }
 BinaryenType BinaryenTypeVec128(void) { return Type::v128; }
 BinaryenType BinaryenTypeFuncref(void) { return Type::funcref; }
 BinaryenType BinaryenTypeExternref(void) { return Type::externref; }
-BinaryenType BinaryenTypeNullref(void) { return Type::nullref; }
 BinaryenType BinaryenTypeExnref(void) { return Type::exnref; }
 BinaryenType BinaryenTypeUnreachable(void) { return Type::unreachable; }
 BinaryenType BinaryenTypeAuto(void) { return uintptr_t(-1); }
@@ -1264,8 +1262,11 @@ BinaryenExpressionRef BinaryenPop(BinaryenModuleRef module, BinaryenType type) {
     Builder(*(Module*)module).makePop(Type(type)));
 }
 
-BinaryenExpressionRef BinaryenRefNull(BinaryenModuleRef module) {
-  return static_cast<Expression*>(Builder(*(Module*)module).makeRefNull());
+BinaryenExpressionRef BinaryenRefNull(BinaryenModuleRef module,
+                                      BinaryenType type) {
+  Type type_(type);
+  assert(type_.isNullable());
+  return static_cast<Expression*>(Builder(*(Module*)module).makeRefNull(type_));
 }
 
 BinaryenExpressionRef BinaryenRefIsNull(BinaryenModuleRef module,
diff --git a/src/binaryen-c.h b/src/binaryen-c.h
index 893d44e3c..beaf72499 100644
--- a/src/binaryen-c.h
+++ b/src/binaryen-c.h
@@ -100,7 +100,6 @@ BINARYEN_API BinaryenType BinaryenTypeFloat64(void);
 BINARYEN_API BinaryenType BinaryenTypeVec128(void);
 BINARYEN_API BinaryenType BinaryenTypeFuncref(void);
 BINARYEN_API BinaryenType BinaryenTypeExternref(void);
-BINARYEN_API BinaryenType BinaryenTypeNullref(void);
 BINARYEN_API BinaryenType BinaryenTypeExnref(void);
 BINARYEN_API BinaryenType BinaryenTypeUnreachable(void);
 // Not a real type. Used as the last parameter to BinaryenBlock to let
@@ -826,7 +825,8 @@ BinaryenMemoryFill(BinaryenModuleRef module,
                    BinaryenExpressionRef dest,
                    BinaryenExpressionRef value,
                    BinaryenExpressionRef size);
-BINARYEN_API BinaryenExpressionRef BinaryenRefNull(BinaryenModuleRef module);
+BINARYEN_API BinaryenExpressionRef BinaryenRefNull(BinaryenModuleRef module,
+                                                   BinaryenType type);
 BINARYEN_API BinaryenExpressionRef
 BinaryenRefIsNull(BinaryenModuleRef module, BinaryenExpressionRef value);
 BINARYEN_API BinaryenExpressionRef BinaryenRefFunc(BinaryenModuleRef module,
diff --git a/src/gen-s-parser.inc b/src/gen-s-parser.inc
index 5e6beb4ac..97ba15c32 100644
--- a/src/gen-s-parser.inc
+++ b/src/gen-s-parser.inc
@@ -2560,17 +2560,9 @@ switch (op[0]) {
       default: goto parse_error;
     }
   }
-  case 'n': {
-    switch (op[1]) {
-      case 'o':
-        if (strcmp(op, "nop") == 0) { return makeNop(); }
-        goto parse_error;
-      case 'u':
-        if (strcmp(op, "nullref.pop") == 0) { return makePop(Type::nullref); }
-        goto parse_error;
-      default: goto parse_error;
-    }
-  }
+  case 'n':
+    if (strcmp(op, "nop") == 0) { return makeNop(); }
+    goto parse_error;
   case 'r': {
     switch (op[2]) {
       case 'f': {
diff --git a/src/ir/ExpressionManipulator.cpp b/src/ir/ExpressionManipulator.cpp
index 57048b9bd..6f64ec77b 100644
--- a/src/ir/ExpressionManipulator.cpp
+++ b/src/ir/ExpressionManipulator.cpp
@@ -227,7 +227,9 @@ flexibleCopy(Expression* original, Module& wasm, CustomCopier custom) {
         builder.makeHost(curr->op, curr->nameOperand, std::move(operands));
       return ret;
     }
-    Expression* visitRefNull(RefNull* curr) { return builder.makeRefNull(); }
+    Expression* visitRefNull(RefNull* curr) {
+      return builder.makeRefNull(curr->type);
+    }
     Expression* visitRefIsNull(RefIsNull* curr) {
       return builder.makeRefIsNull(copy(curr->value));
     }
diff --git a/src/ir/abstract.h b/src/ir/abstract.h
index f706e9972..b00537bf5 100644
--- a/src/ir/abstract.h
+++ b/src/ir/abstract.h
@@ -103,7 +103,6 @@ inline UnaryOp getUnary(Type type, Op op) {
     }
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable: {
@@ -268,7 +267,6 @@ inline BinaryOp getBinary(Type type, Op op) {
     }
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable: {
diff --git a/src/ir/manipulation.h b/src/ir/manipulation.h
index 49ed7e11e..fb1f0181e 100644
--- a/src/ir/manipulation.h
+++ b/src/ir/manipulation.h
@@ -40,9 +40,10 @@ template<typename InputType> inline Nop* nop(InputType* target) {
   return ret;
 }
 
-template<typename InputType> inline RefNull* refNull(InputType* target) {
+template<typename InputType>
+inline RefNull* refNull(InputType* target, Type type) {
   auto* ret = convert<InputType, RefNull>(target);
-  ret->finalize();
+  ret->finalize(type);
   return ret;
 }
 
diff --git a/src/ir/properties.h b/src/ir/properties.h
index 0c6824e4a..ac61f787e 100644
--- a/src/ir/properties.h
+++ b/src/ir/properties.h
@@ -93,10 +93,10 @@ inline bool isConstantExpression(const Expression* curr) {
 inline Literal getSingleLiteral(const Expression* curr) {
   if (auto* c = curr->dynCast<Const>()) {
     return c->value;
-  } else if (curr->is<RefNull>()) {
-    return Literal(Type::nullref);
-  } else if (auto* c = curr->dynCast<RefFunc>()) {
-    return Literal(c->func);
+  } else if (auto* n = curr->dynCast<RefNull>()) {
+    return Literal(n->type);
+  } else if (auto* r = curr->dynCast<RefFunc>()) {
+    return Literal(r->func);
   } else {
     WASM_UNREACHABLE("non-constant expression");
   }
diff --git a/src/js/binaryen.js-post.js b/src/js/binaryen.js-post.js
index 4e673ab4b..66de10848 100644
--- a/src/js/binaryen.js-post.js
+++ b/src/js/binaryen.js-post.js
@@ -35,7 +35,6 @@ function initializeConstants() {
     ['v128', 'Vec128'],
     ['funcref', 'Funcref'],
     ['externref', 'Externref'],
-    ['nullref', 'Nullref'],
     ['exnref', 'Exnref'],
     ['unreachable', 'Unreachable'],
     ['auto', 'Auto']
@@ -2058,12 +2057,6 @@ function wrapModule(module, self = {}) {
     }
   };
 
-  self['nullref'] = {
-    'pop'() {
-      return Module['_BinaryenPop'](module, Module['nullref']);
-    }
-  };
-
   self['exnref'] = {
     'pop'() {
       return Module['_BinaryenPop'](module, Module['exnref']);
@@ -2071,8 +2064,8 @@ function wrapModule(module, self = {}) {
   };
 
   self['ref'] = {
-    'null'() {
-      return Module['_BinaryenRefNull'](module);
+    'null'(type) {
+      return Module['_BinaryenRefNull'](module, type);
     },
     'is_null'(value) {
       return Module['_BinaryenRefIsNull'](module, value);
diff --git a/src/literal.h b/src/literal.h
index 4cbc16786..1b3949d21 100644
--- a/src/literal.h
+++ b/src/literal.h
@@ -39,8 +39,14 @@ class Literal {
     int32_t i32;
     int64_t i64;
     uint8_t v128[16];
-    Name func; // function name for funcref
+    // funcref function name. `isNull()` indicates a `null` value.
+    Name func;
+    // exnref package. `nullptr` indicates a `null` value.
     std::unique_ptr<ExceptionPackage> exn;
+    // TODO: Literals of type `externref` can only be `null` currently but we
+    // will need to represent extern values eventually, to
+    // 1) run the spec tests and fuzzer with reference types enabled and
+    // 2) avoid bailing out when seeing a reference typed value in precompute
   };
 
 public:
@@ -48,10 +54,7 @@ public:
   const Type type;
 
   Literal() : v128(), type(Type::none) {}
-  explicit Literal(Type type) : v128(), type(type) {
-    assert(type != Type::unreachable && type != Type::funcref &&
-           type != Type::exnref);
-  }
+  explicit Literal(Type type);
   explicit Literal(Type::BasicID typeId) : Literal(Type(typeId)) {}
   explicit Literal(int32_t init) : i32(init), type(Type::i32) {}
   explicit Literal(uint32_t init) : i32(init), type(Type::i32) {}
@@ -74,13 +77,25 @@ public:
   Literal(const Literal& other);
   Literal& operator=(const Literal& other);
   ~Literal() {
-    if (type == Type::exnref) {
+    if (type.isException()) {
       exn.~unique_ptr();
     }
   }
 
   bool isConcrete() const { return type != Type::none; }
   bool isNone() const { return type == Type::none; }
+  bool isNull() const {
+    if (type.isNullable()) {
+      if (type.isFunction()) {
+        return func.isNull();
+      }
+      if (type.isException()) {
+        return !exn;
+      }
+      return true;
+    }
+    return false;
+  }
 
   static Literal makeFromInt32(int32_t x, Type type) {
     switch (type.getBasic()) {
@@ -105,9 +120,12 @@ public:
   static Literals makeZero(Type type);
   static Literal makeSingleZero(Type type);
 
-  static Literal makeNullref() { return Literal(Type(Type::nullref)); }
-  static Literal makeFuncref(Name func) { return Literal(func.c_str()); }
-  static Literal makeExnref(std::unique_ptr<ExceptionPackage>&& exn) {
+  static Literal makeNull(Type type) {
+    assert(type.isNullable());
+    return Literal(type);
+  }
+  static Literal makeFunc(Name func) { return Literal(func.c_str()); }
+  static Literal makeExn(std::unique_ptr<ExceptionPackage>&& exn) {
     return Literal(std::move(exn));
   }
 
@@ -134,7 +152,7 @@ public:
   }
   std::array<uint8_t, 16> getv128() const;
   Name getFunc() const {
-    assert(type == Type::funcref);
+    assert(type.isFunction() && !func.isNull());
     return func;
   }
   ExceptionPackage getExceptionPackage() const;
@@ -502,6 +520,12 @@ public:
 struct ExceptionPackage {
   Name event;
   Literals values;
+  bool operator==(const ExceptionPackage& other) const {
+    return event == other.event && values == other.values;
+  }
+  bool operator!=(const ExceptionPackage& other) const {
+    return !(*this == other);
+  }
 };
 
 std::ostream& operator<<(std::ostream& o, wasm::Literal literal);
@@ -554,7 +578,6 @@ template<> struct less<wasm::Literal> {
         return memcmp(a.getv128Ptr(), b.getv128Ptr(), 16) < 0;
       case wasm::Type::funcref:
       case wasm::Type::externref:
-      case wasm::Type::nullref:
       case wasm::Type::exnref:
       case wasm::Type::none:
       case wasm::Type::unreachable:
diff --git a/src/parsing.h b/src/parsing.h
index a3eab1af3..663b901fd 100644
--- a/src/parsing.h
+++ b/src/parsing.h
@@ -265,7 +265,6 @@ parseConst(cashew::IString s, Type type, MixedArena& allocator) {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
       WASM_UNREACHABLE("unexpected const type");
     case Type::none:
diff --git a/src/passes/ConstHoisting.cpp b/src/passes/ConstHoisting.cpp
index 3cef0773c..e3583d3bb 100644
--- a/src/passes/ConstHoisting.cpp
+++ b/src/passes/ConstHoisting.cpp
@@ -96,7 +96,6 @@ private:
       case Type::v128:
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref: {
         return false;
       }
diff --git a/src/passes/Flatten.cpp b/src/passes/Flatten.cpp
index 54da8a86e..c7b4acbd9 100644
--- a/src/passes/Flatten.cpp
+++ b/src/passes/Flatten.cpp
@@ -211,19 +211,19 @@ struct Flatten
             // the return type of the block this branch is targetting, which may
             // not be the same with the innermost block's return type. For
             // example,
-            // (block $any (result externref)
-            //   (block (result nullref)
+            // (block $any (result anyref)
+            //   (block (result funcref)
             //     (local.tee $0
             //       (br_if $any
-            //         (ref.null)
+            //         (ref.null func)
             //         (i32.const 0)
             //       )
             //     )
             //   )
             // )
             // In this case we need two locals to store (ref.null); one with
-            // externref type that's for the target block ($label0) and one more
-            // with nullref type in case for flowing out. Here we create the
+            // funcref type that's for the target block ($label0) and one more
+            // with anyref type in case for flowing out. Here we create the
             // second 'flowing out' local in case two block's types are
             // different.
             if (type != blockType) {
diff --git a/src/passes/FuncCastEmulation.cpp b/src/passes/FuncCastEmulation.cpp
index 13fb89988..160895f23 100644
--- a/src/passes/FuncCastEmulation.cpp
+++ b/src/passes/FuncCastEmulation.cpp
@@ -67,7 +67,6 @@ static Expression* toABI(Expression* value, Module* module) {
     }
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref: {
       WASM_UNREACHABLE("reference types cannot be converted to i64");
     }
@@ -111,7 +110,6 @@ static Expression* fromABI(Expression* value, Type type, Module* module) {
     }
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref: {
       WASM_UNREACHABLE("reference types cannot be converted from i64");
     }
diff --git a/src/passes/InstrumentLocals.cpp b/src/passes/InstrumentLocals.cpp
index f95d169e9..ee288c103 100644
--- a/src/passes/InstrumentLocals.cpp
+++ b/src/passes/InstrumentLocals.cpp
@@ -58,7 +58,6 @@ Name get_f32("get_f32");
 Name get_f64("get_f64");
 Name get_funcref("get_funcref");
 Name get_externref("get_externref");
-Name get_nullref("get_nullref");
 Name get_exnref("get_exnref");
 Name get_v128("get_v128");
 
@@ -68,7 +67,6 @@ Name set_f32("set_f32");
 Name set_f64("set_f64");
 Name set_funcref("set_funcref");
 Name set_externref("set_externref");
-Name set_nullref("set_nullref");
 Name set_exnref("set_exnref");
 Name set_v128("set_v128");
 
@@ -98,9 +96,6 @@ struct InstrumentLocals : public WalkerPass<PostWalker<InstrumentLocals>> {
       case Type::externref:
         import = get_externref;
         break;
-      case Type::nullref:
-        import = get_nullref;
-        break;
       case Type::exnref:
         import = get_exnref;
         break;
@@ -147,9 +142,6 @@ struct InstrumentLocals : public WalkerPass<PostWalker<InstrumentLocals>> {
       case Type::externref:
         import = set_externref;
         break;
-      case Type::nullref:
-        import = set_nullref;
-        break;
       case Type::exnref:
         import = set_exnref;
         break;
@@ -192,14 +184,6 @@ struct InstrumentLocals : public WalkerPass<PostWalker<InstrumentLocals>> {
                 set_externref,
                 {Type::i32, Type::i32, Type::externref},
                 Type::externref);
-      addImport(curr,
-                get_nullref,
-                {Type::i32, Type::i32, Type::nullref},
-                Type::nullref);
-      addImport(curr,
-                set_nullref,
-                {Type::i32, Type::i32, Type::nullref},
-                Type::nullref);
     }
     if (curr->features.hasExceptionHandling()) {
       addImport(
diff --git a/src/passes/Precompute.cpp b/src/passes/Precompute.cpp
index 695b62ab2..0b67a25aa 100644
--- a/src/passes/Precompute.cpp
+++ b/src/passes/Precompute.cpp
@@ -134,7 +134,7 @@ struct Precompute
             curr->finalize();
             return;
           }
-        } else if (singleValue.type == Type::nullref &&
+        } else if (singleValue.isNull() &&
                    curr->value->template is<RefNull>()) {
           return;
         } else if (singleValue.type == Type::funcref) {
diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index f35f0d626..04fcdc0b3 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -1440,7 +1440,10 @@ struct PrintExpressionContents
         break;
     }
   }
-  void visitRefNull(RefNull* curr) { printMedium(o, "ref.null"); }
+  void visitRefNull(RefNull* curr) {
+    printMedium(o, "ref.null ");
+    o << curr->type.getHeapType();
+  }
   void visitRefIsNull(RefIsNull* curr) { printMedium(o, "ref.is_null"); }
   void visitRefFunc(RefFunc* curr) {
     printMedium(o, "ref.func ");
diff --git a/src/shell-interface.h b/src/shell-interface.h
index a32ae6344..92f562b48 100644
--- a/src/shell-interface.h
+++ b/src/shell-interface.h
@@ -117,9 +117,8 @@ struct ShellExternalInterface : ModuleInstance::ExternalInterface {
             assert(false && "v128 not implemented yet");
           case Type::funcref:
           case Type::externref:
-          case Type::nullref:
           case Type::exnref:
-            globals[import->name] = {Literal::makeNullref()};
+            globals[import->name] = {Literal::makeNull(import->type)};
             break;
           case Type::none:
           case Type::unreachable:
diff --git a/src/tools/execution-results.h b/src/tools/execution-results.h
index 38989aedf..c41b0c208 100644
--- a/src/tools/execution-results.h
+++ b/src/tools/execution-results.h
@@ -74,7 +74,7 @@ struct ExecutionResults {
           // while the function contents are still the same
           for (Literal& val : ret) {
             if (val.type == Type::funcref) {
-              val = Literal::makeFuncref(Name("funcref"));
+              val = Literal::makeFunc(Name("funcref"));
             }
           }
           results[exp->name] = ret;
diff --git a/src/tools/fuzzing.h b/src/tools/fuzzing.h
index b3c1212d4..ef7844c60 100644
--- a/src/tools/fuzzing.h
+++ b/src/tools/fuzzing.h
@@ -315,21 +315,7 @@ private:
     }
     SmallVector<Type, 2> options;
     options.push_back(type); // includes itself
-    TODO_SINGLE_COMPOUND(type);
-    switch (type.getBasic()) {
-      case Type::externref:
-        if (wasm.features.hasExceptionHandling()) {
-          options.push_back(Type::exnref);
-        }
-        options.push_back(Type::funcref);
-        // falls through
-      case Type::funcref:
-      case Type::exnref:
-        options.push_back(Type::nullref);
-        break;
-      default:
-        break;
-    }
+    // TODO (GC): subtyping
     return pick(options);
   }
 
@@ -1362,7 +1348,6 @@ private:
       }
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
       case Type::none:
       case Type::unreachable:
@@ -1466,7 +1451,6 @@ private:
       }
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
       case Type::none:
       case Type::unreachable:
@@ -1595,7 +1579,6 @@ private:
           case Type::v128:
           case Type::funcref:
           case Type::externref:
-          case Type::nullref:
           case Type::exnref:
           case Type::none:
           case Type::unreachable:
@@ -1640,7 +1623,6 @@ private:
           case Type::v128:
           case Type::funcref:
           case Type::externref:
-          case Type::nullref:
           case Type::exnref:
           case Type::none:
           case Type::unreachable:
@@ -1708,7 +1690,6 @@ private:
           case Type::v128:
           case Type::funcref:
           case Type::externref:
-          case Type::nullref:
           case Type::exnref:
           case Type::none:
           case Type::unreachable:
@@ -1735,7 +1716,6 @@ private:
           case Type::v128:
           case Type::funcref:
           case Type::externref:
-          case Type::nullref:
           case Type::exnref:
           case Type::none:
           case Type::unreachable:
@@ -1763,7 +1743,7 @@ private:
         }
         return builder.makeRefFunc(target->name);
       }
-      return builder.makeRefNull();
+      return builder.makeRefNull(type);
     }
     if (type.isTuple()) {
       std::vector<Expression*> operands;
@@ -1845,7 +1825,6 @@ private:
           }
           case Type::funcref:
           case Type::externref:
-          case Type::nullref:
           case Type::exnref:
             return makeTrivial(type);
           case Type::none:
@@ -1990,7 +1969,6 @@ private:
       }
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
       case Type::none:
       case Type::unreachable:
@@ -2227,7 +2205,6 @@ private:
       }
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
       case Type::none:
       case Type::unreachable:
@@ -2434,7 +2411,6 @@ private:
       case Type::v128:
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
       case Type::none:
       case Type::unreachable:
@@ -2610,14 +2586,13 @@ private:
   Expression* makeRefIsNull(Type type) {
     assert(type == Type::i32);
     assert(wasm.features.hasReferenceTypes());
-    Type refType;
+    SmallVector<Type, 2> options;
+    options.push_back(Type::externref);
+    options.push_back(Type::funcref);
     if (wasm.features.hasExceptionHandling()) {
-      refType =
-        pick(Type::funcref, Type::externref, Type::nullref, Type::exnref);
-    } else {
-      refType = pick(Type::funcref, Type::externref, Type::nullref);
+      options.push_back(Type::exnref);
     }
-    return builder.makeRefIsNull(make(refType));
+    return builder.makeRefIsNull(make(pick(options)));
   }
 
   Expression* makeMemoryInit() {
@@ -2680,10 +2655,7 @@ private:
       FeatureOptions<Type>()
         .add(FeatureSet::MVP, Type::i32, Type::i64, Type::f32, Type::f64)
         .add(FeatureSet::SIMD, Type::v128)
-        .add(FeatureSet::ReferenceTypes,
-             Type::funcref,
-             Type::externref,
-             Type::nullref)
+        .add(FeatureSet::ReferenceTypes, Type::funcref, Type::externref)
         .add(FeatureSet::ReferenceTypes | FeatureSet::ExceptionHandling,
              Type::exnref));
   }
@@ -2732,7 +2704,6 @@ private:
       FeatureOptions<Type>()
         .add(FeatureSet::MVP, Type::i32, Type::i64, Type::f32, Type::f64)
         .add(FeatureSet::SIMD, Type::v128)
-        .add(FeatureSet::ReferenceTypes, Type::nullref)
         .add(FeatureSet::ReferenceTypes | FeatureSet::ExceptionHandling,
              Type::exnref));
   }
diff --git a/src/tools/spec-wrapper.h b/src/tools/spec-wrapper.h
index 44f92b56d..c073a994c 100644
--- a/src/tools/spec-wrapper.h
+++ b/src/tools/spec-wrapper.h
@@ -50,10 +50,13 @@ static std::string generateSpecWrapper(Module& wasm) {
           ret += "(v128.const i32x4 0 0 0 0)";
           break;
         case Type::funcref:
+          ret += "(ref.null func)";
+          break;
         case Type::externref:
-        case Type::nullref:
+          ret += "(ref.null extern)";
+          break;
         case Type::exnref:
-          ret += "(ref.null)";
+          ret += "(ref.null exn)";
           break;
         case Type::none:
         case Type::unreachable:
diff --git a/src/tools/wasm-reduce.cpp b/src/tools/wasm-reduce.cpp
index 9c9978b63..1a7c3544d 100644
--- a/src/tools/wasm-reduce.cpp
+++ b/src/tools/wasm-reduce.cpp
@@ -597,7 +597,6 @@ struct Reducer
               case Type::v128:
               case Type::funcref:
               case Type::externref:
-              case Type::nullref:
               case Type::exnref:
                 continue; // not implemented yet
               case Type::none:
@@ -623,7 +622,6 @@ struct Reducer
               case Type::v128:
               case Type::funcref:
               case Type::externref:
-              case Type::nullref:
               case Type::exnref:
                 continue; // not implemented yet
               case Type::none:
@@ -649,7 +647,6 @@ struct Reducer
               case Type::v128:
               case Type::funcref:
               case Type::externref:
-              case Type::nullref:
               case Type::exnref:
                 continue; // not implemented yet
               case Type::none:
@@ -675,7 +672,6 @@ struct Reducer
               case Type::v128:
               case Type::funcref:
               case Type::externref:
-              case Type::nullref:
               case Type::exnref:
                 continue; // not implemented yet
               case Type::none:
@@ -687,7 +683,6 @@ struct Reducer
           case Type::v128:
           case Type::funcref:
           case Type::externref:
-          case Type::nullref:
           case Type::exnref:
             continue; // not implemented yet
           case Type::none:
@@ -1015,8 +1010,8 @@ struct Reducer
       return false;
     }
     // try to replace with a trivial value
-    if (curr->type.isRef()) {
-      RefNull* n = builder->makeRefNull();
+    if (curr->type.isNullable()) {
+      RefNull* n = builder->makeRefNull(curr->type);
       return tryToReplaceCurrent(n);
     }
     if (curr->type.isTuple()) {
diff --git a/src/wasm-binary.h b/src/wasm-binary.h
index ab9ee5152..865a882df 100644
--- a/src/wasm-binary.h
+++ b/src/wasm-binary.h
@@ -347,8 +347,6 @@ enum EncodedType {
   funcref = -0x10, // 0x70
   // opaque host reference type
   externref = -0x11, // 0x6f
-  // null reference type
-  nullref = -0x12, // 0x6e
   // exception reference type
   exnref = -0x18, // 0x68
   // func_type form
@@ -357,6 +355,12 @@ enum EncodedType {
   Empty = -0x40 // 0x40
 };
 
+enum EncodedHeapType {
+  func = -0x10,    // 0x70
+  extern_ = -0x11, // 0x6f
+  exn = -0x18,     // 0x68
+};
+
 namespace UserSections {
 extern const char* Name;
 extern const char* SourceMapUrl;
@@ -968,9 +972,6 @@ inline S32LEB binaryType(Type type) {
     case Type::externref:
       ret = BinaryConsts::EncodedType::externref;
       break;
-    case Type::nullref:
-      ret = BinaryConsts::EncodedType::nullref;
-      break;
     case Type::exnref:
       ret = BinaryConsts::EncodedType::exnref;
       break;
@@ -980,6 +981,29 @@ inline S32LEB binaryType(Type type) {
   return S32LEB(ret);
 }
 
+inline S32LEB binaryHeapType(HeapType type) {
+  int ret = 0;
+  switch (type.kind) {
+    case HeapType::FuncKind:
+      ret = BinaryConsts::EncodedHeapType::func;
+      break;
+    case HeapType::ExternKind:
+      ret = BinaryConsts::EncodedHeapType::extern_;
+      break;
+    case HeapType::ExnKind:
+      ret = BinaryConsts::EncodedHeapType::exn;
+      break;
+    case HeapType::AnyKind:
+    case HeapType::EqKind:
+    case HeapType::I31Kind:
+    case HeapType::SignatureKind:
+    case HeapType::StructKind:
+    case HeapType::ArrayKind:
+      WASM_UNREACHABLE("TODO: GC types");
+  }
+  return S32LEB(ret); // TODO: Actually encoded as s33
+}
+
 // Writes out wasm to the binary format
 
 class WasmBinaryWriter {
@@ -1209,6 +1233,7 @@ public:
   int32_t getS32LEB();
   int64_t getS64LEB();
   Type getType();
+  HeapType getHeapType();
   Type getConcreteType();
   Name getInlineString();
   void verifyInt8(int8_t x);
diff --git a/src/wasm-builder.h b/src/wasm-builder.h
index 4e94da090..1ce3a507c 100644
--- a/src/wasm-builder.h
+++ b/src/wasm-builder.h
@@ -528,9 +528,9 @@ public:
     ret->finalize();
     return ret;
   }
-  RefNull* makeRefNull() {
+  RefNull* makeRefNull(Type type) {
     auto* ret = allocator.alloc<RefNull>();
-    ret->finalize();
+    ret->finalize(type);
     return ret;
   }
   RefIsNull* makeRefIsNull(Expression* value) {
@@ -624,13 +624,15 @@ public:
   Expression* makeConstantExpression(Literal value) {
     TODO_SINGLE_COMPOUND(value.type);
     switch (value.type.getBasic()) {
-      case Type::nullref:
-        return makeRefNull();
       case Type::funcref:
-        if (value.getFunc()[0] != 0) {
+        if (!value.isNull()) {
           return makeRefFunc(value.getFunc());
         }
-        return makeRefNull();
+        return makeRefNull(value.type);
+      case Type::externref:
+      case Type::exnref: // TODO: ExceptionPackage?
+        assert(value.isNull());
+        return makeRefNull(value.type);
       default:
         assert(value.type.isNumber());
         return makeConst(value);
@@ -822,9 +824,8 @@ public:
       }
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
-        return ExpressionManipulator::refNull(curr);
+        return ExpressionManipulator::refNull(curr, curr->type);
       case Type::none:
         return ExpressionManipulator::nop(curr);
       case Type::unreachable:
diff --git a/src/wasm-interpreter.h b/src/wasm-interpreter.h
index 3eab81cc5..44cac9d49 100644
--- a/src/wasm-interpreter.h
+++ b/src/wasm-interpreter.h
@@ -1242,7 +1242,7 @@ public:
   Flow visitPop(Pop* curr) { WASM_UNREACHABLE("unimp"); }
   Flow visitRefNull(RefNull* curr) {
     NOTE_ENTER("RefNull");
-    return Literal::makeNullref();
+    return Literal::makeNull(curr->type);
   }
   Flow visitRefIsNull(RefIsNull* curr) {
     NOTE_ENTER("RefIsNull");
@@ -1250,14 +1250,14 @@ public:
     if (flow.breaking()) {
       return flow;
     }
-    Literal value = flow.getSingleValue();
+    const auto& value = flow.getSingleValue();
     NOTE_EVAL1(value);
-    return Literal(value.type == Type::nullref);
+    return Literal(value.isNull());
   }
   Flow visitRefFunc(RefFunc* curr) {
     NOTE_ENTER("RefFunc");
     NOTE_NAME(curr->func);
-    return Literal::makeFuncref(curr->func);
+    return Literal::makeFunc(curr->func);
   }
   Flow visitTry(Try* curr) { WASM_UNREACHABLE("unimp"); }
   Flow visitThrow(Throw* curr) {
@@ -1273,7 +1273,7 @@ public:
     for (auto item : arguments) {
       exn->values.push_back(item);
     }
-    throwException(Literal::makeExnref(std::move(exn)));
+    throwException(Literal::makeExn(std::move(exn)));
     WASM_UNREACHABLE("throw");
   }
   Flow visitRethrow(Rethrow* curr) {
@@ -1282,10 +1282,11 @@ public:
     if (flow.breaking()) {
       return flow;
     }
-    if (flow.getType() == Type::nullref) {
+    const auto& value = flow.getSingleValue();
+    if (value.isNull()) {
       trap("rethrow: argument is null");
     }
-    throwException(flow.getSingleValue());
+    throwException(value);
     WASM_UNREACHABLE("rethrow");
   }
   Flow visitBrOnExn(BrOnExn* curr) {
@@ -1294,10 +1295,11 @@ public:
     if (flow.breaking()) {
       return flow;
     }
-    if (flow.getType() == Type::nullref) {
+    const auto& value = flow.getSingleValue();
+    if (value.isNull()) {
       trap("br_on_exn: argument is null");
     }
-    auto ex = flow.getSingleValue().getExceptionPackage();
+    auto ex = value.getExceptionPackage();
     if (curr->event != ex.event) { // Not taken
       return flow;
     }
@@ -1644,7 +1646,6 @@ public:
           return Literal(load128(addr).data());
         case Type::funcref:
         case Type::externref:
-        case Type::nullref:
         case Type::exnref:
         case Type::none:
         case Type::unreachable:
@@ -1701,7 +1702,6 @@ public:
           break;
         case Type::funcref:
         case Type::externref:
-        case Type::nullref:
         case Type::exnref:
         case Type::none:
         case Type::unreachable:
diff --git a/src/wasm-s-parser.h b/src/wasm-s-parser.h
index 6cbef5599..76a60d7d9 100644
--- a/src/wasm-s-parser.h
+++ b/src/wasm-s-parser.h
@@ -160,6 +160,10 @@ private:
   }
   Type
   stringToType(const char* str, bool allowError = false, bool prefix = false);
+  HeapType stringToHeapType(cashew::IString str, bool prefix = false) {
+    return stringToHeapType(str.str, prefix);
+  }
+  HeapType stringToHeapType(const char* str, bool prefix = false);
   Type elementToType(Element& s);
   Type stringToLaneType(const char* str);
   bool isType(cashew::IString str) {
diff --git a/src/wasm-type.h b/src/wasm-type.h
index 135c2e751..384cc589f 100644
--- a/src/wasm-type.h
+++ b/src/wasm-type.h
@@ -49,7 +49,6 @@ public:
     v128,
     funcref,
     externref,
-    nullref,
     exnref,
     _last_basic_id = exnref
   };
@@ -93,7 +92,6 @@ public:
   // │ anyref      ║ x │   │ x │ x │ f? n  │ │ ┐
   // │ eqref       ║ x │   │ x │ x │    n  │ │ │ TODO (GC)
   // │ i31ref      ║ x │   │ x │ x │       │ │ ┘
-  // │ nullref     ║ x │   │ x │ x │ f? n  │ │ ◄ TODO (removed)
   // │ exnref      ║ x │   │ x │ x │    n  │ │
   // ├─ Compound ──╫───┼───┼───┼───┤───────┤ │
   // │ Ref         ║   │ x │ x │ x │ f? n? │◄┘
@@ -110,6 +108,8 @@ public:
   bool isTuple() const;
   bool isSingle() const { return isConcrete() && !isTuple(); }
   bool isRef() const;
+  bool isFunction() const;
+  bool isException() const;
   bool isNullable() const;
   bool isRtt() const;
 
@@ -154,6 +154,9 @@ public:
   // Returns the feature set required to use this type.
   FeatureSet getFeatures() const;
 
+  // Gets the heap type corresponding to this type
+  HeapType getHeapType() const;
+
   // Returns a number type based on its size in bytes and whether it is a float
   // type.
   static Type get(unsigned byteSize, bool float_);
@@ -368,6 +371,7 @@ struct HeapType {
     assert(isArray() && "Not an array");
     return array;
   }
+  bool isException() const { return kind == ExnKind; }
 
   bool operator==(const HeapType& other) const;
   bool operator!=(const HeapType& other) const { return !(*this == other); }
diff --git a/src/wasm.h b/src/wasm.h
index 3d658d367..edcda4219 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -1095,6 +1095,8 @@ public:
   RefNull(MixedArena& allocator) {}
 
   void finalize();
+  void finalize(HeapType heapType);
+  void finalize(Type type);
 };
 
 class RefIsNull : public SpecificExpression<Expression::RefIsNullId> {
diff --git a/src/wasm/literal.cpp b/src/wasm/literal.cpp
index 3f635ca19..ec8642865 100644
--- a/src/wasm/literal.cpp
+++ b/src/wasm/literal.cpp
@@ -29,37 +29,52 @@ namespace wasm {
 
 template<int N> using LaneArray = std::array<Literal, N>;
 
+Literal::Literal(Type type) : type(type) {
+  assert(type != Type::unreachable && (!type.isRef() || type.isNullable()));
+  if (type.isException()) {
+    new (&exn) std::unique_ptr<ExceptionPackage>();
+  } else {
+    memset(&v128, 0, 16);
+  }
+}
+
 Literal::Literal(const uint8_t init[16]) : type(Type::v128) {
   memcpy(&v128, init, 16);
 }
 
 Literal::Literal(const Literal& other) : type(other.type) {
-  TODO_SINGLE_COMPOUND(type);
-  switch (type.getBasic()) {
-    case Type::i32:
-    case Type::f32:
-      i32 = other.i32;
-      break;
-    case Type::i64:
-    case Type::f64:
-      i64 = other.i64;
-      break;
-    case Type::v128:
-      memcpy(&v128, other.v128, 16);
-      break;
-    case Type::funcref:
-      func = other.func;
-      break;
-    case Type::exnref:
-      // Avoid calling the destructor on an uninitialized value
+  if (type.isException()) {
+    // Avoid calling the destructor on an uninitialized value
+    if (other.exn != nullptr) {
       new (&exn) auto(std::make_unique<ExceptionPackage>(*other.exn));
-      break;
-    case Type::none:
-    case Type::nullref:
-      break;
-    case Type::externref:
-    case Type::unreachable:
-      WASM_UNREACHABLE("unexpected type");
+    } else {
+      new (&exn) std::unique_ptr<ExceptionPackage>();
+    }
+  } else if (type.isFunction()) {
+    func = other.func;
+  } else {
+    TODO_SINGLE_COMPOUND(type);
+    switch (type.getBasic()) {
+      case Type::i32:
+      case Type::f32:
+        i32 = other.i32;
+        break;
+      case Type::i64:
+      case Type::f64:
+        i64 = other.i64;
+        break;
+      case Type::v128:
+        memcpy(&v128, other.v128, 16);
+        break;
+      case Type::none:
+        break;
+      case Type::externref:
+        break; // null
+      case Type::funcref:
+      case Type::exnref:
+      case Type::unreachable:
+        WASM_UNREACHABLE("unexpected type");
+    }
   }
 }
 
@@ -116,7 +131,7 @@ Literals Literal::makeZero(Type type) {
 Literal Literal::makeSingleZero(Type type) {
   assert(type.isSingle());
   if (type.isRef()) {
-    return makeNullref();
+    return makeNull(type);
   } else {
     return makeFromInt32(0, type);
   }
@@ -130,8 +145,8 @@ std::array<uint8_t, 16> Literal::getv128() const {
 }
 
 ExceptionPackage Literal::getExceptionPackage() const {
-  assert(type == Type::exnref);
-  return *exn.get();
+  assert(type.isException() && exn != nullptr);
+  return *exn;
 }
 
 Literal Literal::castToF32() {
@@ -199,11 +214,17 @@ void Literal::getBits(uint8_t (&buf)[16]) const {
     case Type::v128:
       memcpy(buf, &v128, sizeof(v128));
       break;
+    // TODO: investigate changing bits returned for reference types. currently,
+    // `null` values and even non-`null` functions return all zeroes, but only
+    // to avoid introducing a functional change.
     case Type::funcref:
-    case Type::nullref:
       break;
     case Type::externref:
     case Type::exnref:
+      if (isNull()) {
+        break;
+      }
+      // falls through
     case Type::none:
     case Type::unreachable:
       WASM_UNREACHABLE("invalid type");
@@ -211,22 +232,22 @@ void Literal::getBits(uint8_t (&buf)[16]) const {
 }
 
 bool Literal::operator==(const Literal& other) const {
-  if (type.isRef() && other.type.isRef()) {
-    if (type == Type::nullref && other.type == Type::nullref) {
-      return true;
-    }
-    if (type == Type::funcref && other.type == Type::funcref &&
-        func == other.func) {
-      return true;
-    }
-    return false;
-  }
   if (type != other.type) {
     return false;
   }
   if (type == Type::none) {
     return true;
   }
+  if (isNull() || other.isNull()) {
+    return isNull() == other.isNull();
+  }
+  if (type.isFunction()) {
+    return func == other.func;
+  }
+  if (type.isException()) {
+    assert(exn != nullptr && other.exn != nullptr);
+    return *exn == *other.exn;
+  }
   uint8_t bits[16], other_bits[16];
   getBits(bits);
   other.getBits(other_bits);
@@ -350,15 +371,23 @@ std::ostream& operator<<(std::ostream& o, Literal literal) {
       literal.printVec128(o, literal.getv128());
       break;
     case Type::funcref:
-      o << "funcref(" << literal.getFunc() << ")";
-      break;
-    case Type::nullref:
-      o << "nullref";
+      if (literal.isNull()) {
+        o << "funcref(null)";
+      } else {
+        o << "funcref(" << literal.getFunc() << ")";
+      }
       break;
     case Type::exnref:
-      o << "exnref(" << literal.getExceptionPackage() << ")";
+      if (literal.isNull()) {
+        o << "exnref(null)";
+      } else {
+        o << "exnref(" << literal.getExceptionPackage() << ")";
+      }
       break;
     case Type::externref:
+      assert(literal.isNull() && "TODO: non-null externref values");
+      o << "externref(null)";
+      break;
     case Type::unreachable:
       WASM_UNREACHABLE("invalid type");
   }
@@ -582,7 +611,6 @@ Literal Literal::eqz() const {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
@@ -604,7 +632,6 @@ Literal Literal::neg() const {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
@@ -626,7 +653,6 @@ Literal Literal::abs() const {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
@@ -731,7 +757,6 @@ Literal Literal::add(const Literal& other) const {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
@@ -753,7 +778,6 @@ Literal Literal::sub(const Literal& other) const {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
@@ -846,7 +870,6 @@ Literal Literal::mul(const Literal& other) const {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
@@ -1100,7 +1123,6 @@ Literal Literal::eq(const Literal& other) const {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
@@ -1122,7 +1144,6 @@ Literal Literal::ne(const Literal& other) const {
     case Type::v128:
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index ae10687fb..b78d6b86b 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -1136,8 +1136,6 @@ Type WasmBinaryBuilder::getType() {
       return Type::funcref;
     case BinaryConsts::EncodedType::externref:
       return Type::externref;
-    case BinaryConsts::EncodedType::nullref:
-      return Type::nullref;
     case BinaryConsts::EncodedType::exnref:
       return Type::exnref;
     default:
@@ -1146,6 +1144,28 @@ Type WasmBinaryBuilder::getType() {
   WASM_UNREACHABLE("unexpeced type");
 }
 
+HeapType WasmBinaryBuilder::getHeapType() {
+  int type = getS32LEB(); // TODO: Actually encoded as s33
+  // Single heap types are negative; heap type indices are non-negative
+  if (type >= 0) {
+    if (size_t(type) >= signatures.size()) {
+      throwError("invalid signature index: " + std::to_string(type));
+    }
+    return HeapType(signatures[type]);
+  }
+  switch (type) {
+    case BinaryConsts::EncodedHeapType::func:
+      return HeapType::FuncKind;
+    case BinaryConsts::EncodedHeapType::extern_:
+      return HeapType::ExternKind;
+    case BinaryConsts::EncodedHeapType::exn:
+      return HeapType::ExnKind;
+    default:
+      throwError("invalid wasm heap type: " + std::to_string(type));
+  }
+  WASM_UNREACHABLE("unexpeced type");
+}
+
 Type WasmBinaryBuilder::getConcreteType() {
   auto type = getType();
   if (!type.isConcrete()) {
@@ -4689,7 +4709,7 @@ void WasmBinaryBuilder::visitDrop(Drop* curr) {
 
 void WasmBinaryBuilder::visitRefNull(RefNull* curr) {
   BYN_TRACE("zz node: RefNull\n");
-  curr->finalize();
+  curr->finalize(getHeapType());
 }
 
 void WasmBinaryBuilder::visitRefIsNull(RefIsNull* curr) {
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 931cd1bf0..0e4202a24 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -869,9 +869,6 @@ Type SExpressionWasmBuilder::stringToType(const char* str,
   if (strncmp(str, "externref", 9) == 0 && (prefix || str[9] == 0)) {
     return Type::externref;
   }
-  if (strncmp(str, "nullref", 7) == 0 && (prefix || str[7] == 0)) {
-    return Type::nullref;
-  }
   if (strncmp(str, "exnref", 6) == 0 && (prefix || str[6] == 0)) {
     return Type::exnref;
   }
@@ -881,6 +878,41 @@ Type SExpressionWasmBuilder::stringToType(const char* str,
   throw ParseException(std::string("invalid wasm type: ") + str);
 }
 
+HeapType SExpressionWasmBuilder::stringToHeapType(const char* str,
+                                                  bool prefix) {
+  if (str[0] == 'a') {
+    if (str[1] == 'n' && str[2] == 'y' && (prefix || str[3] == 0)) {
+      return HeapType::AnyKind;
+    }
+  }
+  if (str[0] == 'e') {
+    if (str[1] == 'q' && (prefix || str[2] == 0)) {
+      return HeapType::EqKind;
+    }
+    if (str[1] == 'x') {
+      if (str[2] == 'n' && (prefix || str[3] == 0)) {
+        return HeapType::ExnKind;
+      }
+      if (str[2] == 't' && str[3] == 'e' && str[4] == 'r' && str[5] == 'n' &&
+          (prefix || str[6] == 0)) {
+        return HeapType::ExternKind;
+      }
+    }
+  }
+  if (str[0] == 'i') {
+    if (str[1] == '3' && str[2] == '1' && (prefix || str[3] == 0)) {
+      return HeapType::I31Kind;
+    }
+  }
+  if (str[0] == 'f') {
+    if (str[1] == 'u' && str[2] == 'n' && str[3] == 'c' &&
+        (prefix || str[4] == 0)) {
+      return HeapType::FuncKind;
+    }
+  }
+  throw ParseException(std::string("invalid wasm heap type: ") + str);
+}
+
 Type SExpressionWasmBuilder::elementToType(Element& s) {
   if (s.isStr()) {
     return stringToType(s.str(), false, false);
@@ -1779,8 +1811,12 @@ Expression* SExpressionWasmBuilder::makeReturn(Element& s) {
 }
 
 Expression* SExpressionWasmBuilder::makeRefNull(Element& s) {
+  if (s.size() != 2) {
+    throw ParseException("invalid heap type reference", s.line, s.col);
+  }
+  auto heapType = stringToHeapType(s[1]->str());
   auto ret = allocator.alloc<RefNull>();
-  ret->finalize();
+  ret->finalize(heapType);
   return ret;
 }
 
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 88f90378c..aee5079c2 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -190,7 +190,6 @@ void BinaryInstWriter::visitLoad(Load* curr) {
         return;
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
       case Type::none:
         WASM_UNREACHABLE("unexpected type");
@@ -292,7 +291,6 @@ void BinaryInstWriter::visitStore(Store* curr) {
         break;
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
       case Type::none:
       case Type::unreachable:
@@ -695,7 +693,6 @@ void BinaryInstWriter::visitConst(Const* curr) {
     }
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
     case Type::unreachable:
@@ -1686,7 +1683,8 @@ void BinaryInstWriter::visitHost(Host* curr) {
 }
 
 void BinaryInstWriter::visitRefNull(RefNull* curr) {
-  o << int8_t(BinaryConsts::RefNull);
+  o << int8_t(BinaryConsts::RefNull)
+    << binaryHeapType(curr->type.getHeapType());
 }
 
 void BinaryInstWriter::visitRefIsNull(RefIsNull* curr) {
diff --git a/src/wasm/wasm-type.cpp b/src/wasm/wasm-type.cpp
index e46cb5886..729cc88f5 100644
--- a/src/wasm/wasm-type.cpp
+++ b/src/wasm/wasm-type.cpp
@@ -260,7 +260,6 @@ std::unordered_map<TypeInfo, uintptr_t> indices = {
   // * `(ref null any) == anyref`
   // * `(ref null eq) == eqref`
   // * `(ref i31) == i31ref`
-  {TypeInfo({Type::nullref}), Type::nullref}, // TODO (removed)
   {TypeInfo({Type::exnref}), Type::exnref},
   {TypeInfo(HeapType(HeapType::ExnKind), true), Type::exnref},
 };
@@ -347,6 +346,24 @@ bool Type::isRef() const {
   }
 }
 
+bool Type::isFunction() const {
+  if (isBasic()) {
+    return id == funcref;
+  } else {
+    auto* info = getTypeInfo(*this);
+    return info->isRef() && info->ref.heapType.isSignature();
+  }
+}
+
+bool Type::isException() const {
+  if (isBasic()) {
+    return id == exnref;
+  } else {
+    auto* info = getTypeInfo(*this);
+    return info->isRef() && info->ref.heapType.isException();
+  }
+}
+
 bool Type::isNullable() const {
   if (isBasic()) {
     return id >= funcref && id <= exnref;
@@ -389,7 +406,6 @@ unsigned Type::getByteSize() const {
         return 16;
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
       case Type::exnref:
       case Type::none:
       case Type::unreachable:
@@ -432,7 +448,6 @@ FeatureSet Type::getFeatures() const {
         return FeatureSet::SIMD;
       case Type::funcref:
       case Type::externref:
-      case Type::nullref:
         return FeatureSet::ReferenceTypes;
       case Type::exnref:
         return FeatureSet::ReferenceTypes | FeatureSet::ExceptionHandling;
@@ -451,6 +466,25 @@ FeatureSet Type::getFeatures() const {
   return getSingleFeatures(*this);
 }
 
+HeapType Type::getHeapType() const {
+  if (isRef()) {
+    if (isCompound()) {
+      return getTypeInfo(*this)->ref.heapType;
+    }
+    switch (getBasic()) {
+      case funcref:
+        return HeapType::FuncKind;
+      case externref:
+        return HeapType::ExternKind;
+      case exnref:
+        return HeapType::ExnKind;
+      default:
+        break;
+    }
+  }
+  WASM_UNREACHABLE("unexpected type");
+}
+
 Type Type::get(unsigned byteSize, bool float_) {
   if (byteSize < 4) {
     return Type::i32;
@@ -468,13 +502,10 @@ Type Type::get(unsigned byteSize, bool float_) {
 }
 
 bool Type::isSubType(Type left, Type right) {
+  // TODO (GC): subtyping, currently checks for equality only
   if (left == right) {
     return true;
   }
-  if (left.isRef() && right.isRef() &&
-      (right == Type::externref || left == Type::nullref)) {
-    return true;
-  }
   if (left.isTuple() && right.isTuple()) {
     if (left.size() != right.size()) {
       return false;
@@ -513,16 +544,7 @@ Type Type::getLeastUpperBound(Type a, Type b) {
     }
     return Type(types);
   }
-  if (!a.isRef() || !b.isRef()) {
-    return Type::none;
-  }
-  if (a == Type::nullref) {
-    return b;
-  }
-  if (b == Type::nullref) {
-    return a;
-  }
-  return Type::externref;
+  return Type::none;
 }
 
 Type::Iterator Type::end() const {
@@ -554,8 +576,7 @@ const Type& Type::operator[](size_t index) const {
   }
 }
 
-HeapType::HeapType(const HeapType& other) {
-  kind = other.kind;
+HeapType::HeapType(const HeapType& other) : kind(other.kind) {
   switch (kind) {
     case FuncKind:
     case ExternKind:
@@ -708,9 +729,6 @@ std::ostream& operator<<(std::ostream& os, Type type) {
       case Type::externref:
         os << "externref";
         break;
-      case Type::nullref:
-        os << "nullref";
-        break;
       case Type::exnref:
         os << "exnref";
         break;
diff --git a/src/wasm/wasm-validator.cpp b/src/wasm/wasm-validator.cpp
index 3e1a057ce..b236f9120 100644
--- a/src/wasm/wasm-validator.cpp
+++ b/src/wasm/wasm-validator.cpp
@@ -1264,7 +1264,6 @@ void FunctionValidator::validateMemBytes(uint8_t bytes,
       break;
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
       WASM_UNREACHABLE("unexpected type");
@@ -2074,7 +2073,6 @@ void FunctionValidator::validateAlignment(
       break;
     case Type::funcref:
     case Type::externref:
-    case Type::nullref:
     case Type::exnref:
     case Type::none:
       WASM_UNREACHABLE("invalid type");
diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index 387ea577f..fe7c1b229 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -209,10 +209,10 @@ const char* getExpressionName(Expression* curr) {
 Literal getSingleLiteralFromConstExpression(Expression* curr) {
   if (auto* c = curr->dynCast<Const>()) {
     return c->value;
-  } else if (curr->is<RefNull>()) {
-    return Literal::makeNullref();
+  } else if (auto* n = curr->dynCast<RefNull>()) {
+    return Literal::makeNull(n->type);
   } else if (auto* r = curr->dynCast<RefFunc>()) {
-    return Literal::makeFuncref(r->func);
+    return Literal::makeFunc(r->func);
   } else {
     WASM_UNREACHABLE("Not a constant expression");
   }
@@ -896,7 +896,16 @@ void Host::finalize() {
   }
 }
 
-void RefNull::finalize() { type = Type::nullref; }
+void RefNull::finalize(HeapType heapType) { type = Type(heapType, true); }
+
+void RefNull::finalize(Type type_) {
+  assert(type_ == Type::unreachable || type_.isNullable());
+  type = type_;
+}
+
+void RefNull::finalize() {
+  assert(type == Type::unreachable || type.isNullable());
+}
 
 void RefIsNull::finalize() {
   if (value->type == Type::unreachable) {
diff --git a/test/binaryen.js/exception-handling.js.txt b/test/binaryen.js/exception-handling.js.txt
index 380ce34d6..d590d0b4b 100644
--- a/test/binaryen.js/exception-handling.js.txt
+++ b/test/binaryen.js/exception-handling.js.txt
@@ -29,6 +29,6 @@
 )
 
 getExpressionInfo(throw) = {"id":43,"type":1,"event":"e"}
-getExpressionInfo(br_on_exn) = {"id":45,"type":10,"name":"l","event":"e"}
+getExpressionInfo(br_on_exn) = {"id":45,"type":9,"name":"l","event":"e"}
 getExpressionInfo(rethrow) = {"id":44,"type":1}
 getExpressionInfo(try) = {"id":42,"type":0}
diff --git a/test/binaryen.js/kitchen-sink.js b/test/binaryen.js/kitchen-sink.js
index 93ed27334..e82090858 100644
--- a/test/binaryen.js/kitchen-sink.js
+++ b/test/binaryen.js/kitchen-sink.js
@@ -48,44 +48,47 @@ function makeDroppedInt32(x) {
 
 function test_types() {
   console.log("  // BinaryenTypeNone: " + binaryen.none);
-  console.log("  //", binaryen.expandType(binaryen.none));
+  console.log("  //", binaryen.expandType(binaryen.none).join(","));
 
   console.log("  // BinaryenTypeUnreachable: " + binaryen.unreachable);
-  console.log("  //", binaryen.expandType(binaryen.unreachable));
+  console.log("  //", binaryen.expandType(binaryen.unreachable).join(","));
 
   console.log("  // BinaryenTypeInt32: " + binaryen.i32);
-  console.log("  //", binaryen.expandType(binaryen.i32));
+  console.log("  //", binaryen.expandType(binaryen.i32).join(","));
 
   console.log("  // BinaryenTypeInt64: " + binaryen.i64);
-  console.log("  //", binaryen.expandType(binaryen.i64));
+  console.log("  //", binaryen.expandType(binaryen.i64).join(","));
 
   console.log("  // BinaryenTypeFloat32: " + binaryen.f32);
-  console.log("  //", binaryen.expandType(binaryen.f32));
+  console.log("  //", binaryen.expandType(binaryen.f32).join(","));
 
   console.log("  // BinaryenTypeFloat64: " + binaryen.f64);
-  console.log("  //", binaryen.expandType(binaryen.f64));
+  console.log("  //", binaryen.expandType(binaryen.f64).join(","));
 
   console.log("  // BinaryenTypeVec128: " + binaryen.v128);
-  console.log("  //", binaryen.expandType(binaryen.v128));
+  console.log("  //", binaryen.expandType(binaryen.v128).join(","));
+
+  console.log("  // BinaryenTypeFuncref: " + binaryen.funcref);
+  console.log("  //", binaryen.expandType(binaryen.funcref).join(","));
 
   console.log("  // BinaryenTypeExternref: " + binaryen.externref);
-  console.log("  //", binaryen.expandType(binaryen.externref));
+  console.log("  //", binaryen.expandType(binaryen.externref).join(","));
 
   console.log("  // BinaryenTypeExnref: " + binaryen.exnref);
-  console.log("  //", binaryen.expandType(binaryen.exnref));
+  console.log("  //", binaryen.expandType(binaryen.exnref).join(","));
 
   console.log("  // BinaryenTypeAuto: " + binaryen.auto);
 
   var i32_pair = binaryen.createType([binaryen.i32, binaryen.i32]);
-  console.log("  //", binaryen.expandType(i32_pair));
+  console.log("  //", binaryen.expandType(i32_pair).join(","));
 
   var duplicate_pair = binaryen.createType([binaryen.i32, binaryen.i32]);
-  console.log("  //", binaryen.expandType(duplicate_pair));
+  console.log("  //", binaryen.expandType(duplicate_pair).join(","));
 
   assert(i32_pair == duplicate_pair);
 
   var f32_pair = binaryen.createType([binaryen.f32, binaryen.f32]);
-  console.log("  //", binaryen.expandType(f32_pair));
+  console.log("  //", binaryen.expandType(f32_pair).join(","));
 }
 
 function test_features() {
@@ -502,9 +505,10 @@ function test_core() {
     module.return_call_indirect(makeInt32(2449), [ makeInt32(13), makeInt64(37, 0), makeFloat32(1.3), makeFloat64(3.7) ], iIfF, binaryen.i32),
 
     // Reference types
-    module.ref.is_null(module.ref.null()),
+    module.ref.is_null(module.ref.null(binaryen.externref)),
+    module.ref.is_null(module.ref.null(binaryen.funcref)),
     module.ref.is_null(module.ref.func("kitchen()sinker")),
-    module.select(temp10, module.ref.null(), module.ref.func("kitchen()sinker"), binaryen.funcref),
+    module.select(temp10, module.ref.null(binaryen.funcref), module.ref.func("kitchen()sinker"), binaryen.funcref),
 
     // Exception handling
     module.try(
@@ -563,7 +567,6 @@ function test_core() {
     module.v128.pop(),
     module.externref.pop(),
     module.funcref.pop(),
-    module.nullref.pop(),
     module.exnref.pop(),
     // TODO: Host
     module.nop(),
diff --git a/test/binaryen.js/kitchen-sink.js.txt b/test/binaryen.js/kitchen-sink.js.txt
index c58f1f563..917525eeb 100644
--- a/test/binaryen.js/kitchen-sink.js.txt
+++ b/test/binaryen.js/kitchen-sink.js.txt
@@ -1,25 +1,27 @@
   // BinaryenTypeNone: 0
-  // []
+  // 
   // BinaryenTypeUnreachable: 1
-  // [ 1 ]
+  // 1
   // BinaryenTypeInt32: 2
-  // [ 2 ]
+  // 2
   // BinaryenTypeInt64: 3
-  // [ 3 ]
+  // 3
   // BinaryenTypeFloat32: 4
-  // [ 4 ]
+  // 4
   // BinaryenTypeFloat64: 5
-  // [ 5 ]
+  // 5
   // BinaryenTypeVec128: 6
-  // [ 6 ]
+  // 6
+  // BinaryenTypeFuncref: 7
+  // 7
   // BinaryenTypeExternref: 8
-  // [ 8 ]
-  // BinaryenTypeExnref: 10
-  // [ 10 ]
+  // 8
+  // BinaryenTypeExnref: 9
+  // 9
   // BinaryenTypeAuto: -1
-  // [ 2, 2 ]
-  // [ 2, 2 ]
-  // [ 4, 4 ]
+  // 2,2
+  // 2,2
+  // 4,4
 Features.MVP: 0
 Features.Atomics: 1
 Features.BulkMemory: 16
@@ -1811,7 +1813,12 @@ getExpressionInfo(tuple[3])={"id":14,"type":5,"value":3.7}
       )
       (drop
        (ref.is_null
-        (ref.null)
+        (ref.null extern)
+       )
+      )
+      (drop
+       (ref.is_null
+        (ref.null func)
        )
       )
       (drop
@@ -1821,7 +1828,7 @@ getExpressionInfo(tuple[3])={"id":14,"type":5,"value":3.7}
       )
       (drop
        (select (result funcref)
-        (ref.null)
+        (ref.null func)
         (ref.func "$kitchen()sinker")
         (i32.const 1)
        )
@@ -1907,9 +1914,6 @@ getExpressionInfo(tuple[3])={"id":14,"type":5,"value":3.7}
        (funcref.pop)
       )
       (drop
-       (nullref.pop)
-      )
-      (drop
        (exnref.pop)
       )
       (nop)
@@ -3649,7 +3653,12 @@ getExpressionInfo(tuple[3])={"id":14,"type":5,"value":3.7}
       )
       (drop
        (ref.is_null
-        (ref.null)
+        (ref.null extern)
+       )
+      )
+      (drop
+       (ref.is_null
+        (ref.null func)
        )
       )
       (drop
@@ -3659,7 +3668,7 @@ getExpressionInfo(tuple[3])={"id":14,"type":5,"value":3.7}
       )
       (drop
        (select (result funcref)
-        (ref.null)
+        (ref.null func)
         (ref.func "$kitchen()sinker")
         (i32.const 1)
        )
@@ -3745,9 +3754,6 @@ getExpressionInfo(tuple[3])={"id":14,"type":5,"value":3.7}
        (funcref.pop)
       )
       (drop
-       (nullref.pop)
-      )
-      (drop
        (exnref.pop)
       )
       (nop)
diff --git a/test/ctor-eval/bad-indirect-call3.wast b/test/ctor-eval/bad-indirect-call3.wast
index cadff8097..7a16889ce 100644
--- a/test/ctor-eval/bad-indirect-call3.wast
+++ b/test/ctor-eval/bad-indirect-call3.wast
@@ -9,7 +9,7 @@
   )
   (func $sig_mismatch
     (call_indirect (type $funcref_=>_none) ;; unsafe to call, signature mismatch
-      (ref.null)
+      (ref.null func)
       (i32.const 0)
     )
   )
diff --git a/test/ctor-eval/bad-indirect-call3.wast.out b/test/ctor-eval/bad-indirect-call3.wast.out
index 9e4881344..28a7c5ed5 100644
--- a/test/ctor-eval/bad-indirect-call3.wast.out
+++ b/test/ctor-eval/bad-indirect-call3.wast.out
@@ -15,7 +15,7 @@
  )
  (func $sig_mismatch
   (call_indirect (type $funcref_=>_none)
-   (ref.null)
+   (ref.null func)
    (i32.const 0)
   )
  )
diff --git a/test/example/c-api-kitchen-sink.c b/test/example/c-api-kitchen-sink.c
index b1dbae7d5..b0a3ad302 100644
--- a/test/example/c-api-kitchen-sink.c
+++ b/test/example/c-api-kitchen-sink.c
@@ -205,12 +205,6 @@ void test_types() {
   BinaryenTypeExpand(externref, &valueType);
   assert(valueType == externref);
 
-  BinaryenType nullref = BinaryenTypeNullref();
-  printf("  // BinaryenTypeNullref: %d\n", nullref);
-  assert(BinaryenTypeArity(nullref) == 1);
-  BinaryenTypeExpand(nullref, &valueType);
-  assert(valueType == nullref);
-
   BinaryenType exnref = BinaryenTypeExnref();
   printf("  // BinaryenTypeExnref: %d\n", exnref);
   assert(BinaryenTypeArity(exnref) == 1);
@@ -294,9 +288,10 @@ void test_core() {
                         temp10 = makeInt32(module, 1), temp11 = makeInt32(module, 3), temp12 = makeInt32(module, 5),
                         temp13 = makeInt32(module, 10), temp14 = makeInt32(module, 11),
                         temp15 = makeInt32(module, 110), temp16 = makeInt64(module, 111);
-  BinaryenExpressionRef nullrefExpr = BinaryenRefNull(module);
-  BinaryenExpressionRef funcrefExpr =
-    BinaryenRefFunc(module, "kitchen()sinker");
+  BinaryenExpressionRef externrefExpr = BinaryenRefNull(module, BinaryenTypeExternref());
+  BinaryenExpressionRef funcrefExpr = BinaryenRefNull(module, BinaryenTypeFuncref());
+  funcrefExpr = BinaryenRefFunc(module, "kitchen()sinker");
+  BinaryenExpressionRef exnrefExpr = BinaryenRefNull(module, BinaryenTypeExnref());
 
   // Events
   BinaryenAddEvent(
@@ -718,10 +713,11 @@ void test_core() {
                                iIfF,
                                BinaryenTypeInt32()),
     // Reference types
-    BinaryenRefIsNull(module, nullrefExpr),
+    BinaryenRefIsNull(module, externrefExpr),
     BinaryenRefIsNull(module, funcrefExpr),
+    BinaryenRefIsNull(module, exnrefExpr),
     BinaryenSelect(
-      module, temp10, nullrefExpr, funcrefExpr, BinaryenTypeFuncref()),
+      module, temp10, BinaryenRefNull(module, BinaryenTypeFuncref()), BinaryenRefFunc(module, "kitchen()sinker"), BinaryenTypeFuncref()),
     // Exception handling
     BinaryenTry(module, tryBody, catchBody),
     // Atomics
@@ -748,10 +744,6 @@ void test_core() {
     BinaryenPop(module, BinaryenTypeFloat64()),
     BinaryenPop(module, BinaryenTypeFuncref()),
     BinaryenPop(module, BinaryenTypeExternref()),
-    BinaryenPop(module, BinaryenTypeNullref()),
-    BinaryenPop(module, BinaryenTypeExnref()),
-    BinaryenPop(module, BinaryenTypeFuncref()),
-    BinaryenPop(module, BinaryenTypeNullref()),
     BinaryenPop(module, BinaryenTypeExnref()),
 
     // TODO: Host
diff --git a/test/example/c-api-kitchen-sink.txt b/test/example/c-api-kitchen-sink.txt
index b0aae7f3b..288174b99 100644
--- a/test/example/c-api-kitchen-sink.txt
+++ b/test/example/c-api-kitchen-sink.txt
@@ -7,8 +7,7 @@
   // BinaryenTypeVec128: 6
   // BinaryenTypeFuncref: 7
   // BinaryenTypeExternref: 8
-  // BinaryenTypeNullref: 9
-  // BinaryenTypeExnref: 10
+  // BinaryenTypeExnref: 9
   // BinaryenTypeAuto: -1
 BinaryenFeatureMVP: 0
 BinaryenFeatureAtomics: 1
@@ -1753,7 +1752,7 @@ BinaryenFeatureAll: 1023
       )
       (drop
        (ref.is_null
-        (ref.null)
+        (ref.null extern)
        )
       )
       (drop
@@ -1762,8 +1761,13 @@ BinaryenFeatureAll: 1023
        )
       )
       (drop
+       (ref.is_null
+        (ref.null exn)
+       )
+      )
+      (drop
        (select (result funcref)
-        (ref.null)
+        (ref.null func)
         (ref.func "$kitchen()sinker")
         (i32.const 1)
        )
@@ -1846,18 +1850,6 @@ BinaryenFeatureAll: 1023
        (externref.pop)
       )
       (drop
-       (nullref.pop)
-      )
-      (drop
-       (exnref.pop)
-      )
-      (drop
-       (funcref.pop)
-      )
-      (drop
-       (nullref.pop)
-      )
-      (drop
        (exnref.pop)
       )
       (nop)
diff --git a/test/exception-handling.wast b/test/exception-handling.wast
index 7f16a237b..3dcff41e4 100644
--- a/test/exception-handling.wast
+++ b/test/exception-handling.wast
@@ -59,23 +59,4 @@
       )
     )
   )
-
-  ;; Test subtype relationship
-  (func $subtype_test
-    (try
-      (do)
-      (catch
-        (drop (exnref.pop))
-        (drop
-          (block $l0 (result i32)
-            (rethrow
-              (br_on_exn $l0 $e0 (ref.null))
-            )
-          )
-        )
-      )
-    )
-
-    (throw $e1 (ref.null))
-  )
 )
diff --git a/test/exception-handling.wast.from-wast b/test/exception-handling.wast.from-wast
index 4430bf0f0..a5fb02d56 100644
--- a/test/exception-handling.wast.from-wast
+++ b/test/exception-handling.wast.from-wast
@@ -71,28 +71,4 @@
    )
   )
  )
- (func $subtype_test
-  (try
-   (do
-    (nop)
-   )
-   (catch
-    (drop
-     (exnref.pop)
-    )
-    (drop
-     (block $l0 (result i32)
-      (rethrow
-       (br_on_exn $l0 $e0
-        (ref.null)
-       )
-      )
-     )
-    )
-   )
-  )
-  (throw $e1
-   (ref.null)
-  )
- )
 )
diff --git a/test/exception-handling.wast.fromBinary b/test/exception-handling.wast.fromBinary
index fc3dc3804..24af9294e 100644
--- a/test/exception-handling.wast.fromBinary
+++ b/test/exception-handling.wast.fromBinary
@@ -74,29 +74,5 @@
    )
   )
  )
- (func $subtype_test
-  (try
-   (do
-    (nop)
-   )
-   (catch
-    (drop
-     (exnref.pop)
-    )
-    (drop
-     (block $label$3 (result i32)
-      (rethrow
-       (br_on_exn $label$3 $event$0
-        (ref.null)
-       )
-      )
-     )
-    )
-   )
-  )
-  (throw $event$1
-   (ref.null)
-  )
- )
 )
 
diff --git a/test/exception-handling.wast.fromBinary.noDebugInfo b/test/exception-handling.wast.fromBinary.noDebugInfo
index 96cc9c4c6..69abafdbf 100644
--- a/test/exception-handling.wast.fromBinary.noDebugInfo
+++ b/test/exception-handling.wast.fromBinary.noDebugInfo
@@ -74,29 +74,5 @@
    )
   )
  )
- (func $4
-  (try
-   (do
-    (nop)
-   )
-   (catch
-    (drop
-     (exnref.pop)
-    )
-    (drop
-     (block $label$3 (result i32)
-      (rethrow
-       (br_on_exn $label$3 $event$0
-        (ref.null)
-       )
-      )
-     )
-    )
-   )
-  )
-  (throw $event$1
-   (ref.null)
-  )
- )
 )
 
diff --git a/test/multivalue.wast b/test/multivalue.wast
index 01e1237f3..8b0c5664e 100644
--- a/test/multivalue.wast
+++ b/test/multivalue.wast
@@ -129,17 +129,17 @@
   )
  )
  (func $mv-if (result i32 i64 externref)
-  (if (result i32 i64 nullref)
+  (if (result i32 i64 externref)
    (i32.const 1)
    (tuple.make
     (i32.const 42)
     (i64.const 42)
-    (ref.null)
+    (ref.null extern)
    )
    (tuple.make
     (i32.const 42)
     (i64.const 42)
-    (ref.null)
+    (ref.null extern)
    )
   )
  )
diff --git a/test/multivalue.wast.from-wast b/test/multivalue.wast.from-wast
index db0a4b2d0..64449925c 100644
--- a/test/multivalue.wast.from-wast
+++ b/test/multivalue.wast.from-wast
@@ -1,12 +1,11 @@
 (module
  (type $none_=>_i32_i64 (func (result i32 i64)))
  (type $none_=>_none (func))
+ (type $none_=>_i32_i64_externref (func (result i32 i64 externref)))
  (type $none_=>_i64 (func (result i64)))
  (type $none_=>_f32_i64_i32 (func (result f32 i64 i32)))
  (type $none_=>_i32 (func (result i32)))
  (type $none_=>_i32_i64_f32 (func (result i32 i64 f32)))
- (type $none_=>_i32_i64_externref (func (result i32 i64 externref)))
- (type $none_=>_i32_i64_nullref (func (result i32 i64 nullref)))
  (type $none_=>_f32 (func (result f32)))
  (import "env" "pair" (func $pair (result i32 i64)))
  (global $g1 (mut (i32 i64)) (tuple.make
@@ -137,17 +136,17 @@
   )
  )
  (func $mv-if (result i32 i64 externref)
-  (if (result i32 i64 nullref)
+  (if (result i32 i64 externref)
    (i32.const 1)
    (tuple.make
     (i32.const 42)
     (i64.const 42)
-    (ref.null)
+    (ref.null extern)
    )
    (tuple.make
     (i32.const 42)
     (i64.const 42)
-    (ref.null)
+    (ref.null extern)
    )
   )
  )
diff --git a/test/multivalue.wast.fromBinary b/test/multivalue.wast.fromBinary
index 190194fcf..f4a8e20b7 100644
--- a/test/multivalue.wast.fromBinary
+++ b/test/multivalue.wast.fromBinary
@@ -6,7 +6,6 @@
  (type $none_=>_f32_i64_i32 (func (result f32 i64 i32)))
  (type $none_=>_i32 (func (result i32)))
  (type $none_=>_i32_i64_f32 (func (result i32 i64 f32)))
- (type $none_=>_i32_i64_nullref (func (result i32 i64 nullref)))
  (type $none_=>_f32 (func (result f32)))
  (import "env" "pair" (func $pair (result i32 i64)))
  (global $global$0 (mut i32) (i32.const 0))
@@ -391,19 +390,19 @@
   )
  )
  (func $mv-if (result i32 i64 externref)
-  (local $0 (i32 i64 nullref))
+  (local $0 (i32 i64 externref))
   (local.set $0
-   (if (result i32 i64 nullref)
+   (if (result i32 i64 externref)
     (i32.const 1)
     (tuple.make
      (i32.const 42)
      (i64.const 42)
-     (ref.null)
+     (ref.null extern)
     )
     (tuple.make
      (i32.const 42)
      (i64.const 42)
-     (ref.null)
+     (ref.null extern)
     )
    )
   )
diff --git a/test/multivalue.wast.fromBinary.noDebugInfo b/test/multivalue.wast.fromBinary.noDebugInfo
index 226490f26..106e7c436 100644
--- a/test/multivalue.wast.fromBinary.noDebugInfo
+++ b/test/multivalue.wast.fromBinary.noDebugInfo
@@ -6,7 +6,6 @@
  (type $none_=>_f32_i64_i32 (func (result f32 i64 i32)))
  (type $none_=>_i32 (func (result i32)))
  (type $none_=>_i32_i64_f32 (func (result i32 i64 f32)))
- (type $none_=>_i32_i64_nullref (func (result i32 i64 nullref)))
  (type $none_=>_f32 (func (result f32)))
  (import "env" "pair" (func $fimport$0 (result i32 i64)))
  (global $global$0 (mut i32) (i32.const 0))
@@ -391,19 +390,19 @@
   )
  )
  (func $14 (result i32 i64 externref)
-  (local $0 (i32 i64 nullref))
+  (local $0 (i32 i64 externref))
   (local.set $0
-   (if (result i32 i64 nullref)
+   (if (result i32 i64 externref)
     (i32.const 1)
     (tuple.make
      (i32.const 42)
      (i64.const 42)
-     (ref.null)
+     (ref.null extern)
     )
     (tuple.make
      (i32.const 42)
      (i64.const 42)
-     (ref.null)
+     (ref.null extern)
     )
    )
   )
diff --git a/test/passes/dce_all-features.txt b/test/passes/dce_all-features.txt
index 59f32f1be..c5094b301 100644
--- a/test/passes/dce_all-features.txt
+++ b/test/passes/dce_all-features.txt
@@ -547,7 +547,7 @@
  )
  (func $rethrow
   (rethrow
-   (ref.null)
+   (ref.null exn)
   )
  )
 )
diff --git a/test/passes/dce_all-features.wast b/test/passes/dce_all-features.wast
index 77e781097..78324b941 100644
--- a/test/passes/dce_all-features.wast
+++ b/test/passes/dce_all-features.wast
@@ -779,7 +779,7 @@
 
   (func $throw
     (drop
-      (block $label$0 (result nullref)
+      (block $label$0 (result externref)
         (if
           (i32.clz
             (block $label$1 (result i32)
@@ -788,25 +788,25 @@
           )
           (nop)
         )
-        (ref.null)
+        (ref.null extern)
       )
     )
   )
 
   (func $rethrow
     (drop
-      (block $label$0 (result nullref)
+      (block $label$0 (result externref)
         (if
           (i32.clz
             (block $label$1 (result i32)
               (rethrow
-                (ref.null)
+                (ref.null exn)
               )
             )
           )
           (nop)
         )
-        (ref.null)
+        (ref.null extern)
       )
     )
   )
diff --git a/test/passes/flatten_all-features.txt b/test/passes/flatten_all-features.txt
index e52f9e826..896dc4ed0 100644
--- a/test/passes/flatten_all-features.txt
+++ b/test/passes/flatten_all-features.txt
@@ -5,7 +5,6 @@
  (type $i32_=>_i32 (func (param i32) (result i32)))
  (type $none_=>_f32 (func (result f32)))
  (type $i64_i64_=>_i64 (func (param i64 i64) (result i64)))
- (type $none_=>_externref (func (result externref)))
  (memory $0 10)
  (table $0 1 1 funcref)
  (elem (i32.const 0) $call-me)
@@ -2376,53 +2375,6 @@
   )
   (unreachable)
  )
- (func $subtype (result externref)
-  (local $0 nullref)
-  (local $1 externref)
-  (local $2 nullref)
-  (local $3 nullref)
-  (local $4 nullref)
-  (local $5 nullref)
-  (local $6 nullref)
-  (local $7 externref)
-  (block $label0
-   (block $block
-    (local.set $1
-     (ref.null)
-    )
-    (local.set $2
-     (ref.null)
-    )
-    (br_if $label0
-     (i32.const 0)
-    )
-    (local.set $3
-     (local.get $2)
-    )
-    (local.set $0
-     (local.get $3)
-    )
-    (local.set $4
-     (local.get $0)
-    )
-    (local.set $5
-     (local.get $4)
-    )
-   )
-   (local.set $6
-    (local.get $5)
-   )
-   (local.set $1
-    (local.get $6)
-   )
-  )
-  (local.set $7
-   (local.get $1)
-  )
-  (return
-   (local.get $7)
-  )
- )
 )
 (module
  (type $i64_f32_=>_none (func (param i64 f32)))
diff --git a/test/passes/flatten_all-features.wast b/test/passes/flatten_all-features.wast
index f07175bd2..68bd7a64b 100644
--- a/test/passes/flatten_all-features.wast
+++ b/test/passes/flatten_all-features.wast
@@ -1020,6 +1020,7 @@
     (return (i32.sub (i32.const 1) (i32.const 2)))
   )
 
+  ;; TODO (GC)
   ;; subtypes
 
   ;; br_if leaves a value on the stack if not taken, which later can be the last
@@ -1027,18 +1028,19 @@
   ;; targets an outer branch whose return type is a supertype of the br_if's
   ;; value type, we need the value to be set into two locals: one with the outer
   ;; block's type, and one with its value type.
-  (func $subtype (result externref) (local $0 nullref)
-    (block $label0 (result externref)
-      (block (result nullref)
-        (local.tee $0
-          (br_if $label0
-            (ref.null)
-            (i32.const 0)
-          )
-        )
-      )
-    )
-  )
+  ;; (func $subtype (result externref)
+  ;;   (local $0 anyref)
+  ;;   (block $label0 (result externref)
+  ;;     (block (result anyref)
+  ;;       (local.tee $0
+  ;;         (br_if $label0
+  ;;           (ref.null extern)
+  ;;           (i32.const 0)
+  ;;         )
+  ;;       )
+  ;;     )
+  ;;   )
+  ;; )
 )
 (module
  (func $0 (param $0 i64) (param $1 f32)
diff --git a/test/passes/flatten_local-cse_all-features.txt b/test/passes/flatten_local-cse_all-features.txt
index 5f3adace7..201a6f793 100644
--- a/test/passes/flatten_local-cse_all-features.txt
+++ b/test/passes/flatten_local-cse_all-features.txt
@@ -764,52 +764,3 @@
   )
  )
 )
-(module
- (type $none_=>_none (func))
- (type $none_=>_funcref (func (result funcref)))
- (func $subtype-test (result funcref)
-  (local $0 nullref)
-  (local $1 nullref)
-  (local $2 funcref)
-  (local $3 funcref)
-  (block
-   (nop)
-   (loop $label$1
-    (local.set $0
-     (ref.null)
-    )
-   )
-   (local.set $1
-    (local.get $0)
-   )
-   (local.set $2
-    (local.get $0)
-   )
-  )
-  (local.set $3
-   (local.get $2)
-  )
-  (return
-   (local.get $2)
-  )
- )
- (func $test
-  (local $0 externref)
-  (local $1 nullref)
-  (local $2 nullref)
-  (block $label$1
-   (local.set $0
-    (ref.null)
-   )
-   (local.set $1
-    (ref.null)
-   )
-  )
-  (local.set $2
-   (local.get $1)
-  )
-  (drop
-   (local.get $1)
-  )
- )
-)
diff --git a/test/passes/flatten_local-cse_all-features.wast b/test/passes/flatten_local-cse_all-features.wast
index 1b4dc37c2..05fbcb2ac 100644
--- a/test/passes/flatten_local-cse_all-features.wast
+++ b/test/passes/flatten_local-cse_all-features.wast
@@ -288,29 +288,30 @@
  )
 )
 
-(module
- ;; After --flatten, there will be a series of chain copies between multiple
- ;; locals, but some of the locals will be nullref type and others funcref type.
- ;; We cannot make locals of different types a common subexpression.
- (func $subtype-test (result funcref)
-  (nop)
-  (loop $label$1 (result nullref)
-   (ref.null)
-  )
- )
+;; TODO (GC)
+;; (module
+;;  ;; After --flatten, there will be a series of chain copies between multiple
+;;  ;; locals, but some of the locals will be funcref type and others anyref
+;;  ;; type. We cannot make locals of different types a common subexpression.
+;;  (func $subtype-test (result anyref)
+;;   (nop)
+;;   (loop $label$1 (result funcref)
+;;    (ref.null func)
+;;   )
+;;  )
 
- (func $test
-  (local $0 externref)
-  (drop
-   (block $label$1 (result nullref)
-    (local.set $0
-     (ref.null)
-    )
-    ;; After --flatten, this will be assigned to a local of nullref type. After
-    ;; --local-cse, even if we set (ref.null) to local $0 above, this should not
-    ;; be replaced with $0, because it is of type externref.
-    (ref.null)
-   )
-  )
- )
-)
+;;  (func $test
+;;   (local $0 anyref)
+;;   (drop
+;;    (block $label$1 (result funcref)
+;;     (local.set $0
+;;      (ref.null func)
+;;     )
+;;     ;; After --flatten, this will be assigned to a local of funcref type. After
+;;     ;; --local-cse, even if we set (ref.null) to local $0 above, this should not
+;;     ;; be replaced with $0, because it is of type anyref.
+;;     (ref.null func)
+;;    )
+;;   )
+;;  )
+;; )
diff --git a/test/passes/inlining_all-features.txt b/test/passes/inlining_all-features.txt
index cb24b9e8b..b2f483d3d 100644
--- a/test/passes/inlining_all-features.txt
+++ b/test/passes/inlining_all-features.txt
@@ -23,7 +23,7 @@
     (block
      (block $__inlined_func$func_inner
       (local.set $1
-       (ref.null)
+       (ref.null exn)
       )
       (drop
        (block $l0 (result i32)
diff --git a/test/passes/instrument-locals_all-features.txt b/test/passes/instrument-locals_all-features.txt
index e2ba3e107..91e71a48d 100644
--- a/test/passes/instrument-locals_all-features.txt
+++ b/test/passes/instrument-locals_all-features.txt
@@ -6,7 +6,6 @@
  (type $i32_i32_v128_=>_v128 (func (param i32 i32 v128) (result v128)))
  (type $i32_i32_funcref_=>_funcref (func (param i32 i32 funcref) (result funcref)))
  (type $i32_i32_externref_=>_externref (func (param i32 i32 externref) (result externref)))
- (type $i32_i32_nullref_=>_nullref (func (param i32 i32 nullref) (result nullref)))
  (type $i32_i32_exnref_=>_exnref (func (param i32 i32 exnref) (result exnref)))
  (type $none_=>_none (func))
  (import "env" "get_i32" (func $get_i32 (param i32 i32 i32) (result i32)))
@@ -21,8 +20,6 @@
  (import "env" "set_funcref" (func $set_funcref (param i32 i32 funcref) (result funcref)))
  (import "env" "get_externref" (func $get_externref (param i32 i32 externref) (result externref)))
  (import "env" "set_externref" (func $set_externref (param i32 i32 externref) (result externref)))
- (import "env" "get_nullref" (func $get_nullref (param i32 i32 nullref) (result nullref)))
- (import "env" "set_nullref" (func $set_nullref (param i32 i32 nullref) (result nullref)))
  (import "env" "get_exnref" (func $get_exnref (param i32 i32 exnref) (result exnref)))
  (import "env" "set_exnref" (func $set_exnref (param i32 i32 exnref) (result exnref)))
  (import "env" "get_v128" (func $get_v128 (param i32 i32 v128) (result v128)))
@@ -34,7 +31,6 @@
   (local $w f64)
   (local $F funcref)
   (local $X externref)
-  (local $N nullref)
   (local $E exnref)
   (local $S v128)
   (drop
@@ -76,22 +72,15 @@
    )
   )
   (drop
-   (call $get_nullref
-    (i32.const 5)
-    (i32.const 6)
-    (local.get $N)
-   )
-  )
-  (drop
    (call $get_exnref
+    (i32.const 5)
     (i32.const 6)
-    (i32.const 7)
     (local.get $E)
    )
   )
   (drop
    (call $get_i32
-    (i32.const 7)
+    (i32.const 6)
     (i32.const 0)
     (local.get $x)
    )
@@ -101,49 +90,42 @@
   )
   (drop
    (call $get_f32
-    (i32.const 8)
+    (i32.const 7)
     (i32.const 2)
     (local.get $z)
    )
   )
   (drop
    (call $get_f64
-    (i32.const 9)
+    (i32.const 8)
     (i32.const 3)
     (local.get $w)
    )
   )
   (drop
    (call $get_funcref
-    (i32.const 10)
+    (i32.const 9)
     (i32.const 4)
     (local.get $F)
    )
   )
   (drop
    (call $get_externref
-    (i32.const 11)
+    (i32.const 10)
     (i32.const 5)
     (local.get $X)
    )
   )
   (drop
-   (call $get_nullref
-    (i32.const 12)
-    (i32.const 6)
-    (local.get $N)
-   )
-  )
-  (drop
    (call $get_exnref
-    (i32.const 13)
-    (i32.const 7)
+    (i32.const 11)
+    (i32.const 6)
     (local.get $E)
    )
   )
   (local.set $x
    (call $set_i32
-    (i32.const 14)
+    (i32.const 12)
     (i32.const 0)
     (i32.const 1)
    )
@@ -153,57 +135,50 @@
   )
   (local.set $z
    (call $set_f32
-    (i32.const 15)
+    (i32.const 13)
     (i32.const 2)
     (f32.const 3.2100000381469727)
    )
   )
   (local.set $w
    (call $set_f64
-    (i32.const 16)
+    (i32.const 14)
     (i32.const 3)
     (f64.const 4.321)
    )
   )
   (local.set $F
    (call $set_funcref
-    (i32.const 17)
+    (i32.const 15)
     (i32.const 4)
     (ref.func $test)
    )
   )
   (local.set $X
    (call $set_externref
-    (i32.const 19)
+    (i32.const 17)
     (i32.const 5)
     (call $get_externref
-     (i32.const 18)
+     (i32.const 16)
      (i32.const 5)
      (local.get $X)
     )
    )
   )
-  (local.set $N
-   (call $set_nullref
-    (i32.const 20)
-    (i32.const 6)
-    (ref.null)
-   )
-  )
   (local.set $E
    (call $set_exnref
-    (i32.const 22)
-    (i32.const 7)
+    (i32.const 19)
+    (i32.const 6)
     (call $get_exnref
-     (i32.const 21)
-     (i32.const 7)
+     (i32.const 18)
+     (i32.const 6)
      (local.get $E)
     )
    )
   )
   (local.set $x
    (call $set_i32
-    (i32.const 23)
+    (i32.const 20)
     (i32.const 0)
     (i32.const 11)
    )
@@ -213,24 +188,24 @@
   )
   (local.set $z
    (call $set_f32
-    (i32.const 24)
+    (i32.const 21)
     (i32.const 2)
     (f32.const 33.209999084472656)
    )
   )
   (local.set $w
    (call $set_f64
-    (i32.const 25)
+    (i32.const 22)
     (i32.const 3)
     (f64.const 44.321)
    )
   )
   (local.set $F
    (call $set_funcref
-    (i32.const 27)
+    (i32.const 24)
     (i32.const 4)
     (call $get_funcref
-     (i32.const 26)
+     (i32.const 23)
      (i32.const 4)
      (local.get $F)
     )
@@ -238,33 +213,22 @@
   )
   (local.set $X
    (call $set_externref
-    (i32.const 29)
+    (i32.const 26)
     (i32.const 5)
     (call $get_externref
-     (i32.const 28)
+     (i32.const 25)
      (i32.const 5)
      (local.get $X)
     )
    )
   )
-  (local.set $N
-   (call $set_nullref
-    (i32.const 31)
-    (i32.const 6)
-    (call $get_nullref
-     (i32.const 30)
-     (i32.const 6)
-     (local.get $N)
-    )
-   )
-  )
   (local.set $E
    (call $set_exnref
-    (i32.const 33)
-    (i32.const 7)
+    (i32.const 28)
+    (i32.const 6)
     (call $get_exnref
-     (i32.const 32)
-     (i32.const 7)
+     (i32.const 27)
+     (i32.const 6)
      (local.get $E)
     )
    )
@@ -275,23 +239,20 @@
   (local.set $X
    (externref.pop)
   )
-  (local.set $N
-   (nullref.pop)
-  )
   (local.set $E
    (exnref.pop)
   )
   (drop
    (call $get_v128
-    (i32.const 34)
-    (i32.const 8)
+    (i32.const 29)
+    (i32.const 7)
     (local.get $S)
    )
   )
   (local.set $S
    (call $set_v128
-    (i32.const 35)
-    (i32.const 8)
+    (i32.const 30)
+    (i32.const 7)
     (v128.const i32x4 0x00000000 0x00000001 0x00000002 0x00000003)
    )
   )
diff --git a/test/passes/instrument-locals_all-features.wast b/test/passes/instrument-locals_all-features.wast
index 5640b1661..2110ce7db 100644
--- a/test/passes/instrument-locals_all-features.wast
+++ b/test/passes/instrument-locals_all-features.wast
@@ -6,7 +6,6 @@
     (local $w f64)
     (local $F funcref)
     (local $X externref)
-    (local $N nullref)
     (local $E exnref)
     (local $S v128)
 
@@ -16,7 +15,6 @@
     (drop (local.get $w))
     (drop (local.get $F))
     (drop (local.get $X))
-    (drop (local.get $N))
     (drop (local.get $E))
 
     (drop (local.get $x))
@@ -25,7 +23,6 @@
     (drop (local.get $w))
     (drop (local.get $F))
     (drop (local.get $X))
-    (drop (local.get $N))
     (drop (local.get $E))
 
     (local.set $x (i32.const 1))
@@ -34,7 +31,6 @@
     (local.set $w (f64.const 4.321))
     (local.set $F (ref.func $test))
     (local.set $X (local.get $X))
-    (local.set $N (ref.null))
     (local.set $E (local.get $E))
 
     (local.set $x (i32.const 11))
@@ -43,13 +39,11 @@
     (local.set $w (f64.const 44.321))
     (local.set $F (local.get $F))
     (local.set $X (local.get $X))
-    (local.set $N (local.get $N))
     (local.set $E (local.get $E))
 
     ;; Pop instructions should not be instrumented
     (local.set $F (funcref.pop))
     (local.set $X (externref.pop))
-    (local.set $N (nullref.pop))
     (local.set $E (exnref.pop))
 
     ;; Add new instructions here so expected output doesn't change too much, it
diff --git a/test/passes/merge-locals_all-features.txt b/test/passes/merge-locals_all-features.txt
index e4d325695..15039b4ce 100644
--- a/test/passes/merge-locals_all-features.txt
+++ b/test/passes/merge-locals_all-features.txt
@@ -1,7 +1,6 @@
 (module
  (type $i32_i32_=>_none (func (param i32 i32)))
  (type $i32_i32_=>_i32 (func (param i32 i32) (result i32)))
- (type $none_=>_none (func))
  (type $i32_i32_i32_=>_none (func (param i32 i32 i32)))
  (type $i32_f32_f32_=>_i64 (func (param i32 f32 f32) (result i64)))
  (global $global$0 (mut i32) (i32.const 10))
@@ -457,15 +456,4 @@
    )
   )
  )
- (func $subtype-test
-  (local $0 externref)
-  (local $1 nullref)
-  (local $2 nullref)
-  (local.set $0
-   (local.get $1)
-  )
-  (local.set $2
-   (local.get $1)
-  )
- )
 )
diff --git a/test/passes/merge-locals_all-features.wast b/test/passes/merge-locals_all-features.wast
index 2a0a3d292..c12a02426 100644
--- a/test/passes/merge-locals_all-features.wast
+++ b/test/passes/merge-locals_all-features.wast
@@ -375,17 +375,18 @@
    )
   )
  )
- (func $subtype-test
-  (local $0 externref)
-  (local $1 nullref)
-  (local $2 nullref)
-  (local.set $0
-   (local.get $1)
-  )
-  (local.set $2
-    ;; This should NOT become $0, because types of $0 and $1 are different
-   (local.get $1)
-  )
- )
+ ;; TODO (GC)
+ ;; (func $subtype-test
+ ;;  (local $0 anyref)
+ ;;  (local $1 funcref)
+ ;;  (local $2 funcref)
+ ;;  (local.set $0
+ ;;   (local.get $1)
+ ;;  )
+ ;;  (local.set $2
+ ;;    ;; This should NOT become $0, because types of $0 and $1 are different
+ ;;   (local.get $1)
+ ;;  )
+ ;; )
 )
 
diff --git a/test/passes/optimize-instructions_all-features.txt b/test/passes/optimize-instructions_all-features.txt
index 2aaba9071..5677624cb 100644
--- a/test/passes/optimize-instructions_all-features.txt
+++ b/test/passes/optimize-instructions_all-features.txt
@@ -14,7 +14,6 @@
  (type $i32_i32_f64_f64_=>_none (func (param i32 i32 f64 f64)))
  (type $i32_i64_f64_i32_=>_none (func (param i32 i64 f64 i32)))
  (type $none_=>_f64 (func (result f64)))
- (type $none_=>_externref (func (result externref)))
  (memory $0 0)
  (export "load-off-2" (func $load-off-2))
  (func $f (param $i1 i32) (param $i2 i64)
@@ -3712,9 +3711,6 @@
    (unreachable)
   )
  )
- (func $if-arms-subtype (result externref)
-  (ref.null)
- )
  (func $optimize-boolean-context (param $x i32) (param $y i32)
   (if
    (local.get $x)
diff --git a/test/passes/optimize-instructions_all-features.wast b/test/passes/optimize-instructions_all-features.wast
index e336ac2f9..37d0d7618 100644
--- a/test/passes/optimize-instructions_all-features.wast
+++ b/test/passes/optimize-instructions_all-features.wast
@@ -4207,14 +4207,15 @@
       (unreachable)
     )
   )
+  ;; TODO (GC)
   ;; Tests when if arms are subtype of if's type
-  (func $if-arms-subtype (result externref)
-    (if (result externref)
-      (i32.const 0)
-      (ref.null)
-      (ref.null)
-    )
-  )
+  ;; (func $if-arms-subtype (result anyref)
+  ;;   (if (result anyref)
+  ;;     (i32.const 0)
+  ;;     (ref.null extern)
+  ;;     (ref.null func)
+  ;;   )
+  ;; )
   (func $optimize-boolean-context (param $x i32) (param $y i32)
     ;; 0 - x   ==>   x
     (if
diff --git a/test/passes/precompute_all-features.txt b/test/passes/precompute_all-features.txt
index 4253d3c42..89f40adf5 100644
--- a/test/passes/precompute_all-features.txt
+++ b/test/passes/precompute_all-features.txt
@@ -5,7 +5,7 @@
  (type $none_=>_v128 (func (result v128)))
  (type $i32_=>_none (func (param i32)))
  (type $none_=>_i32_i64 (func (result i32 i64)))
- (type $none_=>_nullref (func (result nullref)))
+ (type $none_=>_externref (func (result externref)))
  (memory $0 512 512)
  (data (i32.const 0) "passive")
  (global $global i32 (i32.const 1))
@@ -262,8 +262,8 @@
  (func $loop-precompute (result i32)
   (i32.const 1)
  )
- (func $reftype-test (result nullref)
-  (ref.null)
+ (func $reftype-test (result externref)
+  (ref.null extern)
  )
  (func $dummy
   (nop)
@@ -285,18 +285,18 @@
    )
   )
   (drop
-   (block $l2 (result nullref)
+   (block $l2 (result externref)
     (drop
      (block $l3
       (global.set $global-mut
        (i32.const 1)
       )
       (br $l2
-       (ref.null)
+       (ref.null extern)
       )
      )
     )
-    (ref.null)
+    (ref.null extern)
    )
   )
   (drop
@@ -311,7 +311,7 @@
       )
      )
     )
-    (ref.null)
+    (ref.null func)
    )
   )
  )
diff --git a/test/passes/precompute_all-features.wast b/test/passes/precompute_all-features.wast
index 343b01ff1..ca849b88c 100644
--- a/test/passes/precompute_all-features.wast
+++ b/test/passes/precompute_all-features.wast
@@ -385,13 +385,13 @@
   )
 
   ;; Check if Precompute pass does not crash on reference types
-  (func $reftype-test (result nullref)
-    (ref.null)
+  (func $reftype-test (result externref)
+    (ref.null extern)
   )
 
   ;; Check if constant nodes (const, ref.null, and ref.func) are correctly
   ;; reused. (We shouldn't reuse a const node for something like ref.null, which
-  ;; will incorrectly cause an expression like 'nullref.const'.)
+  ;; will incorrectly cause an expression like 'someref.const'.)
   (func $dummy)
   (func $br_reuse_node
    (drop
@@ -418,7 +418,7 @@
    )
 
    (drop
-    (block $l2 (result nullref)
+    (block $l2 (result externref)
      (drop
       (block $l3 (result i32)
        (global.set $global-mut
@@ -428,14 +428,14 @@
         (i32.const 1)
         (ref.is_null
          (br_if $l2
-          (ref.null)
+          (ref.null extern)
           (i32.const 3)
          )
         )
        )
       )
      )
-     (ref.null)
+     (ref.null extern)
     )
    )
 
@@ -457,7 +457,7 @@
        )
       )
      )
-     (ref.null)
+     (ref.null func)
     )
    )
   )
@@ -469,7 +469,7 @@
     (block $label$1
       (drop
         (br_on_exn $label$1 $event$0
-          (loop $label$2 (result nullref)
+          (loop $label$2 (result exnref)
             (br $label$2)
           )
         )
diff --git a/test/passes/remove-unused-names_code-folding_all-features.txt b/test/passes/remove-unused-names_code-folding_all-features.txt
index 1cb02c26e..946545144 100644
--- a/test/passes/remove-unused-names_code-folding_all-features.txt
+++ b/test/passes/remove-unused-names_code-folding_all-features.txt
@@ -1799,7 +1799,7 @@
     (call $foo)
     (call $foo)
     (return
-     (ref.null)
+     (ref.null exn)
     )
    )
    (catch
@@ -1811,11 +1811,11 @@
     (call $foo)
     (call $foo)
     (return
-     (ref.null)
+     (ref.null exn)
     )
    )
   )
-  (ref.null)
+  (ref.null exn)
  )
  (func $try-call-optimize-expression-tails
   (local $exn exnref)
diff --git a/test/passes/remove-unused-names_code-folding_all-features.wast b/test/passes/remove-unused-names_code-folding_all-features.wast
index ab5f222ca..b982a10fb 100644
--- a/test/passes/remove-unused-names_code-folding_all-features.wast
+++ b/test/passes/remove-unused-names_code-folding_all-features.wast
@@ -1254,7 +1254,7 @@
         (call $foo)
         (call $foo)
         (call $foo)
-        (return (ref.null))
+        (return (ref.null exn))
       )
       (catch
         (drop (exnref.pop))
@@ -1262,10 +1262,10 @@
         (call $foo)
         (call $foo)
         (call $foo)
-        (return (ref.null))
+        (return (ref.null exn))
       )
     )
-    (ref.null)
+    (ref.null exn)
   )
 
   (func $try-call-optimize-expression-tails (local $exn exnref)
diff --git a/test/passes/simplify-globals_all-features.txt b/test/passes/simplify-globals_all-features.txt
index dc766683e..ace056aac 100644
--- a/test/passes/simplify-globals_all-features.txt
+++ b/test/passes/simplify-globals_all-features.txt
@@ -215,7 +215,7 @@
  (type $none_=>_none (func))
  (import "env" "global-1" (global $g1 externref))
  (global $g2 externref (global.get $g1))
- (global $g3 externref (ref.null))
+ (global $g3 externref (ref.null extern))
  (func $test1
   (drop
    (global.get $g1)
@@ -226,7 +226,7 @@
  )
  (func $test2
   (drop
-   (ref.null)
+   (ref.null extern)
   )
  )
 )
diff --git a/test/passes/simplify-globals_all-features.wast b/test/passes/simplify-globals_all-features.wast
index 3c7c61a9f..83c23bae5 100644
--- a/test/passes/simplify-globals_all-features.wast
+++ b/test/passes/simplify-globals_all-features.wast
@@ -130,7 +130,7 @@
 (module
   (import "env" "global-1" (global $g1 externref))
   (global $g2 (mut externref) (global.get $g1))
-  (global $g3 externref (ref.null))
+  (global $g3 externref (ref.null extern))
   (func $test1
     (drop (global.get $g1))
     (drop (global.get $g2))
diff --git a/test/passes/simplify-locals_all-features.txt b/test/passes/simplify-locals_all-features.txt
index 34efb8726..f461a7580 100644
--- a/test/passes/simplify-locals_all-features.txt
+++ b/test/passes/simplify-locals_all-features.txt
@@ -1882,19 +1882,6 @@
  )
 )
 (module
- (type $none_=>_funcref (func (result funcref)))
- (func $subtype-test (result funcref)
-  (local $0 nullref)
-  (local $1 funcref)
-  (local $2 funcref)
-  (block $block
-   (nop)
-  )
-  (nop)
-  (local.get $0)
- )
-)
-(module
  (type $none_=>_none (func))
  (type $i32_exnref_=>_none (func (param i32 exnref)))
  (type $exnref_=>_none (func (param exnref)))
@@ -1907,7 +1894,7 @@
   (block $label$0
    (local.set $0
     (br_on_exn $label$0 $event$0
-     (ref.null)
+     (ref.null exn)
     )
    )
   )
@@ -1918,7 +1905,7 @@
   (drop
    (block $label$1 (result exnref)
     (br_on_exn $label$1 $event$1
-     (ref.null)
+     (ref.null exn)
     )
    )
   )
@@ -1930,7 +1917,7 @@
     (try
      (do
       (rethrow
-       (ref.null)
+       (ref.null exn)
       )
      )
      (catch
@@ -1973,7 +1960,7 @@
      (i32.const 3)
      (try (result exnref)
       (do
-       (ref.null)
+       (ref.null exn)
       )
       (catch
        (exnref.pop)
diff --git a/test/passes/simplify-locals_all-features.wast b/test/passes/simplify-locals_all-features.wast
index 3edffca7e..b32da3df8 100644
--- a/test/passes/simplify-locals_all-features.wast
+++ b/test/passes/simplify-locals_all-features.wast
@@ -1655,22 +1655,23 @@
   )
  )
 )
-(module
- (func $subtype-test (result funcref)
-  (local $0 nullref)
-  (local $1 funcref)
-  (local $2 funcref)
-  (block
-   (local.set $1
-    (local.get $0)
-   )
-  )
-  (local.set $2
-   (local.get $1)
-  )
-  (local.get $1)
- )
-)
+;; TODO (GC)
+;; (module
+;;  (func $subtype-test (result anyref)
+;;   (local $0 anyref)
+;;   (local $1 externref)
+;;   (local $2 externref)
+;;   (block
+;;    (local.set $1
+;;     (local.get $0)
+;;    )
+;;   )
+;;   (local.set $2
+;;    (local.get $1)
+;;   )
+;;   (local.get $1)
+;;  )
+;; )
 (module
   (event $event$0 (attr 0) (param))
   (func $unoptimizable-br_on_exn-block (result exnref) (local $0 exnref)
@@ -1678,7 +1679,7 @@
       (local.set $0
         ;; br_on_exn's target block cannot be optimized to have a return value
         (br_on_exn $label$0 $event$0
-          (ref.null)
+          (ref.null exn)
         )
       )
     )
@@ -1692,7 +1693,7 @@
     (local.set $0
       (block $label$1 (result exnref)
         (br_on_exn $label$1 $event$1
-          (ref.null)
+          (ref.null exn)
         )
       )
     )
@@ -1704,7 +1705,7 @@
     (local.set $0
       (block $label$1 (result i32)
         (try
-          (do (rethrow (ref.null)))
+          (do (rethrow (ref.null exn)))
           (catch)
         )
         (i32.const 0)
@@ -1738,7 +1739,7 @@
         ;; try-catch, so it is OK.
         (local.set $0
           (try (result exnref)
-            (do (ref.null))
+            (do (ref.null exn))
             (catch (exnref.pop))
           )
         )
diff --git a/test/passes/simplify-locals_all-features_disable-exception-handling.txt b/test/passes/simplify-locals_all-features_disable-exception-handling.txt
index 0d035234b..b01941639 100644
--- a/test/passes/simplify-locals_all-features_disable-exception-handling.txt
+++ b/test/passes/simplify-locals_all-features_disable-exception-handling.txt
@@ -1875,16 +1875,3 @@
   )
  )
 )
-(module
- (type $none_=>_funcref (func (result funcref)))
- (func $subtype-test (result funcref)
-  (local $0 nullref)
-  (local $1 funcref)
-  (local $2 funcref)
-  (block $block
-   (nop)
-  )
-  (nop)
-  (local.get $0)
- )
-)
diff --git a/test/passes/simplify-locals_all-features_disable-exception-handling.wast b/test/passes/simplify-locals_all-features_disable-exception-handling.wast
index a819dda15..c0f279cd0 100644
--- a/test/passes/simplify-locals_all-features_disable-exception-handling.wast
+++ b/test/passes/simplify-locals_all-features_disable-exception-handling.wast
@@ -1655,19 +1655,20 @@
   )
  )
 )
-(module
- (func $subtype-test (result funcref)
-  (local $0 nullref)
-  (local $1 funcref)
-  (local $2 funcref)
-  (block
-   (local.set $1
-    (local.get $0)
-   )
-  )
-  (local.set $2
-   (local.get $1)
-  )
-  (local.get $1)
- )
-)
+;; TODO (GC)
+;; (module
+;;  (func $subtype-test (result anyref)
+;;   (local $0 funcref)
+;;   (local $1 anyref)
+;;   (local $2 anyref)
+;;   (block
+;;    (local.set $1
+;;     (local.get $0)
+;;    )
+;;   )
+;;   (local.set $2
+;;    (local.get $1)
+;;   )
+;;   (local.get $1)
+;;  )
+;; )
diff --git a/test/passes/strip-target-features_roundtrip_print-features_all-features.txt b/test/passes/strip-target-features_roundtrip_print-features_all-features.txt
index e6ff57ce1..d54c7bb4e 100644
--- a/test/passes/strip-target-features_roundtrip_print-features_all-features.txt
+++ b/test/passes/strip-target-features_roundtrip_print-features_all-features.txt
@@ -13,7 +13,7 @@
  (func $foo (result v128 externref)
   (tuple.make
    (v128.const i32x4 0x00000000 0x00000000 0x00000000 0x00000000)
-   (ref.null)
+   (ref.null extern)
   )
  )
  (func $bar (result v128 externref)
diff --git a/test/passes/strip-target-features_roundtrip_print-features_all-features.wast b/test/passes/strip-target-features_roundtrip_print-features_all-features.wast
index 614804f9d..f073de7a4 100644
--- a/test/passes/strip-target-features_roundtrip_print-features_all-features.wast
+++ b/test/passes/strip-target-features_roundtrip_print-features_all-features.wast
@@ -5,7 +5,7 @@
   (func $foo (result v128 externref )
     (tuple.make
       (v128.const i32x4 0 0 0 0)
-      (ref.null)
+      (ref.null extern)
     )
   )
   (func $bar (result v128 externref)
diff --git a/test/passes/translate-to-fuzz_all-features.txt b/test/passes/translate-to-fuzz_all-features.txt
index 5cfe2bc41..ab9a5b946 100644
--- a/test/passes/translate-to-fuzz_all-features.txt
+++ b/test/passes/translate-to-fuzz_all-features.txt
@@ -1,54 +1,53 @@
 (module
  (type $none_=>_none (func))
- (type $f32_=>_none (func (param f32)))
- (type $nullref_=>_none (func (param nullref)))
- (type $none_=>_externref_exnref_exnref_exnref (func (result externref exnref exnref exnref)))
- (type $none_=>_exnref (func (result exnref)))
  (type $i32_=>_none (func (param i32)))
+ (type $none_=>_funcref_exnref_i32_externref (func (result funcref exnref i32 externref)))
+ (type $i32_funcref_f64_v128_i32_=>_none (func (param i32 funcref f64 v128 i32)))
  (type $i64_=>_none (func (param i64)))
+ (type $f32_=>_none (func (param f32)))
  (type $f64_=>_none (func (param f64)))
- (type $f64_i32_i64_f64_v128_=>_none (func (param f64 i32 i64 f64 v128)))
  (type $v128_=>_none (func (param v128)))
  (type $exnref_=>_none (func (param exnref)))
  (type $none_=>_i32 (func (result i32)))
- (type $funcref_f64_f32_v128_exnref_f32_=>_i64 (func (param funcref f64 f32 v128 exnref f32) (result i64)))
- (type $externref_externref_f32_v128_funcref_funcref_=>_v128 (func (param externref externref f32 v128 funcref funcref) (result v128)))
- (type $v128_=>_funcref (func (param v128) (result funcref)))
+ (type $i32_v128_f64_i32_=>_i32 (func (param i32 v128 f64 i32) (result i32)))
+ (type $none_=>_i64 (func (result i64)))
+ (type $none_=>_f32 (func (result f32)))
+ (type $i64_f32_=>_f64 (func (param i64 f32) (result f64)))
+ (type $none_=>_v128 (func (result v128)))
+ (type $none_=>_funcref (func (result funcref)))
  (import "fuzzing-support" "log-i32" (func $log-i32 (param i32)))
  (import "fuzzing-support" "log-i64" (func $log-i64 (param i64)))
  (import "fuzzing-support" "log-f32" (func $log-f32 (param f32)))
  (import "fuzzing-support" "log-f64" (func $log-f64 (param f64)))
  (import "fuzzing-support" "log-v128" (func $log-v128 (param v128)))
- (import "fuzzing-support" "log-nullref" (func $log-nullref (param nullref)))
  (import "fuzzing-support" "log-exnref" (func $log-exnref (param exnref)))
  (memory $0 (shared 1 1))
  (data (i32.const 0) "N\0fN\f5\f9\b1\ff\fa\eb\e5\fe\a7\ec\fb\fc\f4\a6\e4\ea\f0\ae\e3")
- (table $0 2 2 funcref)
- (elem (i32.const 0) $func_8 $func_12)
- (global $global$5 (mut f32) (f32.const 74))
- (global $global$4 (mut nullref) (ref.null))
- (global $global$3 (mut i32) (i32.const 1263230471))
- (global $global$2 (mut i32) (i32.const -131072))
- (global $global$1 (mut (funcref nullref nullref externref exnref f64)) (tuple.make
-  (ref.null)
-  (ref.null)
-  (ref.null)
-  (ref.null)
-  (ref.null)
-  (f64.const 1.1754943508222875e-38)
+ (table $0 5 5 funcref)
+ (elem (i32.const 0) $func_9 $func_10 $func_12 $func_12 $func_14)
+ (global $global$5 (mut exnref) (ref.null exn))
+ (global $global$4 (mut f64) (f64.const 13))
+ (global $global$3 (mut f32) (f32.const 16448))
+ (global $global$2 (mut (v128 i32 i32 f64 exnref exnref)) (tuple.make
+  (v128.const i32x4 0x4d5affff 0x055b007b 0xff830011 0xffee0040)
+  (i32.const -32767)
+  (i32.const 44)
+  (f64.const 1797693134862315708145274e284)
+  (ref.null exn)
+  (ref.null exn)
  ))
+ (global $global$1 (mut exnref) (ref.null exn))
  (global $hangLimit (mut i32) (i32.const 10))
- (event $event$0 (attr 0) (param nullref))
- (event $event$1 (attr 0) (param f32))
+ (event $event$0 (attr 0) (param i32))
  (export "hashMemory" (func $hashMemory))
  (export "memory" (memory $0))
- (export "func_8" (func $func_8))
- (export "func_8_invoker" (func $func_8_invoker))
- (export "func_11" (func $func_11))
+ (export "func_7_invoker" (func $func_7_invoker))
+ (export "func_9" (func $func_9))
+ (export "func_10_invoker" (func $func_10_invoker))
  (export "func_12" (func $func_12))
  (export "func_12_invoker" (func $func_12_invoker))
- (export "func_14" (func $func_14))
- (export "func_15" (func $func_15))
+ (export "func_16_invoker" (func $func_16_invoker))
+ (export "func_19" (func $func_19))
  (export "hangLimitInitializer" (func $hangLimitInitializer))
  (func $hashMemory (result i32)
   (local $0 i32)
@@ -281,17 +280,14 @@
   )
   (local.get $0)
  )
- (func $func_8 (result exnref)
-  (local $0 i64)
-  (local $1 i64)
-  (local $2 exnref)
+ (func $func_7 (param $0 i32) (param $1 v128) (param $2 f64) (param $3 i32) (result i32)
   (block
    (if
     (i32.eqz
      (global.get $hangLimit)
     )
     (return
-     (ref.null)
+     (i32.const 4883)
     )
    )
    (global.set $hangLimit
@@ -301,26 +297,65 @@
     )
    )
   )
-  (ref.null)
- )
- (func $func_8_invoker
-  (drop
-   (call $func_8)
+  (local.tee $3
+   (local.tee $0
+    (local.get $3)
+   )
   )
+ )
+ (func $func_7_invoker
   (drop
-   (call $func_8)
+   (call $func_7
+    (i32.const -119)
+    (v128.const i32x4 0x00000000 0x40410000 0x00000000 0x3ff00000)
+    (f64.const 3.433897990215153e-220)
+    (i32.const 255)
+   )
   )
   (call $log-i32
    (call $hashMemory)
   )
-  (drop
-   (call $func_8)
+ )
+ (func $func_9 (result funcref)
+  (local $0 i64)
+  (local $1 i64)
+  (block
+   (if
+    (i32.eqz
+     (global.get $hangLimit)
+    )
+    (return
+     (ref.func $log-f32)
+    )
+   )
+   (global.set $hangLimit
+    (i32.sub
+     (global.get $hangLimit)
+     (i32.const 1)
+    )
+   )
   )
-  (call $log-i32
-   (call $hashMemory)
+  (block $label$0
+   (f64.store offset=22 align=2
+    (i32.and
+     (i32.const -65535)
+     (i32.const 15)
+    )
+    (f64.const 8589934593)
+   )
+   (return
+    (ref.func $log-exnref)
+   )
   )
  )
- (func $func_10 (result externref exnref exnref exnref)
+ (func $func_10 (result funcref exnref i32 externref)
+  (local $0 i64)
+  (local $1 exnref)
+  (local $2 f32)
+  (local $3 externref)
+  (local $4 externref)
+  (local $5 f32)
+  (local $6 i64)
   (block
    (if
     (i32.eqz
@@ -328,10 +363,10 @@
     )
     (return
      (tuple.make
-      (ref.null)
-      (ref.null)
-      (ref.null)
-      (ref.null)
+      (ref.func $func_10)
+      (ref.null exn)
+      (i32.const 0)
+      (ref.null extern)
      )
     )
    )
@@ -343,14 +378,22 @@
    )
   )
   (tuple.make
-   (ref.null)
-   (ref.null)
-   (ref.null)
-   (ref.null)
+   (ref.func $log-v128)
+   (ref.null exn)
+   (i32.const 26155)
+   (ref.null extern)
   )
  )
- (func $func_11 (param $0 f64) (param $1 i32) (param $2 i64) (param $3 f64) (param $4 v128)
-  (local $5 nullref)
+ (func $func_10_invoker
+  (drop
+   (call $func_10)
+  )
+  (call $log-i32
+   (call $hashMemory)
+  )
+ )
+ (func $func_12
+  (local $0 exnref)
   (block
    (if
     (i32.eqz
@@ -365,30 +408,56 @@
     )
    )
   )
-  (block $label$0
-   (call $log-i32
-    (call $hashMemory)
+  (call $log-i32
+   (i32.const 1)
+  )
+ )
+ (func $func_12_invoker
+  (call $func_12)
+ )
+ (func $func_14 (result v128)
+  (local $0 i32)
+  (local $1 f32)
+  (local $2 f32)
+  (local $3 externref)
+  (local $4 exnref)
+  (local $5 f64)
+  (local $6 i64)
+  (block
+   (if
+    (i32.eqz
+     (global.get $hangLimit)
+    )
+    (return
+     (v128.const i32x4 0x5ea21f0a 0x52800ae0 0x002a5300 0xe4010058)
+    )
    )
-   (call $log-exnref
-    (ref.null)
+   (global.set $hangLimit
+    (i32.sub
+     (global.get $hangLimit)
+     (i32.const 1)
+    )
    )
   )
+  (v128.const i32x4 0x1d00ff00 0x2a255500 0x01fbf800 0x0a000002)
  )
- (func $func_12 (param $0 funcref) (param $1 f64) (param $2 f32) (param $3 v128) (param $4 exnref) (param $5 f32) (result i64)
-  (local $6 nullref)
-  (local $7 f32)
-  (local $8 exnref)
-  (local $9 f32)
-  (local $10 f64)
-  (local $11 i64)
-  (local $12 i32)
+ (func $func_15 (result i64)
+  (local $0 f32)
+  (local $1 funcref)
+  (local $2 f32)
+  (local $3 i32)
+  (local $4 f32)
+  (local $5 v128)
+  (local $6 f64)
+  (local $7 funcref)
+  (local $8 externref)
   (block
    (if
     (i32.eqz
      (global.get $hangLimit)
     )
     (return
-     (local.get $11)
+     (i64.const -2097152)
     )
    )
    (global.set $hangLimit
@@ -399,55 +468,64 @@
    )
   )
   (block $label$0
-   (call $log-f32
-    (f32.const -nan:0x7fffe0)
-   )
+   (nop)
    (return
-    (local.get $11)
+    (i64.const -61)
    )
   )
  )
- (func $func_12_invoker
-  (drop
-   (call $func_12
-    (ref.null)
-    (f64.const -nan:0xfffffffffffec)
-    (f32.const 244)
-    (v128.const i32x4 0x5e58601d 0x5e555c53 0xffff0001 0xffffffff)
-    (ref.null)
-    (f32.const 72)
+ (func $func_16 (param $0 i32) (param $1 funcref) (param $2 f64) (param $3 v128) (param $4 i32)
+  (local $5 (i32 f64))
+  (local $6 i64)
+  (local $7 (i32 i64))
+  (local $8 i32)
+  (local $9 funcref)
+  (local $10 f32)
+  (local $11 (i64 v128 f32))
+  (block
+   (if
+    (i32.eqz
+     (global.get $hangLimit)
+    )
+    (return)
    )
-  )
-  (drop
-   (call $func_12
-    (ref.func $log-v128)
-    (f64.const 32)
-    (f32.const 18014398509481984)
-    (v128.const i32x4 0x367f7324 0x5f000000 0x4e80108b 0xcf000000)
-    (ref.null)
-    (f32.const -549755813888)
+   (global.set $hangLimit
+    (i32.sub
+     (global.get $hangLimit)
+     (i32.const 1)
+    )
    )
   )
-  (drop
-   (call $func_12
-    (ref.func $func_12)
-    (f64.const 4294967295.799)
-    (f32.const 1279937664)
-    (v128.const i32x4 0xffffffb6 0x00000000 0x4041414b 0x4478405c)
-    (ref.null)
-    (f32.const 10284)
-   )
+  (nop)
+ )
+ (func $func_16_invoker
+  (call $func_16
+   (i32.const -19)
+   (ref.func $hashMemory)
+   (f64.const -2305843009213693952)
+   (v128.const i32x4 0x2b27212f 0x322e2366 0x0000343b 0x00000000)
+   (i32.const 24)
+  )
+  (call $func_16
+   (i32.const 2147483646)
+   (ref.null func)
+   (f64.const 23348)
+   (v128.const i32x4 0x0000007c 0x00000000 0x00000000 0xc0000000)
+   (i32.const 521672456)
   )
  )
- (func $func_14 (param $0 externref) (param $1 externref) (param $2 f32) (param $3 v128) (param $4 funcref) (param $5 funcref) (result v128)
-  (local $6 (i64 i32 i32 i64 funcref))
+ (func $func_18 (param $0 i64) (param $1 f32) (result f64)
+  (local $2 (f64 f64 i32))
+  (local $3 i64)
+  (local $4 f32)
+  (local $5 externref)
   (block
    (if
     (i32.eqz
      (global.get $hangLimit)
     )
     (return
-     (local.get $3)
+     (f64.const -1073741824)
     )
    )
    (global.set $hangLimit
@@ -457,118 +535,168 @@
     )
    )
   )
-  (block $label$0 (result v128)
-   (i32.atomic.store8 offset=3
-    (i32.and
-     (if (result i32)
-      (global.get $global$3)
-      (i32.const 15)
-      (i32.const 1)
+  (select
+   (f64.const 35184372088832)
+   (f64x2.extract_lane 0
+    (v128.const i32x4 0x55800000 0x4f800000 0x3def9db2 0x4e6dcc9d)
+   )
+   (loop $label$0 (result i32)
+    (block
+     (if
+      (i32.eqz
+       (global.get $hangLimit)
+      )
+      (return
+       (f64.const 4294967213)
+      )
      )
-     (i32.const 15)
-    )
-    (i32.load offset=3 align=2
-     (i32.and
-      (i32.const 15)
-      (i32.const 15)
+     (global.set $hangLimit
+      (i32.sub
+       (global.get $hangLimit)
+       (i32.const 1)
+      )
      )
     )
-   )
-   (local.tee $3
-    (block $label$16 (result v128)
-     (loop $label$17
-      (block
-       (if
-        (i32.eqz
-         (global.get $hangLimit)
-        )
-        (return
-         (v128.const i32x4 0xffff0009 0xfffeffff 0x00005a18 0xffff7fff)
-        )
-       )
-       (global.set $hangLimit
-        (i32.sub
-         (global.get $hangLimit)
-         (i32.const 1)
-        )
-       )
+    (block (result i32)
+     (block $label$1
+      (call_indirect (type $none_=>_none)
+       (i32.const 2)
       )
-      (block
-       (local.set $5
-        (tuple.extract 2
-         (tuple.make
-          (f32.const 3366576023666688)
-          (f32.const 1897033472)
-          (ref.null)
-          (ref.func $log-exnref)
-          (ref.null)
+      (nop)
+     )
+     (br_if $label$0
+      (i32.eqz
+       (loop $label$2 (result i32)
+        (block
+         (if
+          (i32.eqz
+           (global.get $hangLimit)
+          )
+          (return
+           (f64.const 8589934591.815)
+          )
+         )
+         (global.set $hangLimit
+          (i32.sub
+           (global.get $hangLimit)
+           (i32.const 1)
+          )
          )
         )
-       )
-       (local.set $5
-        (tuple.extract 2
-         (tuple.make
-          (f32.const 3366576023666688)
-          (f32.const 1897033472)
-          (ref.null)
-          (ref.func $log-exnref)
-          (ref.null)
+        (block (result i32)
+         (block $label$15
+          (memory.copy
+           (i32.and
+            (i32.const -8192)
+            (i32.const 15)
+           )
+           (i32.and
+            (i8x16.extract_lane_s 1
+             (v128.const i32x4 0x3329287c 0x00007fff 0x00000002 0x00002966)
+            )
+            (i32.const 15)
+           )
+           (i32.atomic.rmw8.add_u offset=1
+            (i32.and
+             (i32.const -93)
+             (i32.const 15)
+            )
+            (i32.const 26)
+           )
+          )
+          (br_if $label$15
+           (i32.eqz
+            (i32.const 169416729)
+           )
+          )
+         )
+         (br_if $label$2
+          (i32.const 1397565735)
+         )
+         (tuple.extract 1
+          (tuple.make
+           (f64.const -2.2250738585072014e-308)
+           (i32.const -86)
+          )
          )
         )
        )
-       (if
-        (i32.eqz
-         (i8x16.extract_lane_u 13
-          (i16x8.neg
-           (local.get $3)
+      )
+     )
+     (if (result i32)
+      (if (result i32)
+       (i32.const -33)
+       (i32.trunc_f32_s
+        (f32.load offset=4 align=1
+         (i32.const 1347440720)
+        )
+       )
+       (i32.const -83)
+      )
+      (block $label$12 (result i32)
+       (nop)
+       (i32.const -5)
+      )
+      (if (result i32)
+       (i32.eqz
+        (i32.load offset=3 align=1
+         (i32.and
+          (block $label$23
+           (nop)
+           (return
+            (f64.const -1)
+           )
           )
+          (i32.const 15)
          )
         )
-        (block $label$18
-         (loop $label$19
-          (block
-           (if
-            (i32.eqz
-             (global.get $hangLimit)
+       )
+       (block $label$13 (result i32)
+        (call $log-i32
+         (i32.load offset=4 align=1
+          (i32.and
+           (i32.const 2049)
+           (block $label$24
+            (global.set $global$4
+             (f64.const 3.475623083072852e-234)
             )
             (return
-             (v128.const i32x4 0x2a230007 0x24000cff 0x01000405 0xe6abf412)
-            )
-           )
-           (global.set $hangLimit
-            (i32.sub
-             (global.get $hangLimit)
-             (i32.const 1)
+             (f64.const -2147483647.157)
             )
            )
           )
-          (drop
-           (v128.const i32x4 0xffff8001 0xffffffff 0xfc000000 0xffffffff)
-          )
          )
-         (call $func_12_invoker)
         )
-        (drop
-         (local.tee $0
-          (local.get $1)
+        (block $label$14
+         (call $log-i64
+          (local.get $0)
+         )
+         (nop)
+        )
+        (f32.gt
+         (f32.sqrt
+          (local.tee $4
+           (local.get $1)
+          )
          )
+         (f32.const 512.2849731445312)
         )
        )
+       (i32.const 0)
       )
      )
-     (local.get $3)
     )
    )
   )
  )
- (func $func_15 (param $0 v128) (result funcref)
+ (func $func_19 (result f32)
   (block
    (if
     (i32.eqz
      (global.get $hangLimit)
     )
     (return
-     (ref.null)
+     (f32.const 8589934592)
     )
    )
    (global.set $hangLimit
@@ -578,88 +706,34 @@
     )
    )
   )
-  (select (result nullref)
-   (if (result nullref)
-    (loop $label$10 (result i32)
-     (block
-      (if
-       (i32.eqz
-        (global.get $hangLimit)
-       )
-       (return
-        (ref.func $log-f64)
-       )
-      )
-      (global.set $hangLimit
-       (i32.sub
-        (global.get $hangLimit)
-        (i32.const 1)
-       )
-      )
-     )
-     (block (result i32)
-      (block $label$11
-       (i32.atomic.store8 offset=4
-        (i32.and
-         (i32.load8_s offset=3
+  (f32.load offset=4 align=2
+   (i32.and
+    (i32.popcnt
+     (ref.is_null
+      (block $label$0 (result exnref)
+       (nop)
+       (call $log-f32
+        (f32.convert_i64_s
+         (i32.atomic.rmw.cmpxchg offset=22
           (i32.and
-           (i32.const 1026044209)
+           (block $label$1
+            (atomic.fence)
+            (return
+             (f32.const -512.8049926757812)
+            )
+           )
            (i32.const 15)
           )
+          (i64.const -28)
+          (i64.const -524289)
          )
-         (i32.const 15)
         )
-        (i32.const 0)
-       )
-       (drop
-        (local.get $0)
-       )
-      )
-      (br_if $label$10
-       (i32.const 128)
-      )
-      (select
-       (select
-        (i32.const -127)
-        (i32.const -65537)
-        (i32.const -254)
        )
-       (i32.const 102650628)
-       (i32.const 810034249)
+       (ref.null exn)
       )
      )
     )
-    (ref.null)
-    (block $label$13 (result nullref)
-     (loop $label$14
-      (block
-       (if
-        (i32.eqz
-         (global.get $hangLimit)
-        )
-        (return
-         (ref.func $func_8)
-        )
-       )
-       (global.set $hangLimit
-        (i32.sub
-         (global.get $hangLimit)
-         (i32.const 1)
-        )
-       )
-      )
-      (nop)
-     )
-     (ref.null)
-    )
-   )
-   (ref.null)
-   (i32.atomic.load8_u offset=1
-    (ref.is_null
-     (call_indirect (type $none_=>_exnref)
-      (i32.const 0)
-     )
-    )
+    (i32.const 15)
    )
   )
  )
diff --git a/test/reference-types.wast b/test/reference-types.wast
index 8bea4e8e4..80755124e 100644
--- a/test/reference-types.wast
+++ b/test/reference-types.wast
@@ -1,88 +1,156 @@
-;; reftype :: externref | funcref | exnref | nullref
+;; reftype :: externref | funcref | exnref
 
-;; t <: externref for all reftypes t
-;; nullref <: externref, nullref <: funcref and nullref <: exnref
-;; TODO: the subtyping relationship has been removed from the current proposal
-;; so it also needs to be removed from Binaryen still both in the tests but
-;; also inside the validation, fuzzing, etc.
-;; https://github.com/WebAssembly/reference-types/pull/87
+;; TODO (GC): the subtyping relationship has been removed from the current
+;; proposal so the relevant test cases have been disabled. Once `anyref` becomes
+;; enabled, these tests can be uncommented again.
 
 (module
   (type $sig_externref (func (param externref)))
   (type $sig_funcref (func (param funcref)))
   (type $sig_exnref (func (param exnref)))
-  (type $sig_nullref (func (param nullref)))
+  ;; (type $sig_anyref (func (param anyref)))
 
   (func $take_externref (param externref))
   (func $take_funcref (param funcref))
   (func $take_exnref (param exnref))
-  (func $take_nullref (param nullref))
+  ;; (func $take_anyref (param anyref))
   (func $foo)
 
-  (table funcref (elem $take_externref $take_funcref $take_exnref $take_nullref))
+  (table funcref (elem $take_externref $take_funcref $take_exnref)) ;; $take_anyref
 
   (import "env" "import_func" (func $import_func (param externref) (result funcref)))
   (import "env" "import_global" (global $import_global externref))
   (export "export_func" (func $import_func (param externref) (result funcref)))
   (export "export_global" (global $import_global))
 
+  ;; Test global initializer expressions
+  (global $global_externref (mut externref) (ref.null extern))
+  (global $global_funcref (mut funcref) (ref.null func))
+  (global $global_funcref_func (mut funcref) (ref.func $foo))
+  (global $global_exnref (mut exnref) (ref.null exn))
+  ;; (global $global_anyref (mut anyref) (ref.null any))
+
   ;; Test subtype relationship in global initializer expressions
-  (global $global_externref (mut externref) (ref.null))
-  (global $global_funcref (mut funcref) (ref.null))
-  (global $global_exnref (mut exnref) (ref.null))
-  (global $global_nullref (mut nullref) (ref.null))
-  (global $global_externref2 (mut externref) (ref.func $foo))
-  (global $global_funcref2 (mut funcref) (ref.func $foo))
+  ;; (global $global_anyref2 (mut anyref) (ref.null extern))
+  ;; (global $global_anyref3 (mut anyref) (ref.null func))
+  ;; (global $global_anyref4 (mut anyref) (ref.func $foo))
+  ;; (global $global_anyref5 (mut anyref) (ref.null exn))
+
+  (func $test
+    (local $local_externref externref)
+    (local $local_funcref funcref)
+    (local $local_exnref exnref)
+    ;; (local $local_anyref anyref)
 
-  (func $test (local $local_externref externref) (local $local_funcref funcref)
-        (local $local_exnref exnref) (local $local_nullref nullref)
-    ;; Test subtype relationship for local.set & Test types for local.get
+    ;; Test types for local.get/set
     (local.set $local_externref (local.get $local_externref))
-    (local.set $local_externref (local.get $local_funcref))
-    (local.set $local_externref (local.get $local_exnref))
-    (local.set $local_externref (local.get $local_nullref))
-    (local.set $local_externref (ref.null))
-    (local.set $local_externref (ref.func $foo))
+    (local.set $local_externref (global.get $global_externref))
+    (local.set $local_externref (ref.null extern))
     (local.set $local_funcref (local.get $local_funcref))
-    (local.set $local_funcref (ref.null))
+    (local.set $local_funcref (global.get $global_funcref))
+    (local.set $local_funcref (ref.null func))
     (local.set $local_funcref (ref.func $foo))
     (local.set $local_exnref (local.get $local_exnref))
-    (local.set $local_exnref (ref.null))
-    (local.set $local_nullref (local.get $local_nullref))
-    (local.set $local_nullref (ref.null))
+    (local.set $local_exnref (global.get $global_exnref))
+    (local.set $local_exnref (ref.null exn))
+    ;; (local.set $local_anyref (local.get $local_anyref))
+    ;; (local.set $local_anyref (global.get $global_anyref))
+    ;; (local.set $local_anyref (ref.null any))
 
-    ;; Test subtype relationship for global.set & Test types for global.get
+    ;; Test subtype relationship for local.set
+    ;; (local.set $local_anyref (local.get $local_externref))
+    ;; (local.set $local_anyref (global.get $global_externref))
+    ;; (local.set $local_anyref (ref.null extern))
+    ;; (local.set $local_anyref (local.get $local_funcref))
+    ;; (local.set $local_anyref (global.get $global_funcref))
+    ;; (local.set $local_anyref (ref.null func))
+    ;; (local.set $local_anyref (ref.func $foo))
+    ;; (local.set $local_anyref (local.get $local_exnref))
+    ;; (local.set $local_anyref (global.get $global_exnref))
+    ;; (local.set $local_anyref (ref.null exn))
+
+    ;; Test types for global.get/set
     (global.set $global_externref (global.get $global_externref))
-    (global.set $global_externref (global.get $global_funcref))
-    (global.set $global_externref (global.get $global_exnref))
-    (global.set $global_externref (global.get $global_nullref))
-    (global.set $global_externref (ref.null))
-    (global.set $global_externref (ref.func $foo))
+    (global.set $global_externref (local.get $local_externref))
+    (global.set $global_externref (ref.null extern))
     (global.set $global_funcref (global.get $global_funcref))
-    (global.set $global_funcref (ref.null))
+    (global.set $global_funcref (local.get $local_funcref))
+    (global.set $global_funcref (ref.null func))
     (global.set $global_funcref (ref.func $foo))
     (global.set $global_exnref (global.get $global_exnref))
-    (global.set $global_exnref (ref.null))
-    (global.set $global_nullref (global.get $global_nullref))
-    (global.set $global_nullref (ref.null))
+    (global.set $global_exnref (local.get $local_exnref))
+    (global.set $global_exnref (ref.null exn))
+    ;; (global.set $global_anyref (global.get $global_anyref))
+    ;; (global.set $global_anyref (local.get $local_anyref))
+    ;; (global.set $global_anyref (ref.null any))
+
+    ;; Test subtype relationship for global.set
+    ;; (global.set $global_anyref (global.get $global_externref))
+    ;; (global.set $global_anyref (local.get $local_externref))
+    ;; (global.set $global_anyref (ref.null extern))
+    ;; (global.set $global_anyref (global.get $global_funcref))
+    ;; (global.set $global_anyref (local.get $local_funcref))
+    ;; (global.set $global_anyref (ref.null func))
+    ;; (global.set $global_anyref (ref.func $foo))
+    ;; (global.set $global_anyref (global.get $global_exnref))
+    ;; (global.set $global_anyref (local.get $local_exnref))
+    ;; (global.set $global_anyref (ref.null exn))
 
-    ;; Test subtype relationship for function call / call_indirect params
+    ;; Test function call params
     (call $take_externref (local.get $local_externref))
-    (call $take_externref (local.get $local_funcref))
-    (call $take_externref (local.get $local_exnref))
-    (call $take_externref (ref.null))
+    (call $take_externref (global.get $global_externref))
+    (call $take_externref (ref.null extern))
+    (call $take_funcref (local.get $local_funcref))
+    (call $take_funcref (global.get $global_funcref))
+    (call $take_funcref (ref.null func))
+    (call $take_funcref (ref.func $foo))
+    (call $take_exnref (local.get $local_exnref))
+    (call $take_exnref (global.get $global_exnref))
+    (call $take_exnref (ref.null exn))
+    ;; (call $take_anyref (local.get $local_anyref))
+    ;; (call $take_anyref (global.get $global_anyref))
+    ;; (call $take_anyref (ref.null any))
+
+    ;; Test subtype relationship for function call params
+    ;; (call $take_anyref (local.get $local_externref))
+    ;; (call $take_anyref (global.get $global_externref))
+    ;; (call $take_anyref (ref.null extern))
+    ;; (call $take_anyref (local.get $local_funcref))
+    ;; (call $take_anyref (global.get $global_funcref))
+    ;; (call $take_anyref (ref.null func))
+    ;; (call $take_anyref (ref.func $foo))
+    ;; (call $take_anyref (local.get $local_exnref))
+    ;; (call $take_anyref (global.get $global_exnref))
+    ;; (call $take_anyref (ref.null exn))
+
+    ;; Test call_indirect params
     (call_indirect (type $sig_externref) (local.get $local_externref) (i32.const 0))
-    (call_indirect (type $sig_externref) (local.get $local_funcref) (i32.const 0))
-    (call_indirect (type $sig_externref) (local.get $local_exnref) (i32.const 0))
-    (call_indirect (type $sig_externref) (ref.null) (i32.const 0))
+    (call_indirect (type $sig_externref) (global.get $global_externref) (i32.const 0))
+    (call_indirect (type $sig_externref) (ref.null extern) (i32.const 0))
     (call_indirect (type $sig_funcref) (local.get $local_funcref) (i32.const 1))
-    (call_indirect (type $sig_funcref) (ref.null) (i32.const 1))
+    (call_indirect (type $sig_funcref) (global.get $global_funcref) (i32.const 1))
+    (call_indirect (type $sig_funcref) (ref.null func) (i32.const 1))
+    (call_indirect (type $sig_funcref) (ref.func $foo) (i32.const 1))
     (call_indirect (type $sig_exnref) (local.get $local_exnref) (i32.const 2))
-    (call_indirect (type $sig_exnref) (ref.null) (i32.const 2))
-    (call_indirect (type $sig_nullref) (local.get $local_nullref) (i32.const 3))
-    (call_indirect (type $sig_nullref) (ref.null) (i32.const 3))
+    (call_indirect (type $sig_exnref) (global.get $global_exnref) (i32.const 2))
+    (call_indirect (type $sig_exnref) (ref.null exn) (i32.const 2))
+    ;; (call_indirect (type $sig_anyref) (local.get $local_anyref) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (global.get $global_anyref) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (ref.null any) (i32.const 3))
 
-    ;; Test subtype relationship for block return type
+    ;; Test subtype relationship for call_indirect params
+    ;; (call_indirect (type $sig_anyref) (local.get $local_externref) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (global.get $global_externref) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (ref.null extern) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (local.get $local_funcref) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (global.get $global_funcref) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (ref.null func) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (ref.func $foo) (i32.const 3))
+    ;; (call_indirect (type $sig_anyref) (local.get $local_exnref) (i32.const 3)
+    ;; (call_indirect (type $sig_anyref) (global.get $global_exnref) (i32.const 3)
+    ;; (call_indirect (type $sig_anyref) (ref.null exn) (i32.const 3))
+
+    ;; Test block return type
     (drop
       (block (result externref)
         (br_if 0 (local.get $local_externref) (i32.const 1))
@@ -90,36 +158,103 @@
     )
     (drop
       (block (result externref)
-        (br_if 0 (local.get $local_funcref) (i32.const 1))
+        (br_if 0 (global.get $global_externref) (i32.const 1))
       )
     )
     (drop
       (block (result externref)
-        (br_if 0 (local.get $local_exnref) (i32.const 1))
+        (br_if 0 (ref.null extern) (i32.const 1))
       )
     )
     (drop
-      (block (result externref)
-        (br_if 0 (ref.null) (i32.const 1))
+      (block (result funcref)
+        (br_if 0 (local.get $local_funcref) (i32.const 1))
+      )
+    )
+    (drop
+      (block (result funcref)
+        (br_if 0 (global.get $global_funcref) (i32.const 1))
+      )
+    )
+    (drop
+      (block (result funcref)
+        (br_if 0 (ref.null func) (i32.const 1))
       )
     )
     (drop
       (block (result funcref)
-        (br_if 0 (ref.null) (i32.const 1))
+        (br_if 0 (ref.func $foo) (i32.const 1))
       )
     )
     (drop
       (block (result exnref)
-        (br_if 0 (ref.null) (i32.const 1))
+        (br_if 0 (local.get $local_exnref) (i32.const 1))
       )
     )
     (drop
-      (block (result nullref)
-        (br_if 0 (ref.null) (i32.const 1))
+      (block (result exnref)
+        (br_if 0 (global.get $global_exnref) (i32.const 1))
       )
     )
+    (drop
+      (block (result exnref)
+        (br_if 0 (ref.null exn) (i32.const 1))
+      )
+    )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (local.get $local_anyref) (i32.const 1))
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (global.get $global_anyref) (i32.const 1))
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (ref.null any) (i32.const 1))
+    ;;   )
+    ;; )
 
-    ;; Test subtype relationship for loop return type
+    ;; Test subtype relationship for block return type
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (local.get $local_externref) (i32.const 1))
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (local.get $local_funcref) (i32.const 1))
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (local.get $local_exnref) (i32.const 1))
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (ref.null extern) (i32.const 1))
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (ref.null func) (i32.const 1))
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (ref.func $foo) (i32.const 1))
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (block (result anyref)
+    ;;     (br_if 0 (ref.null exn) (i32.const 1))
+    ;;   )
+    ;; )
+
+    ;; Test loop return type
     (drop
       (loop (result externref)
         (local.get $local_externref)
@@ -127,101 +262,207 @@
     )
     (drop
       (loop (result externref)
-        (local.get $local_funcref)
+        (global.get $global_externref)
       )
     )
     (drop
       (loop (result externref)
-        (local.get $local_exnref)
+        (ref.null extern)
       )
     )
     (drop
-      (loop (result externref)
-        (ref.null)
+      (loop (result funcref)
+        (local.get $local_funcref)
       )
     )
     (drop
       (loop (result funcref)
-        (local.get $local_funcref)
+        (global.get $global_funcref)
       )
     )
     (drop
       (loop (result funcref)
-        (ref.null)
+        (ref.null func)
       )
     )
     (drop
-      (loop (result exnref)
-        (local.get $local_exnref)
+      (loop (result funcref)
+        (ref.func $foo)
       )
     )
     (drop
       (loop (result exnref)
-        (ref.null)
+        (local.get $local_exnref)
       )
     )
     (drop
-      (loop (result nullref)
-        (ref.null)
+      (loop (result exnref)
+        (global.get $global_exnref)
       )
     )
+    (drop
+      (loop (result exnref)
+        (ref.null exn)
+      )
+    )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (local.get $local_anyref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (global.get $global_anyref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (ref.null any)
+    ;;   )
+    ;; )
 
-    ;; Test subtype relationship for if return type
+    ;; Test subtype relationship for loop return type
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (local.get $local_externref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (global.get $global_externref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (ref.null extern)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (local.get $local_funcref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (global.get $global_funcref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (ref.null func)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (ref.func $foo)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (local.get $local_exnref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (global.get $global_exnref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (loop (result anyref)
+    ;;     (ref.null exn)
+    ;;   )
+    ;; )
+
+    ;; Test if return type
     (drop
       (if (result externref)
         (i32.const 1)
         (local.get $local_externref)
-        (local.get $local_exnref)
-      )
-    )
-    (drop
-      (if (result externref)
-        (i32.const 1)
-        (ref.func $foo)
-        (ref.null)
+        (ref.null extern)
       )
     )
     (drop
       (if (result funcref)
         (i32.const 1)
-        (ref.func $foo)
-        (ref.null)
+        (local.get $local_funcref)
+        (ref.null func)
       )
     )
     (drop
       (if (result exnref)
         (i32.const 1)
         (local.get $local_exnref)
-        (ref.null)
-      )
-    )
-    (drop
-      (if (result nullref)
-        (i32.const 1)
-        (local.get $local_nullref)
-        (ref.null)
+        (ref.null exn)
       )
     )
+    ;; (drop
+    ;;   (if (result anyref)
+    ;;     (i32.const 1)
+    ;;     (local.get $local_anyref)
+    ;;     (ref.null any)
+    ;;   )
+    ;; )
 
-    ;; Test subtype relationship for try return type
+    ;; Test subtype relationship for if return type
+    ;; (drop
+    ;;   (if (result anyref)
+    ;;     (i32.const 1)
+    ;;     (local.get $local_externref)
+    ;;     (local.get $local_funcref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (if (result anyref)
+    ;;     (i32.const 1)
+    ;;     (local.get $local_externref)
+    ;;     (local.get $local_exnref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (if (result anyref)
+    ;;     (i32.const 1)
+    ;;     (local.get $local_funcref)
+    ;;     (local.get $local_exnref)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (if (result anyref)
+    ;;     (i32.const 1)
+    ;;     (ref.null extern)
+    ;;     (ref.null func)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (if (result anyref)
+    ;;     (i32.const 1)
+    ;;     (ref.null extern)
+    ;;     (ref.null exn)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (if (result anyref)
+    ;;     (i32.const 1)
+    ;;     (ref.null func)
+    ;;     (ref.null exn)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (if (result anyref)
+    ;;     (i32.const 1)
+    ;;     (ref.func $foo)
+    ;;     (ref.null extern)
+    ;;   )
+    ;; )
+
+    ;; Test try return type
     (drop
       (try (result externref)
         (do
           (local.get $local_externref)
         )
         (catch
-          (exnref.pop)
-        )
-      )
-    )
-    (drop
-      (try (result externref)
-        (do
-          (ref.func $foo)
-        )
-        (catch
           (drop (exnref.pop))
-          (ref.null)
+          (ref.null extern)
         )
       )
     )
@@ -232,79 +473,106 @@
         )
         (catch
           (drop (exnref.pop))
-          (ref.null)
+          (ref.null func)
         )
       )
     )
     (drop
       (try (result exnref)
         (do
-          (ref.null)
+          (ref.null exn)
         )
         (catch
           (exnref.pop)
         )
       )
     )
-    (drop
-      (try (result nullref)
-        (do
-          (ref.null)
-        )
-        (catch
-          (drop (exnref.pop))
-          (ref.null)
-        )
-      )
-    )
 
-    ;; Test subtype relationship for typed select
-    (drop
-      (select (result externref)
-        (local.get $local_externref)
-        (ref.func $foo)
-        (i32.const 1)
-      )
-    )
-    (drop
-      (select (result externref)
-        (local.get $local_exnref)
-        (local.get $local_externref)
-        (i32.const 1)
-      )
-    )
+    ;; Test subtype relationship for try return type
+    ;; (drop
+    ;;   (try (result anyref)
+    ;;     (do
+    ;;       (local.get $local_externref)
+    ;;     )
+    ;;     (catch
+    ;;       (drop (exnref.pop))
+    ;;       (ref.func $foo)
+    ;;     )
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (try (result anyref)
+    ;;     (do
+    ;;       (local.get $local_externref)
+    ;;     )
+    ;;     (catch
+    ;;       (exnref.pop)
+    ;;     )
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (try (result anyref)
+    ;;     (do
+    ;;       (ref.func $foo)
+    ;;     )
+    ;;     (catch
+    ;;       (drop (exnref.pop))
+    ;;       (local.get $local_externref)
+    ;;     )
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (try (result anyref)
+    ;;     (do
+    ;;       (ref.func $foo)
+    ;;     )
+    ;;     (catch
+    ;;       (exnref.pop)
+    ;;     )
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (try (result anyref)
+    ;;     (do
+    ;;       (ref.null exn)
+    ;;     )
+    ;;     (catch
+    ;;       (drop (exnref.pop))
+    ;;       (local.get $local_externref)
+    ;;     )
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (try (result anyref) 
+    ;;     (do
+    ;;       (ref.null exn)
+    ;;     )
+    ;;     (catch
+    ;;       (drop (exnref.pop))
+    ;;       (ref.func $foo)
+    ;;     )
+    ;;   )
+    ;; )
+
+    ;; Test typed select
     (drop
       (select (result externref)
         (local.get $local_externref)
-        (ref.null)
-        (i32.const 1)
-      )
-    )
-    (drop
-      (select (result externref)
-        (ref.null)
-        (ref.func $foo)
+        (ref.null extern)
         (i32.const 1)
       )
     )
     (drop
       (select (result funcref)
-        (ref.func $foo)
-        (ref.null)
+        (local.get $local_funcref)
+        (ref.null func)
         (i32.const 1)
       )
     )
     (drop
       (select (result exnref)
-        (ref.null)
         (local.get $local_exnref)
-        (i32.const 1)
-      )
-    )
-    (drop
-      (select (result nullref)
-        (ref.null)
-        (ref.null)
+        (ref.null exn)
         (i32.const 1)
       )
     )
@@ -316,60 +584,187 @@
       )
     )
 
+    ;; Test subtype relationship for typed select
+    ;; (drop
+    ;;   (select (result anyref) 
+    ;;     (local.get $local_externref)
+    ;;     (local.get $local_funcref)
+    ;;     (i32.const 1)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (select (result anyref)
+    ;;     (local.get $local_externref)
+    ;;     (local.get $local_exnref)
+    ;;     (i32.const 1)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (select (result anyref)
+    ;;     (local.get $local_funcref)
+    ;;     (local.get $local_externref)
+    ;;     (i32.const 1)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (select (result anyref)
+    ;;     (local.get $local_funcref)
+    ;;     (local.get $local_exnref)
+    ;;     (i32.const 1)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (select (result anyref)
+    ;;     (local.get $local_exnref)
+    ;;     (local.get $local_externref)
+    ;;     (i32.const 1)
+    ;;   )
+    ;; )
+    ;; (drop
+    ;;   (select (result anyref)
+    ;;     (local.get $local_exnref)
+    ;;     (local.get $local_funcref)
+    ;;     (i32.const 1)
+    ;;   )
+    ;; )
+
     ;; ref.is_null takes any reference types
     (drop (ref.is_null (local.get $local_externref)))
-    (drop (ref.is_null (local.get $local_exnref)))
+    (drop (ref.is_null (global.get $global_externref)))
+    (drop (ref.is_null (ref.null extern)))
+    (drop (ref.is_null (local.get $local_funcref)))
+    (drop (ref.is_null (global.get $global_funcref)))
+    (drop (ref.is_null (ref.null func)))
     (drop (ref.is_null (ref.func $foo)))
-    (drop (ref.is_null (ref.null)))
+    (drop (ref.is_null (local.get $local_exnref)))
+    (drop (ref.is_null (global.get $global_exnref)))
+    (drop (ref.is_null (ref.null exn)))
+    ;; (drop (ref.is_null (local.get $local_anyref)))
+    ;; (drop (ref.is_null (global.get $global_anyref)))
+    ;; (drop (ref.is_null (ref.null any)))
   )
 
-  ;; Test subtype relationship in function return type
-  (func $return_externref (result externref) (local $local_externref externref)
+  ;; Test function return type
+  (func $return_externref_local (result externref)
+    (local $local_externref externref)
     (local.get $local_externref)
   )
-  (func $return_externref2 (result externref)
-    (ref.func $foo)
+  (func $return_externref_global (result externref)
+    (global.get $global_externref)
   )
-  (func $return_externref3 (result externref) (local $local_exnref exnref)
-    (local.get $local_exnref)
+  (func $return_externref_null (result externref)
+    (ref.null extern)
   )
-  (func $return_externref4 (result externref)
-    (ref.null)
+  (func $return_funcref_local (result funcref)
+    (local $local_funcref funcref)
+    (local.get $local_funcref)
   )
-  (func $return_funcref (result funcref)
-    (ref.func $foo)
+  (func $return_funcref_global (result funcref)
+    (global.get $global_funcref)
+  )
+  (func $return_funcref_null (result funcref)
+    (ref.null func)
   )
-  (func $return_funcref2 (result funcref)
-    (ref.null)
+  (func $return_funcref_func (result funcref)
+    (ref.func $foo)
   )
-  (func $return_exnref (result exnref) (local $local_exnref exnref)
+  (func $return_exnref_local (result exnref)
+    (local $local_exnref exnref)
     (local.get $local_exnref)
   )
-  (func $return_exnref2 (result exnref)
-    (ref.null)
+  (func $return_exnref_global (result exnref)
+    (global.get $global_exnref)
   )
-  (func $return_nullref (result nullref) (local $local_nullref nullref)
-    (local.get $local_nullref)
+  (func $return_exnref_null (result exnref)
+    (ref.null exn)
   )
+  ;; (func $return_anyref_local (result anyref)
+  ;;   (local $local_anyref anyref)
+  ;;   (local.get $local_anyref)
+  ;; )
+  ;; (func $return_anyref_global (result anyref)
+  ;;   (global.get $global_anyref)
+  ;; )
+  ;; (func $return_anyref_null (result anyref)
+  ;;   (ref.null any)
+  ;; )
 
-  ;; Test subtype relationship in returns
-  (func $return_externref_returns (result externref) (local $local_externref externref)
-        (local $local_exnref exnref)
+  ;; Test subtype relationship in function return type
+  ;; (func $return_anyref2 (result anyref)
+  ;;   (local $local_externref externref)
+  ;;   (local.get $local_externref)
+  ;; )
+  ;; (func $return_anyref3 (result anyref)
+  ;;   (global.get $global_externref)
+  ;; )
+  ;; (func $return_anyref4 (result anyref)
+  ;;   (ref.null extern)
+  ;; )
+  ;; (func $return_anyref5 (result anyref)
+  ;;   (local $local_funcref funcref)
+  ;;   (local.get $local_funcref)
+  ;; )
+  ;; (func $return_anyref6 (result anyref)
+  ;;   (global.get $global_funcref)
+  ;; )
+  ;; (func $return_anyref7 (result anyref)
+  ;;   (ref.null func)
+  ;; )
+  ;; (func $return_anyref8 (result anyref)
+  ;;   (ref.func $foo)
+  ;; )
+  ;; (func $return_anyref9 (result anyref)
+  ;;   (local $local_exnnref exnref)
+  ;;   (local.get $local_exnref)
+  ;; )
+  ;; (func $return_anyref10 (result anyref)
+  ;;   (global.get $global_exnref)
+  ;; )
+  ;; (func $return_anyref11 (result anyref)
+  ;;   (ref.null exn)
+  ;; )
+
+  ;; Test returns
+  (func $returns_externref (result externref)
+    (local $local_externref externref)
     (return (local.get $local_externref))
-    (return (local.get $local_exnref))
-    (return (ref.func $foo))
-    (return (ref.null))
+    (return (global.get $global_externref))
+    (return (ref.null extern))
   )
-  (func $return_funcref_returns (result funcref)
+  (func $returns_funcref (result funcref)
+    (local $local_funcref funcref)
+    (return (local.get $local_funcref))
+    (return (global.get $global_funcref))
     (return (ref.func $foo))
-    (return (ref.null))
+    (return (ref.null func))
   )
-  (func $return_exnref_returns (result exnref) (local $local_exnref exnref)
+  (func $returns_exnref (result exnref)
+    (local $local_exnref exnref)
     (return (local.get $local_exnref))
-    (return (ref.null))
-  )
-  (func $return_nullref_returns (result nullref) (local $local_nullref nullref)
-    (return (local.get $local_nullref))
-    (return (ref.null))
+    (return (global.get $global_exnref))
+    (return (ref.null exn))
   )
+  ;; (func $returns_anyref (result anyref)
+  ;;   (local $local_anyref anyref)
+  ;;   (return (local.get $local_anyref))
+  ;;   (return (global.get $global_anyref))
+  ;;   (return (ref.null any))
+  ;; )
+
+  ;; Test subtype relationship in returns
+  ;; (func $returns_anyref2 (result anyref)
+  ;;   (local $local_externref externref)
+  ;;   (local $local_funcref funcref)
+  ;;   (local $local_exnref exnref)
+  ;;   (return (local.get $local_externref))
+  ;;   (return (global.get $global_externref))
+  ;;   (return (ref.null extern))
+  ;;   (return (local.get $local_funcref))
+  ;;   (return (global.get $global_funcref))
+  ;;   (return (ref.func $foo))
+  ;;   (return (ref.null func))
+  ;;   (return (local.get $local_exnref))
+  ;;   (return (global.get $global_exnref))
+  ;;   (return (ref.null exn))
+  ;; )
 )
diff --git a/test/reference-types.wast.from-wast b/test/reference-types.wast.from-wast
index 3916606c0..ac9660531 100644
--- a/test/reference-types.wast.from-wast
+++ b/test/reference-types.wast.from-wast
@@ -1,24 +1,20 @@
 (module
- (type $externref_=>_none (func (param externref)))
- (type $none_=>_externref (func (result externref)))
  (type $funcref_=>_none (func (param funcref)))
- (type $nullref_=>_none (func (param nullref)))
- (type $exnref_=>_none (func (param exnref)))
  (type $none_=>_funcref (func (result funcref)))
+ (type $externref_=>_none (func (param externref)))
+ (type $exnref_=>_none (func (param exnref)))
+ (type $none_=>_externref (func (result externref)))
  (type $none_=>_exnref (func (result exnref)))
  (type $none_=>_none (func))
- (type $none_=>_nullref (func (result nullref)))
  (type $externref_=>_funcref (func (param externref) (result funcref)))
  (import "env" "import_global" (global $import_global externref))
  (import "env" "import_func" (func $import_func (param externref) (result funcref)))
- (table $0 4 4 funcref)
- (elem (i32.const 0) $take_externref $take_funcref $take_exnref $take_nullref)
- (global $global_externref (mut externref) (ref.null))
- (global $global_funcref (mut funcref) (ref.null))
- (global $global_exnref (mut exnref) (ref.null))
- (global $global_nullref (mut nullref) (ref.null))
- (global $global_externref2 (mut externref) (ref.func $foo))
- (global $global_funcref2 (mut funcref) (ref.func $foo))
+ (table $0 3 3 funcref)
+ (elem (i32.const 0) $take_externref $take_funcref $take_exnref)
+ (global $global_externref (mut externref) (ref.null extern))
+ (global $global_funcref (mut funcref) (ref.null func))
+ (global $global_funcref_func (mut funcref) (ref.func $foo))
+ (global $global_exnref (mut exnref) (ref.null exn))
  (export "export_func" (func $import_func))
  (export "export_global" (global $import_global))
  (func $take_externref (param $0 externref)
@@ -30,9 +26,6 @@
  (func $take_exnref (param $0 exnref)
   (nop)
  )
- (func $take_nullref (param $0 nullref)
-  (nop)
- )
  (func $foo
   (nop)
  )
@@ -40,30 +33,23 @@
   (local $local_externref externref)
   (local $local_funcref funcref)
   (local $local_exnref exnref)
-  (local $local_nullref nullref)
   (local.set $local_externref
    (local.get $local_externref)
   )
   (local.set $local_externref
-   (local.get $local_funcref)
-  )
-  (local.set $local_externref
-   (local.get $local_exnref)
-  )
-  (local.set $local_externref
-   (local.get $local_nullref)
-  )
-  (local.set $local_externref
-   (ref.null)
+   (global.get $global_externref)
   )
   (local.set $local_externref
-   (ref.func $foo)
+   (ref.null extern)
   )
   (local.set $local_funcref
    (local.get $local_funcref)
   )
   (local.set $local_funcref
-   (ref.null)
+   (global.get $global_funcref)
+  )
+  (local.set $local_funcref
+   (ref.null func)
   )
   (local.set $local_funcref
    (ref.func $foo)
@@ -72,37 +58,28 @@
    (local.get $local_exnref)
   )
   (local.set $local_exnref
-   (ref.null)
-  )
-  (local.set $local_nullref
-   (local.get $local_nullref)
+   (global.get $global_exnref)
   )
-  (local.set $local_nullref
-   (ref.null)
+  (local.set $local_exnref
+   (ref.null exn)
   )
   (global.set $global_externref
    (global.get $global_externref)
   )
   (global.set $global_externref
-   (global.get $global_funcref)
-  )
-  (global.set $global_externref
-   (global.get $global_exnref)
-  )
-  (global.set $global_externref
-   (global.get $global_nullref)
-  )
-  (global.set $global_externref
-   (ref.null)
+   (local.get $local_externref)
   )
   (global.set $global_externref
-   (ref.func $foo)
+   (ref.null extern)
   )
   (global.set $global_funcref
    (global.get $global_funcref)
   )
   (global.set $global_funcref
-   (ref.null)
+   (local.get $local_funcref)
+  )
+  (global.set $global_funcref
+   (ref.null func)
   )
   (global.set $global_funcref
    (ref.func $foo)
@@ -111,40 +88,51 @@
    (global.get $global_exnref)
   )
   (global.set $global_exnref
-   (ref.null)
-  )
-  (global.set $global_nullref
-   (global.get $global_nullref)
+   (local.get $local_exnref)
   )
-  (global.set $global_nullref
-   (ref.null)
+  (global.set $global_exnref
+   (ref.null exn)
   )
   (call $take_externref
    (local.get $local_externref)
   )
   (call $take_externref
-   (local.get $local_funcref)
+   (global.get $global_externref)
   )
   (call $take_externref
+   (ref.null extern)
+  )
+  (call $take_funcref
+   (local.get $local_funcref)
+  )
+  (call $take_funcref
+   (global.get $global_funcref)
+  )
+  (call $take_funcref
+   (ref.null func)
+  )
+  (call $take_funcref
+   (ref.func $foo)
+  )
+  (call $take_exnref
    (local.get $local_exnref)
   )
-  (call $take_externref
-   (ref.null)
+  (call $take_exnref
+   (global.get $global_exnref)
   )
-  (call_indirect (type $externref_=>_none)
-   (local.get $local_externref)
-   (i32.const 0)
+  (call $take_exnref
+   (ref.null exn)
   )
   (call_indirect (type $externref_=>_none)
-   (local.get $local_funcref)
+   (local.get $local_externref)
    (i32.const 0)
   )
   (call_indirect (type $externref_=>_none)
-   (local.get $local_exnref)
+   (global.get $global_externref)
    (i32.const 0)
   )
   (call_indirect (type $externref_=>_none)
-   (ref.null)
+   (ref.null extern)
    (i32.const 0)
   )
   (call_indirect (type $funcref_=>_none)
@@ -152,7 +140,15 @@
    (i32.const 1)
   )
   (call_indirect (type $funcref_=>_none)
-   (ref.null)
+   (global.get $global_funcref)
+   (i32.const 1)
+  )
+  (call_indirect (type $funcref_=>_none)
+   (ref.null func)
+   (i32.const 1)
+  )
+  (call_indirect (type $funcref_=>_none)
+   (ref.func $foo)
    (i32.const 1)
   )
   (call_indirect (type $exnref_=>_none)
@@ -160,16 +156,12 @@
    (i32.const 2)
   )
   (call_indirect (type $exnref_=>_none)
-   (ref.null)
+   (global.get $global_exnref)
    (i32.const 2)
   )
-  (call_indirect (type $nullref_=>_none)
-   (local.get $local_nullref)
-   (i32.const 3)
-  )
-  (call_indirect (type $nullref_=>_none)
-   (ref.null)
-   (i32.const 3)
+  (call_indirect (type $exnref_=>_none)
+   (ref.null exn)
+   (i32.const 2)
   )
   (drop
    (block $block (result externref)
@@ -182,7 +174,7 @@
   (drop
    (block $block0 (result externref)
     (br_if $block0
-     (local.get $local_funcref)
+     (global.get $global_externref)
      (i32.const 1)
     )
    )
@@ -190,15 +182,15 @@
   (drop
    (block $block1 (result externref)
     (br_if $block1
-     (local.get $local_exnref)
+     (ref.null extern)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $block2 (result externref)
+   (block $block2 (result funcref)
     (br_if $block2
-     (ref.null)
+     (local.get $local_funcref)
      (i32.const 1)
     )
    )
@@ -206,23 +198,47 @@
   (drop
    (block $block3 (result funcref)
     (br_if $block3
-     (ref.null)
+     (global.get $global_funcref)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $block4 (result exnref)
+   (block $block4 (result funcref)
     (br_if $block4
-     (ref.null)
+     (ref.null func)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $block5 (result nullref)
+   (block $block5 (result funcref)
     (br_if $block5
-     (ref.null)
+     (ref.func $foo)
+     (i32.const 1)
+    )
+   )
+  )
+  (drop
+   (block $block6 (result exnref)
+    (br_if $block6
+     (local.get $local_exnref)
+     (i32.const 1)
+    )
+   )
+  )
+  (drop
+   (block $block7 (result exnref)
+    (br_if $block7
+     (global.get $global_exnref)
+     (i32.const 1)
+    )
+   )
+  )
+  (drop
+   (block $block8 (result exnref)
+    (br_if $block8
+     (ref.null exn)
      (i32.const 1)
     )
    )
@@ -233,78 +249,69 @@
    )
   )
   (drop
-   (loop $loop-in6 (result externref)
-    (local.get $local_funcref)
+   (loop $loop-in9 (result externref)
+    (global.get $global_externref)
    )
   )
   (drop
-   (loop $loop-in7 (result externref)
-    (local.get $local_exnref)
+   (loop $loop-in10 (result externref)
+    (ref.null extern)
    )
   )
   (drop
-   (loop $loop-in8 (result externref)
-    (ref.null)
+   (loop $loop-in11 (result funcref)
+    (local.get $local_funcref)
    )
   )
   (drop
-   (loop $loop-in9 (result funcref)
-    (local.get $local_funcref)
+   (loop $loop-in12 (result funcref)
+    (global.get $global_funcref)
    )
   )
   (drop
-   (loop $loop-in10 (result funcref)
-    (ref.null)
+   (loop $loop-in13 (result funcref)
+    (ref.null func)
    )
   )
   (drop
-   (loop $loop-in11 (result exnref)
-    (local.get $local_exnref)
+   (loop $loop-in14 (result funcref)
+    (ref.func $foo)
    )
   )
   (drop
-   (loop $loop-in12 (result exnref)
-    (ref.null)
+   (loop $loop-in15 (result exnref)
+    (local.get $local_exnref)
    )
   )
   (drop
-   (loop $loop-in13 (result nullref)
-    (ref.null)
+   (loop $loop-in16 (result exnref)
+    (global.get $global_exnref)
    )
   )
   (drop
-   (if (result externref)
-    (i32.const 1)
-    (local.get $local_externref)
-    (local.get $local_exnref)
+   (loop $loop-in17 (result exnref)
+    (ref.null exn)
    )
   )
   (drop
    (if (result externref)
     (i32.const 1)
-    (ref.func $foo)
-    (ref.null)
+    (local.get $local_externref)
+    (ref.null extern)
    )
   )
   (drop
    (if (result funcref)
     (i32.const 1)
-    (ref.func $foo)
-    (ref.null)
+    (local.get $local_funcref)
+    (ref.null func)
    )
   )
   (drop
    (if (result exnref)
     (i32.const 1)
     (local.get $local_exnref)
-    (ref.null)
-   )
-  )
-  (drop
-   (if (result nullref)
-    (i32.const 1)
-    (local.get $local_nullref)
-    (ref.null)
+    (ref.null exn)
    )
   )
   (drop
@@ -313,20 +320,10 @@
      (local.get $local_externref)
     )
     (catch
-     (exnref.pop)
-    )
-   )
-  )
-  (drop
-   (try (result externref)
-    (do
-     (ref.func $foo)
-    )
-    (catch
      (drop
       (exnref.pop)
      )
-     (ref.null)
+     (ref.null extern)
     )
    )
   )
@@ -339,14 +336,14 @@
      (drop
       (exnref.pop)
      )
-     (ref.null)
+     (ref.null func)
     )
    )
   )
   (drop
    (try (result exnref)
     (do
-     (ref.null)
+     (ref.null exn)
     )
     (catch
      (exnref.pop)
@@ -354,77 +351,66 @@
    )
   )
   (drop
-   (try (result nullref)
-    (do
-     (ref.null)
-    )
-    (catch
-     (drop
-      (exnref.pop)
-     )
-     (ref.null)
-    )
+   (select (result externref)
+    (local.get $local_externref)
+    (ref.null extern)
+    (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (local.get $local_externref)
-    (ref.func $foo)
+   (select (result funcref)
+    (local.get $local_funcref)
+    (ref.null func)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
+   (select (result exnref)
     (local.get $local_exnref)
-    (local.get $local_externref)
+    (ref.null exn)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (local.get $local_externref)
-    (ref.null)
+   (select
+    (i32.const 0)
+    (i32.const 2)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (ref.null)
-    (ref.func $foo)
-    (i32.const 1)
+   (ref.is_null
+    (local.get $local_externref)
    )
   )
   (drop
-   (select (result funcref)
-    (ref.func $foo)
-    (ref.null)
-    (i32.const 1)
+   (ref.is_null
+    (global.get $global_externref)
    )
   )
   (drop
-   (select (result exnref)
-    (ref.null)
-    (local.get $local_exnref)
-    (i32.const 1)
+   (ref.is_null
+    (ref.null extern)
    )
   )
   (drop
-   (select (result nullref)
-    (ref.null)
-    (ref.null)
-    (i32.const 1)
+   (ref.is_null
+    (local.get $local_funcref)
    )
   )
   (drop
-   (select
-    (i32.const 0)
-    (i32.const 2)
-    (i32.const 1)
+   (ref.is_null
+    (global.get $global_funcref)
    )
   )
   (drop
    (ref.is_null
-    (local.get $local_externref)
+    (ref.null func)
+   )
+  )
+  (drop
+   (ref.is_null
+    (ref.func $foo)
    )
   )
   (drop
@@ -434,86 +420,85 @@
   )
   (drop
    (ref.is_null
-    (ref.func $foo)
+    (global.get $global_exnref)
    )
   )
   (drop
    (ref.is_null
-    (ref.null)
+    (ref.null exn)
    )
   )
  )
- (func $return_externref (result externref)
+ (func $return_externref_local (result externref)
   (local $local_externref externref)
   (local.get $local_externref)
  )
- (func $return_externref2 (result externref)
-  (ref.func $foo)
+ (func $return_externref_global (result externref)
+  (global.get $global_externref)
  )
- (func $return_externref3 (result externref)
-  (local $local_exnref exnref)
-  (local.get $local_exnref)
+ (func $return_externref_null (result externref)
+  (ref.null extern)
+ )
+ (func $return_funcref_local (result funcref)
+  (local $local_funcref funcref)
+  (local.get $local_funcref)
  )
- (func $return_externref4 (result externref)
-  (ref.null)
+ (func $return_funcref_global (result funcref)
+  (global.get $global_funcref)
  )
- (func $return_funcref (result funcref)
-  (ref.func $foo)
+ (func $return_funcref_null (result funcref)
+  (ref.null func)
  )
- (func $return_funcref2 (result funcref)
-  (ref.null)
+ (func $return_funcref_func (result funcref)
+  (ref.func $foo)
  )
- (func $return_exnref (result exnref)
+ (func $return_exnref_local (result exnref)
   (local $local_exnref exnref)
   (local.get $local_exnref)
  )
- (func $return_exnref2 (result exnref)
-  (ref.null)
+ (func $return_exnref_global (result exnref)
+  (global.get $global_exnref)
  )
- (func $return_nullref (result nullref)
-  (local $local_nullref nullref)
-  (local.get $local_nullref)
+ (func $return_exnref_null (result exnref)
+  (ref.null exn)
  )
- (func $return_externref_returns (result externref)
+ (func $returns_externref (result externref)
   (local $local_externref externref)
-  (local $local_exnref exnref)
   (return
    (local.get $local_externref)
   )
   (return
-   (local.get $local_exnref)
+   (global.get $global_externref)
   )
   (return
-   (ref.func $foo)
+   (ref.null extern)
   )
+ )
+ (func $returns_funcref (result funcref)
+  (local $local_funcref funcref)
   (return
-   (ref.null)
+   (local.get $local_funcref)
+  )
+  (return
+   (global.get $global_funcref)
   )
- )
- (func $return_funcref_returns (result funcref)
   (return
    (ref.func $foo)
   )
   (return
-   (ref.null)
+   (ref.null func)
   )
  )
- (func $return_exnref_returns (result exnref)
+ (func $returns_exnref (result exnref)
   (local $local_exnref exnref)
   (return
    (local.get $local_exnref)
   )
   (return
-   (ref.null)
-  )
- )
- (func $return_nullref_returns (result nullref)
-  (local $local_nullref nullref)
-  (return
-   (local.get $local_nullref)
+   (global.get $global_exnref)
   )
   (return
-   (ref.null)
+   (ref.null exn)
   )
  )
 )
diff --git a/test/reference-types.wast.fromBinary b/test/reference-types.wast.fromBinary
index ae36b9209..f4a958d99 100644
--- a/test/reference-types.wast.fromBinary
+++ b/test/reference-types.wast.fromBinary
@@ -1,24 +1,20 @@
 (module
- (type $externref_=>_none (func (param externref)))
- (type $none_=>_externref (func (result externref)))
  (type $funcref_=>_none (func (param funcref)))
- (type $nullref_=>_none (func (param nullref)))
- (type $exnref_=>_none (func (param exnref)))
  (type $none_=>_funcref (func (result funcref)))
+ (type $externref_=>_none (func (param externref)))
+ (type $exnref_=>_none (func (param exnref)))
+ (type $none_=>_externref (func (result externref)))
  (type $none_=>_exnref (func (result exnref)))
  (type $none_=>_none (func))
- (type $none_=>_nullref (func (result nullref)))
  (type $externref_=>_funcref (func (param externref) (result funcref)))
  (import "env" "import_global" (global $gimport$1 externref))
  (import "env" "import_func" (func $import_func (param externref) (result funcref)))
- (table $0 4 4 funcref)
- (elem (i32.const 0) $take_externref $take_funcref $take_exnref $take_nullref)
- (global $global$0 (mut externref) (ref.null))
- (global $global$1 (mut funcref) (ref.null))
- (global $global$2 (mut exnref) (ref.null))
- (global $global$3 (mut nullref) (ref.null))
- (global $global$4 (mut externref) (ref.func $foo))
- (global $global$5 (mut funcref) (ref.func $foo))
+ (table $0 3 3 funcref)
+ (elem (i32.const 0) $take_externref $take_funcref $take_exnref)
+ (global $global$0 (mut externref) (ref.null extern))
+ (global $global$1 (mut funcref) (ref.null func))
+ (global $global$2 (mut funcref) (ref.func $foo))
+ (global $global$3 (mut exnref) (ref.null exn))
  (export "export_func" (func $import_func))
  (export "export_global" (global $gimport$1))
  (func $take_externref (param $0 externref)
@@ -30,121 +26,113 @@
  (func $take_exnref (param $0 exnref)
   (nop)
  )
- (func $take_nullref (param $0 nullref)
-  (nop)
- )
  (func $foo
   (nop)
  )
  (func $test
   (local $0 funcref)
   (local $1 externref)
-  (local $2 nullref)
-  (local $3 exnref)
+  (local $2 exnref)
   (local.set $1
    (local.get $1)
   )
   (local.set $1
-   (local.get $0)
-  )
-  (local.set $1
-   (local.get $3)
-  )
-  (local.set $1
-   (local.get $2)
-  )
-  (local.set $1
-   (ref.null)
+   (global.get $global$0)
   )
   (local.set $1
-   (ref.func $foo)
+   (ref.null extern)
   )
   (local.set $0
    (local.get $0)
   )
   (local.set $0
-   (ref.null)
+   (global.get $global$1)
   )
   (local.set $0
-   (ref.func $foo)
-  )
-  (local.set $3
-   (local.get $3)
+   (ref.null func)
   )
-  (local.set $3
-   (ref.null)
+  (local.set $0
+   (ref.func $foo)
   )
   (local.set $2
    (local.get $2)
   )
   (local.set $2
-   (ref.null)
-  )
-  (global.set $global$0
-   (global.get $global$0)
-  )
-  (global.set $global$0
-   (global.get $global$1)
+   (global.get $global$3)
   )
-  (global.set $global$0
-   (global.get $global$2)
+  (local.set $2
+   (ref.null exn)
   )
   (global.set $global$0
-   (global.get $global$3)
+   (global.get $global$0)
   )
   (global.set $global$0
-   (ref.null)
+   (local.get $1)
   )
   (global.set $global$0
-   (ref.func $foo)
+   (ref.null extern)
   )
   (global.set $global$1
    (global.get $global$1)
   )
   (global.set $global$1
-   (ref.null)
+   (local.get $0)
   )
   (global.set $global$1
-   (ref.func $foo)
-  )
-  (global.set $global$2
-   (global.get $global$2)
+   (ref.null func)
   )
-  (global.set $global$2
-   (ref.null)
+  (global.set $global$1
+   (ref.func $foo)
   )
   (global.set $global$3
    (global.get $global$3)
   )
   (global.set $global$3
-   (ref.null)
+   (local.get $2)
+  )
+  (global.set $global$3
+   (ref.null exn)
   )
   (call $take_externref
    (local.get $1)
   )
   (call $take_externref
-   (local.get $0)
+   (global.get $global$0)
   )
   (call $take_externref
-   (local.get $3)
+   (ref.null extern)
   )
-  (call $take_externref
-   (ref.null)
+  (call $take_funcref
+   (local.get $0)
   )
-  (call_indirect (type $externref_=>_none)
-   (local.get $1)
-   (i32.const 0)
+  (call $take_funcref
+   (global.get $global$1)
+  )
+  (call $take_funcref
+   (ref.null func)
+  )
+  (call $take_funcref
+   (ref.func $foo)
+  )
+  (call $take_exnref
+   (local.get $2)
+  )
+  (call $take_exnref
+   (global.get $global$3)
+  )
+  (call $take_exnref
+   (ref.null exn)
   )
   (call_indirect (type $externref_=>_none)
-   (local.get $0)
+   (local.get $1)
    (i32.const 0)
   )
   (call_indirect (type $externref_=>_none)
-   (local.get $3)
+   (global.get $global$0)
    (i32.const 0)
   )
   (call_indirect (type $externref_=>_none)
-   (ref.null)
+   (ref.null extern)
    (i32.const 0)
   )
   (call_indirect (type $funcref_=>_none)
@@ -152,24 +140,28 @@
    (i32.const 1)
   )
   (call_indirect (type $funcref_=>_none)
-   (ref.null)
+   (global.get $global$1)
+   (i32.const 1)
+  )
+  (call_indirect (type $funcref_=>_none)
+   (ref.null func)
+   (i32.const 1)
+  )
+  (call_indirect (type $funcref_=>_none)
+   (ref.func $foo)
    (i32.const 1)
   )
   (call_indirect (type $exnref_=>_none)
-   (local.get $3)
+   (local.get $2)
    (i32.const 2)
   )
   (call_indirect (type $exnref_=>_none)
-   (ref.null)
+   (global.get $global$3)
    (i32.const 2)
   )
-  (call_indirect (type $nullref_=>_none)
-   (local.get $2)
-   (i32.const 3)
-  )
-  (call_indirect (type $nullref_=>_none)
-   (ref.null)
-   (i32.const 3)
+  (call_indirect (type $exnref_=>_none)
+   (ref.null exn)
+   (i32.const 2)
   )
   (drop
    (block $label$1 (result externref)
@@ -182,7 +174,7 @@
   (drop
    (block $label$2 (result externref)
     (br_if $label$2
-     (local.get $0)
+     (global.get $global$0)
      (i32.const 1)
     )
    )
@@ -190,15 +182,15 @@
   (drop
    (block $label$3 (result externref)
     (br_if $label$3
-     (local.get $3)
+     (ref.null extern)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $label$4 (result externref)
+   (block $label$4 (result funcref)
     (br_if $label$4
-     (ref.null)
+     (local.get $0)
      (i32.const 1)
     )
    )
@@ -206,105 +198,120 @@
   (drop
    (block $label$5 (result funcref)
     (br_if $label$5
-     (ref.null)
+     (global.get $global$1)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $label$6 (result exnref)
+   (block $label$6 (result funcref)
     (br_if $label$6
-     (ref.null)
+     (ref.null func)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $label$7 (result nullref)
+   (block $label$7 (result funcref)
     (br_if $label$7
-     (ref.null)
+     (ref.func $foo)
      (i32.const 1)
     )
    )
   )
   (drop
-   (loop $label$8 (result externref)
-    (local.get $1)
+   (block $label$8 (result exnref)
+    (br_if $label$8
+     (local.get $2)
+     (i32.const 1)
+    )
    )
   )
   (drop
-   (loop $label$9 (result externref)
-    (local.get $0)
+   (block $label$9 (result exnref)
+    (br_if $label$9
+     (global.get $global$3)
+     (i32.const 1)
+    )
    )
   )
   (drop
-   (loop $label$10 (result externref)
-    (local.get $3)
+   (block $label$10 (result exnref)
+    (br_if $label$10
+     (ref.null exn)
+     (i32.const 1)
+    )
    )
   )
   (drop
    (loop $label$11 (result externref)
-    (ref.null)
+    (local.get $1)
    )
   )
   (drop
-   (loop $label$12 (result funcref)
+   (loop $label$12 (result externref)
+    (global.get $global$0)
+   )
+  )
+  (drop
+   (loop $label$13 (result externref)
+    (ref.null extern)
+   )
+  )
+  (drop
+   (loop $label$14 (result funcref)
     (local.get $0)
    )
   )
   (drop
-   (loop $label$13 (result funcref)
-    (ref.null)
+   (loop $label$15 (result funcref)
+    (global.get $global$1)
    )
   )
   (drop
-   (loop $label$14 (result exnref)
-    (local.get $3)
+   (loop $label$16 (result funcref)
+    (ref.null func)
    )
   )
   (drop
-   (loop $label$15 (result exnref)
-    (ref.null)
+   (loop $label$17 (result funcref)
+    (ref.func $foo)
    )
   )
   (drop
-   (loop $label$16 (result nullref)
-    (ref.null)
+   (loop $label$18 (result exnref)
+    (local.get $2)
    )
   )
   (drop
-   (if (result externref)
-    (i32.const 1)
-    (local.get $1)
-    (local.get $3)
+   (loop $label$19 (result exnref)
+    (global.get $global$3)
    )
   )
   (drop
-   (if (result externref)
-    (i32.const 1)
-    (ref.func $foo)
-    (ref.null)
+   (loop $label$20 (result exnref)
+    (ref.null exn)
    )
   )
   (drop
-   (if (result funcref)
+   (if (result externref)
     (i32.const 1)
-    (ref.func $foo)
-    (ref.null)
+    (local.get $1)
+    (ref.null extern)
    )
   )
   (drop
-   (if (result exnref)
+   (if (result funcref)
     (i32.const 1)
-    (local.get $3)
-    (ref.null)
+    (local.get $0)
+    (ref.null func)
    )
   )
   (drop
-   (if (result nullref)
+   (if (result exnref)
     (i32.const 1)
     (local.get $2)
-    (ref.null)
+    (ref.null exn)
    )
   )
   (drop
@@ -313,20 +320,10 @@
      (local.get $1)
     )
     (catch
-     (exnref.pop)
-    )
-   )
-  )
-  (drop
-   (try (result externref)
-    (do
-     (ref.func $foo)
-    )
-    (catch
      (drop
       (exnref.pop)
      )
-     (ref.null)
+     (ref.null extern)
     )
    )
   )
@@ -339,14 +336,14 @@
      (drop
       (exnref.pop)
      )
-     (ref.null)
+     (ref.null func)
     )
    )
   )
   (drop
    (try (result exnref)
     (do
-     (ref.null)
+     (ref.null exn)
     )
     (catch
      (exnref.pop)
@@ -354,82 +351,61 @@
    )
   )
   (drop
-   (try (result nullref)
-    (do
-     (ref.null)
-    )
-    (catch
-     (drop
-      (exnref.pop)
-     )
-     (ref.null)
-    )
-   )
-  )
-  (drop
    (select (result externref)
     (local.get $1)
-    (ref.func $foo)
+    (ref.null extern)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (local.get $3)
-    (local.get $1)
+   (select (result funcref)
+    (local.get $0)
+    (ref.null func)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (local.get $1)
-    (ref.null)
+   (select (result exnref)
+    (local.get $2)
+    (ref.null exn)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (ref.null)
-    (ref.func $foo)
+   (select
+    (i32.const 0)
+    (i32.const 2)
     (i32.const 1)
    )
   )
   (drop
-   (select (result funcref)
-    (ref.func $foo)
-    (ref.null)
-    (i32.const 1)
+   (ref.is_null
+    (local.get $1)
    )
   )
   (drop
-   (select (result exnref)
-    (ref.null)
-    (local.get $3)
-    (i32.const 1)
+   (ref.is_null
+    (global.get $global$0)
    )
   )
   (drop
-   (select (result nullref)
-    (ref.null)
-    (ref.null)
-    (i32.const 1)
+   (ref.is_null
+    (ref.null extern)
    )
   )
   (drop
-   (select
-    (i32.const 0)
-    (i32.const 2)
-    (i32.const 1)
+   (ref.is_null
+    (local.get $0)
    )
   )
   (drop
    (ref.is_null
-    (local.get $1)
+    (global.get $global$1)
    )
   )
   (drop
    (ref.is_null
-    (local.get $3)
+    (ref.null func)
    )
   )
   (drop
@@ -439,61 +415,67 @@
   )
   (drop
    (ref.is_null
-    (ref.null)
+    (local.get $2)
+   )
+  )
+  (drop
+   (ref.is_null
+    (global.get $global$3)
+   )
+  )
+  (drop
+   (ref.is_null
+    (ref.null exn)
    )
   )
  )
- (func $return_externref (result externref)
+ (func $return_externref_local (result externref)
   (local $0 externref)
   (local.get $0)
  )
- (func $return_externref2 (result externref)
-  (ref.func $foo)
+ (func $return_externref_global (result externref)
+  (global.get $global$0)
  )
- (func $return_externref3 (result externref)
-  (local $0 exnref)
+ (func $return_externref_null (result externref)
+  (ref.null extern)
+ )
+ (func $return_funcref_local (result funcref)
+  (local $0 funcref)
   (local.get $0)
  )
- (func $return_externref4 (result externref)
-  (ref.null)
+ (func $return_funcref_global (result funcref)
+  (global.get $global$1)
  )
- (func $return_funcref (result funcref)
-  (ref.func $foo)
+ (func $return_funcref_null (result funcref)
+  (ref.null func)
  )
- (func $return_funcref2 (result funcref)
-  (ref.null)
+ (func $return_funcref_func (result funcref)
+  (ref.func $foo)
  )
- (func $return_exnref (result exnref)
+ (func $return_exnref_local (result exnref)
   (local $0 exnref)
   (local.get $0)
  )
- (func $return_exnref2 (result exnref)
-  (ref.null)
+ (func $return_exnref_global (result exnref)
+  (global.get $global$3)
  )
- (func $return_nullref (result nullref)
-  (local $0 nullref)
-  (local.get $0)
+ (func $return_exnref_null (result exnref)
+  (ref.null exn)
  )
- (func $return_externref_returns (result externref)
+ (func $returns_externref (result externref)
   (local $0 externref)
-  (local $1 exnref)
   (return
    (local.get $0)
   )
  )
- (func $return_funcref_returns (result funcref)
-  (return
-   (ref.func $foo)
-  )
- )
- (func $return_exnref_returns (result exnref)
-  (local $0 exnref)
+ (func $returns_funcref (result funcref)
+  (local $0 funcref)
   (return
    (local.get $0)
   )
  )
- (func $return_nullref_returns (result nullref)
-  (local $0 nullref)
+ (func $returns_exnref (result exnref)
+  (local $0 exnref)
   (return
    (local.get $0)
   )
diff --git a/test/reference-types.wast.fromBinary.noDebugInfo b/test/reference-types.wast.fromBinary.noDebugInfo
index 9e8dac3a3..f0282f1e2 100644
--- a/test/reference-types.wast.fromBinary.noDebugInfo
+++ b/test/reference-types.wast.fromBinary.noDebugInfo
@@ -1,24 +1,20 @@
 (module
- (type $externref_=>_none (func (param externref)))
- (type $none_=>_externref (func (result externref)))
  (type $funcref_=>_none (func (param funcref)))
- (type $nullref_=>_none (func (param nullref)))
- (type $exnref_=>_none (func (param exnref)))
  (type $none_=>_funcref (func (result funcref)))
+ (type $externref_=>_none (func (param externref)))
+ (type $exnref_=>_none (func (param exnref)))
+ (type $none_=>_externref (func (result externref)))
  (type $none_=>_exnref (func (result exnref)))
  (type $none_=>_none (func))
- (type $none_=>_nullref (func (result nullref)))
  (type $externref_=>_funcref (func (param externref) (result funcref)))
  (import "env" "import_global" (global $gimport$1 externref))
  (import "env" "import_func" (func $fimport$0 (param externref) (result funcref)))
- (table $0 4 4 funcref)
- (elem (i32.const 0) $0 $1 $2 $3)
- (global $global$0 (mut externref) (ref.null))
- (global $global$1 (mut funcref) (ref.null))
- (global $global$2 (mut exnref) (ref.null))
- (global $global$3 (mut nullref) (ref.null))
- (global $global$4 (mut externref) (ref.func $4))
- (global $global$5 (mut funcref) (ref.func $4))
+ (table $0 3 3 funcref)
+ (elem (i32.const 0) $0 $1 $2)
+ (global $global$0 (mut externref) (ref.null extern))
+ (global $global$1 (mut funcref) (ref.null func))
+ (global $global$2 (mut funcref) (ref.func $3))
+ (global $global$3 (mut exnref) (ref.null exn))
  (export "export_func" (func $fimport$0))
  (export "export_global" (global $gimport$1))
  (func $0 (param $0 externref)
@@ -30,121 +26,113 @@
  (func $2 (param $0 exnref)
   (nop)
  )
- (func $3 (param $0 nullref)
+ (func $3
   (nop)
  )
  (func $4
-  (nop)
- )
- (func $5
   (local $0 funcref)
   (local $1 externref)
-  (local $2 nullref)
-  (local $3 exnref)
+  (local $2 exnref)
   (local.set $1
    (local.get $1)
   )
   (local.set $1
-   (local.get $0)
-  )
-  (local.set $1
-   (local.get $3)
-  )
-  (local.set $1
-   (local.get $2)
-  )
-  (local.set $1
-   (ref.null)
+   (global.get $global$0)
   )
   (local.set $1
-   (ref.func $4)
+   (ref.null extern)
   )
   (local.set $0
    (local.get $0)
   )
   (local.set $0
-   (ref.null)
+   (global.get $global$1)
   )
   (local.set $0
-   (ref.func $4)
-  )
-  (local.set $3
-   (local.get $3)
+   (ref.null func)
   )
-  (local.set $3
-   (ref.null)
+  (local.set $0
+   (ref.func $3)
   )
   (local.set $2
    (local.get $2)
   )
   (local.set $2
-   (ref.null)
-  )
-  (global.set $global$0
-   (global.get $global$0)
-  )
-  (global.set $global$0
-   (global.get $global$1)
+   (global.get $global$3)
   )
-  (global.set $global$0
-   (global.get $global$2)
+  (local.set $2
+   (ref.null exn)
   )
   (global.set $global$0
-   (global.get $global$3)
+   (global.get $global$0)
   )
   (global.set $global$0
-   (ref.null)
+   (local.get $1)
   )
   (global.set $global$0
-   (ref.func $4)
+   (ref.null extern)
   )
   (global.set $global$1
    (global.get $global$1)
   )
   (global.set $global$1
-   (ref.null)
+   (local.get $0)
   )
   (global.set $global$1
-   (ref.func $4)
-  )
-  (global.set $global$2
-   (global.get $global$2)
+   (ref.null func)
   )
-  (global.set $global$2
-   (ref.null)
+  (global.set $global$1
+   (ref.func $3)
   )
   (global.set $global$3
    (global.get $global$3)
   )
   (global.set $global$3
-   (ref.null)
+   (local.get $2)
+  )
+  (global.set $global$3
+   (ref.null exn)
   )
   (call $0
    (local.get $1)
   )
   (call $0
-   (local.get $0)
+   (global.get $global$0)
   )
   (call $0
-   (local.get $3)
+   (ref.null extern)
   )
-  (call $0
-   (ref.null)
+  (call $1
+   (local.get $0)
   )
-  (call_indirect (type $externref_=>_none)
-   (local.get $1)
-   (i32.const 0)
+  (call $1
+   (global.get $global$1)
+  )
+  (call $1
+   (ref.null func)
+  )
+  (call $1
+   (ref.func $3)
+  )
+  (call $2
+   (local.get $2)
+  )
+  (call $2
+   (global.get $global$3)
+  )
+  (call $2
+   (ref.null exn)
   )
   (call_indirect (type $externref_=>_none)
-   (local.get $0)
+   (local.get $1)
    (i32.const 0)
   )
   (call_indirect (type $externref_=>_none)
-   (local.get $3)
+   (global.get $global$0)
    (i32.const 0)
   )
   (call_indirect (type $externref_=>_none)
-   (ref.null)
+   (ref.null extern)
    (i32.const 0)
   )
   (call_indirect (type $funcref_=>_none)
@@ -152,24 +140,28 @@
    (i32.const 1)
   )
   (call_indirect (type $funcref_=>_none)
-   (ref.null)
+   (global.get $global$1)
+   (i32.const 1)
+  )
+  (call_indirect (type $funcref_=>_none)
+   (ref.null func)
+   (i32.const 1)
+  )
+  (call_indirect (type $funcref_=>_none)
+   (ref.func $3)
    (i32.const 1)
   )
   (call_indirect (type $exnref_=>_none)
-   (local.get $3)
+   (local.get $2)
    (i32.const 2)
   )
   (call_indirect (type $exnref_=>_none)
-   (ref.null)
+   (global.get $global$3)
    (i32.const 2)
   )
-  (call_indirect (type $nullref_=>_none)
-   (local.get $2)
-   (i32.const 3)
-  )
-  (call_indirect (type $nullref_=>_none)
-   (ref.null)
-   (i32.const 3)
+  (call_indirect (type $exnref_=>_none)
+   (ref.null exn)
+   (i32.const 2)
   )
   (drop
    (block $label$1 (result externref)
@@ -182,7 +174,7 @@
   (drop
    (block $label$2 (result externref)
     (br_if $label$2
-     (local.get $0)
+     (global.get $global$0)
      (i32.const 1)
     )
    )
@@ -190,15 +182,15 @@
   (drop
    (block $label$3 (result externref)
     (br_if $label$3
-     (local.get $3)
+     (ref.null extern)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $label$4 (result externref)
+   (block $label$4 (result funcref)
     (br_if $label$4
-     (ref.null)
+     (local.get $0)
      (i32.const 1)
     )
    )
@@ -206,105 +198,120 @@
   (drop
    (block $label$5 (result funcref)
     (br_if $label$5
-     (ref.null)
+     (global.get $global$1)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $label$6 (result exnref)
+   (block $label$6 (result funcref)
     (br_if $label$6
-     (ref.null)
+     (ref.null func)
      (i32.const 1)
     )
    )
   )
   (drop
-   (block $label$7 (result nullref)
+   (block $label$7 (result funcref)
     (br_if $label$7
-     (ref.null)
+     (ref.func $3)
      (i32.const 1)
     )
    )
   )
   (drop
-   (loop $label$8 (result externref)
-    (local.get $1)
+   (block $label$8 (result exnref)
+    (br_if $label$8
+     (local.get $2)
+     (i32.const 1)
+    )
    )
   )
   (drop
-   (loop $label$9 (result externref)
-    (local.get $0)
+   (block $label$9 (result exnref)
+    (br_if $label$9
+     (global.get $global$3)
+     (i32.const 1)
+    )
    )
   )
   (drop
-   (loop $label$10 (result externref)
-    (local.get $3)
+   (block $label$10 (result exnref)
+    (br_if $label$10
+     (ref.null exn)
+     (i32.const 1)
+    )
    )
   )
   (drop
    (loop $label$11 (result externref)
-    (ref.null)
+    (local.get $1)
    )
   )
   (drop
-   (loop $label$12 (result funcref)
+   (loop $label$12 (result externref)
+    (global.get $global$0)
+   )
+  )
+  (drop
+   (loop $label$13 (result externref)
+    (ref.null extern)
+   )
+  )
+  (drop
+   (loop $label$14 (result funcref)
     (local.get $0)
    )
   )
   (drop
-   (loop $label$13 (result funcref)
-    (ref.null)
+   (loop $label$15 (result funcref)
+    (global.get $global$1)
    )
   )
   (drop
-   (loop $label$14 (result exnref)
-    (local.get $3)
+   (loop $label$16 (result funcref)
+    (ref.null func)
    )
   )
   (drop
-   (loop $label$15 (result exnref)
-    (ref.null)
+   (loop $label$17 (result funcref)
+    (ref.func $3)
    )
   )
   (drop
-   (loop $label$16 (result nullref)
-    (ref.null)
+   (loop $label$18 (result exnref)
+    (local.get $2)
    )
   )
   (drop
-   (if (result externref)
-    (i32.const 1)
-    (local.get $1)
-    (local.get $3)
+   (loop $label$19 (result exnref)
+    (global.get $global$3)
    )
   )
   (drop
-   (if (result externref)
-    (i32.const 1)
-    (ref.func $4)
-    (ref.null)
+   (loop $label$20 (result exnref)
+    (ref.null exn)
    )
   )
   (drop
-   (if (result funcref)
+   (if (result externref)
     (i32.const 1)
-    (ref.func $4)
-    (ref.null)
+    (local.get $1)
+    (ref.null extern)
    )
   )
   (drop
-   (if (result exnref)
+   (if (result funcref)
     (i32.const 1)
-    (local.get $3)
-    (ref.null)
+    (local.get $0)
+    (ref.null func)
    )
   )
   (drop
-   (if (result nullref)
+   (if (result exnref)
     (i32.const 1)
     (local.get $2)
-    (ref.null)
+    (ref.null exn)
    )
   )
   (drop
@@ -313,40 +320,30 @@
      (local.get $1)
     )
     (catch
-     (exnref.pop)
-    )
-   )
-  )
-  (drop
-   (try (result externref)
-    (do
-     (ref.func $4)
-    )
-    (catch
      (drop
       (exnref.pop)
      )
-     (ref.null)
+     (ref.null extern)
     )
    )
   )
   (drop
    (try (result funcref)
     (do
-     (ref.func $4)
+     (ref.func $3)
     )
     (catch
      (drop
       (exnref.pop)
      )
-     (ref.null)
+     (ref.null func)
     )
    )
   )
   (drop
    (try (result exnref)
     (do
-     (ref.null)
+     (ref.null exn)
     )
     (catch
      (exnref.pop)
@@ -354,136 +351,127 @@
    )
   )
   (drop
-   (try (result nullref)
-    (do
-     (ref.null)
-    )
-    (catch
-     (drop
-      (exnref.pop)
-     )
-     (ref.null)
-    )
-   )
-  )
-  (drop
    (select (result externref)
     (local.get $1)
-    (ref.func $4)
+    (ref.null extern)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (local.get $3)
-    (local.get $1)
+   (select (result funcref)
+    (local.get $0)
+    (ref.null func)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (local.get $1)
-    (ref.null)
+   (select (result exnref)
+    (local.get $2)
+    (ref.null exn)
     (i32.const 1)
    )
   )
   (drop
-   (select (result externref)
-    (ref.null)
-    (ref.func $4)
+   (select
+    (i32.const 0)
+    (i32.const 2)
     (i32.const 1)
    )
   )
   (drop
-   (select (result funcref)
-    (ref.func $4)
-    (ref.null)
-    (i32.const 1)
+   (ref.is_null
+    (local.get $1)
    )
   )
   (drop
-   (select (result exnref)
-    (ref.null)
-    (local.get $3)
-    (i32.const 1)
+   (ref.is_null
+    (global.get $global$0)
    )
   )
   (drop
-   (select (result nullref)
-    (ref.null)
-    (ref.null)
-    (i32.const 1)
+   (ref.is_null
+    (ref.null extern)
    )
   )
   (drop
-   (select
-    (i32.const 0)
-    (i32.const 2)
-    (i32.const 1)
+   (ref.is_null
+    (local.get $0)
    )
   )
   (drop
    (ref.is_null
-    (local.get $1)
+    (global.get $global$1)
    )
   )
   (drop
    (ref.is_null
-    (local.get $3)
+    (ref.null func)
    )
   )
   (drop
    (ref.is_null
-    (ref.func $4)
+    (ref.func $3)
    )
   )
   (drop
    (ref.is_null
-    (ref.null)
+    (local.get $2)
+   )
+  )
+  (drop
+   (ref.is_null
+    (global.get $global$3)
+   )
+  )
+  (drop
+   (ref.is_null
+    (ref.null exn)
    )
   )
  )
- (func $6 (result externref)
+ (func $5 (result externref)
   (local $0 externref)
   (local.get $0)
  )
+ (func $6 (result externref)
+  (global.get $global$0)
+ )
  (func $7 (result externref)
-  (ref.func $4)
+  (ref.null extern)
  )
- (func $8 (result externref)
-  (local $0 exnref)
+ (func $8 (result funcref)
+  (local $0 funcref)
   (local.get $0)
  )
- (func $9 (result externref)
-  (ref.null)
+ (func $9 (result funcref)
+  (global.get $global$1)
  )
  (func $10 (result funcref)
-  (ref.func $4)
+  (ref.null func)
  )
  (func $11 (result funcref)
-  (ref.null)
+  (ref.func $3)
  )
  (func $12 (result exnref)
   (local $0 exnref)
   (local.get $0)
  )
  (func $13 (result exnref)
-  (ref.null)
+  (global.get $global$3)
  )
- (func $14 (result nullref)
-  (local $0 nullref)
-  (local.get $0)
+ (func $14 (result exnref)
+  (ref.null exn)
  )
  (func $15 (result externref)
   (local $0 externref)
-  (local $1 exnref)
   (return
    (local.get $0)
   )
  )
  (func $16 (result funcref)
+  (local $0 funcref)
   (return
-   (ref.func $4)
+   (local.get $0)
   )
  )
  (func $17 (result exnref)
@@ -492,11 +480,5 @@
    (local.get $0)
   )
  )
- (func $18 (result nullref)
-  (local $0 nullref)
-  (return
-   (local.get $0)
-  )
- )
 )
 
diff --git a/test/spec/call_indirect_sig_mismatch.wast b/test/spec/call_indirect_sig_mismatch.wast
index 15e5d6a5a..69cca17ba 100644
--- a/test/spec/call_indirect_sig_mismatch.wast
+++ b/test/spec/call_indirect_sig_mismatch.wast
@@ -5,7 +5,7 @@
   (func $callee (param $0 exnref))
   (func $sig_mismatch
     (call_indirect (type $funcref_=>_none)
-      (ref.null)
+      (ref.null func)
       (i32.const 0)
     )
   )
diff --git a/test/spec/exception-handling.wast b/test/spec/exception-handling.wast
index c3b80896e..0188865ac 100644
--- a/test/spec/exception-handling.wast
+++ b/test/spec/exception-handling.wast
@@ -11,8 +11,8 @@
     (throw $e-i32-f32 (i32.const 3) (f32.const 3.5))
   )
 
-  (func (export "rethrow_nullref")
-    (rethrow (ref.null))
+  (func (export "rethrow_null")
+    (rethrow (ref.null exn))
   )
 
   (func (export "try_nothrow") (result i32)
@@ -74,10 +74,10 @@
     )
   )
 
-  (func (export "br_on_exn_nullref") (result i32)
+  (func (export "br_on_exn_null") (result i32)
     (block $l0 (result i32)
       (drop
-        (br_on_exn $l0 $e-i32 (ref.null))
+        (br_on_exn $l0 $e-i32 (ref.null exn))
       )
       (i32.const 0)
     )
@@ -185,13 +185,13 @@
 
 (assert_trap (invoke "throw_single_value"))
 (assert_trap (invoke "throw_multiple_values"))
-(assert_trap (invoke "rethrow_nullref"))
+(assert_trap (invoke "rethrow_null"))
 (assert_return (invoke "try_nothrow") (i32.const 3))
 (assert_return (invoke "try_throw_catch") (i32.const 3))
 (assert_return (invoke "try_call_catch") (i32.const 3))
 (assert_trap (invoke "try_throw_rethrow"))
 (assert_trap (invoke "try_call_rethrow"))
-(assert_trap (invoke "br_on_exn_nullref"))
+(assert_trap (invoke "br_on_exn_null"))
 (assert_return (invoke "br_on_exn_match_no_value"))
 (assert_return (invoke "br_on_exn_match_single_value") (i32.const 5))
 (assert_return (invoke "br_on_exn_match_multiple_values") (tuple.make (i32.const 3) (f32.const 3.5)))
diff --git a/test/spec/old_select.wast b/test/spec/old_select.wast
index e1dd40654..5228017b0 100644
--- a/test/spec/old_select.wast
+++ b/test/spec/old_select.wast
@@ -23,9 +23,6 @@
     (select (result f64) (local.get 0) (local.get 1) (local.get 2))
   )
 
-  (func (export "select-nullref") (param nullref nullref i32) (result nullref)
-    (select (result nullref) (local.get 0) (local.get 1) (local.get 2))
-  )
   (func (export "select-funcref") (param funcref funcref i32) (result funcref)
     (select (result funcref) (local.get 0) (local.get 1) (local.get 2))
   )
@@ -38,24 +35,6 @@
    (select (unreachable) (i32.const 0) (local.get $cond)))
   (func (export "select_trap_r") (param $cond i32) (result i32)
    (select (i32.const 0) (unreachable) (local.get $cond)))
-
-  (func (export "join-nullref") (param i32) (result externref)
-    (select (result externref) (ref.null) (ref.null) (local.get 0))
-  )
-  (func (export "join-funcref") (param i32) (result externref)
-    (select (result externref)
-      (ref.func $dummy)
-      (ref.null)
-      (local.get 0)
-    )
-  )
-  (func (export "join-externref") (param i32) (param externref) (result externref)
-    (select (result externref)
-      (ref.func $dummy)
-      (local.get 1)
-      (local.get 0)
-    )
-  )
 )
 
 (assert_return (invoke "select_i32" (i32.const 1) (i32.const 2) (i32.const 1)) (i32.const 1))
@@ -90,15 +69,11 @@
 (assert_return (invoke "select-i64-t" (i64.const 2) (i64.const 1) (i32.const 1)) (i64.const 2))
 (assert_return (invoke "select-f32-t" (f32.const 1) (f32.const 2) (i32.const 1)) (f32.const 1))
 (assert_return (invoke "select-f64-t" (f64.const 1) (f64.const 2) (i32.const 1)) (f64.const 1))
-(assert_return (invoke "select-nullref" (ref.null) (ref.null) (i32.const 1)) (ref.null))
-(assert_return (invoke "select-funcref" (ref.func "dummy") (ref.null) (i32.const 1)) (ref.func "dummy"))
-(assert_return (invoke "select-externref" (ref.null) (ref.func "dummy") (i32.const 1)) (ref.null))
 
 (assert_return (invoke "select-i32-t" (i32.const 1) (i32.const 2) (i32.const 0)) (i32.const 2))
 (assert_return (invoke "select-i32-t" (i32.const 2) (i32.const 1) (i32.const 0)) (i32.const 1))
 (assert_return (invoke "select-i64-t" (i64.const 2) (i64.const 1) (i32.const -1)) (i64.const 2))
 (assert_return (invoke "select-i64-t" (i64.const 2) (i64.const 1) (i32.const 0xf0f0f0f0)) (i64.const 2))
-(assert_return (invoke "select-externref" (ref.null) (ref.func "dummy") (i32.const 0)) (ref.func "dummy"))
 
 (assert_return (invoke "select-f32-t" (f32.const nan) (f32.const 1) (i32.const 1)) (f32.const nan))
 (assert_return (invoke "select-f32-t" (f32.const nan:0x20304) (f32.const 1) (i32.const 1)) (f32.const nan:0x20304))
@@ -118,14 +93,10 @@
 (assert_return (invoke "select-f64-t" (f64.const 2) (f64.const nan) (i32.const 0)) (f64.const nan))
 (assert_return (invoke "select-f64-t" (f64.const 2) (f64.const nan:0x20304) (i32.const 0)) (f64.const nan:0x20304))
 
-(assert_return (invoke "join-nullref" (i32.const 1)) (ref.null))
-(assert_return (invoke "join-nullref" (i32.const 0)) (ref.null))
-
-(assert_return_func (invoke "join-funcref" (i32.const 1)))
-(assert_return (invoke "join-funcref" (i32.const 0)) (ref.null))
-
-(assert_return_func (invoke "join-externref" (i32.const 1) (ref.null)))
-(assert_return (invoke "join-externref" (i32.const 0) (ref.null)) (ref.null))
+(assert_return (invoke "select-funcref" (ref.func "dummy") (ref.null func) (i32.const 1)) (ref.func "dummy"))
+(assert_return (invoke "select-funcref" (ref.func "dummy") (ref.null func) (i32.const 0)) (ref.null func))
+(assert_return (invoke "select-externref" (ref.null extern) (ref.null extern) (i32.const 1)) (ref.null extern))
+(assert_return (invoke "select-externref" (ref.null extern) (ref.null extern) (i32.const 0)) (ref.null extern))
 
 (assert_trap (invoke "select_trap_l" (i32.const 1)) "unreachable executed")
 (assert_trap (invoke "select_trap_l" (i32.const 0)) "unreachable executed")
diff --git a/test/spec/ref_func.wast b/test/spec/ref_func.wast
index 79bf584be..f68e6166d 100644
--- a/test/spec/ref_func.wast
+++ b/test/spec/ref_func.wast
@@ -5,8 +5,7 @@
   (func $f (import "M" "f") (param i32) (result i32))
   (func $g (param $x i32) (result i32) (i32.add (local.get $x) (i32.const 1)))
 
-  (global externref (ref.func $f))
-  (global externref (ref.func $g))
+  (global externref (ref.null extern))
   (global funcref (ref.func $f))
   (global funcref (ref.func $g))
   (global $v (mut funcref) (ref.func $f))
diff --git a/test/spec/ref_is_null.wast b/test/spec/ref_is_null.wast
index e44fcf496..8f820d2bc 100644
--- a/test/spec/ref_is_null.wast
+++ b/test/spec/ref_is_null.wast
@@ -1,15 +1,11 @@
 (module
-  (func $f1 (export "nullref") (param $x nullref) (result i32)
+  (func $f1 (export "externref") (param $x externref) (result i32)
     (ref.is_null (local.get $x))
   )
-  (func $f2 (export "externref") (param $x externref) (result i32)
-    (ref.is_null (local.get $x))
-  )
-  (func $f3 (export "funcref") (param $x funcref) (result i32)
+  (func $f2 (export "funcref") (param $x funcref) (result i32)
     (ref.is_null (local.get $x))
   )
 )
 
-(assert_return (invoke "nullref" (ref.null)) (i32.const 1))
-(assert_return (invoke "externref" (ref.null)) (i32.const 1))
-(assert_return (invoke "funcref" (ref.null)) (i32.const 1))
+(assert_return (invoke "externref" (ref.null extern)) (i32.const 1))
+(assert_return (invoke "funcref" (ref.null func)) (i32.const 1))
diff --git a/test/spec/ref_null.wast b/test/spec/ref_null.wast
index 93e6acbd2..b88b0888f 100644
--- a/test/spec/ref_null.wast
+++ b/test/spec/ref_null.wast
@@ -1,13 +1,10 @@
 (module
-  (func (export "externref") (result externref) (ref.null))
-  (func (export "funcref") (result funcref) (ref.null))
-  (func (export "nullref") (result nullref) (ref.null))
+  (func (export "externref") (result externref) (ref.null extern))
+  (func (export "funcref") (result funcref) (ref.null func))
 
-  (global externref (ref.null))
-  (global funcref (ref.null))
-  (global nullref (ref.null))
+  (global externref (ref.null extern))
+  (global funcref (ref.null func))
 )
 
-(assert_return (invoke "externref") (ref.null))
-(assert_return (invoke "funcref") (ref.null))
-(assert_return (invoke "nullref") (ref.null))
+(assert_return (invoke "externref") (ref.null extern))
+(assert_return (invoke "funcref") (ref.null func))