8332745: Method::is_vanilla_constructor is never used

Reviewed-by: coleenp, ayang

src/hotspot/share/classfile/classFileParser.cpp

@@ -2827,11 +2827,6 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
       _has_finalizer = true;
     }
   }
-  if (name == vmSymbols::object_initializer_name() &&
-      signature == vmSymbols::void_method_signature() &&
-      m->is_vanilla_constructor()) {
-    _has_vanilla_constructor = true;
-  }
 
   NOT_PRODUCT(m->verify());
   return m;
@@ -4162,29 +4157,6 @@ void ClassFileParser::set_precomputed_flags(InstanceKlass* ik) {
     }
   }
 
-  // Check if this klass has a vanilla default constructor
-  if (super == nullptr) {
-    // java.lang.Object has empty default constructor
-    ik->set_has_vanilla_constructor();
-  } else {
-    if (super->has_vanilla_constructor() &&
-        _has_vanilla_constructor) {
-      ik->set_has_vanilla_constructor();
-    }
-#ifdef ASSERT
-    bool v = false;
-    if (super->has_vanilla_constructor()) {
-      const Method* const constructor =
-        ik->find_method(vmSymbols::object_initializer_name(),
-                       vmSymbols::void_method_signature());
-      if (constructor != nullptr && constructor->is_vanilla_constructor()) {
-        v = true;
-      }
-    }
-    assert(v == ik->has_vanilla_constructor(), "inconsistent has_vanilla_constructor");
-#endif
-  }
-
   // If it cannot be fast-path allocated, set a bit in the layout helper.
   // See documentation of InstanceKlass::can_be_fastpath_allocated().
   assert(ik->size_helper() > 0, "layout_helper is initialized");
@@ -5371,7 +5343,7 @@ void ClassFileParser::fill_instance_klass(InstanceKlass* ik,
     ik->set_has_contended_annotations(true);
   }
 
-  // Fill in has_finalizer, has_vanilla_constructor, and layout_helper
+  // Fill in has_finalizer and layout_helper
   set_precomputed_flags(ik);
 
   // check if this class can access its super class
@@ -5557,7 +5529,6 @@ ClassFileParser::ClassFileParser(ClassFileStream* stream,
   _has_contended_fields(false),
   _has_finalizer(false),
   _has_empty_finalizer(false),
-  _has_vanilla_constructor(false),
   _max_bootstrap_specifier_index(-1) {
 
   _class_name = name != nullptr ? name : vmSymbols::unknown_class_name();

src/hotspot/share/classfile/classFileParser.hpp

@@ -197,7 +197,6 @@ class ClassFileParser {
   // precomputed flags
   bool _has_finalizer;
   bool _has_empty_finalizer;
-  bool _has_vanilla_constructor;
   int _max_bootstrap_specifier_index;  // detects BSS values
 
   void parse_stream(const ClassFileStream* const stream, TRAPS);

src/hotspot/share/oops/instanceKlass.hpp

@@ -766,8 +766,6 @@ public:
   bool declares_nonstatic_concrete_methods() const { return _misc_flags.declares_nonstatic_concrete_methods(); }
   void set_declares_nonstatic_concrete_methods(bool b) { _misc_flags.set_declares_nonstatic_concrete_methods(b); }
 
-  bool has_vanilla_constructor() const  { return _misc_flags.has_vanilla_constructor(); }
-  void set_has_vanilla_constructor()    { _misc_flags.set_has_vanilla_constructor(true); }
   bool has_miranda_methods () const     { return _misc_flags.has_miranda_methods(); }
   void set_has_miranda_methods()        { _misc_flags.set_has_miranda_methods(true); }
   bool has_final_method() const         { return _misc_flags.has_final_method(); }

src/hotspot/share/oops/instanceKlassFlags.hpp

@@ -53,8 +53,7 @@ class InstanceKlassFlags {
     flag(has_contended_annotations          , 1 << 10) /* has @Contended annotation */ \
     flag(has_localvariable_table            , 1 << 11) /* has localvariable information */ \
     flag(has_miranda_methods                , 1 << 12) /* True if this class has miranda methods in it's vtable */ \
-    flag(has_vanilla_constructor            , 1 << 13) /* True if klass has a vanilla default constructor */ \
-    flag(has_final_method                   , 1 << 14) /* True if klass has final method */ \
+    flag(has_final_method                   , 1 << 13) /* True if klass has final method */ \
     /* end of list */
 
 #define IK_FLAGS_ENUM_NAME(name, value)    _misc_##name = value,

src/hotspot/share/oops/method.cpp

@@ -661,49 +661,6 @@ int Method::extra_stack_words() {
   return extra_stack_entries() * Interpreter::stackElementSize;
 }
 
-bool Method::is_vanilla_constructor() const {
-  // Returns true if this method is a vanilla constructor, i.e. an "<init>" "()V" method
-  // which only calls the superclass vanilla constructor and possibly does stores of
-  // zero constants to local fields:
-  //
-  //   aload_0
-  //   invokespecial
-  //   indexbyte1
-  //   indexbyte2
-  //
-  // followed by an (optional) sequence of:
-  //
-  //   aload_0
-  //   aconst_null / iconst_0 / fconst_0 / dconst_0
-  //   putfield
-  //   indexbyte1
-  //   indexbyte2
-  //
-  // followed by:
-  //
-  //   return
-
-  assert(name() == vmSymbols::object_initializer_name(),    "Should only be called for default constructors");
-  assert(signature() == vmSymbols::void_method_signature(), "Should only be called for default constructors");
-  int size = code_size();
-  // Check if size match
-  if (size == 0 || size % 5 != 0) return false;
-  address cb = code_base();
-  int last = size - 1;
-  if (cb[0] != Bytecodes::_aload_0 || cb[1] != Bytecodes::_invokespecial || cb[last] != Bytecodes::_return) {
-    // Does not call superclass default constructor
-    return false;
-  }
-  // Check optional sequence
-  for (int i = 4; i < last; i += 5) {
-    if (cb[i] != Bytecodes::_aload_0) return false;
-    if (!Bytecodes::is_zero_const(Bytecodes::cast(cb[i+1]))) return false;
-    if (cb[i+2] != Bytecodes::_putfield) return false;
-  }
-  return true;
-}
-
-
 bool Method::compute_has_loops_flag() {
   BytecodeStream bcs(methodHandle(Thread::current(), this));
   Bytecodes::Code bc;