Remove ref.is_null type parameter (#1474)

See https://github.com/WebAssembly/reference-types/issues/99.

This change also updates the testsuite, so the spec tests pass too.

In addition, the behavior of `br_table` is no longer different from MVP,
and has a text to confirm this. That is now fixed in `type-checker.cc`
too.

16 files changed, 37 insertions, 33 deletions

diff --git a/src/binary-reader-ir.cc b/src/binary-reader-ir.cc
index e1b41697..0dc9b2b1 100644
--- a/src/binary-reader-ir.cc
+++ b/src/binary-reader-ir.cc
@@ -185,7 +185,7 @@ class BinaryReaderIR : public BinaryReaderNop {
   Result OnTableFillExpr(Index table_index) override;
   Result OnRefFuncExpr(Index func_index) override;
   Result OnRefNullExpr(Type type) override;
-  Result OnRefIsNullExpr(Type type) override;
+  Result OnRefIsNullExpr() override;
   Result OnNopExpr() override;
   Result OnRethrowExpr() override;
   Result OnReturnExpr() override;
@@ -919,8 +919,8 @@ Result BinaryReaderIR::OnRefNullExpr(Type type) {
   return AppendExpr(MakeUnique<RefNullExpr>(type));
 }
 
-Result BinaryReaderIR::OnRefIsNullExpr(Type type) {
-  return AppendExpr(MakeUnique<RefIsNullExpr>(type));
+Result BinaryReaderIR::OnRefIsNullExpr() {
+  return AppendExpr(MakeUnique<RefIsNullExpr>());
 }
 
 Result BinaryReaderIR::OnNopExpr() {
diff --git a/src/binary-reader-logging.cc b/src/binary-reader-logging.cc
index ef24ad0e..e5d72772 100644
--- a/src/binary-reader-logging.cc
+++ b/src/binary-reader-logging.cc
@@ -790,7 +790,7 @@ DEFINE_INDEX(OnTableSizeExpr)
 DEFINE_INDEX_DESC(OnTableFillExpr, "table index")
 DEFINE_INDEX(OnRefFuncExpr)
 DEFINE_TYPE(OnRefNullExpr)
-DEFINE_TYPE(OnRefIsNullExpr)
+DEFINE0(OnRefIsNullExpr)
 DEFINE0(OnNopExpr)
 DEFINE0(OnRethrowExpr);
 DEFINE_INDEX_DESC(OnReturnCallExpr, "func_index")
diff --git a/src/binary-reader-logging.h b/src/binary-reader-logging.h
index f5936562..fd1ac13f 100644
--- a/src/binary-reader-logging.h
+++ b/src/binary-reader-logging.h
@@ -201,7 +201,7 @@ class BinaryReaderLogging : public BinaryReaderDelegate {
   Result OnTableFillExpr(Index table) override;
   Result OnRefFuncExpr(Index index) override;
   Result OnRefNullExpr(Type type) override;
-  Result OnRefIsNullExpr(Type type) override;
+  Result OnRefIsNullExpr() override;
   Result OnNopExpr() override;
   Result OnRethrowExpr() override;
   Result OnReturnCallExpr(Index func_index) override;
diff --git a/src/binary-reader-nop.h b/src/binary-reader-nop.h
index 1159476a..a00d6b05 100644
--- a/src/binary-reader-nop.h
+++ b/src/binary-reader-nop.h
@@ -278,7 +278,7 @@ class BinaryReaderNop : public BinaryReaderDelegate {
   Result OnTableFillExpr(Index table_index) override { return Result::Ok; }
   Result OnRefFuncExpr(Index func_index) override { return Result::Ok; }
   Result OnRefNullExpr(Type type) override { return Result::Ok; }
-  Result OnRefIsNullExpr(Type type) override { return Result::Ok; }
+  Result OnRefIsNullExpr() override { return Result::Ok; }
   Result OnNopExpr() override { return Result::Ok; }
   Result OnRethrowExpr() override { return Result::Ok; }
   Result OnReturnCallExpr(Index sig_index) override { return Result::Ok; }
diff --git a/src/binary-reader.cc b/src/binary-reader.cc
index ebc088dd..7f195356 100644
--- a/src/binary-reader.cc
+++ b/src/binary-reader.cc
@@ -1573,13 +1573,10 @@ Result BinaryReader::ReadFunctionBody(Offset end_offset) {
         break;
       }
 
-      case Opcode::RefIsNull: {
-        Type type;
-        CHECK_RESULT(ReadRefType(&type, "ref.is_null type"));
-        CALLBACK(OnRefIsNullExpr, type);
-        CALLBACK(OnOpcodeType, type);
+      case Opcode::RefIsNull:
+        CALLBACK(OnRefIsNullExpr);
+        CALLBACK(OnOpcodeBare);
         break;
-      }
 
       default:
         return ReportUnexpectedOpcode(opcode);
diff --git a/src/binary-reader.h b/src/binary-reader.h
index eae1e87d..e50f4b9d 100644
--- a/src/binary-reader.h
+++ b/src/binary-reader.h
@@ -267,7 +267,7 @@ class BinaryReaderDelegate {
   virtual Result OnTableFillExpr(Index table_index) = 0;
   virtual Result OnRefFuncExpr(Index func_index) = 0;
   virtual Result OnRefNullExpr(Type type) = 0;
-  virtual Result OnRefIsNullExpr(Type type) = 0;
+  virtual Result OnRefIsNullExpr() = 0;
   virtual Result OnNopExpr() = 0;
   virtual Result OnRethrowExpr() = 0;
   virtual Result OnReturnExpr() = 0;
diff --git a/src/binary-writer.cc b/src/binary-writer.cc
index fd2b0c24..261190fd 100644
--- a/src/binary-writer.cc
+++ b/src/binary-writer.cc
@@ -684,11 +684,9 @@ void BinaryWriter::WriteExpr(const Func* func, const Expr* expr) {
       WriteType(stream_, cast<RefNullExpr>(expr)->type, "ref.null type");
       break;
     }
-    case ExprType::RefIsNull: {
+    case ExprType::RefIsNull:
       WriteOpcode(stream_, Opcode::RefIsNull);
-      WriteType(stream_, cast<RefIsNullExpr>(expr)->type, "ref.is_null type");
       break;
-    }
     case ExprType::Nop:
       WriteOpcode(stream_, Opcode::Nop);
       break;
diff --git a/src/interp/binary-reader-interp.cc b/src/interp/binary-reader-interp.cc
index 20a8368c..8b44cdaf 100644
--- a/src/interp/binary-reader-interp.cc
+++ b/src/interp/binary-reader-interp.cc
@@ -192,7 +192,7 @@ class BinaryReaderInterp : public BinaryReaderNop {
   Result OnMemorySizeExpr() override;
   Result OnRefFuncExpr(Index func_index) override;
   Result OnRefNullExpr(Type type) override;
-  Result OnRefIsNullExpr(Type type) override;
+  Result OnRefIsNullExpr() override;
   Result OnNopExpr() override;
   Result OnReturnExpr() override;
   Result OnSelectExpr(Type result_type) override;
@@ -1240,8 +1240,8 @@ Result BinaryReaderInterp::OnRefNullExpr(Type type) {
   return Result::Ok;
 }
 
-Result BinaryReaderInterp::OnRefIsNullExpr(Type type) {
-  CHECK_RESULT(validator_.OnRefIsNull(loc, type));
+Result BinaryReaderInterp::OnRefIsNullExpr() {
+  CHECK_RESULT(validator_.OnRefIsNull(loc));
   istream_.Emit(Opcode::RefIsNull);
   return Result::Ok;
 }
diff --git a/src/ir.h b/src/ir.h
index 424a11f5..9b456a7b 100644
--- a/src/ir.h
+++ b/src/ir.h
@@ -409,7 +409,7 @@ class RefTypeExpr : public ExprMixin<TypeEnum> {
 };
 
 typedef RefTypeExpr<ExprType::RefNull> RefNullExpr;
-typedef RefTypeExpr<ExprType::RefIsNull> RefIsNullExpr;
+typedef ExprMixin<ExprType::RefIsNull> RefIsNullExpr;
 
 template <ExprType TypeEnum>
 class OpcodeExpr : public ExprMixin<TypeEnum> {
diff --git a/src/shared-validator.cc b/src/shared-validator.cc
index f4a7303e..8b6bef80 100644
--- a/src/shared-validator.cc
+++ b/src/shared-validator.cc
@@ -968,10 +968,10 @@ Result SharedValidator::OnRefFunc(const Location& loc, Var func_var) {
   return result;
 }
 
-Result SharedValidator::OnRefIsNull(const Location& loc, Type type) {
+Result SharedValidator::OnRefIsNull(const Location& loc) {
   Result result = Result::Ok;
   expr_loc_ = &loc;
-  result |= typechecker_.OnRefIsNullExpr(type);
+  result |= typechecker_.OnRefIsNullExpr();
   return result;
 }
 
diff --git a/src/shared-validator.h b/src/shared-validator.h
index dadb0930..3f77c403 100644
--- a/src/shared-validator.h
+++ b/src/shared-validator.h
@@ -150,7 +150,7 @@ class SharedValidator {
   Result OnMemorySize(const Location&);
   Result OnNop(const Location&);
   Result OnRefFunc(const Location&, Var func_var);
-  Result OnRefIsNull(const Location&, Type type);
+  Result OnRefIsNull(const Location&);
   Result OnRefNull(const Location&, Type type);
   Result OnRethrow(const Location&);
   Result OnReturnCall(const Location&, Var func_var);
diff --git a/src/type-checker.cc b/src/type-checker.cc
index b823ce81..5526640a 100644
--- a/src/type-checker.cc
+++ b/src/type-checker.cc
@@ -670,8 +670,21 @@ Result TypeChecker::OnRefNullExpr(Type type) {
   return Result::Ok;
 }
 
-Result TypeChecker::OnRefIsNullExpr(Type type) {
-  Result result = PopAndCheck1Type(type, "ref.is_null");
+Result TypeChecker::OnRefIsNullExpr() {
+  Type type;
+  Result result = PeekType(0, &type);
+  if (!type.IsRef()) {
+    TypeVector actual;
+    if (Succeeded(result)) {
+      actual.push_back(type);
+    }
+    std::string message =
+        "type mismatch in ref.is_null, expected reference but got " +
+        TypesToString(actual);
+    PrintError("%s", message.c_str());
+    result = Result::Error;
+  }
+  result |= DropTypes(1);
   PushType(Type::I32);
   return result;
 }
diff --git a/src/type-checker.h b/src/type-checker.h
index 0b3560a9..00edef41 100644
--- a/src/type-checker.h
+++ b/src/type-checker.h
@@ -110,7 +110,7 @@ class TypeChecker {
   Result OnTableFill(Type elem_type);
   Result OnRefFuncExpr(Index func_index);
   Result OnRefNullExpr(Type type);
-  Result OnRefIsNullExpr(Type type);
+  Result OnRefIsNullExpr();
   Result OnRethrow();
   Result OnReturn();
   Result OnSelect(Type expected);
diff --git a/src/validator.cc b/src/validator.cc
index e23d5be1..58e32e9d 100644
--- a/src/validator.cc
+++ b/src/validator.cc
@@ -438,7 +438,7 @@ Result Validator::OnRefNullExpr(RefNullExpr* expr) {
 }
 
 Result Validator::OnRefIsNullExpr(RefIsNullExpr* expr) {
-  result_ |= validator_.OnRefIsNull(expr->loc, expr->type);
+  result_ |= validator_.OnRefIsNull(expr->loc);
   return Result::Ok;
 }
 
diff --git a/src/wast-parser.cc b/src/wast-parser.cc
index 90d92f87..c3ed9d28 100644
--- a/src/wast-parser.cc
+++ b/src/wast-parser.cc
@@ -1996,13 +1996,10 @@ Result WastParser::ParsePlainInstr(std::unique_ptr<Expr>* out_expr) {
       break;
     }
 
-    case TokenType::RefIsNull: {
+    case TokenType::RefIsNull:
       ErrorUnlessOpcodeEnabled(Consume());
-      Type type;
-      CHECK_RESULT(ParseRefKind(&type));
-      out_expr->reset(new RefIsNullExpr(type, loc));
+      out_expr->reset(new RefIsNullExpr(loc));
       break;
-    }
 
     case TokenType::Throw:
       ErrorUnlessOpcodeEnabled(Consume());
diff --git a/src/wat-writer.cc b/src/wat-writer.cc
index 66aaf07b..6bdc9f9e 100644
--- a/src/wat-writer.cc
+++ b/src/wat-writer.cc
@@ -824,7 +824,6 @@ Result WatWriter::ExprVisitorDelegate::OnRefNullExpr(RefNullExpr* expr) {
 
 Result WatWriter::ExprVisitorDelegate::OnRefIsNullExpr(RefIsNullExpr* expr) {
   writer_->WritePutsSpace(Opcode::RefIsNull_Opcode.GetName());
-  writer_->WriteRefKind(expr->type, NextChar::Newline);
   return Result::Ok;
 }