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src/hotspot/share/opto/type.cpp

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@@ -21,10 +21,13 @@
   * questions.
   *
   */
  
  #include "precompiled.hpp"
+ #include "ci/ciFlatArrayKlass.hpp"
+ #include "ci/ciField.hpp"
+ #include "ci/ciInlineKlass.hpp"
  #include "ci/ciMethodData.hpp"
  #include "ci/ciTypeFlow.hpp"
  #include "classfile/javaClasses.hpp"
  #include "classfile/symbolTable.hpp"
  #include "compiler/compileLog.hpp"

@@ -47,10 +50,55 @@
  
  // Optimization - Graph Style
  
  // Dictionary of types shared among compilations.
  Dict* Type::_shared_type_dict = nullptr;
+ const Type::Offset Type::Offset::top(Type::OffsetTop);
+ const Type::Offset Type::Offset::bottom(Type::OffsetBot);
+ 
+ const Type::Offset Type::Offset::meet(const Type::Offset other) const {
+   // Either is 'TOP' offset?  Return the other offset!
+   if (_offset == OffsetTop) return other;
+   if (other._offset == OffsetTop) return *this;
+   // If either is different, return 'BOTTOM' offset
+   if (_offset != other._offset) return bottom;
+   return Offset(_offset);
+ }
+ 
+ const Type::Offset Type::Offset::dual() const {
+   if (_offset == OffsetTop) return bottom;// Map 'TOP' into 'BOTTOM'
+   if (_offset == OffsetBot) return top;// Map 'BOTTOM' into 'TOP'
+   return Offset(_offset);               // Map everything else into self
+ }
+ 
+ const Type::Offset Type::Offset::add(intptr_t offset) const {
+   // Adding to 'TOP' offset?  Return 'TOP'!
+   if (_offset == OffsetTop || offset == OffsetTop) return top;
+   // Adding to 'BOTTOM' offset?  Return 'BOTTOM'!
+   if (_offset == OffsetBot || offset == OffsetBot) return bottom;
+   // Addition overflows or "accidentally" equals to OffsetTop? Return 'BOTTOM'!
+   offset += (intptr_t)_offset;
+   if (offset != (int)offset || offset == OffsetTop) return bottom;
+ 
+   // assert( _offset >= 0 && _offset+offset >= 0, "" );
+   // It is possible to construct a negative offset during PhaseCCP
+ 
+   return Offset((int)offset);        // Sum valid offsets
+ }
+ 
+ void Type::Offset::dump2(outputStream *st) const {
+   if (_offset == 0) {
+     return;
+   } else if (_offset == OffsetTop) {
+     st->print("+top");
+   }
+   else if (_offset == OffsetBot) {
+     st->print("+bot");
+   } else if (_offset) {
+     st->print("+%d", _offset);
+   }
+ }
  
  // Array which maps compiler types to Basic Types
  const Type::TypeInfo Type::_type_info[Type::lastype] = {
    { Bad,             T_ILLEGAL,    "bad",           false, Node::NotAMachineReg, relocInfo::none          },  // Bad
    { Control,         T_ILLEGAL,    "control",       false, 0,                    relocInfo::none          },  // Control

@@ -221,10 +269,13 @@
  
    case T_ADDRESS:
      assert(type->is_return_address(), "");
      return TypeRawPtr::make((address)(intptr_t)type->as_return_address()->bci());
  
+   case T_OBJECT:
+     return Type::get_const_type(type->unwrap())->join_speculative(type->is_null_free() ? TypePtr::NOTNULL : TypePtr::BOTTOM);
+ 
    default:
      // make sure we did not mix up the cases:
      assert(type != ciTypeFlow::StateVector::bottom_type(), "");
      assert(type != ciTypeFlow::StateVector::top_type(), "");
      assert(type != ciTypeFlow::StateVector::null_type(), "");

@@ -533,13 +584,13 @@
    const Type **floop =(const Type**)shared_type_arena->AmallocWords(2*sizeof(Type*));
    floop[0] = Type::CONTROL;
    floop[1] = TypeInt::INT;
    TypeTuple::LOOPBODY = TypeTuple::make( 2, floop );
  
-   TypePtr::NULL_PTR= TypePtr::make(AnyPtr, TypePtr::Null, 0);
-   TypePtr::NOTNULL = TypePtr::make(AnyPtr, TypePtr::NotNull, OffsetBot);
-   TypePtr::BOTTOM  = TypePtr::make(AnyPtr, TypePtr::BotPTR, OffsetBot);
+   TypePtr::NULL_PTR= TypePtr::make(AnyPtr, TypePtr::Null, Offset(0));
+   TypePtr::NOTNULL = TypePtr::make(AnyPtr, TypePtr::NotNull, Offset::bottom);
+   TypePtr::BOTTOM  = TypePtr::make(AnyPtr, TypePtr::BotPTR, Offset::bottom);
  
    TypeRawPtr::BOTTOM = TypeRawPtr::make( TypePtr::BotPTR );
    TypeRawPtr::NOTNULL= TypeRawPtr::make( TypePtr::NotNull );
  
    const Type **fmembar = TypeTuple::fields(0);

@@ -552,16 +603,16 @@
  
    TypeInstPtr::NOTNULL = TypeInstPtr::make(TypePtr::NotNull, current->env()->Object_klass());
    TypeInstPtr::BOTTOM  = TypeInstPtr::make(TypePtr::BotPTR,  current->env()->Object_klass());
    TypeInstPtr::MIRROR  = TypeInstPtr::make(TypePtr::NotNull, current->env()->Class_klass());
    TypeInstPtr::MARK    = TypeInstPtr::make(TypePtr::BotPTR,  current->env()->Object_klass(),
-                                            false, nullptr, oopDesc::mark_offset_in_bytes());
+                                            false, nullptr, Offset(oopDesc::mark_offset_in_bytes()));
    TypeInstPtr::KLASS   = TypeInstPtr::make(TypePtr::BotPTR,  current->env()->Object_klass(),
-                                            false, nullptr, oopDesc::klass_offset_in_bytes());
-   TypeOopPtr::BOTTOM  = TypeOopPtr::make(TypePtr::BotPTR, OffsetBot, TypeOopPtr::InstanceBot);
+                                            false, nullptr, Offset(oopDesc::klass_offset_in_bytes()));
+   TypeOopPtr::BOTTOM  = TypeOopPtr::make(TypePtr::BotPTR, Offset::bottom, TypeOopPtr::InstanceBot);
  
-   TypeMetadataPtr::BOTTOM = TypeMetadataPtr::make(TypePtr::BotPTR, nullptr, OffsetBot);
+   TypeMetadataPtr::BOTTOM = TypeMetadataPtr::make(TypePtr::BotPTR, nullptr, Offset::bottom);
  
    TypeNarrowOop::NULL_PTR = TypeNarrowOop::make( TypePtr::NULL_PTR );
    TypeNarrowOop::BOTTOM   = TypeNarrowOop::make( TypeInstPtr::BOTTOM );
  
    TypeNarrowKlass::NULL_PTR = TypeNarrowKlass::make( TypePtr::NULL_PTR );

@@ -580,47 +631,49 @@
    array_interfaces.push(current->env()->Cloneable_klass());
    array_interfaces.push(current->env()->Serializable_klass());
    TypeAryPtr::_array_interfaces = TypeInterfaces::make(&array_interfaces);
    TypeAryKlassPtr::_array_interfaces = TypeAryPtr::_array_interfaces;
  
-   TypeAryPtr::RANGE   = TypeAryPtr::make( TypePtr::BotPTR, TypeAry::make(Type::BOTTOM,TypeInt::POS), nullptr /* current->env()->Object_klass() */, false, arrayOopDesc::length_offset_in_bytes());
+   TypeAryPtr::RANGE   = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(Type::BOTTOM,TypeInt::POS), nullptr /* current->env()->Object_klass() */, false, Offset(arrayOopDesc::length_offset_in_bytes()));
  
-   TypeAryPtr::NARROWOOPS = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeNarrowOop::BOTTOM, TypeInt::POS), nullptr /*ciArrayKlass::make(o)*/,  false,  Type::OffsetBot);
+   TypeAryPtr::NARROWOOPS = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeNarrowOop::BOTTOM, TypeInt::POS), nullptr /*ciArrayKlass::make(o)*/,  false,  Offset::bottom);
  
  #ifdef _LP64
    if (UseCompressedOops) {
      assert(TypeAryPtr::NARROWOOPS->is_ptr_to_narrowoop(), "array of narrow oops must be ptr to narrow oop");
      TypeAryPtr::OOPS  = TypeAryPtr::NARROWOOPS;
    } else
  #endif
    {
      // There is no shared klass for Object[].  See note in TypeAryPtr::klass().
-     TypeAryPtr::OOPS  = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInstPtr::BOTTOM,TypeInt::POS), nullptr /*ciArrayKlass::make(o)*/,  false,  Type::OffsetBot);
+     TypeAryPtr::OOPS  = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInstPtr::BOTTOM,TypeInt::POS), nullptr /*ciArrayKlass::make(o)*/,  false,  Offset::bottom);
    }
-   TypeAryPtr::BYTES   = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInt::BYTE      ,TypeInt::POS), ciTypeArrayKlass::make(T_BYTE),   true,  Type::OffsetBot);
-   TypeAryPtr::SHORTS  = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInt::SHORT     ,TypeInt::POS), ciTypeArrayKlass::make(T_SHORT),  true,  Type::OffsetBot);
-   TypeAryPtr::CHARS   = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInt::CHAR      ,TypeInt::POS), ciTypeArrayKlass::make(T_CHAR),   true,  Type::OffsetBot);
-   TypeAryPtr::INTS    = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInt::INT       ,TypeInt::POS), ciTypeArrayKlass::make(T_INT),    true,  Type::OffsetBot);
-   TypeAryPtr::LONGS   = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeLong::LONG     ,TypeInt::POS), ciTypeArrayKlass::make(T_LONG),   true,  Type::OffsetBot);
-   TypeAryPtr::FLOATS  = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(Type::FLOAT        ,TypeInt::POS), ciTypeArrayKlass::make(T_FLOAT),  true,  Type::OffsetBot);
-   TypeAryPtr::DOUBLES = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(Type::DOUBLE       ,TypeInt::POS), ciTypeArrayKlass::make(T_DOUBLE), true,  Type::OffsetBot);
+   TypeAryPtr::BYTES   = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInt::BYTE      ,TypeInt::POS), ciTypeArrayKlass::make(T_BYTE),   true,  Offset::bottom);
+   TypeAryPtr::SHORTS  = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInt::SHORT     ,TypeInt::POS), ciTypeArrayKlass::make(T_SHORT),  true,  Offset::bottom);
+   TypeAryPtr::CHARS   = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInt::CHAR      ,TypeInt::POS), ciTypeArrayKlass::make(T_CHAR),   true,  Offset::bottom);
+   TypeAryPtr::INTS    = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInt::INT       ,TypeInt::POS), ciTypeArrayKlass::make(T_INT),    true,  Offset::bottom);
+   TypeAryPtr::LONGS   = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeLong::LONG     ,TypeInt::POS), ciTypeArrayKlass::make(T_LONG),   true,  Offset::bottom);
+   TypeAryPtr::FLOATS  = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(Type::FLOAT        ,TypeInt::POS), ciTypeArrayKlass::make(T_FLOAT),  true,  Offset::bottom);
+   TypeAryPtr::DOUBLES = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(Type::DOUBLE       ,TypeInt::POS), ciTypeArrayKlass::make(T_DOUBLE), true,  Offset::bottom);
+   TypeAryPtr::INLINES = TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(TypeInstPtr::BOTTOM,TypeInt::POS, /* stable= */ false, /* flat= */ true), nullptr, false, Offset::bottom);
  
    // Nobody should ask _array_body_type[T_NARROWOOP]. Use null as assert.
    TypeAryPtr::_array_body_type[T_NARROWOOP] = nullptr;
    TypeAryPtr::_array_body_type[T_OBJECT]  = TypeAryPtr::OOPS;
+   TypeAryPtr::_array_body_type[T_PRIMITIVE_OBJECT] = TypeAryPtr::OOPS;
    TypeAryPtr::_array_body_type[T_ARRAY]   = TypeAryPtr::OOPS; // arrays are stored in oop arrays
    TypeAryPtr::_array_body_type[T_BYTE]    = TypeAryPtr::BYTES;
    TypeAryPtr::_array_body_type[T_BOOLEAN] = TypeAryPtr::BYTES;  // boolean[] is a byte array
    TypeAryPtr::_array_body_type[T_SHORT]   = TypeAryPtr::SHORTS;
    TypeAryPtr::_array_body_type[T_CHAR]    = TypeAryPtr::CHARS;
    TypeAryPtr::_array_body_type[T_INT]     = TypeAryPtr::INTS;
    TypeAryPtr::_array_body_type[T_LONG]    = TypeAryPtr::LONGS;
    TypeAryPtr::_array_body_type[T_FLOAT]   = TypeAryPtr::FLOATS;
    TypeAryPtr::_array_body_type[T_DOUBLE]  = TypeAryPtr::DOUBLES;
  
-   TypeInstKlassPtr::OBJECT = TypeInstKlassPtr::make(TypePtr::NotNull, current->env()->Object_klass(), 0);
-   TypeInstKlassPtr::OBJECT_OR_NULL = TypeInstKlassPtr::make(TypePtr::BotPTR, current->env()->Object_klass(), 0);
+   TypeInstKlassPtr::OBJECT = TypeInstKlassPtr::make(TypePtr::NotNull, current->env()->Object_klass(), Offset(0));
+   TypeInstKlassPtr::OBJECT_OR_NULL = TypeInstKlassPtr::make(TypePtr::BotPTR, current->env()->Object_klass(), Offset(0));
  
    const Type **fi2c = TypeTuple::fields(2);
    fi2c[TypeFunc::Parms+0] = TypeInstPtr::BOTTOM; // Method*
    fi2c[TypeFunc::Parms+1] = TypeRawPtr::BOTTOM; // argument pointer
    TypeTuple::START_I2C = TypeTuple::make(TypeFunc::Parms+2, fi2c);

@@ -655,10 +708,11 @@
    _const_basic_type[T_LONG]        = TypeLong::LONG;
    _const_basic_type[T_FLOAT]       = Type::FLOAT;
    _const_basic_type[T_DOUBLE]      = Type::DOUBLE;
    _const_basic_type[T_OBJECT]      = TypeInstPtr::BOTTOM;
    _const_basic_type[T_ARRAY]       = TypeInstPtr::BOTTOM; // there is no separate bottom for arrays
+   _const_basic_type[T_PRIMITIVE_OBJECT] = TypeInstPtr::BOTTOM;
    _const_basic_type[T_VOID]        = TypePtr::NULL_PTR;   // reflection represents void this way
    _const_basic_type[T_ADDRESS]     = TypeRawPtr::BOTTOM;  // both interpreter return addresses & random raw ptrs
    _const_basic_type[T_CONFLICT]    = Type::BOTTOM;        // why not?
  
    _zero_type[T_NARROWOOP]   = TypeNarrowOop::NULL_PTR;

@@ -671,10 +725,11 @@
    _zero_type[T_LONG]        = TypeLong::ZERO;
    _zero_type[T_FLOAT]       = TypeF::ZERO;
    _zero_type[T_DOUBLE]      = TypeD::ZERO;
    _zero_type[T_OBJECT]      = TypePtr::NULL_PTR;
    _zero_type[T_ARRAY]       = TypePtr::NULL_PTR; // null array is null oop
+   _zero_type[T_PRIMITIVE_OBJECT] = TypePtr::NULL_PTR;
    _zero_type[T_ADDRESS]     = TypePtr::NULL_PTR; // raw pointers use the same null
    _zero_type[T_VOID]        = Type::TOP;         // the only void value is no value at all
  
    // get_zero_type() should not happen for T_CONFLICT
    _zero_type[T_CONFLICT]= nullptr;

@@ -941,10 +996,13 @@
  };
  
  void Type::check_symmetrical(const Type* t, const Type* mt, const VerifyMeet& verify) const {
    Compile* C = Compile::current();
    const Type* mt2 = verify.meet(t, this);
+ 
+   // Verify that:
+   //      this meet t == t meet this
    if (mt != mt2) {
      tty->print_cr("=== Meet Not Commutative ===");
      tty->print("t           = ");   t->dump(); tty->cr();
      tty->print("this        = ");      dump(); tty->cr();
      tty->print("t meet this = "); mt2->dump(); tty->cr();

@@ -957,10 +1015,16 @@
  
    // Interface meet Oop is Not Symmetric:
    // Interface:AnyNull meet Oop:AnyNull == Interface:AnyNull
    // Interface:NotNull meet Oop:NotNull == java/lang/Object:NotNull
  
+   // Verify that:
+   //      !(t meet this)  meet !t ==
+   //      (!t join !this) meet !t == !t
+   // and
+   //      !(t meet this)  meet !this ==
+   //      (!t join !this) meet !this == !this
    if (t2t != t->_dual || t2this != this->_dual) {
      tty->print_cr("=== Meet Not Symmetric ===");
      tty->print("t   =                   ");              t->dump(); tty->cr();
      tty->print("this=                   ");                 dump(); tty->cr();
      tty->print("mt=(t meet this)=       ");             mt->dump(); tty->cr();

@@ -2127,15 +2191,32 @@
  const TypeTuple *TypeTuple::INT_PAIR;
  const TypeTuple *TypeTuple::LONG_PAIR;
  const TypeTuple *TypeTuple::INT_CC_PAIR;
  const TypeTuple *TypeTuple::LONG_CC_PAIR;
  
+ static void collect_inline_fields(ciInlineKlass* vk, const Type** field_array, uint& pos) {
+   for (int j = 0; j < vk->nof_nonstatic_fields(); j++) {
+     ciField* field = vk->nonstatic_field_at(j);
+     BasicType bt = field->type()->basic_type();
+     const Type* ft = Type::get_const_type(field->type());
+     field_array[pos++] = ft;
+     if (type2size[bt] == 2) {
+       field_array[pos++] = Type::HALF;
+     }
+   }
+ }
+ 
  //------------------------------make-------------------------------------------
  // Make a TypeTuple from the range of a method signature
- const TypeTuple *TypeTuple::make_range(ciSignature* sig, InterfaceHandling interface_handling) {
+ const TypeTuple *TypeTuple::make_range(ciSignature* sig, InterfaceHandling interface_handling, bool ret_vt_fields) {
    ciType* return_type = sig->return_type();
    uint arg_cnt = return_type->size();
+   if (ret_vt_fields) {
+     arg_cnt = return_type->as_inline_klass()->inline_arg_slots() + 1;
+     // InlineTypeNode::IsInit field used for null checking
+     arg_cnt++;
+   }
    const Type **field_array = fields(arg_cnt);
    switch (return_type->basic_type()) {
    case T_LONG:
      field_array[TypeFunc::Parms]   = TypeLong::LONG;
      field_array[TypeFunc::Parms+1] = Type::HALF;

@@ -2143,10 +2224,21 @@
    case T_DOUBLE:
      field_array[TypeFunc::Parms]   = Type::DOUBLE;
      field_array[TypeFunc::Parms+1] = Type::HALF;
      break;
    case T_OBJECT:
+     if (return_type->is_inlinetype() && ret_vt_fields) {
+       uint pos = TypeFunc::Parms;
+       field_array[pos++] = get_const_type(return_type); // Oop might be null when returning as fields
+       collect_inline_fields(return_type->as_inline_klass(), field_array, pos);
+       // InlineTypeNode::IsInit field used for null checking
+       field_array[pos++] = get_const_basic_type(T_BOOLEAN);
+       break;
+     } else {
+       field_array[TypeFunc::Parms] = get_const_type(return_type, interface_handling)->join_speculative(TypePtr::BOTTOM);
+     }
+     break;
    case T_ARRAY:
    case T_BOOLEAN:
    case T_CHAR:
    case T_FLOAT:
    case T_BYTE:

@@ -2161,38 +2253,55 @@
    }
    return (TypeTuple*)(new TypeTuple(TypeFunc::Parms + arg_cnt, field_array))->hashcons();
  }
  
  // Make a TypeTuple from the domain of a method signature
- const TypeTuple *TypeTuple::make_domain(ciInstanceKlass* recv, ciSignature* sig, InterfaceHandling interface_handling) {
-   uint arg_cnt = sig->size();
+ const TypeTuple *TypeTuple::make_domain(ciMethod* method, InterfaceHandling interface_handling, bool vt_fields_as_args) {
+   ciSignature* sig = method->signature();
+   uint arg_cnt = sig->size() + (method->is_static() ? 0 : 1);
+   if (vt_fields_as_args) {
+     arg_cnt = 0;
+     assert(method->get_sig_cc() != nullptr, "Should have scalarized signature");
+     for (ExtendedSignature sig_cc = ExtendedSignature(method->get_sig_cc(), SigEntryFilter()); !sig_cc.at_end(); ++sig_cc) {
+       arg_cnt += type2size[(*sig_cc)._bt];
+     }
+   }
  
    uint pos = TypeFunc::Parms;
-   const Type **field_array;
-   if (recv != nullptr) {
-     arg_cnt++;
-     field_array = fields(arg_cnt);
-     // Use get_const_type here because it respects UseUniqueSubclasses:
-     field_array[pos++] = get_const_type(recv, interface_handling)->join_speculative(TypePtr::NOTNULL);
-   } else {
-     field_array = fields(arg_cnt);
+   const Type** field_array = fields(arg_cnt);
+   if (!method->is_static()) {
+     ciInstanceKlass* recv = method->holder();
+     if (vt_fields_as_args && recv->is_inlinetype() && recv->as_inline_klass()->can_be_passed_as_fields() && method->is_scalarized_arg(0)) {
+       collect_inline_fields(recv->as_inline_klass(), field_array, pos);
+     } else {
+       field_array[pos++] = get_const_type(recv, interface_handling)->join_speculative(TypePtr::NOTNULL);
+     }
    }
  
    int i = 0;
    while (pos < TypeFunc::Parms + arg_cnt) {
      ciType* type = sig->type_at(i);
+     BasicType bt = type->basic_type();
  
-     switch (type->basic_type()) {
+     switch (bt) {
      case T_LONG:
        field_array[pos++] = TypeLong::LONG;
        field_array[pos++] = Type::HALF;
        break;
      case T_DOUBLE:
        field_array[pos++] = Type::DOUBLE;
        field_array[pos++] = Type::HALF;
        break;
      case T_OBJECT:
+       if (type->is_inlinetype() && vt_fields_as_args && method->is_scalarized_arg(i + (method->is_static() ? 0 : 1))) {
+         // InlineTypeNode::IsInit field used for null checking
+         field_array[pos++] = get_const_basic_type(T_BOOLEAN);
+         collect_inline_fields(type->as_inline_klass(), field_array, pos);
+       } else {
+         field_array[pos++] = get_const_type(type, interface_handling);
+       }
+       break;
      case T_ARRAY:
      case T_FLOAT:
      case T_INT:
        field_array[pos++] = get_const_type(type, interface_handling);
        break;

@@ -2205,10 +2314,11 @@
      default:
        ShouldNotReachHere();
      }
      i++;
    }
+   assert(pos == TypeFunc::Parms + arg_cnt, "wrong number of arguments");
  
    return (TypeTuple*)(new TypeTuple(TypeFunc::Parms + arg_cnt, field_array))->hashcons();
  }
  
  const TypeTuple *TypeTuple::make( uint cnt, const Type **fields ) {

@@ -2339,16 +2449,17 @@
    else
      return size;
  }
  
  //------------------------------make-------------------------------------------
- const TypeAry* TypeAry::make(const Type* elem, const TypeInt* size, bool stable) {
+ const TypeAry* TypeAry::make(const Type* elem, const TypeInt* size, bool stable,
+                              bool flat, bool not_flat, bool not_null_free) {
    if (UseCompressedOops && elem->isa_oopptr()) {
      elem = elem->make_narrowoop();
    }
    size = normalize_array_size(size);
-   return (TypeAry*)(new TypeAry(elem,size,stable))->hashcons();
+   return (TypeAry*)(new TypeAry(elem, size, stable, flat, not_flat, not_null_free))->hashcons();
  }
  
  //------------------------------meet-------------------------------------------
  // Compute the MEET of two types.  It returns a new Type object.
  const Type *TypeAry::xmeet( const Type *t ) const {

@@ -2366,11 +2477,14 @@
  
    case Array: {                 // Meeting 2 arrays?
      const TypeAry *a = t->is_ary();
      return TypeAry::make(_elem->meet_speculative(a->_elem),
                           _size->xmeet(a->_size)->is_int(),
-                          _stable && a->_stable);
+                          _stable && a->_stable,
+                          _flat && a->_flat,
+                          _not_flat && a->_not_flat,
+                          _not_null_free && a->_not_null_free);
    }
    case Top:
      break;
    }
    return this;                  // Return the double constant

@@ -2379,40 +2493,45 @@
  //------------------------------xdual------------------------------------------
  // Dual: compute field-by-field dual
  const Type *TypeAry::xdual() const {
    const TypeInt* size_dual = _size->dual()->is_int();
    size_dual = normalize_array_size(size_dual);
-   return new TypeAry(_elem->dual(), size_dual, !_stable);
+   return new TypeAry(_elem->dual(), size_dual, !_stable, !_flat, !_not_flat, !_not_null_free);
  }
  
  //------------------------------eq---------------------------------------------
  // Structural equality check for Type representations
  bool TypeAry::eq( const Type *t ) const {
    const TypeAry *a = (const TypeAry*)t;
    return _elem == a->_elem &&
      _stable == a->_stable &&
-     _size == a->_size;
+     _size == a->_size &&
+     _flat == a->_flat &&
+     _not_flat == a->_not_flat &&
+     _not_null_free == a->_not_null_free;
+ 
  }
  
  //------------------------------hash-------------------------------------------
  // Type-specific hashing function.
  uint TypeAry::hash(void) const {
-   return (uint)(uintptr_t)_elem + (uint)(uintptr_t)_size + (uint)(_stable ? 43 : 0);
+   return (uint)(uintptr_t)_elem + (uint)(uintptr_t)_size + (uint)(_stable ? 43 : 0) +
+       (uint)(_flat ? 44 : 0) + (uint)(_not_flat ? 45 : 0) + (uint)(_not_null_free ? 46 : 0);
  }
  
  /**
   * Return same type without a speculative part in the element
   */
  const TypeAry* TypeAry::remove_speculative() const {
-   return make(_elem->remove_speculative(), _size, _stable);
+   return make(_elem->remove_speculative(), _size, _stable, _flat, _not_flat, _not_null_free);
  }
  
  /**
   * Return same type with cleaned up speculative part of element
   */
  const Type* TypeAry::cleanup_speculative() const {
-   return make(_elem->cleanup_speculative(), _size, _stable);
+   return make(_elem->cleanup_speculative(), _size, _stable, _flat, _not_flat, _not_null_free);
  }
  
  /**
   * Return same type but with a different inline depth (used for speculation)
   *

@@ -2427,10 +2546,15 @@
  
  //------------------------------dump2------------------------------------------
  #ifndef PRODUCT
  void TypeAry::dump2( Dict &d, uint depth, outputStream *st ) const {
    if (_stable)  st->print("stable:");
+   if (_flat) st->print("flat:");
+   if (Verbose) {
+     if (_not_flat) st->print("not flat:");
+     if (_not_null_free) st->print("not null free:");
+   }
    _elem->dump2(d, depth, st);
    st->print("[");
    _size->dump2(d, depth, st);
    st->print("]");
  }

@@ -2466,12 +2590,20 @@
    const TypeInstPtr* tinst;
    if (_elem->isa_narrowoop())
      tinst = _elem->make_ptr()->isa_instptr();
    else
      tinst = _elem->isa_instptr();
-   if (tinst)
-     return tinst->instance_klass()->is_final();
+   if (tinst) {
+     if (tinst->instance_klass()->is_final()) {
+       // Even though MyValue is final, [LMyValue is not exact because null-free [LMyValue is a subtype.
+       if (tinst->is_inlinetypeptr() && (tinst->ptr() == TypePtr::BotPTR || tinst->ptr() == TypePtr::TopPTR)) {
+         return false;
+       }
+       return true;
+     }
+     return false;
+   }
    const TypeAryPtr*  tap;
    if (_elem->isa_narrowoop())
      tap = _elem->make_ptr()->isa_aryptr();
    else
      tap = _elem->isa_aryptr();

@@ -2642,11 +2774,11 @@
    { /* NotNull */ NotNull,   NotNull,   NotNull,  BotPTR, NotNull, BotPTR,},
    { /* BotPTR  */ BotPTR,    BotPTR,    BotPTR,   BotPTR, BotPTR,  BotPTR,}
  };
  
  //------------------------------make-------------------------------------------
- const TypePtr *TypePtr::make(TYPES t, enum PTR ptr, int offset, const TypePtr* speculative, int inline_depth) {
+ const TypePtr* TypePtr::make(TYPES t, enum PTR ptr, Offset offset, const TypePtr* speculative, int inline_depth) {
    return (TypePtr*)(new TypePtr(t,ptr,offset, speculative, inline_depth))->hashcons();
  }
  
  //------------------------------cast_to_ptr_type-------------------------------
  const TypePtr* TypePtr::cast_to_ptr_type(PTR ptr) const {

@@ -2656,11 +2788,11 @@
  }
  
  //------------------------------get_con----------------------------------------
  intptr_t TypePtr::get_con() const {
    assert( _ptr == Null, "" );
-   return _offset;
+   return offset();
  }
  
  //------------------------------meet-------------------------------------------
  // Compute the MEET of two types.  It returns a new Type object.
  const Type *TypePtr::xmeet(const Type *t) const {

@@ -2727,24 +2859,17 @@
    }
    return this;
  }
  
  //------------------------------meet_offset------------------------------------
- int TypePtr::meet_offset( int offset ) const {
-   // Either is 'TOP' offset?  Return the other offset!
-   if( _offset == OffsetTop ) return offset;
-   if( offset == OffsetTop ) return _offset;
-   // If either is different, return 'BOTTOM' offset
-   if( _offset != offset ) return OffsetBot;
-   return _offset;
+ Type::Offset TypePtr::meet_offset(int offset) const {
+   return _offset.meet(Offset(offset));
  }
  
  //------------------------------dual_offset------------------------------------
- int TypePtr::dual_offset( ) const {
-   if( _offset == OffsetTop ) return OffsetBot;// Map 'TOP' into 'BOTTOM'
-   if( _offset == OffsetBot ) return OffsetTop;// Map 'BOTTOM' into 'TOP'
-   return _offset;               // Map everything else into self
+ Type::Offset TypePtr::dual_offset() const {
+   return _offset.dual();
  }
  
  //------------------------------xdual------------------------------------------
  // Dual: compute field-by-field dual
  const TypePtr::PTR TypePtr::ptr_dual[TypePtr::lastPTR] = {

@@ -2753,45 +2878,34 @@
  const Type *TypePtr::xdual() const {
    return new TypePtr(AnyPtr, dual_ptr(), dual_offset(), dual_speculative(), dual_inline_depth());
  }
  
  //------------------------------xadd_offset------------------------------------
- int TypePtr::xadd_offset( intptr_t offset ) const {
-   // Adding to 'TOP' offset?  Return 'TOP'!
-   if( _offset == OffsetTop || offset == OffsetTop ) return OffsetTop;
-   // Adding to 'BOTTOM' offset?  Return 'BOTTOM'!
-   if( _offset == OffsetBot || offset == OffsetBot ) return OffsetBot;
-   // Addition overflows or "accidentally" equals to OffsetTop? Return 'BOTTOM'!
-   offset += (intptr_t)_offset;
-   if (offset != (int)offset || offset == OffsetTop) return OffsetBot;
- 
-   // assert( _offset >= 0 && _offset+offset >= 0, "" );
-   // It is possible to construct a negative offset during PhaseCCP
- 
-   return (int)offset;        // Sum valid offsets
+ Type::Offset TypePtr::xadd_offset(intptr_t offset) const {
+   return _offset.add(offset);
  }
  
  //------------------------------add_offset-------------------------------------
  const TypePtr *TypePtr::add_offset( intptr_t offset ) const {
    return make(AnyPtr, _ptr, xadd_offset(offset), _speculative, _inline_depth);
  }
  
  const TypePtr *TypePtr::with_offset(intptr_t offset) const {
-   return make(AnyPtr, _ptr, offset, _speculative, _inline_depth);
+   return make(AnyPtr, _ptr, Offset(offset), _speculative, _inline_depth);
  }
  
  //------------------------------eq---------------------------------------------
  // Structural equality check for Type representations
  bool TypePtr::eq( const Type *t ) const {
    const TypePtr *a = (const TypePtr*)t;
-   return _ptr == a->ptr() && _offset == a->offset() && eq_speculative(a) && _inline_depth == a->_inline_depth;
+   return _ptr == a->ptr() && _offset == a->_offset && eq_speculative(a) && _inline_depth == a->_inline_depth;
  }
  
  //------------------------------hash-------------------------------------------
  // Type-specific hashing function.
  uint TypePtr::hash(void) const {
-   return (uint)_ptr + (uint)_offset + (uint)hash_speculative() + (uint)_inline_depth;
+   return (uint)_ptr + (uint)offset() + (uint)hash_speculative() + (uint)_inline_depth;
  }
  
  /**
   * Return same type without a speculative part
   */

@@ -3053,13 +3167,11 @@
  
  #ifndef PRODUCT
  void TypePtr::dump2( Dict &d, uint depth, outputStream *st ) const {
    if( _ptr == Null ) st->print("null");
    else st->print("%s *", ptr_msg[_ptr]);
-   if( _offset == OffsetTop ) st->print("+top");
-   else if( _offset == OffsetBot ) st->print("+bot");
-   else if( _offset ) st->print("+%d", _offset);
+   _offset.dump2(st);
    dump_inline_depth(st);
    dump_speculative(st);
  }
  
  /**

@@ -3090,15 +3202,15 @@
  //------------------------------singleton--------------------------------------
  // TRUE if Type is a singleton type, FALSE otherwise.   Singletons are simple
  // constants
  bool TypePtr::singleton(void) const {
    // TopPTR, Null, AnyNull, Constant are all singletons
-   return (_offset != OffsetBot) && !below_centerline(_ptr);
+   return (_offset != Offset::bottom) && !below_centerline(_ptr);
  }
  
  bool TypePtr::empty(void) const {
-   return (_offset == OffsetTop) || above_centerline(_ptr);
+   return (_offset == Offset::top) || above_centerline(_ptr);
  }
  
  //=============================================================================
  // Convenience common pre-built types.
  const TypeRawPtr *TypeRawPtr::BOTTOM;

@@ -3495,11 +3607,11 @@
    ShouldNotReachHere();
    return Type::singleton();
  }
  
  //------------------------------TypeOopPtr-------------------------------------
- TypeOopPtr::TypeOopPtr(TYPES t, PTR ptr, ciKlass* k, const TypeInterfaces* interfaces, bool xk, ciObject* o, int offset,
+ TypeOopPtr::TypeOopPtr(TYPES t, PTR ptr, ciKlass* k, const TypeInterfaces* interfaces, bool xk, ciObject* o, Offset offset, Offset field_offset,
                         int instance_id, const TypePtr* speculative, int inline_depth)
    : TypePtr(t, ptr, offset, speculative, inline_depth),
      _const_oop(o), _klass(k),
      _interfaces(interfaces),
      _klass_is_exact(xk),

@@ -3511,58 +3623,66 @@
    if (klass() != nullptr && klass()->is_loaded()) {
      interfaces->verify_is_loaded();
    }
  #endif
    if (Compile::current()->eliminate_boxing() && (t == InstPtr) &&
-       (offset > 0) && xk && (k != nullptr) && k->is_instance_klass()) {
-     _is_ptr_to_boxed_value = k->as_instance_klass()->is_boxed_value_offset(offset);
+       (offset.get() > 0) && xk && (k != nullptr) && k->is_instance_klass()) {
+     _is_ptr_to_boxed_value = k->as_instance_klass()->is_boxed_value_offset(offset.get());
    }
  #ifdef _LP64
-   if (_offset > 0 || _offset == Type::OffsetTop || _offset == Type::OffsetBot) {
-     if (_offset == oopDesc::klass_offset_in_bytes()) {
+   if (this->offset() > 0 || this->offset() == Type::OffsetTop || this->offset() == Type::OffsetBot) {
+     if (this->offset() == oopDesc::klass_offset_in_bytes()) {
        _is_ptr_to_narrowklass = UseCompressedClassPointers;
      } else if (klass() == nullptr) {
        // Array with unknown body type
        assert(this->isa_aryptr(), "only arrays without klass");
        _is_ptr_to_narrowoop = UseCompressedOops;
-     } else if (this->isa_aryptr()) {
-       _is_ptr_to_narrowoop = (UseCompressedOops && klass()->is_obj_array_klass() &&
-                              _offset != arrayOopDesc::length_offset_in_bytes());
+     } else if (UseCompressedOops && this->isa_aryptr() && this->offset() != arrayOopDesc::length_offset_in_bytes()) {
+       if (klass()->is_obj_array_klass()) {
+         _is_ptr_to_narrowoop = true;
+       } else if (klass()->is_flat_array_klass() && field_offset != Offset::top && field_offset != Offset::bottom) {
+         // Check if the field of the inline type array element contains oops
+         ciInlineKlass* vk = klass()->as_flat_array_klass()->element_klass()->as_inline_klass();
+         int foffset = field_offset.get() + vk->first_field_offset();
+         ciField* field = vk->get_field_by_offset(foffset, false);
+         assert(field != nullptr, "missing field");
+         BasicType bt = field->layout_type();
+         _is_ptr_to_narrowoop = UseCompressedOops && ::is_reference_type(bt);
+       }
      } else if (klass()->is_instance_klass()) {
-       ciInstanceKlass* ik = klass()->as_instance_klass();
        if (this->isa_klassptr()) {
          // Perm objects don't use compressed references
-       } else if (_offset == OffsetBot || _offset == OffsetTop) {
+       } else if (_offset == Offset::bottom || _offset == Offset::top) {
          // unsafe access
          _is_ptr_to_narrowoop = UseCompressedOops;
        } else {
          assert(this->isa_instptr(), "must be an instance ptr.");
- 
          if (klass() == ciEnv::current()->Class_klass() &&
-             (_offset == java_lang_Class::klass_offset() ||
-              _offset == java_lang_Class::array_klass_offset())) {
+             (this->offset() == java_lang_Class::klass_offset() ||
+              this->offset() == java_lang_Class::array_klass_offset())) {
            // Special hidden fields from the Class.
            assert(this->isa_instptr(), "must be an instance ptr.");
            _is_ptr_to_narrowoop = false;
          } else if (klass() == ciEnv::current()->Class_klass() &&
-                    _offset >= InstanceMirrorKlass::offset_of_static_fields()) {
+                    this->offset() >= InstanceMirrorKlass::offset_of_static_fields()) {
            // Static fields
            ciField* field = nullptr;
            if (const_oop() != nullptr) {
              ciInstanceKlass* k = const_oop()->as_instance()->java_lang_Class_klass()->as_instance_klass();
-             field = k->get_field_by_offset(_offset, true);
+             field = k->get_field_by_offset(this->offset(), true);
            }
            if (field != nullptr) {
              BasicType basic_elem_type = field->layout_type();
              _is_ptr_to_narrowoop = UseCompressedOops && ::is_reference_type(basic_elem_type);
            } else {
              // unsafe access
              _is_ptr_to_narrowoop = UseCompressedOops;
            }
          } else {
            // Instance fields which contains a compressed oop references.
-           ciField* field = ik->get_field_by_offset(_offset, false);
+           ciInstanceKlass* ik = klass()->as_instance_klass();
+           ciField* field = ik->get_field_by_offset(this->offset(), false);
            if (field != nullptr) {
              BasicType basic_elem_type = field->layout_type();
              _is_ptr_to_narrowoop = UseCompressedOops && ::is_reference_type(basic_elem_type);
            } else if (klass()->equals(ciEnv::current()->Object_klass())) {
              // Compile::find_alias_type() cast exactness on all types to verify

@@ -3578,18 +3698,18 @@
    }
  #endif
  }
  
  //------------------------------make-------------------------------------------
- const TypeOopPtr *TypeOopPtr::make(PTR ptr, int offset, int instance_id,
-                                      const TypePtr* speculative, int inline_depth) {
+ const TypeOopPtr *TypeOopPtr::make(PTR ptr, Offset offset, int instance_id,
+                                    const TypePtr* speculative, int inline_depth) {
    assert(ptr != Constant, "no constant generic pointers");
    ciKlass*  k = Compile::current()->env()->Object_klass();
    bool      xk = false;
    ciObject* o = nullptr;
    const TypeInterfaces* interfaces = TypeInterfaces::make();
-   return (TypeOopPtr*)(new TypeOopPtr(OopPtr, ptr, k, interfaces, xk, o, offset, instance_id, speculative, inline_depth))->hashcons();
+   return (TypeOopPtr*)(new TypeOopPtr(OopPtr, ptr, k, interfaces, xk, o, offset, Offset::bottom, instance_id, speculative, inline_depth))->hashcons();
  }
  
  
  //------------------------------cast_to_ptr_type-------------------------------
  const TypeOopPtr* TypeOopPtr::cast_to_ptr_type(PTR ptr) const {

@@ -3610,11 +3730,10 @@
    // There is no such thing as an exact general oop.
    // Return self unchanged.
    return this;
  }
  
- 
  //------------------------------as_klass_type----------------------------------
  // Return the klass type corresponding to this instance or array type.
  // It is the type that is loaded from an object of this type.
  const TypeKlassPtr* TypeOopPtr::as_klass_type(bool try_for_exact) const {
    ShouldNotReachHere();

@@ -3656,11 +3775,11 @@
      return TypePtr::BOTTOM;     // Oop meet raw is not well defined
  
    case AnyPtr: {
      // Found an AnyPtr type vs self-OopPtr type
      const TypePtr *tp = t->is_ptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      const TypePtr* speculative = xmeet_speculative(tp);
      int depth = meet_inline_depth(tp->inline_depth());
      switch (tp->ptr()) {
      case Null:

@@ -3698,17 +3817,17 @@
  //------------------------------xdual------------------------------------------
  // Dual of a pure heap pointer.  No relevant klass or oop information.
  const Type *TypeOopPtr::xdual() const {
    assert(klass() == Compile::current()->env()->Object_klass(), "no klasses here");
    assert(const_oop() == nullptr,             "no constants here");
-   return new TypeOopPtr(_base, dual_ptr(), klass(), _interfaces, klass_is_exact(), const_oop(), dual_offset(), dual_instance_id(), dual_speculative(), dual_inline_depth());
+   return new TypeOopPtr(_base, dual_ptr(), klass(), _interfaces, klass_is_exact(), const_oop(), dual_offset(), Offset::bottom, dual_instance_id(), dual_speculative(), dual_inline_depth());
  }
  
  //--------------------------make_from_klass_common-----------------------------
  // Computes the element-type given a klass.
- const TypeOopPtr* TypeOopPtr::make_from_klass_common(ciKlass* klass, bool klass_change, bool try_for_exact, InterfaceHandling interface_handling) {
-   if (klass->is_instance_klass()) {
+ const TypeOopPtr* TypeOopPtr::make_from_klass_common(ciKlass *klass, bool klass_change, bool try_for_exact, InterfaceHandling interface_handling) {
+   if (klass->is_instance_klass() || klass->is_inlinetype()) {
      Compile* C = Compile::current();
      Dependencies* deps = C->dependencies();
      assert((deps != nullptr) == (C->method() != nullptr && C->method()->code_size() > 0), "sanity");
      // Element is an instance
      bool klass_is_exact = false;

@@ -3731,29 +3850,44 @@
          deps->assert_leaf_type(ik);
          klass_is_exact = true;
        }
      }
      const TypeInterfaces* interfaces = TypePtr::interfaces(klass, true, true, false, interface_handling);
-     return TypeInstPtr::make(TypePtr::BotPTR, klass, interfaces, klass_is_exact, nullptr, 0);
+     return TypeInstPtr::make(TypePtr::BotPTR, klass, interfaces, klass_is_exact, nullptr, Offset(0));
    } else if (klass->is_obj_array_klass()) {
-     // Element is an object array. Recursively call ourself.
-     ciKlass* eklass = klass->as_obj_array_klass()->element_klass();
-     const TypeOopPtr *etype = TypeOopPtr::make_from_klass_common(eklass, false, try_for_exact, interface_handling);
-     bool xk = etype->klass_is_exact();
-     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::POS);
+     // Element is an object or inline type array. Recursively call ourself.
+     const TypeOopPtr* etype = TypeOopPtr::make_from_klass_common(klass->as_array_klass()->element_klass(), /* klass_change= */ false, try_for_exact, interface_handling);
+     // Determine null-free/flat properties
+     const TypeOopPtr* exact_etype = etype;
+     if (etype->can_be_inline_type()) {
+       // Use exact type if element can be an inline type
+       exact_etype = TypeOopPtr::make_from_klass_common(klass->as_array_klass()->element_klass(), /* klass_change= */ true, /* try_for_exact= */ true, interface_handling);
+     }
+     bool not_null_free = !exact_etype->can_be_inline_type();
+     bool not_flat = !UseFlatArray || not_null_free || (exact_etype->is_inlinetypeptr() && !exact_etype->inline_klass()->flat_in_array());
+     // Even though MyValue is final, [LMyValue is not exact because null-free [LMyValue is a subtype.
+     bool xk = etype->klass_is_exact() && !etype->is_inlinetypeptr();
+     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::POS, /* stable= */ false, /* flat= */ false, not_flat, not_null_free);
      // We used to pass NotNull in here, asserting that the sub-arrays
      // are all not-null.  This is not true in generally, as code can
-     // slam nulls down in the subarrays.
-     const TypeAryPtr* arr = TypeAryPtr::make(TypePtr::BotPTR, arr0, nullptr, xk, 0);
+     // slam nullptrs down in the subarrays.
+     const TypeAryPtr* arr = TypeAryPtr::make(TypePtr::BotPTR, arr0, nullptr, xk, Offset(0));
      return arr;
    } else if (klass->is_type_array_klass()) {
      // Element is an typeArray
      const Type* etype = get_const_basic_type(klass->as_type_array_klass()->element_type());
-     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::POS);
+     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::POS,
+                                         /* stable= */ false, /* flat= */ false, /* not_flat= */ true, /* not_null_free= */ true);
      // We used to pass NotNull in here, asserting that the array pointer
      // is not-null. That was not true in general.
-     const TypeAryPtr* arr = TypeAryPtr::make(TypePtr::BotPTR, arr0, klass, true, 0);
+     const TypeAryPtr* arr = TypeAryPtr::make(TypePtr::BotPTR, arr0, klass, true, Offset(0));
+     return arr;
+   } else if (klass->is_flat_array_klass()) {
+     const TypeOopPtr* etype = TypeOopPtr::make_from_klass_raw(klass->as_array_klass()->element_klass(), trust_interfaces);
+     etype = etype->join_speculative(TypePtr::NOTNULL)->is_oopptr();
+     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::POS, /* stable= */ false, /* flat= */ true);
+     const TypeAryPtr* arr = TypeAryPtr::make(TypePtr::BotPTR, arr0, klass, true, Offset(0));
      return arr;
    } else {
      ShouldNotReachHere();
      return nullptr;
    }

@@ -3765,54 +3899,71 @@
    assert(!o->is_null_object(), "null object not yet handled here.");
  
    const bool make_constant = require_constant || o->should_be_constant();
  
    ciKlass* klass = o->klass();
-   if (klass->is_instance_klass()) {
-     // Element is an instance
+   if (klass->is_instance_klass() || klass->is_inlinetype()) {
+     // Element is an instance or inline type
      if (make_constant) {
        return TypeInstPtr::make(o);
      } else {
-       return TypeInstPtr::make(TypePtr::NotNull, klass, true, nullptr, 0);
+       return TypeInstPtr::make(TypePtr::NotNull, klass, true, nullptr, Offset(0));
      }
    } else if (klass->is_obj_array_klass()) {
      // Element is an object array. Recursively call ourself.
-     const TypeOopPtr *etype =
-       TypeOopPtr::make_from_klass_raw(klass->as_obj_array_klass()->element_klass(), trust_interfaces);
-     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::make(o->as_array()->length()));
+     const TypeOopPtr* etype = TypeOopPtr::make_from_klass_raw(klass->as_array_klass()->element_klass(), trust_interfaces);
+     bool is_flat = o->as_obj_array()->is_flat();
+     bool is_null_free = o->as_obj_array()->is_null_free();
+     if (is_null_free) {
+       etype = etype->join_speculative(TypePtr::NOTNULL)->is_oopptr();
+     }
+     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::make(o->as_array()->length()),
+                                         /* stable= */ false, /* flat= */ false, /* not_flat= */ !is_flat, /* not_null_free= */ !is_null_free);
      // We used to pass NotNull in here, asserting that the sub-arrays
      // are all not-null.  This is not true in generally, as code can
      // slam nulls down in the subarrays.
      if (make_constant) {
-       return TypeAryPtr::make(TypePtr::Constant, o, arr0, klass, true, 0);
+       return TypeAryPtr::make(TypePtr::Constant, o, arr0, klass, true, Offset(0));
      } else {
-       return TypeAryPtr::make(TypePtr::NotNull, arr0, klass, true, 0);
+       return TypeAryPtr::make(TypePtr::NotNull, arr0, klass, true, Offset(0));
      }
    } else if (klass->is_type_array_klass()) {
      // Element is an typeArray
-     const Type* etype =
-       (Type*)get_const_basic_type(klass->as_type_array_klass()->element_type());
-     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::make(o->as_array()->length()));
+     const Type* etype = (Type*)get_const_basic_type(klass->as_type_array_klass()->element_type());
+     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::make(o->as_array()->length()),
+                                         /* stable= */ false, /* flat= */ false, /* not_flat= */ true, /* not_null_free= */ true);
      // We used to pass NotNull in here, asserting that the array pointer
      // is not-null. That was not true in general.
      if (make_constant) {
-       return TypeAryPtr::make(TypePtr::Constant, o, arr0, klass, true, 0);
+       return TypeAryPtr::make(TypePtr::Constant, o, arr0, klass, true, Offset(0));
+     } else {
+       return TypeAryPtr::make(TypePtr::NotNull, arr0, klass, true, Offset(0));
+     }
+   } else if (klass->is_flat_array_klass()) {
+     const TypeOopPtr* etype = TypeOopPtr::make_from_klass_raw(klass->as_array_klass()->element_klass(), trust_interfaces);
+     etype = etype->join_speculative(TypePtr::NOTNULL)->is_oopptr();
+     const TypeAry* arr0 = TypeAry::make(etype, TypeInt::make(o->as_array()->length()), /* stable= */ false, /* flat= */ true);
+     // We used to pass NotNull in here, asserting that the sub-arrays
+     // are all not-null.  This is not true in generally, as code can
+     // slam nullptrs down in the subarrays.
+     if (make_constant) {
+       return TypeAryPtr::make(TypePtr::Constant, o, arr0, klass, true, Offset(0));
      } else {
-       return TypeAryPtr::make(TypePtr::NotNull, arr0, klass, true, 0);
+       return TypeAryPtr::make(TypePtr::NotNull, arr0, klass, true, Offset(0));
      }
    }
  
    fatal("unhandled object type");
    return nullptr;
  }
  
  //------------------------------get_con----------------------------------------
  intptr_t TypeOopPtr::get_con() const {
    assert( _ptr == Null || _ptr == Constant, "" );
-   assert( _offset >= 0, "" );
+   assert(offset() >= 0, "");
  
-   if (_offset != 0) {
+   if (offset() != 0) {
      // After being ported to the compiler interface, the compiler no longer
      // directly manipulates the addresses of oops.  Rather, it only has a pointer
      // to a handle at compile time.  This handle is embedded in the generated
      // code and dereferenced at the time the nmethod is made.  Until that time,
      // it is not reasonable to do arithmetic with the addresses of oops (we don't

@@ -3869,16 +4020,11 @@
  #ifndef PRODUCT
  void TypeOopPtr::dump2( Dict &d, uint depth, outputStream *st ) const {
    st->print("oopptr:%s", ptr_msg[_ptr]);
    if( _klass_is_exact ) st->print(":exact");
    if( const_oop() ) st->print(INTPTR_FORMAT, p2i(const_oop()));
-   switch( _offset ) {
-   case OffsetTop: st->print("+top"); break;
-   case OffsetBot: st->print("+any"); break;
-   case         0: break;
-   default:        st->print("+%d",_offset); break;
-   }
+   _offset.dump2(st);
    if (_instance_id == InstanceTop)
      st->print(",iid=top");
    else if (_instance_id != InstanceBot)
      st->print(",iid=%d",_instance_id);
  

@@ -3891,20 +4037,20 @@
  // TRUE if Type is a singleton type, FALSE otherwise.   Singletons are simple
  // constants
  bool TypeOopPtr::singleton(void) const {
    // detune optimizer to not generate constant oop + constant offset as a constant!
    // TopPTR, Null, AnyNull, Constant are all singletons
-   return (_offset == 0) && !below_centerline(_ptr);
+   return (offset() == 0) && !below_centerline(_ptr);
  }
  
  //------------------------------add_offset-------------------------------------
  const TypePtr* TypeOopPtr::add_offset(intptr_t offset) const {
    return make(_ptr, xadd_offset(offset), _instance_id, add_offset_speculative(offset), _inline_depth);
  }
  
  const TypeOopPtr* TypeOopPtr::with_offset(intptr_t offset) const {
-   return make(_ptr, offset, _instance_id, with_offset_speculative(offset), _inline_depth);
+   return make(_ptr, Offset(offset), _instance_id, with_offset_speculative(offset), _inline_depth);
  }
  
  /**
   * Return same type without a speculative part
   */

@@ -4013,26 +4159,30 @@
    }
    return _interfaces->exact_klass();
  }
  
  //------------------------------TypeInstPtr-------------------------------------
- TypeInstPtr::TypeInstPtr(PTR ptr, ciKlass* k, const TypeInterfaces* interfaces, bool xk, ciObject* o, int off,
-                          int instance_id, const TypePtr* speculative, int inline_depth)
-   : TypeOopPtr(InstPtr, ptr, k, interfaces, xk, o, off, instance_id, speculative, inline_depth) {
+ TypeInstPtr::TypeInstPtr(PTR ptr, ciKlass* k, const TypeInterfaces* interfaces, bool xk, ciObject* o, Offset off,
+                          bool flat_in_array, int instance_id, const TypePtr* speculative, int inline_depth)
+   : TypeOopPtr(InstPtr, ptr, k, interfaces, xk, o, off, Offset::bottom, instance_id, speculative, inline_depth),
+     _flat_in_array(flat_in_array) {
    assert(k == nullptr || !k->is_loaded() || !k->is_interface(), "no interface here");
    assert(k != nullptr &&
           (k->is_loaded() || o == nullptr),
           "cannot have constants with non-loaded klass");
+   assert(!klass()->flat_in_array() || flat_in_array, "Should be flat in array");
+   assert(!flat_in_array || can_be_inline_type(), "Only inline types can be flat in array");
  };
  
  //------------------------------make-------------------------------------------
  const TypeInstPtr *TypeInstPtr::make(PTR ptr,
                                       ciKlass* k,
                                       const TypeInterfaces* interfaces,
                                       bool xk,
                                       ciObject* o,
-                                      int offset,
+                                      Offset offset,
+                                      bool flat_in_array,
                                       int instance_id,
                                       const TypePtr* speculative,
                                       int inline_depth) {
    assert( !k->is_loaded() || k->is_instance_klass(), "Must be for instance");
    // Either const_oop() is null or else ptr is Constant

@@ -4050,13 +4200,16 @@
      if (!xk && ik->is_final())     xk = true;   // no inexact final klass
      assert(!ik->is_interface(), "no interface here");
      if (xk && ik->is_interface())  xk = false;  // no exact interface
    }
  
+   // Check if this type is known to be flat in arrays
+   flat_in_array = flat_in_array || k->flat_in_array();
+ 
    // Now hash this baby
    TypeInstPtr *result =
-     (TypeInstPtr*)(new TypeInstPtr(ptr, k, interfaces, xk, o ,offset, instance_id, speculative, inline_depth))->hashcons();
+     (TypeInstPtr*)(new TypeInstPtr(ptr, k, interfaces, xk, o, offset, flat_in_array, instance_id, speculative, inline_depth))->hashcons();
  
    return result;
  }
  
  const TypeInterfaces* TypePtr::interfaces(ciKlass*& k, bool klass, bool interface, bool array, InterfaceHandling interface_handling) {

@@ -4118,35 +4271,35 @@
  //------------------------------cast_to_ptr_type-------------------------------
  const TypeInstPtr* TypeInstPtr::cast_to_ptr_type(PTR ptr) const {
    if( ptr == _ptr ) return this;
    // Reconstruct _sig info here since not a problem with later lazy
    // construction, _sig will show up on demand.
-   return make(ptr, klass(), _interfaces, klass_is_exact(), ptr == Constant ? const_oop() : nullptr, _offset, _instance_id, _speculative, _inline_depth);
+   return make(ptr, klass(), _interfaces, klass_is_exact(), ptr == Constant ? const_oop() : nullptr, _offset, _flat_in_array, _instance_id, _speculative, _inline_depth);
  }
  
  
  //-----------------------------cast_to_exactness-------------------------------
  const TypeInstPtr* TypeInstPtr::cast_to_exactness(bool klass_is_exact) const {
    if( klass_is_exact == _klass_is_exact ) return this;
    if (!_klass->is_loaded())  return this;
    ciInstanceKlass* ik = _klass->as_instance_klass();
    if( (ik->is_final() || _const_oop) )  return this;  // cannot clear xk
    assert(!ik->is_interface(), "no interface here");
-   return make(ptr(), klass(), _interfaces, klass_is_exact, const_oop(), _offset, _instance_id, _speculative, _inline_depth);
+   return make(ptr(), klass(), _interfaces, klass_is_exact, const_oop(), _offset, _flat_in_array, _instance_id, _speculative, _inline_depth);
  }
  
  //-----------------------------cast_to_instance_id----------------------------
  const TypeInstPtr* TypeInstPtr::cast_to_instance_id(int instance_id) const {
    if( instance_id == _instance_id ) return this;
-   return make(_ptr, klass(),  _interfaces, _klass_is_exact, const_oop(), _offset, instance_id, _speculative, _inline_depth);
+   return make(_ptr, klass(), _interfaces, _klass_is_exact, const_oop(), _offset, _flat_in_array, instance_id, _speculative, _inline_depth);
  }
  
  //------------------------------xmeet_unloaded---------------------------------
  // Compute the MEET of two InstPtrs when at least one is unloaded.
  // Assume classes are different since called after check for same name/class-loader
  const TypeInstPtr *TypeInstPtr::xmeet_unloaded(const TypeInstPtr *tinst, const TypeInterfaces* interfaces) const {
-   int off = meet_offset(tinst->offset());
+   Offset off = meet_offset(tinst->offset());
    PTR ptr = meet_ptr(tinst->ptr());
    int instance_id = meet_instance_id(tinst->instance_id());
    const TypePtr* speculative = xmeet_speculative(tinst);
    int depth = meet_inline_depth(tinst->inline_depth());
  

@@ -4167,11 +4320,11 @@
      //  BOTTOM  | ........................Object-BOTTOM ..................|
      //
      assert(loaded->ptr() != TypePtr::Null, "insanity check");
      //
      if (loaded->ptr() == TypePtr::TopPTR)        { return unloaded->with_speculative(speculative); }
-     else if (loaded->ptr() == TypePtr::AnyNull)  { return make(ptr, unloaded->klass(), interfaces, false, nullptr, off, instance_id, speculative, depth); }
+     else if (loaded->ptr() == TypePtr::AnyNull)  { return make(ptr, unloaded->klass(), interfaces, false, nullptr, off, false, instance_id, speculative, depth); }
      else if (loaded->ptr() == TypePtr::BotPTR)   { return TypeInstPtr::BOTTOM->with_speculative(speculative); }
      else if (loaded->ptr() == TypePtr::Constant || loaded->ptr() == TypePtr::NotNull) {
        if (unloaded->ptr() == TypePtr::BotPTR)    { return TypeInstPtr::BOTTOM->with_speculative(speculative);  }
        else                                       { return TypeInstPtr::NOTNULL->with_speculative(speculative); }
      }

@@ -4228,20 +4381,20 @@
    }
  
    case OopPtr: {                // Meeting to OopPtrs
      // Found a OopPtr type vs self-InstPtr type
      const TypeOopPtr *tp = t->is_oopptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      switch (tp->ptr()) {
      case TopPTR:
      case AnyNull: {
        int instance_id = meet_instance_id(InstanceTop);
        const TypePtr* speculative = xmeet_speculative(tp);
        int depth = meet_inline_depth(tp->inline_depth());
        return make(ptr, klass(), _interfaces, klass_is_exact(),
-                   (ptr == Constant ? const_oop() : nullptr), offset, instance_id, speculative, depth);
+                   (ptr == Constant ? const_oop() : nullptr), offset, flat_in_array(), instance_id, speculative, depth);
      }
      case NotNull:
      case BotPTR: {
        int instance_id = meet_instance_id(tp->instance_id());
        const TypePtr* speculative = xmeet_speculative(tp);

@@ -4253,11 +4406,11 @@
    }
  
    case AnyPtr: {                // Meeting to AnyPtrs
      // Found an AnyPtr type vs self-InstPtr type
      const TypePtr *tp = t->is_ptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      int instance_id = meet_instance_id(InstanceTop);
      const TypePtr* speculative = xmeet_speculative(tp);
      int depth = meet_inline_depth(tp->inline_depth());
      switch (tp->ptr()) {

@@ -4265,11 +4418,11 @@
        if( ptr == Null ) return TypePtr::make(AnyPtr, ptr, offset, speculative, depth);
        // else fall through to AnyNull
      case TopPTR:
      case AnyNull: {
        return make(ptr, klass(), _interfaces, klass_is_exact(),
-                   (ptr == Constant ? const_oop() : nullptr), offset, instance_id, speculative, depth);
+                   (ptr == Constant ? const_oop() : nullptr), offset, flat_in_array(), instance_id, speculative, depth);
      }
      case NotNull:
      case BotPTR:
        return TypePtr::make(AnyPtr, ptr, offset, speculative,depth);
      default: typerr(t);

@@ -4293,11 +4446,11 @@
    */
  
    case InstPtr: {                // Meeting 2 Oops?
      // Found an InstPtr sub-type vs self-InstPtr type
      const TypeInstPtr *tinst = t->is_instptr();
-     int off = meet_offset(tinst->offset());
+     Offset off = meet_offset(tinst->offset());
      PTR ptr = meet_ptr(tinst->ptr());
      int instance_id = meet_instance_id(tinst->instance_id());
      const TypePtr* speculative = xmeet_speculative(tinst);
      int depth = meet_inline_depth(tinst->inline_depth());
      const TypeInterfaces* interfaces = meet_interfaces(tinst);

@@ -4305,12 +4458,13 @@
      ciKlass* tinst_klass = tinst->klass();
      ciKlass* this_klass  = klass();
  
      ciKlass* res_klass = nullptr;
      bool res_xk = false;
+     bool res_flat_in_array = false;
      const Type* res;
-     MeetResult kind = meet_instptr(ptr, interfaces, this, tinst, res_klass, res_xk);
+     MeetResult kind = meet_instptr(ptr, interfaces, this, tinst, res_klass, res_xk, res_flat_in_array);
  
      if (kind == UNLOADED) {
        // One of these classes has not been loaded
        const TypeInstPtr* unloaded_meet = xmeet_unloaded(tinst, interfaces);
  #ifndef PRODUCT

@@ -4347,11 +4501,11 @@
            assert(!this_klass->is_interface(), "");
            o = this_oop;
          } else
            ptr = NotNull;
        }
-       res = make(ptr, res_klass, interfaces, res_xk, o, off, instance_id, speculative, depth);
+       res = make(ptr, res_klass, interfaces, res_xk, o, off, res_flat_in_array, instance_id, speculative, depth);
      }
  
      return res;
  
    } // End of case InstPtr

@@ -4359,26 +4513,32 @@
    } // End of switch
    return this;                  // Return the double constant
  }
  
  template<class T> TypePtr::MeetResult TypePtr::meet_instptr(PTR& ptr, const TypeInterfaces*& interfaces, const T* this_type, const T* other_type,
-                                                             ciKlass*& res_klass, bool& res_xk) {
+                                                             ciKlass*& res_klass, bool& res_xk, bool& res_flat_in_array) {
    ciKlass* this_klass = this_type->klass();
    ciKlass* other_klass = other_type->klass();
+   const bool this_flat_in_array = this_type->flat_in_array();
+   const bool other_flat_in_array = other_type->flat_in_array();
+   const bool this_not_flat_in_array = this_type->not_flat_in_array();
+   const bool other_not_flat_in_array = other_type->not_flat_in_array();
+ 
    bool this_xk = this_type->klass_is_exact();
    bool other_xk = other_type->klass_is_exact();
    PTR this_ptr = this_type->ptr();
    PTR other_ptr = other_type->ptr();
    const TypeInterfaces* this_interfaces = this_type->interfaces();
    const TypeInterfaces* other_interfaces = other_type->interfaces();
    // Check for easy case; klasses are equal (and perhaps not loaded!)
    // If we have constants, then we created oops so classes are loaded
    // and we can handle the constants further down.  This case handles
    // both-not-loaded or both-loaded classes
-   if (ptr != Constant && this_klass->equals(other_klass) && this_xk == other_xk) {
+   if (ptr != Constant && this_klass->equals(other_klass) && this_xk == other_xk && this_flat_in_array == other_flat_in_array) {
      res_klass = this_klass;
      res_xk = this_xk;
+     res_flat_in_array = this_flat_in_array;
      return QUICK;
    }
  
    // Classes require inspection in the Java klass hierarchy.  Must be loaded.
    if (!other_klass->is_loaded() || !this_klass->is_loaded()) {

@@ -4408,34 +4568,54 @@
    // If a proper supertype is exact, there can be no subtyping relationship!
    // If both types are equal to the subtype, exactness is and-ed below the
    // centerline and or-ed above it.  (N.B. Constants are always exact.)
  
    // Check for subtyping:
+   // Flat in array matrix, yes = y, no = n, maybe = m, top/empty = T:
+   //        yes maybe no   -> Super Klass
+   //   yes   y    y    y
+   // maybe   y    m    m
+   //    no   T    n    n
+   //    |
+   //    v
+   // Sub Klass
+ 
    const T* subtype = nullptr;
    bool subtype_exact = false;
+   bool flat_in_array = false;
    if (this_type->is_same_java_type_as(other_type)) {
      subtype = this_type;
      subtype_exact = below_centerline(ptr) ? (this_xk && other_xk) : (this_xk || other_xk);
-   } else if (!other_xk && this_type->is_meet_subtype_of(other_type)) {
+     flat_in_array = below_centerline(ptr) ? (this_flat_in_array && other_flat_in_array) : (this_flat_in_array || other_flat_in_array);
+   } else if (!other_xk && is_meet_subtype_of(this_type, other_type)) {
      subtype = this_type;     // Pick subtyping class
      subtype_exact = this_xk;
-   } else if(!this_xk && other_type->is_meet_subtype_of(this_type)) {
+     bool other_flat_this_maybe_flat = other_flat_in_array && (!this_flat_in_array && !this_not_flat_in_array);
+     flat_in_array = this_flat_in_array || other_flat_this_maybe_flat;
+   } else if (!this_xk && is_meet_subtype_of(other_type, this_type)) {
      subtype = other_type;    // Pick subtyping class
      subtype_exact = other_xk;
+     bool this_flat_other_maybe_flat = this_flat_in_array && (!other_flat_in_array && !other_not_flat_in_array);
+     flat_in_array = other_flat_in_array || this_flat_other_maybe_flat;
    }
  
    if (subtype) {
-     if (above_centerline(ptr)) { // both are up?
+     if (above_centerline(ptr)) {
+       // Both types are empty.
        this_type = other_type = subtype;
        this_xk = other_xk = subtype_exact;
      } else if (above_centerline(this_ptr) && !above_centerline(other_ptr)) {
-       this_type = other_type; // tinst is down; keep down man
+       // this_type is empty while other_type is not. Take other_type.
+       this_type = other_type;
        this_xk = other_xk;
+       flat_in_array = other_flat_in_array;
      } else if (above_centerline(other_ptr) && !above_centerline(this_ptr)) {
+       // other_type is empty while this_type is not. Take this_type.
        other_type = this_type; // this is down; keep down man
-       other_xk = this_xk;
+       flat_in_array = this_flat_in_array;
      } else {
+       // this_type and other_type are both non-empty.
        this_xk = subtype_exact;  // either they are equal, or we'll do an LCA
      }
    }
  
    // Check for classes now being equal

@@ -4443,10 +4623,11 @@
      // If the klasses are equal, the constants may still differ.  Fall to
      // NotNull if they do (neither constant is null; that is a special case
      // handled elsewhere).
      res_klass = this_type->klass();
      res_xk = this_xk;
+     res_flat_in_array = subtype ? flat_in_array : this_flat_in_array;
      return SUBTYPE;
    } // Else classes are not equal
  
    // Since klasses are different, we require a LCA in the Java
    // class hierarchy - which means we have to fall to at least NotNull.

@@ -4459,47 +4640,52 @@
    // Now we find the LCA of Java classes
    ciKlass* k = this_klass->least_common_ancestor(other_klass);
  
    res_klass = k;
    res_xk = false;
+   res_flat_in_array = this_flat_in_array && other_flat_in_array;
  
    return LCA;
  }
  
+ template<class T> bool TypePtr::is_meet_subtype_of(const T* sub_type, const T* super_type) {
+   return sub_type->is_meet_subtype_of(super_type) && !(super_type->flat_in_array() && sub_type->not_flat_in_array());
+ }
+ 
  //------------------------java_mirror_type--------------------------------------
- ciType* TypeInstPtr::java_mirror_type() const {
+ ciType* TypeInstPtr::java_mirror_type(bool* is_null_free_array) const {
    // must be a singleton type
    if( const_oop() == nullptr )  return nullptr;
  
    // must be of type java.lang.Class
    if( klass() != ciEnv::current()->Class_klass() )  return nullptr;
- 
-   return const_oop()->as_instance()->java_mirror_type();
+   return const_oop()->as_instance()->java_mirror_type(is_null_free_array);
  }
  
  
  //------------------------------xdual------------------------------------------
  // Dual: do NOT dual on klasses.  This means I do NOT understand the Java
  // inheritance mechanism.
  const Type *TypeInstPtr::xdual() const {
-   return new TypeInstPtr(dual_ptr(), klass(), _interfaces, klass_is_exact(), const_oop(), dual_offset(), dual_instance_id(), dual_speculative(), dual_inline_depth());
+   return new TypeInstPtr(dual_ptr(), klass(), _interfaces, klass_is_exact(), const_oop(), dual_offset(), flat_in_array(), dual_instance_id(), dual_speculative(), dual_inline_depth());
  }
  
  //------------------------------eq---------------------------------------------
  // Structural equality check for Type representations
  bool TypeInstPtr::eq( const Type *t ) const {
    const TypeInstPtr *p = t->is_instptr();
    return
      klass()->equals(p->klass()) &&
+     flat_in_array() == p->flat_in_array() &&
      _interfaces->eq(p->_interfaces) &&
      TypeOopPtr::eq(p);          // Check sub-type stuff
  }
  
  //------------------------------hash-------------------------------------------
  // Type-specific hashing function.
  uint TypeInstPtr::hash(void) const {
-   return klass()->hash() + TypeOopPtr::hash() + _interfaces->hash();
+   return klass()->hash() + TypeOopPtr::hash() + _interfaces->hash() + (uint)flat_in_array();
  }
  
  bool TypeInstPtr::is_java_subtype_of_helper(const TypeOopPtr* other, bool this_exact, bool other_exact) const {
    return TypePtr::is_java_subtype_of_helper_for_instance(this, other, this_exact, other_exact);
  }

@@ -4549,17 +4735,18 @@
      break;
    default:
      break;
    }
  
-   if( _offset ) {               // Dump offset, if any
-     if( _offset == OffsetBot )      st->print("+any");
-     else if( _offset == OffsetTop ) st->print("+unknown");
-     else st->print("+%d", _offset);
-   }
+   _offset.dump2(st);
  
    st->print(" *");
+ 
+   if (flat_in_array() && !klass()->is_inlinetype()) {
+     st->print(" (flat in array)");
+   }
+ 
    if (_instance_id == InstanceTop)
      st->print(",iid=top");
    else if (_instance_id != InstanceBot)
      st->print(",iid=%d",_instance_id);
  

@@ -4568,42 +4755,46 @@
  }
  #endif
  
  //------------------------------add_offset-------------------------------------
  const TypePtr* TypeInstPtr::add_offset(intptr_t offset) const {
-   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), xadd_offset(offset),
+   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), xadd_offset(offset), flat_in_array(),
                _instance_id, add_offset_speculative(offset), _inline_depth);
  }
  
  const TypeInstPtr* TypeInstPtr::with_offset(intptr_t offset) const {
-   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), offset,
+   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), Offset(offset), flat_in_array(),
                _instance_id, with_offset_speculative(offset), _inline_depth);
  }
  
  const TypeInstPtr* TypeInstPtr::remove_speculative() const {
    if (_speculative == nullptr) {
      return this;
    }
    assert(_inline_depth == InlineDepthTop || _inline_depth == InlineDepthBottom, "non speculative type shouldn't have inline depth");
-   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset,
+   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset, flat_in_array(),
                _instance_id, nullptr, _inline_depth);
  }
  
  const TypeInstPtr* TypeInstPtr::with_speculative(const TypePtr* speculative) const {
-   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset, _instance_id, speculative, _inline_depth);
+   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset, flat_in_array(), _instance_id, speculative, _inline_depth);
  }
  
  const TypePtr* TypeInstPtr::with_inline_depth(int depth) const {
    if (!UseInlineDepthForSpeculativeTypes) {
      return this;
    }
-   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset, _instance_id, _speculative, depth);
+   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset, flat_in_array(), _instance_id, _speculative, depth);
  }
  
  const TypePtr* TypeInstPtr::with_instance_id(int instance_id) const {
    assert(is_known_instance(), "should be known");
-   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset, instance_id, _speculative, _inline_depth);
+   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset, flat_in_array(), instance_id, _speculative, _inline_depth);
+ }
+ 
+ const TypeInstPtr *TypeInstPtr::cast_to_flat_in_array() const {
+   return make(_ptr, klass(), _interfaces, klass_is_exact(), const_oop(), _offset, true, _instance_id, _speculative, _inline_depth);
  }
  
  const TypeKlassPtr* TypeInstPtr::as_klass_type(bool try_for_exact) const {
    bool xk = klass_is_exact();
    ciInstanceKlass* ik = klass()->as_instance_klass();

@@ -4613,11 +4804,11 @@
        Dependencies* deps = C->dependencies();
        deps->assert_leaf_type(ik);
        xk = true;
      }
    }
-   return TypeInstKlassPtr::make(xk ? TypePtr::Constant : TypePtr::NotNull, klass(), _interfaces, 0);
+   return TypeInstKlassPtr::make(xk ? TypePtr::Constant : TypePtr::NotNull, klass(), _interfaces, Offset(0), flat_in_array());
  }
  
  template <class T1, class T2> bool TypePtr::is_meet_subtype_of_helper_for_instance(const T1* this_one, const T2* other, bool this_xk, bool other_xk) {
    static_assert(std::is_base_of<T2, T1>::value, "");
  

@@ -4658,11 +4849,10 @@
    const TypePtr* other_elem = other_ary->elem()->make_ptr();
    const TypePtr* this_elem = this_one->elem()->make_ptr();
    if (other_elem != nullptr && this_elem != nullptr) {
      return this_one->is_reference_type(this_elem)->is_meet_subtype_of_helper(this_one->is_reference_type(other_elem), this_xk, other_xk);
    }
- 
    if (other_elem == nullptr && this_elem == nullptr) {
      return this_one->klass()->is_subtype_of(other->klass());
    }
  
    return false;

@@ -4690,27 +4880,31 @@
  const TypeAryPtr *TypeAryPtr::CHARS;
  const TypeAryPtr *TypeAryPtr::INTS;
  const TypeAryPtr *TypeAryPtr::LONGS;
  const TypeAryPtr *TypeAryPtr::FLOATS;
  const TypeAryPtr *TypeAryPtr::DOUBLES;
+ const TypeAryPtr *TypeAryPtr::INLINES;
  
  //------------------------------make-------------------------------------------
- const TypeAryPtr *TypeAryPtr::make(PTR ptr, const TypeAry *ary, ciKlass* k, bool xk, int offset,
+ const TypeAryPtr* TypeAryPtr::make(PTR ptr, const TypeAry *ary, ciKlass* k, bool xk, Offset offset, Offset field_offset,
                                     int instance_id, const TypePtr* speculative, int inline_depth) {
    assert(!(k == nullptr && ary->_elem->isa_int()),
           "integral arrays must be pre-equipped with a class");
    if (!xk)  xk = ary->ary_must_be_exact();
    assert(instance_id <= 0 || xk, "instances are always exactly typed");
    if (k != nullptr && k->is_loaded() && k->is_obj_array_klass() &&
        k->as_obj_array_klass()->base_element_klass()->is_interface()) {
      k = nullptr;
    }
-   return (TypeAryPtr*)(new TypeAryPtr(ptr, nullptr, ary, k, xk, offset, instance_id, false, speculative, inline_depth))->hashcons();
+   if (k != nullptr && k->is_flat_array_klass() && !ary->_flat) {
+     k = nullptr;
+   }
+   return (TypeAryPtr*)(new TypeAryPtr(ptr, nullptr, ary, k, xk, offset, field_offset, instance_id, false, speculative, inline_depth))->hashcons();
  }
  
  //------------------------------make-------------------------------------------
- const TypeAryPtr *TypeAryPtr::make(PTR ptr, ciObject* o, const TypeAry *ary, ciKlass* k, bool xk, int offset,
+ const TypeAryPtr* TypeAryPtr::make(PTR ptr, ciObject* o, const TypeAry *ary, ciKlass* k, bool xk, Offset offset, Offset field_offset,
                                     int instance_id, const TypePtr* speculative, int inline_depth,
                                     bool is_autobox_cache) {
    assert(!(k == nullptr && ary->_elem->isa_int()),
           "integral arrays must be pre-equipped with a class");
    assert( (ptr==Constant && o) || (ptr!=Constant && !o), "" );

@@ -4718,31 +4912,34 @@
    assert(instance_id <= 0 || xk, "instances are always exactly typed");
    if (k != nullptr && k->is_loaded() && k->is_obj_array_klass() &&
        k->as_obj_array_klass()->base_element_klass()->is_interface()) {
      k = nullptr;
    }
-   return (TypeAryPtr*)(new TypeAryPtr(ptr, o, ary, k, xk, offset, instance_id, is_autobox_cache, speculative, inline_depth))->hashcons();
+   if (k != nullptr && k->is_flat_array_klass() && !ary->_flat) {
+     k = nullptr;
+   }
+   return (TypeAryPtr*)(new TypeAryPtr(ptr, o, ary, k, xk, offset, field_offset, instance_id, is_autobox_cache, speculative, inline_depth))->hashcons();
  }
  
  //------------------------------cast_to_ptr_type-------------------------------
  const TypeAryPtr* TypeAryPtr::cast_to_ptr_type(PTR ptr) const {
    if( ptr == _ptr ) return this;
-   return make(ptr, ptr == Constant ? const_oop() : nullptr, _ary, klass(), klass_is_exact(), _offset, _instance_id, _speculative, _inline_depth);
+   return make(ptr, ptr == Constant ? const_oop() : nullptr, _ary, klass(), klass_is_exact(), _offset, _field_offset, _instance_id, _speculative, _inline_depth, _is_autobox_cache);
  }
  
  
  //-----------------------------cast_to_exactness-------------------------------
  const TypeAryPtr* TypeAryPtr::cast_to_exactness(bool klass_is_exact) const {
    if( klass_is_exact == _klass_is_exact ) return this;
    if (_ary->ary_must_be_exact())  return this;  // cannot clear xk
-   return make(ptr(), const_oop(), _ary, klass(), klass_is_exact, _offset, _instance_id, _speculative, _inline_depth);
+   return make(ptr(), const_oop(), _ary, klass(), klass_is_exact, _offset, _field_offset, _instance_id, _speculative, _inline_depth, _is_autobox_cache);
  }
  
  //-----------------------------cast_to_instance_id----------------------------
  const TypeAryPtr* TypeAryPtr::cast_to_instance_id(int instance_id) const {
    if( instance_id == _instance_id ) return this;
-   return make(_ptr, const_oop(), _ary, klass(), _klass_is_exact, _offset, instance_id, _speculative, _inline_depth);
+   return make(_ptr, const_oop(), _ary, klass(), _klass_is_exact, _offset, _field_offset, instance_id, _speculative, _inline_depth, _is_autobox_cache);
  }
  
  
  //-----------------------------max_array_length-------------------------------
  // A wrapper around arrayOopDesc::max_array_length(etype) with some input normalization.

@@ -4794,12 +4991,72 @@
  //-------------------------------cast_to_size----------------------------------
  const TypeAryPtr* TypeAryPtr::cast_to_size(const TypeInt* new_size) const {
    assert(new_size != nullptr, "");
    new_size = narrow_size_type(new_size);
    if (new_size == size())  return this;
-   const TypeAry* new_ary = TypeAry::make(elem(), new_size, is_stable());
-   return make(ptr(), const_oop(), new_ary, klass(), klass_is_exact(), _offset, _instance_id, _speculative, _inline_depth);
+   const TypeAry* new_ary = TypeAry::make(elem(), new_size, is_stable(), is_flat(), is_not_flat(), is_not_null_free());
+   return make(ptr(), const_oop(), new_ary, klass(), klass_is_exact(), _offset, _field_offset, _instance_id, _speculative, _inline_depth, _is_autobox_cache);
+ }
+ 
+ //-------------------------------cast_to_not_flat------------------------------
+ const TypeAryPtr* TypeAryPtr::cast_to_not_flat(bool not_flat) const {
+   if (not_flat == is_not_flat()) {
+     return this;
+   }
+   assert(!not_flat || !is_flat(), "inconsistency");
+   const TypeAry* new_ary = TypeAry::make(elem(), size(), is_stable(), is_flat(), not_flat, is_not_null_free());
+   const TypeAryPtr* res = make(ptr(), const_oop(), new_ary, klass(), klass_is_exact(), _offset, _field_offset, _instance_id, _speculative, _inline_depth, _is_autobox_cache);
+   // We keep the speculative part if it contains information about flat-/nullability.
+   // Make sure it's removed if it's not better than the non-speculative type anymore.
+   if (res->speculative() == res->remove_speculative()) {
+     return res->remove_speculative();
+   }
+   return res;
+ }
+ 
+ //-------------------------------cast_to_not_null_free-------------------------
+ const TypeAryPtr* TypeAryPtr::cast_to_not_null_free(bool not_null_free) const {
+   if (not_null_free == is_not_null_free()) {
+     return this;
+   }
+   assert(!not_null_free || !is_flat(), "inconsistency");
+   const TypeAry* new_ary = TypeAry::make(elem(), size(), is_stable(), is_flat(), /* not_flat= */ not_null_free ? true : is_not_flat(), not_null_free);
+   const TypeAryPtr* res = make(ptr(), const_oop(), new_ary, klass(), klass_is_exact(), _offset, _field_offset,
+                                _instance_id, _speculative, _inline_depth, _is_autobox_cache);
+   // We keep the speculative part if it contains information about flat-/nullability.
+   // Make sure it's removed if it's not better than the non-speculative type anymore.
+   if (res->speculative() == res->remove_speculative()) {
+     return res->remove_speculative();
+   }
+   return res;
+ }
+ 
+ //---------------------------------update_properties---------------------------
+ const TypeAryPtr* TypeAryPtr::update_properties(const TypeAryPtr* from) const {
+   if ((from->is_flat()          && is_not_flat()) ||
+       (from->is_not_flat()      && is_flat()) ||
+       (from->is_null_free()     && is_not_null_free()) ||
+       (from->is_not_null_free() && is_null_free())) {
+     return nullptr; // Inconsistent properties
+   } else if (from->is_not_null_free()) {
+     return cast_to_not_null_free(); // Implies not flat
+   } else if (from->is_not_flat()) {
+     return cast_to_not_flat();
+   }
+   return this;
+ }
+ 
+ jint TypeAryPtr::flat_layout_helper() const {
+   return klass()->as_flat_array_klass()->layout_helper();
+ }
+ 
+ int TypeAryPtr::flat_elem_size() const {
+   return klass()->as_flat_array_klass()->element_byte_size();
+ }
+ 
+ int TypeAryPtr::flat_log_elem_size() const {
+   return klass()->as_flat_array_klass()->log2_element_size();
  }
  
  //------------------------------cast_to_stable---------------------------------
  const TypeAryPtr* TypeAryPtr::cast_to_stable(bool stable, int stable_dimension) const {
    if (stable_dimension <= 0 || (stable_dimension == 1 && stable == this->is_stable()))

@@ -4811,13 +5068,13 @@
    if (stable_dimension > 1 && elem_ptr != nullptr && elem_ptr->isa_aryptr()) {
      // If this is widened from a narrow oop, TypeAry::make will re-narrow it.
      elem = elem_ptr = elem_ptr->is_aryptr()->cast_to_stable(stable, stable_dimension - 1);
    }
  
-   const TypeAry* new_ary = TypeAry::make(elem, size(), stable);
+   const TypeAry* new_ary = TypeAry::make(elem, size(), stable, is_flat(), is_not_flat(), is_not_null_free());
  
-   return make(ptr(), const_oop(), new_ary, klass(), klass_is_exact(), _offset, _instance_id, _speculative, _inline_depth);
+   return make(ptr(), const_oop(), new_ary, klass(), klass_is_exact(), _offset, _field_offset, _instance_id, _speculative, _inline_depth, _is_autobox_cache);
  }
  
  //-----------------------------stable_dimension--------------------------------
  int TypeAryPtr::stable_dimension() const {
    if (!is_stable())  return 0;

@@ -4833,27 +5090,28 @@
    if (is_autobox_cache())  return this;
    const TypeOopPtr* etype = elem()->make_oopptr();
    if (etype == nullptr)  return this;
    // The pointers in the autobox arrays are always non-null.
    etype = etype->cast_to_ptr_type(TypePtr::NotNull)->is_oopptr();
-   const TypeAry* new_ary = TypeAry::make(etype, size(), is_stable());
-   return make(ptr(), const_oop(), new_ary, klass(), klass_is_exact(), _offset, _instance_id, _speculative, _inline_depth, /*is_autobox_cache=*/true);
+   const TypeAry* new_ary = TypeAry::make(etype, size(), is_stable(), is_flat(), is_not_flat(), is_not_null_free());
+   return make(ptr(), const_oop(), new_ary, klass(), klass_is_exact(), _offset, _field_offset, _instance_id, _speculative, _inline_depth, /*is_autobox_cache=*/true);
  }
  
  //------------------------------eq---------------------------------------------
  // Structural equality check for Type representations
  bool TypeAryPtr::eq( const Type *t ) const {
    const TypeAryPtr *p = t->is_aryptr();
    return
      _ary == p->_ary &&  // Check array
-     TypeOopPtr::eq(p);  // Check sub-parts
+     TypeOopPtr::eq(p) &&// Check sub-parts
+     _field_offset == p->_field_offset;
  }
  
  //------------------------------hash-------------------------------------------
  // Type-specific hashing function.
  uint TypeAryPtr::hash(void) const {
-   return (uint)(uintptr_t)_ary + TypeOopPtr::hash();
+   return (uint)(uintptr_t)_ary + TypeOopPtr::hash() + _field_offset.get();
  }
  
  bool TypeAryPtr::is_java_subtype_of_helper(const TypeOopPtr* other, bool this_exact, bool other_exact) const {
    return TypePtr::is_java_subtype_of_helper_for_array(this, other, this_exact, other_exact);
  }

@@ -4893,20 +5151,20 @@
      typerr(t);
  
    case OopPtr: {                // Meeting to OopPtrs
      // Found a OopPtr type vs self-AryPtr type
      const TypeOopPtr *tp = t->is_oopptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      int depth = meet_inline_depth(tp->inline_depth());
      const TypePtr* speculative = xmeet_speculative(tp);
      switch (tp->ptr()) {
      case TopPTR:
      case AnyNull: {
        int instance_id = meet_instance_id(InstanceTop);
        return make(ptr, (ptr == Constant ? const_oop() : nullptr),
-                   _ary, _klass, _klass_is_exact, offset, instance_id, speculative, depth);
+                   _ary, _klass, _klass_is_exact, offset, _field_offset, instance_id, speculative, depth);
      }
      case BotPTR:
      case NotNull: {
        int instance_id = meet_instance_id(tp->instance_id());
        return TypeOopPtr::make(ptr, offset, instance_id, speculative, depth);

@@ -4916,11 +5174,11 @@
    }
  
    case AnyPtr: {                // Meeting two AnyPtrs
      // Found an AnyPtr type vs self-AryPtr type
      const TypePtr *tp = t->is_ptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      const TypePtr* speculative = xmeet_speculative(tp);
      int depth = meet_inline_depth(tp->inline_depth());
      switch (tp->ptr()) {
      case TopPTR:

@@ -4932,11 +5190,11 @@
        if( ptr == Null ) return TypePtr::make(AnyPtr, ptr, offset, speculative, depth);
        // else fall through to AnyNull
      case AnyNull: {
        int instance_id = meet_instance_id(InstanceTop);
        return make(ptr, (ptr == Constant ? const_oop() : nullptr),
-                   _ary, _klass, _klass_is_exact, offset, instance_id, speculative, depth);
+                   _ary, _klass, _klass_is_exact, offset, _field_offset, instance_id, speculative, depth);
      }
      default: ShouldNotReachHere();
      }
    }
  

@@ -4946,22 +5204,40 @@
    case AryKlassPtr:
    case RawPtr: return TypePtr::BOTTOM;
  
    case AryPtr: {                // Meeting 2 references?
      const TypeAryPtr *tap = t->is_aryptr();
-     int off = meet_offset(tap->offset());
+     Offset off = meet_offset(tap->offset());
+     Offset field_off = meet_field_offset(tap->field_offset());
      const TypeAry *tary = _ary->meet_speculative(tap->_ary)->is_ary();
      PTR ptr = meet_ptr(tap->ptr());
      int instance_id = meet_instance_id(tap->instance_id());
      const TypePtr* speculative = xmeet_speculative(tap);
      int depth = meet_inline_depth(tap->inline_depth());
  
      ciKlass* res_klass = nullptr;
      bool res_xk = false;
+     bool res_flat = false;
+     bool res_not_flat = false;
+     bool res_not_null_free = false;
      const Type* elem = tary->_elem;
-     if (meet_aryptr(ptr, elem, this, tap, res_klass, res_xk) == NOT_SUBTYPE) {
+     if (meet_aryptr(ptr, elem, this, tap, res_klass, res_xk, res_flat, res_not_flat, res_not_null_free) == NOT_SUBTYPE) {
        instance_id = InstanceBot;
+     } else if (this->is_flat() != tap->is_flat()) {
+       // Meeting flat inline type array with non-flat array. Adjust (field) offset accordingly.
+       if (tary->_flat) {
+         // Result is in a flat representation
+         off = Offset(is_flat() ? offset() : tap->offset());
+         field_off = is_flat() ? field_offset() : tap->field_offset();
+       } else if (below_centerline(ptr)) {
+         // Result is in a non-flat representation
+         off = Offset(flat_offset()).meet(Offset(tap->flat_offset()));
+         field_off = (field_off == Offset::top) ? Offset::top : Offset::bottom;
+       } else if (flat_offset() == tap->flat_offset()) {
+         off = Offset(!is_flat() ? offset() : tap->offset());
+         field_off = !is_flat() ? field_offset() : tap->field_offset();
+       }
      }
  
      ciObject* o = nullptr;             // Assume not constant when done
      ciObject* this_oop = const_oop();
      ciObject* tap_oop = tap->const_oop();

@@ -4975,17 +5251,17 @@
          o = this_oop;
        } else {
          ptr = NotNull;
        }
      }
-     return make(ptr, o, TypeAry::make(elem, tary->_size, tary->_stable), res_klass, res_xk, off, instance_id, speculative, depth);
+     return make(ptr, o, TypeAry::make(elem, tary->_size, tary->_stable, res_flat, res_not_flat, res_not_null_free), res_klass, res_xk, off, field_off, instance_id, speculative, depth);
    }
  
    // All arrays inherit from Object class
    case InstPtr: {
      const TypeInstPtr *tp = t->is_instptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      int instance_id = meet_instance_id(tp->instance_id());
      const TypePtr* speculative = xmeet_speculative(tp);
      int depth = meet_inline_depth(tp->inline_depth());
      const TypeInterfaces* interfaces = meet_interfaces(tp);

@@ -4996,18 +5272,18 @@
      case TopPTR:
      case AnyNull:                // Fall 'down' to dual of object klass
        // For instances when a subclass meets a superclass we fall
        // below the centerline when the superclass is exact. We need to
        // do the same here.
-       if (tp->klass()->equals(ciEnv::current()->Object_klass()) && this_interfaces->contains(tp_interfaces) && !tp->klass_is_exact()) {
-         return TypeAryPtr::make(ptr, _ary, _klass, _klass_is_exact, offset, instance_id, speculative, depth);
+       if (tp->klass()->equals(ciEnv::current()->Object_klass()) && this_interfaces->contains(tp_interfaces) && !tp->klass_is_exact() && !tp->flat_in_array()) {
+         return TypeAryPtr::make(ptr, _ary, _klass, _klass_is_exact, offset, _field_offset, instance_id, speculative, depth);
        } else {
          // cannot subclass, so the meet has to fall badly below the centerline
          ptr = NotNull;
          instance_id = InstanceBot;
          interfaces = this_interfaces->intersection_with(tp_interfaces);
-         return TypeInstPtr::make(ptr, ciEnv::current()->Object_klass(), interfaces, false, nullptr,offset, instance_id, speculative, depth);
+         return TypeInstPtr::make(ptr, ciEnv::current()->Object_klass(), interfaces, false, nullptr, offset, false, instance_id, speculative, depth);
        }
      case Constant:
      case NotNull:
      case BotPTR:                // Fall down to object klass
        // LCA is object_klass, but if we subclass from the top we can do better

@@ -5015,14 +5291,14 @@
          // If 'tp'  is above the centerline and it is Object class
          // then we can subclass in the Java class hierarchy.
          // For instances when a subclass meets a superclass we fall
          // below the centerline when the superclass is exact. We need
          // to do the same here.
-         if (tp->klass()->equals(ciEnv::current()->Object_klass()) && this_interfaces->contains(tp_interfaces) && !tp->klass_is_exact()) {
+         if (tp->klass()->equals(ciEnv::current()->Object_klass()) && this_interfaces->contains(tp_interfaces) && !tp->klass_is_exact() && !tp->flat_in_array()) {
            // that is, my array type is a subtype of 'tp' klass
            return make(ptr, (ptr == Constant ? const_oop() : nullptr),
-                       _ary, _klass, _klass_is_exact, offset, instance_id, speculative, depth);
+                       _ary, _klass, _klass_is_exact, offset, _field_offset, instance_id, speculative, depth);
          }
        }
        // The other case cannot happen, since t cannot be a subtype of an array.
        // The meet falls down to Object class below centerline.
        if (ptr == Constant) {

@@ -5030,38 +5306,48 @@
        }
        if (instance_id > 0) {
          instance_id = InstanceBot;
        }
        interfaces = this_interfaces->intersection_with(tp_interfaces);
-       return TypeInstPtr::make(ptr, ciEnv::current()->Object_klass(), interfaces, false, nullptr, offset, instance_id, speculative, depth);
+       return TypeInstPtr::make(ptr, ciEnv::current()->Object_klass(), interfaces, false, nullptr, offset, false, instance_id, speculative, depth);
      default: typerr(t);
      }
    }
    }
    return this;                  // Lint noise
  }
  
  
- template<class T> TypePtr::MeetResult TypePtr::meet_aryptr(PTR& ptr, const Type*& elem, const T* this_ary,
-                                                            const T* other_ary, ciKlass*& res_klass, bool& res_xk) {
+ template<class T> TypePtr::MeetResult TypePtr::meet_aryptr(PTR& ptr, const Type*& elem, const T* this_ary, const T* other_ary,
+                                                            ciKlass*& res_klass, bool& res_xk, bool &res_flat, bool& res_not_flat, bool& res_not_null_free) {
    int dummy;
    bool this_top_or_bottom = (this_ary->base_element_type(dummy) == Type::TOP || this_ary->base_element_type(dummy) == Type::BOTTOM);
    bool other_top_or_bottom = (other_ary->base_element_type(dummy) == Type::TOP || other_ary->base_element_type(dummy) == Type::BOTTOM);
    ciKlass* this_klass = this_ary->klass();
    ciKlass* other_klass = other_ary->klass();
    bool this_xk = this_ary->klass_is_exact();
    bool other_xk = other_ary->klass_is_exact();
    PTR this_ptr = this_ary->ptr();
    PTR other_ptr = other_ary->ptr();
+   bool this_flat = this_ary->is_flat();
+   bool this_not_flat = this_ary->is_not_flat();
+   bool other_flat = other_ary->is_flat();
+   bool other_not_flat = other_ary->is_not_flat();
+   bool this_not_null_free = this_ary->is_not_null_free();
+   bool other_not_null_free = other_ary->is_not_null_free();
    res_klass = nullptr;
    MeetResult result = SUBTYPE;
+   res_flat = this_flat && other_flat;
+   res_not_flat = this_not_flat && other_not_flat;
+   res_not_null_free = this_not_null_free && other_not_null_free;
+ 
    if (elem->isa_int()) {
      // Integral array element types have irrelevant lattice relations.
      // It is the klass that determines array layout, not the element type.
-     if (this_top_or_bottom)
-       res_klass = other_klass;
-     else if (other_top_or_bottom || other_klass == this_klass) {
+       if (this_top_or_bottom) {
+         res_klass = other_klass;
+       } else if (other_top_or_bottom || other_klass == this_klass) {
        res_klass = this_klass;
      } else {
        // Something like byte[int+] meets char[int+].
        // This must fall to bottom, not (int[-128..65535])[int+].
        // instance_id = InstanceBot;

@@ -5099,35 +5385,51 @@
      case AnyNull:
      case TopPTR:
        // Compute new klass on demand, do not use tap->_klass
        if (below_centerline(this_ptr)) {
          res_xk = this_xk;
+         if (this_ary->is_flat()) {
+           elem = this_ary->elem();
+         }
        } else {
          res_xk = (other_xk || this_xk);
        }
-       return result;
+       break;
      case Constant: {
        if (this_ptr == Constant) {
          res_xk = true;
-       } else if(above_centerline(this_ptr)) {
+       } else if (above_centerline(this_ptr)) {
          res_xk = true;
        } else {
          // Only precise for identical arrays
          res_xk = this_xk && (this_ary->is_same_java_type_as(other_ary) || (this_top_or_bottom && other_top_or_bottom));
+         // Even though MyValue is final, [LMyValue is only exact if the array
+         // is null-free due to null-free [LMyValue <: null-able [LMyValue.
+         if (res_xk && !res_not_null_free) {
+           res_xk = false;
+         }
        }
-       return result;
+       break;
      }
      case NotNull:
      case BotPTR:
        // Compute new klass on demand, do not use tap->_klass
        if (above_centerline(this_ptr)) {
          res_xk = other_xk;
+         if (other_ary->is_flat()) {
+           elem = other_ary->elem();
+         }
        } else {
          res_xk = (other_xk && this_xk) &&
                   (this_ary->is_same_java_type_as(other_ary) || (this_top_or_bottom && other_top_or_bottom)); // Only precise for identical arrays
+         // Even though MyValue is final, [LMyValue is only exact if the array
+         // is null-free due to null-free [LMyValue <: null-able [LMyValue.
+         if (res_xk && !res_not_null_free) {
+           res_xk = false;
+         }
        }
-       return result;
+       break;
      default:  {
        ShouldNotReachHere();
        return result;
      }
    }

@@ -5136,11 +5438,20 @@
  
  
  //------------------------------xdual------------------------------------------
  // Dual: compute field-by-field dual
  const Type *TypeAryPtr::xdual() const {
-   return new TypeAryPtr(dual_ptr(), _const_oop, _ary->dual()->is_ary(),_klass, _klass_is_exact, dual_offset(), dual_instance_id(), is_autobox_cache(), dual_speculative(), dual_inline_depth());
+   return new TypeAryPtr(dual_ptr(), _const_oop, _ary->dual()->is_ary(), _klass, _klass_is_exact, dual_offset(), dual_field_offset(), dual_instance_id(), is_autobox_cache(), dual_speculative(), dual_inline_depth());
+ }
+ 
+ Type::Offset TypeAryPtr::meet_field_offset(const Type::Offset offset) const {
+   return _field_offset.meet(offset);
+ }
+ 
+ //------------------------------dual_offset------------------------------------
+ Type::Offset TypeAryPtr::dual_field_offset() const {
+   return _field_offset.dual();
  }
  
  //------------------------------dump2------------------------------------------
  #ifndef PRODUCT
  void TypeAryPtr::dump2( Dict &d, uint depth, outputStream *st ) const {

@@ -5164,22 +5475,31 @@
      break;
    default:
      break;
    }
  
-   if( _offset != 0 ) {
+   if (is_flat()) {
+     st->print(":flat");
+     st->print("(");
+     _field_offset.dump2(st);
+     st->print(")");
+   }
+   if (is_null_free()) {
+     st->print(":null_free");
+   }
+   if (offset() != 0) {
      BasicType basic_elem_type = elem()->basic_type();
      int header_size = arrayOopDesc::base_offset_in_bytes(basic_elem_type);
-     if( _offset == OffsetTop )       st->print("+undefined");
-     else if( _offset == OffsetBot )  st->print("+any");
-     else if( _offset < header_size ) st->print("+%d", _offset);
+     if( _offset == Offset::top )       st->print("+undefined");
+     else if( _offset == Offset::bottom )  st->print("+any");
+     else if( offset() < header_size ) st->print("+%d", offset());
      else {
        if (basic_elem_type == T_ILLEGAL) {
          st->print("+any");
        } else {
          int elem_size = type2aelembytes(basic_elem_type);
-         st->print("[%d]", (_offset - header_size)/elem_size);
+         st->print("[%d]", (offset() - header_size)/elem_size);
        }
      }
    }
    st->print(" *");
    if (_instance_id == InstanceTop)

@@ -5192,48 +5512,109 @@
  }
  #endif
  
  bool TypeAryPtr::empty(void) const {
    if (_ary->empty())       return true;
+   // FIXME: Does this belong here? Or in the meet code itself?
+   if (is_flat() && is_not_flat()) {
+     return true;
+   }
    return TypeOopPtr::empty();
  }
  
  //------------------------------add_offset-------------------------------------
  const TypePtr* TypeAryPtr::add_offset(intptr_t offset) const {
-   return make(_ptr, _const_oop, _ary, _klass, _klass_is_exact, xadd_offset(offset), _instance_id, add_offset_speculative(offset), _inline_depth);
+   return make(_ptr, _const_oop, _ary, _klass, _klass_is_exact, xadd_offset(offset), _field_offset, _instance_id, add_offset_speculative(offset), _inline_depth, _is_autobox_cache);
  }
  
  const TypeAryPtr* TypeAryPtr::with_offset(intptr_t offset) const {
-   return make(_ptr, _const_oop, _ary, _klass, _klass_is_exact, offset, _instance_id, with_offset_speculative(offset), _inline_depth);
+   return make(_ptr, _const_oop, _ary, _klass, _klass_is_exact, Offset(offset), _field_offset, _instance_id, with_offset_speculative(offset), _inline_depth, _is_autobox_cache);
  }
  
  const TypeAryPtr* TypeAryPtr::with_ary(const TypeAry* ary) const {
-   return make(_ptr, _const_oop, ary, _klass, _klass_is_exact, _offset, _instance_id, _speculative, _inline_depth);
+   return make(_ptr, _const_oop, ary, _klass, _klass_is_exact, _offset, _field_offset, _instance_id, _speculative, _inline_depth, _is_autobox_cache);
  }
  
  const TypeAryPtr* TypeAryPtr::remove_speculative() const {
    if (_speculative == nullptr) {
      return this;
    }
    assert(_inline_depth == InlineDepthTop || _inline_depth == InlineDepthBottom, "non speculative type shouldn't have inline depth");
-   return make(_ptr, _const_oop, _ary->remove_speculative()->is_ary(), _klass, _klass_is_exact, _offset, _instance_id, nullptr, _inline_depth);
+   return make(_ptr, _const_oop, _ary->remove_speculative()->is_ary(), _klass, _klass_is_exact, _offset, _field_offset, _instance_id, nullptr, _inline_depth, _is_autobox_cache);
+ }
+ 
+ const Type* TypeAryPtr::cleanup_speculative() const {
+   if (speculative() == nullptr) {
+     return this;
+   }
+   // Keep speculative part if it contains information about flat-/nullability
+   const TypeAryPtr* spec_aryptr = speculative()->isa_aryptr();
+   if (spec_aryptr != nullptr && !above_centerline(spec_aryptr->ptr()) &&
+       (spec_aryptr->is_not_flat() || spec_aryptr->is_not_null_free())) {
+     return this;
+   }
+   return TypeOopPtr::cleanup_speculative();
  }
  
  const TypePtr* TypeAryPtr::with_inline_depth(int depth) const {
    if (!UseInlineDepthForSpeculativeTypes) {
      return this;
    }
-   return make(_ptr, _const_oop, _ary->remove_speculative()->is_ary(), _klass, _klass_is_exact, _offset, _instance_id, _speculative, depth);
+   return make(_ptr, _const_oop, _ary->remove_speculative()->is_ary(), _klass, _klass_is_exact, _offset, _field_offset, _instance_id, _speculative, depth, _is_autobox_cache);
+ }
+ 
+ const TypeAryPtr* TypeAryPtr::with_field_offset(int offset) const {
+   return make(_ptr, _const_oop, _ary->remove_speculative()->is_ary(), _klass, _klass_is_exact, _offset, Offset(offset), _instance_id, _speculative, _inline_depth, _is_autobox_cache);
+ }
+ 
+ const TypePtr* TypeAryPtr::add_field_offset_and_offset(intptr_t offset) const {
+   int adj = 0;
+   if (is_flat() && offset != Type::OffsetBot && offset != Type::OffsetTop) {
+     if (_offset.get() != OffsetBot && _offset.get() != OffsetTop) {
+       adj = _offset.get();
+       offset += _offset.get();
+     }
+     uint header = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
+     if (_field_offset.get() != OffsetBot && _field_offset.get() != OffsetTop) {
+       offset += _field_offset.get();
+       if (_offset.get() == OffsetBot || _offset.get() == OffsetTop) {
+         offset += header;
+       }
+     }
+     if (elem()->make_oopptr()->is_inlinetypeptr() && (offset >= (intptr_t)header || offset < 0)) {
+       // Try to get the field of the inline type array element we are pointing to
+       ciInlineKlass* vk = elem()->inline_klass();
+       int shift = flat_log_elem_size();
+       int mask = (1 << shift) - 1;
+       intptr_t field_offset = ((offset - header) & mask);
+       ciField* field = vk->get_field_by_offset(field_offset + vk->first_field_offset(), false);
+       if (field != nullptr) {
+         return with_field_offset(field_offset)->add_offset(offset - field_offset - adj);
+       }
+     }
+   }
+   return add_offset(offset - adj);
+ }
+ 
+ // Return offset incremented by field_offset for flat inline type arrays
+ int TypeAryPtr::flat_offset() const {
+   int offset = _offset.get();
+   if (offset != Type::OffsetBot && offset != Type::OffsetTop &&
+       _field_offset != Offset::bottom && _field_offset != Offset::top) {
+     offset += _field_offset.get();
+   }
+   return offset;
  }
  
  const TypePtr* TypeAryPtr::with_instance_id(int instance_id) const {
    assert(is_known_instance(), "should be known");
-   return make(_ptr, _const_oop, _ary->remove_speculative()->is_ary(), _klass, _klass_is_exact, _offset, instance_id, _speculative, _inline_depth);
+   return make(_ptr, _const_oop, _ary->remove_speculative()->is_ary(), _klass, _klass_is_exact, _offset, _field_offset, instance_id, _speculative, _inline_depth);
  }
  
  //=============================================================================
  
+ 
  //------------------------------hash-------------------------------------------
  // Type-specific hashing function.
  uint TypeNarrowPtr::hash(void) const {
    return _ptrtype->hash() + 7;
  }

@@ -5320,11 +5701,10 @@
    case KlassPtr:
    case InstKlassPtr:
    case AryKlassPtr:
    case NarrowOop:
    case NarrowKlass:
- 
    case Bottom:                  // Ye Olde Default
      return Type::BOTTOM;
    case Top:
      return this;
  

@@ -5404,11 +5784,11 @@
  // TRUE if Type is a singleton type, FALSE otherwise.   Singletons are simple
  // constants
  bool TypeMetadataPtr::singleton(void) const {
    // detune optimizer to not generate constant metadata + constant offset as a constant!
    // TopPTR, Null, AnyNull, Constant are all singletons
-   return (_offset == 0) && !below_centerline(_ptr);
+   return (offset() == 0) && !below_centerline(_ptr);
  }
  
  //------------------------------add_offset-------------------------------------
  const TypePtr* TypeMetadataPtr::add_offset( intptr_t offset ) const {
    return make( _ptr, _metadata, xadd_offset(offset));

@@ -5424,13 +5804,13 @@
  }
  
   //------------------------------get_con----------------------------------------
  intptr_t TypeMetadataPtr::get_con() const {
    assert( _ptr == Null || _ptr == Constant, "" );
-   assert( _offset >= 0, "" );
+   assert(offset() >= 0, "");
  
-   if (_offset != 0) {
+   if (offset() != 0) {
      // After being ported to the compiler interface, the compiler no longer
      // directly manipulates the addresses of oops.  Rather, it only has a pointer
      // to a handle at compile time.  This handle is embedded in the generated
      // code and dereferenced at the time the nmethod is made.  Until that time,
      // it is not reasonable to do arithmetic with the addresses of oops (we don't

@@ -5477,11 +5857,11 @@
      typerr(t);
  
    case AnyPtr: {
      // Found an AnyPtr type vs self-OopPtr type
      const TypePtr *tp = t->is_ptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      switch (tp->ptr()) {
      case Null:
        if (ptr == Null)  return TypePtr::make(AnyPtr, ptr, offset, tp->speculative(), tp->inline_depth());
        // else fall through:

@@ -5505,11 +5885,11 @@
    case AryPtr:
      return TypePtr::BOTTOM;     // Oop meet raw is not well defined
  
    case MetadataPtr: {
      const TypeMetadataPtr *tp = t->is_metadataptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR tptr = tp->ptr();
      PTR ptr = meet_ptr(tptr);
      ciMetadata* md = (tptr == TopPTR) ? metadata() : tp->metadata();
      if (tptr == TopPTR || _ptr == TopPTR ||
          metadata()->equals(tp->metadata())) {

@@ -5538,76 +5918,77 @@
  //------------------------------dump2------------------------------------------
  #ifndef PRODUCT
  void TypeMetadataPtr::dump2( Dict &d, uint depth, outputStream *st ) const {
    st->print("metadataptr:%s", ptr_msg[_ptr]);
    if( metadata() ) st->print(INTPTR_FORMAT, p2i(metadata()));
-   switch( _offset ) {
+   switch (offset()) {
    case OffsetTop: st->print("+top"); break;
    case OffsetBot: st->print("+any"); break;
    case         0: break;
-   default:        st->print("+%d",_offset); break;
+   default:        st->print("+%d",offset()); break;
    }
  }
  #endif
  
  
  //=============================================================================
  // Convenience common pre-built type.
  const TypeMetadataPtr *TypeMetadataPtr::BOTTOM;
  
- TypeMetadataPtr::TypeMetadataPtr(PTR ptr, ciMetadata* metadata, int offset):
+ TypeMetadataPtr::TypeMetadataPtr(PTR ptr, ciMetadata* metadata, Offset offset):
    TypePtr(MetadataPtr, ptr, offset), _metadata(metadata) {
  }
  
  const TypeMetadataPtr* TypeMetadataPtr::make(ciMethod* m) {
-   return make(Constant, m, 0);
+   return make(Constant, m, Offset(0));
  }
  const TypeMetadataPtr* TypeMetadataPtr::make(ciMethodData* m) {
-   return make(Constant, m, 0);
+   return make(Constant, m, Offset(0));
  }
  
  //------------------------------make-------------------------------------------
  // Create a meta data constant
- const TypeMetadataPtr *TypeMetadataPtr::make(PTR ptr, ciMetadata* m, int offset) {
+ const TypeMetadataPtr* TypeMetadataPtr::make(PTR ptr, ciMetadata* m, Offset offset) {
    assert(m == nullptr || !m->is_klass(), "wrong type");
    return (TypeMetadataPtr*)(new TypeMetadataPtr(ptr, m, offset))->hashcons();
  }
  
  
  const TypeKlassPtr* TypeAryPtr::as_klass_type(bool try_for_exact) const {
    const Type* elem = _ary->_elem;
    bool xk = klass_is_exact();
    if (elem->make_oopptr() != nullptr) {
      elem = elem->make_oopptr()->as_klass_type(try_for_exact);
-     if (elem->is_klassptr()->klass_is_exact()) {
+     if (elem->is_klassptr()->klass_is_exact() &&
+         // Even though MyValue is final, [LMyValue is only exact if the array
+         // is null-free due to null-free [LMyValue <: null-able [LMyValue.
+         (is_null_free() || !_ary->_elem->make_oopptr()->is_inlinetypeptr())) {
        xk = true;
      }
    }
-   return TypeAryKlassPtr::make(xk ? TypePtr::Constant : TypePtr::NotNull, elem, klass(), 0);
+   return TypeAryKlassPtr::make(xk ? TypePtr::Constant : TypePtr::NotNull, elem, klass(), Offset(0), is_not_flat(), is_not_null_free(), is_null_free());
  }
  
- const TypeKlassPtr* TypeKlassPtr::make(ciKlass *klass, InterfaceHandling interface_handling) {
+ const TypeKlassPtr* TypeKlassPtr::make(ciKlass* klass, InterfaceHandling interface_handling) {
    if (klass->is_instance_klass()) {
      return TypeInstKlassPtr::make(klass, interface_handling);
    }
    return TypeAryKlassPtr::make(klass, interface_handling);
  }
  
- const TypeKlassPtr* TypeKlassPtr::make(PTR ptr, ciKlass* klass, int offset, InterfaceHandling interface_handling) {
+ const TypeKlassPtr* TypeKlassPtr::make(PTR ptr, ciKlass* klass, Offset offset, InterfaceHandling interface_handling) {
    if (klass->is_instance_klass()) {
      const TypeInterfaces* interfaces = TypePtr::interfaces(klass, true, true, false, interface_handling);
      return TypeInstKlassPtr::make(ptr, klass, interfaces, offset);
    }
    return TypeAryKlassPtr::make(ptr, klass, offset, interface_handling);
  }
  
- 
- //------------------------------TypeKlassPtr-----------------------------------
- TypeKlassPtr::TypeKlassPtr(TYPES t, PTR ptr, ciKlass* klass, const TypeInterfaces* interfaces, int offset)
+ TypeKlassPtr::TypeKlassPtr(TYPES t, PTR ptr, ciKlass* klass, const TypeInterfaces* interfaces, Offset offset)
    : TypePtr(t, ptr, offset), _klass(klass), _interfaces(interfaces) {
    assert(klass == nullptr || !klass->is_loaded() || (klass->is_instance_klass() && !klass->is_interface()) ||
-          klass->is_type_array_klass() || !klass->as_obj_array_klass()->base_element_klass()->is_interface(), "no interface here");
+          klass->is_type_array_klass() || klass->is_flat_array_klass() || !klass->as_obj_array_klass()->base_element_klass()->is_interface(), "no interface here");
  }
  
  // Is there a single ciKlass* that can represent that type?
  ciKlass* TypeKlassPtr::exact_klass_helper() const {
    assert(_klass->is_instance_klass() && !_klass->is_interface(), "No interface");

@@ -5642,11 +6023,11 @@
  // TRUE if Type is a singleton type, FALSE otherwise.   Singletons are simple
  // constants
  bool TypeKlassPtr::singleton(void) const {
    // detune optimizer to not generate constant klass + constant offset as a constant!
    // TopPTR, Null, AnyNull, Constant are all singletons
-   return (_offset == 0) && !below_centerline(_ptr);
+   return (offset() == 0) && !below_centerline(_ptr);
  }
  
  // Do not allow interface-vs.-noninterface joins to collapse to top.
  const Type *TypeKlassPtr::filter_helper(const Type *kills, bool include_speculative) const {
    // logic here mirrors the one from TypeOopPtr::filter. See comments

@@ -5674,13 +6055,13 @@
  }
  
  //------------------------------get_con----------------------------------------
  intptr_t TypeKlassPtr::get_con() const {
    assert( _ptr == Null || _ptr == Constant, "" );
-   assert( _offset >= 0, "" );
+   assert( offset() >= 0, "" );
  
-   if (_offset != 0) {
+   if (offset() != 0) {
      // After being ported to the compiler interface, the compiler no longer
      // directly manipulates the addresses of oops.  Rather, it only has a pointer
      // to a handle at compile time.  This handle is embedded in the generated
      // code and dereferenced at the time the nmethod is made.  Until that time,
      // it is not reasonable to do arithmetic with the addresses of oops (we don't

@@ -5720,17 +6101,14 @@
      if (_ptr == Constant) st->print(":exact");
      break;
    default:
      break;
    }
- 
-   if (_offset) {               // Dump offset, if any
-     if (_offset == OffsetBot)      { st->print("+any"); }
-     else if (_offset == OffsetTop) { st->print("+unknown"); }
-     else                            { st->print("+%d", _offset); }
+   if (Verbose) {
+     if (isa_instklassptr() && is_instklassptr()->flat_in_array()) st->print(":flat in array");
    }
- 
+   _offset.dump2(st);
    st->print(" *");
  }
  #endif
  
  //=============================================================================

@@ -5742,39 +6120,42 @@
  
  bool TypeInstKlassPtr::eq(const Type *t) const {
    const TypeKlassPtr *p = t->is_klassptr();
    return
      klass()->equals(p->klass()) &&
+     flat_in_array() == p->flat_in_array() &&
      TypeKlassPtr::eq(p);
  }
  
  uint TypeInstKlassPtr::hash(void) const {
-   return klass()->hash() + TypeKlassPtr::hash();
+   return klass()->hash() + TypeKlassPtr::hash() + (uint)flat_in_array();
  }
  
- const TypeInstKlassPtr *TypeInstKlassPtr::make(PTR ptr, ciKlass* k, const TypeInterfaces* interfaces, int offset) {
+ const TypeInstKlassPtr *TypeInstKlassPtr::make(PTR ptr, ciKlass* k, const TypeInterfaces* interfaces, Offset offset, bool flat_in_array) {
+   flat_in_array = flat_in_array || k->flat_in_array();
+ 
    TypeInstKlassPtr *r =
-     (TypeInstKlassPtr*)(new TypeInstKlassPtr(ptr, k, interfaces, offset))->hashcons();
+     (TypeInstKlassPtr*)(new TypeInstKlassPtr(ptr, k, interfaces, offset, flat_in_array))->hashcons();
  
    return r;
  }
  
  //------------------------------add_offset-------------------------------------
  // Access internals of klass object
- const TypePtr* TypeInstKlassPtr::add_offset( intptr_t offset ) const {
-   return make( _ptr, klass(), _interfaces, xadd_offset(offset) );
+ const TypePtr *TypeInstKlassPtr::add_offset( intptr_t offset ) const {
+   return make(_ptr, klass(), _interfaces, xadd_offset(offset), flat_in_array());
  }
  
  const TypeInstKlassPtr* TypeInstKlassPtr::with_offset(intptr_t offset) const {
-   return make(_ptr, klass(), _interfaces, offset);
+   return make(_ptr, klass(), _interfaces, Offset(offset), flat_in_array());
  }
  
  //------------------------------cast_to_ptr_type-------------------------------
  const TypeInstKlassPtr* TypeInstKlassPtr::cast_to_ptr_type(PTR ptr) const {
    assert(_base == InstKlassPtr, "subclass must override cast_to_ptr_type");
    if( ptr == _ptr ) return this;
-   return make(ptr, _klass, _interfaces, _offset);
+   return make(ptr, _klass, _interfaces, _offset, flat_in_array());
  }
  
  
  bool TypeInstKlassPtr::must_be_exact() const {
    if (!_klass->is_loaded())  return false;

@@ -5786,11 +6167,11 @@
  //-----------------------------cast_to_exactness-------------------------------
  const TypeKlassPtr* TypeInstKlassPtr::cast_to_exactness(bool klass_is_exact) const {
    if (klass_is_exact == (_ptr == Constant)) return this;
    if (must_be_exact()) return this;
    ciKlass* k = klass();
-   return make(klass_is_exact ? Constant : NotNull, k, _interfaces, _offset);
+   return make(klass_is_exact ? Constant : NotNull, k, _interfaces, _offset, flat_in_array());
  }
  
  
  //-----------------------------as_instance_type--------------------------------
  // Corresponding type for an instance of the given class.

@@ -5818,11 +6199,11 @@
            xk = sub->is_final();
          }
        }
      }
    }
-   return TypeInstPtr::make(TypePtr::BotPTR, k, interfaces, xk, nullptr, 0);
+   return TypeInstPtr::make(TypePtr::BotPTR, k, interfaces, xk, nullptr, Offset(0), flat_in_array() && !klass()->is_inlinetype());
  }
  
  //------------------------------xmeet------------------------------------------
  // Compute the MEET of two types, return a new Type object.
  const Type    *TypeInstKlassPtr::xmeet( const Type *t ) const {

@@ -5851,19 +6232,19 @@
      typerr(t);
  
    case AnyPtr: {                // Meeting to AnyPtrs
      // Found an AnyPtr type vs self-KlassPtr type
      const TypePtr *tp = t->is_ptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      switch (tp->ptr()) {
      case TopPTR:
        return this;
      case Null:
        if( ptr == Null ) return TypePtr::make(AnyPtr, ptr, offset, tp->speculative(), tp->inline_depth());
      case AnyNull:
-       return make( ptr, klass(), _interfaces, offset );
+       return make(ptr, klass(), _interfaces, offset, flat_in_array());
      case BotPTR:
      case NotNull:
        return TypePtr::make(AnyPtr, ptr, offset, tp->speculative(), tp->inline_depth());
      default: typerr(t);
      }

@@ -5872,11 +6253,11 @@
    case RawPtr:
    case MetadataPtr:
    case OopPtr:
    case AryPtr:                  // Meet with AryPtr
    case InstPtr:                 // Meet with InstPtr
-     return TypePtr::BOTTOM;
+       return TypePtr::BOTTOM;
  
    //
    //             A-top         }
    //           /   |   \       }  Tops
    //       B-top A-any C-top   }

@@ -5892,34 +6273,35 @@
    //             A-bot         }
    //
  
    case InstKlassPtr: {  // Meet two KlassPtr types
      const TypeInstKlassPtr *tkls = t->is_instklassptr();
-     int  off     = meet_offset(tkls->offset());
+     Offset  off     = meet_offset(tkls->offset());
      PTR  ptr     = meet_ptr(tkls->ptr());
      const TypeInterfaces* interfaces = meet_interfaces(tkls);
  
      ciKlass* res_klass = nullptr;
      bool res_xk = false;
-     switch(meet_instptr(ptr, interfaces, this, tkls, res_klass, res_xk)) {
+     bool res_flat_in_array = false;
+     switch(meet_instptr(ptr, interfaces, this, tkls, res_klass, res_xk, res_flat_in_array)) {
        case UNLOADED:
          ShouldNotReachHere();
        case SUBTYPE:
        case NOT_SUBTYPE:
        case LCA:
        case QUICK: {
          assert(res_xk == (ptr == Constant), "");
-         const Type* res = make(ptr, res_klass, interfaces, off);
+         const Type* res = make(ptr, res_klass, interfaces, off, res_flat_in_array);
          return res;
        }
        default:
          ShouldNotReachHere();
      }
    } // End of case KlassPtr
    case AryKlassPtr: {                // All arrays inherit from Object class
      const TypeAryKlassPtr *tp = t->is_aryklassptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      const TypeInterfaces* interfaces = meet_interfaces(tp);
      const TypeInterfaces* tp_interfaces = tp->_interfaces;
      const TypeInterfaces* this_interfaces = _interfaces;
  

@@ -5928,16 +6310,16 @@
      case AnyNull:                // Fall 'down' to dual of object klass
        // For instances when a subclass meets a superclass we fall
        // below the centerline when the superclass is exact. We need to
        // do the same here.
        if (klass()->equals(ciEnv::current()->Object_klass()) && tp_interfaces->contains(this_interfaces) && !klass_is_exact()) {
-         return TypeAryKlassPtr::make(ptr, tp->elem(), tp->klass(), offset);
+         return TypeAryKlassPtr::make(ptr, tp->elem(), tp->klass(), offset, tp->is_not_flat(), tp->is_not_null_free(), tp->is_null_free());
        } else {
          // cannot subclass, so the meet has to fall badly below the centerline
          ptr = NotNull;
          interfaces = _interfaces->intersection_with(tp->_interfaces);
-         return make(ptr, ciEnv::current()->Object_klass(), interfaces, offset);
+         return make(ptr, ciEnv::current()->Object_klass(), interfaces, offset, false);
        }
      case Constant:
      case NotNull:
      case BotPTR:                // Fall down to object klass
        // LCA is object_klass, but if we subclass from the top we can do better

@@ -5947,20 +6329,19 @@
          // For instances when a subclass meets a superclass we fall
          // below the centerline when the superclass is exact. We need
          // to do the same here.
          if (klass()->equals(ciEnv::current()->Object_klass()) && tp_interfaces->contains(this_interfaces) && !klass_is_exact()) {
            // that is, tp's array type is a subtype of my klass
-           return TypeAryKlassPtr::make(ptr,
-                                        tp->elem(), tp->klass(), offset);
+           return TypeAryKlassPtr::make(ptr, tp->elem(), tp->klass(), offset, tp->is_not_flat(), tp->is_not_null_free(), tp->is_null_free());
          }
        }
        // The other case cannot happen, since I cannot be a subtype of an array.
        // The meet falls down to Object class below centerline.
        if( ptr == Constant )
           ptr = NotNull;
        interfaces = this_interfaces->intersection_with(tp_interfaces);
-       return make(ptr, ciEnv::current()->Object_klass(), interfaces, offset);
+       return make(ptr, ciEnv::current()->Object_klass(), interfaces, offset, false);
      default: typerr(t);
      }
    }
  
    } // End of switch

@@ -5968,11 +6349,11 @@
  }
  
  //------------------------------xdual------------------------------------------
  // Dual: compute field-by-field dual
  const Type    *TypeInstKlassPtr::xdual() const {
-   return new TypeInstKlassPtr(dual_ptr(), klass(), _interfaces, dual_offset());
+   return new TypeInstKlassPtr(dual_ptr(), klass(), _interfaces, dual_offset(), flat_in_array());
  }
  
  template <class T1, class T2> bool TypePtr::is_java_subtype_of_helper_for_instance(const T1* this_one, const T2* other, bool this_exact, bool other_exact) {
    static_assert(std::is_base_of<T2, T1>::value, "");
    if (!this_one->is_loaded() || !other->is_loaded()) {

@@ -6069,48 +6450,82 @@
      }
    }
    return this;
  }
  
+ bool TypeInstKlassPtr::can_be_inline_array() const {
+   return _klass->equals(ciEnv::current()->Object_klass()) && TypeAryKlassPtr::_array_interfaces->contains(_interfaces);
+ }
+ 
+ bool TypeAryKlassPtr::can_be_inline_array() const {
+   return _elem->isa_instklassptr() && _elem->is_instklassptr()->_klass->can_be_inline_klass();
+ }
+ 
+ bool TypeInstPtr::can_be_inline_array() const {
+   return _klass->equals(ciEnv::current()->Object_klass()) && TypeAryPtr::_array_interfaces->contains(_interfaces);
+ }
+ 
+ bool TypeAryPtr::can_be_inline_array() const {
+   return elem()->make_ptr() && elem()->make_ptr()->isa_instptr() && elem()->make_ptr()->is_instptr()->_klass->can_be_inline_klass();
+ }
  
- const TypeAryKlassPtr *TypeAryKlassPtr::make(PTR ptr, const Type* elem, ciKlass* k, int offset) {
-   return (TypeAryKlassPtr*)(new TypeAryKlassPtr(ptr, elem, k, offset))->hashcons();
+ const TypeAryKlassPtr *TypeAryKlassPtr::make(PTR ptr, const Type* elem, ciKlass* k, Offset offset, bool not_flat, bool not_null_free, bool null_free) {
+   return (TypeAryKlassPtr*)(new TypeAryKlassPtr(ptr, elem, k, offset, not_flat, not_null_free, null_free))->hashcons();
  }
  
- const TypeAryKlassPtr *TypeAryKlassPtr::make(PTR ptr, ciKlass* k, int offset, InterfaceHandling interface_handling) {
+ const TypeAryKlassPtr* TypeAryKlassPtr::make(PTR ptr, ciKlass* k, Offset offset, InterfaceHandling interface_handling, bool not_flat, bool not_null_free, bool null_free) {
    if (k->is_obj_array_klass()) {
      // Element is an object array. Recursively call ourself.
      ciKlass* eklass = k->as_obj_array_klass()->element_klass();
-     const TypeKlassPtr *etype = TypeKlassPtr::make(eklass, interface_handling)->cast_to_exactness(false);
-     return TypeAryKlassPtr::make(ptr, etype, nullptr, offset);
+     const TypeKlassPtr* etype = TypeKlassPtr::make(eklass, interface_handling)->cast_to_exactness(false);
+     return TypeAryKlassPtr::make(ptr, etype, nullptr, offset, not_flat, not_null_free, null_free);
    } else if (k->is_type_array_klass()) {
      // Element is an typeArray
      const Type* etype = get_const_basic_type(k->as_type_array_klass()->element_type());
-     return TypeAryKlassPtr::make(ptr, etype, k, offset);
+     return TypeAryKlassPtr::make(ptr, etype, k, offset, not_flat, not_null_free, null_free);
+   } else if (k->is_flat_array_klass()) {
+     ciKlass* eklass = k->as_flat_array_klass()->element_klass();
+     const TypeKlassPtr* etype = TypeKlassPtr::make(eklass);
+     return TypeAryKlassPtr::make(ptr, etype, k, offset, not_flat, not_null_free, null_free);
    } else {
      ShouldNotReachHere();
      return nullptr;
    }
  }
  
+ const TypeAryKlassPtr* TypeAryKlassPtr::make(PTR ptr, ciKlass* k, Offset offset, InterfaceHandling interface_handling) {
+   bool null_free = k->as_array_klass()->is_elem_null_free();
+   bool not_null_free = (ptr == Constant) ? !null_free : !k->is_flat_array_klass() && (k->is_type_array_klass() || !k->as_array_klass()->element_klass()->can_be_inline_klass(false));
+ 
+   bool not_flat = !UseFlatArray || not_null_free || (k->as_array_klass()->element_klass() != nullptr &&
+                                                      k->as_array_klass()->element_klass()->is_inlinetype() &&
+                                                      !k->as_array_klass()->element_klass()->flat_in_array());
+ 
+   return TypeAryKlassPtr::make(ptr, k, offset, interface_handling, not_flat, not_null_free, null_free);
+ }
+ 
  const TypeAryKlassPtr* TypeAryKlassPtr::make(ciKlass* klass, InterfaceHandling interface_handling) {
-   return TypeAryKlassPtr::make(Constant, klass, 0, interface_handling);
+   return TypeAryKlassPtr::make(Constant, klass, Offset(0), interface_handling);
  }
  
  //------------------------------eq---------------------------------------------
  // Structural equality check for Type representations
  bool TypeAryKlassPtr::eq(const Type *t) const {
    const TypeAryKlassPtr *p = t->is_aryklassptr();
    return
      _elem == p->_elem &&  // Check array
+     _not_flat == p->_not_flat &&
+     _not_null_free == p->_not_null_free &&
+     _null_free == p->_null_free &&
      TypeKlassPtr::eq(p);  // Check sub-parts
  }
  
  //------------------------------hash-------------------------------------------
  // Type-specific hashing function.
  uint TypeAryKlassPtr::hash(void) const {
-   return (uint)(uintptr_t)_elem + TypeKlassPtr::hash();
+   return (uint)(uintptr_t)_elem + TypeKlassPtr::hash() + (uint)(_not_flat ? 43 : 0) +
+       (uint)(_not_null_free ? 44 : 0) + (uint)(_null_free ? 45 : 0);
  }
  
  //----------------------compute_klass------------------------------------------
  // Compute the defining klass for this class
  ciKlass* TypeAryPtr::compute_klass() const {

@@ -6122,14 +6537,19 @@
    if (el->isa_narrowoop()) {
      el = el->make_ptr();
    }
  
    // Get element klass
-   if ((tinst = el->isa_instptr()) != nullptr) {
-     // Leave k_ary at null.
+   if (is_flat() && el->is_inlinetypeptr()) {
+     // Klass is required by TypeAryPtr::flat_layout_helper() and others
+     if (el->inline_klass() != nullptr) {
+       k_ary = ciArrayKlass::make(el->inline_klass(), /* null_free */ true);
+     }
+   } else if ((tinst = el->isa_instptr()) != nullptr) {
+     // Leave k_ary at nullptr.
    } else if ((tary = el->isa_aryptr()) != nullptr) {
-     // Leave k_ary at null.
+     // Leave k_ary at nullptr.
    } else if ((el->base() == Type::Top) ||
               (el->base() == Type::Bottom)) {
      // element type of Bottom occurs from meet of basic type
      // and object; Top occurs when doing join on Bottom.
      // Leave k_ary at null.

@@ -6173,11 +6593,11 @@
    if (_ary->_elem->make_ptr() && _ary->_elem->make_ptr()->isa_oopptr()) {
      ciKlass* k = _ary->_elem->make_ptr()->is_oopptr()->exact_klass_helper();
      if (k == nullptr) {
        return nullptr;
      }
-     k = ciObjArrayKlass::make(k);
+     k = ciArrayKlass::make(k, is_null_free());
      return k;
    }
  
    return klass();
  }

@@ -6193,44 +6613,70 @@
  }
  
  //------------------------------add_offset-------------------------------------
  // Access internals of klass object
  const TypePtr* TypeAryKlassPtr::add_offset(intptr_t offset) const {
-   return make(_ptr, elem(), klass(), xadd_offset(offset));
+   return make(_ptr, elem(), klass(), xadd_offset(offset), is_not_flat(), is_not_null_free(), _null_free);
  }
  
  const TypeAryKlassPtr* TypeAryKlassPtr::with_offset(intptr_t offset) const {
-   return make(_ptr, elem(), klass(), offset);
+   return make(_ptr, elem(), klass(), Offset(offset), is_not_flat(), is_not_null_free(), _null_free);
  }
  
  //------------------------------cast_to_ptr_type-------------------------------
  const TypeAryKlassPtr* TypeAryKlassPtr::cast_to_ptr_type(PTR ptr) const {
    assert(_base == AryKlassPtr, "subclass must override cast_to_ptr_type");
    if (ptr == _ptr) return this;
-   return make(ptr, elem(), _klass, _offset);
+   return make(ptr, elem(), _klass, _offset, is_not_flat(), is_not_null_free(), _null_free);
  }
  
  bool TypeAryKlassPtr::must_be_exact() const {
    if (_elem == Type::BOTTOM) return false;
    if (_elem == Type::TOP   ) return false;
    const TypeKlassPtr*  tk = _elem->isa_klassptr();
    if (!tk)             return true;   // a primitive type, like int
+   // Even though MyValue is final, [LMyValue is only exact if the array
+   // is null-free due to null-free [LMyValue <: null-able [LMyValue.
+   if (tk->isa_instklassptr() && tk->klass()->is_inlinetype() && !is_null_free()) {
+     return false;
+   }
    return tk->must_be_exact();
  }
  
  
  //-----------------------------cast_to_exactness-------------------------------
  const TypeKlassPtr *TypeAryKlassPtr::cast_to_exactness(bool klass_is_exact) const {
-   if (must_be_exact()) return this;  // cannot clear xk
+   if (must_be_exact() && !klass_is_exact) return this;  // cannot clear xk
+   if (klass_is_exact == this->klass_is_exact()) {
+     return this;
+   }
    ciKlass* k = _klass;
    const Type* elem = this->elem();
    if (elem->isa_klassptr() && !klass_is_exact) {
      elem = elem->is_klassptr()->cast_to_exactness(klass_is_exact);
    }
-   return make(klass_is_exact ? Constant : NotNull, elem, k, _offset);
+   bool not_flat = is_not_flat();
+   bool not_null_free = is_not_null_free();
+   if (_elem->isa_klassptr()) {
+     if (klass_is_exact || _elem->isa_aryklassptr()) {
+       assert(!is_null_free() && !is_flat(), "null-free (or flat) inline type arrays should always be exact");
+       // An array can't be null-free (or flat) if the klass is exact
+       not_null_free = true;
+       not_flat = true;
+     } else {
+       // Klass is not exact (anymore), re-compute null-free/flat properties
+       const TypeOopPtr* exact_etype = TypeOopPtr::make_from_klass_unique(_elem->is_instklassptr()->instance_klass());
+       not_null_free = !exact_etype->can_be_inline_type();
+       not_flat = !UseFlatArray || not_null_free || (exact_etype->is_inlinetypeptr() && !exact_etype->inline_klass()->flat_in_array());
+     }
+   }
+   return make(klass_is_exact ? Constant : NotNull, elem, k, _offset, not_flat, not_null_free, _null_free);
  }
  
+ const TypeAryKlassPtr* TypeAryKlassPtr::cast_to_null_free() const {
+   return make(_ptr, elem(), klass(), _offset, is_not_flat(), false, true);
+ }
  
  //-----------------------------as_instance_type--------------------------------
  // Corresponding type for an instance of the given class.
  // It will be NotNull, and exact if and only if the klass type is exact.
  const TypeOopPtr* TypeAryKlassPtr::as_instance_type(bool klass_change) const {

@@ -6241,11 +6687,15 @@
      el = elem()->is_klassptr()->as_instance_type(false)->cast_to_exactness(false);
      k = nullptr;
    } else {
      el = elem();
    }
-   return TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(el, TypeInt::POS), k, xk, 0);
+   bool null_free = _null_free;
+   if (null_free && el->isa_ptr()) {
+     el = el->is_ptr()->join_speculative(TypePtr::NOTNULL);
+   }
+   return TypeAryPtr::make(TypePtr::BotPTR, TypeAry::make(el, TypeInt::POS, false, is_flat(), is_not_flat(), is_not_null_free()), k, xk, Offset(0));
  }
  
  
  //------------------------------xmeet------------------------------------------
  // Compute the MEET of two types, return a new Type object.

@@ -6275,19 +6725,19 @@
      typerr(t);
  
    case AnyPtr: {                // Meeting to AnyPtrs
      // Found an AnyPtr type vs self-KlassPtr type
      const TypePtr *tp = t->is_ptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      switch (tp->ptr()) {
      case TopPTR:
        return this;
      case Null:
        if( ptr == Null ) return TypePtr::make(AnyPtr, ptr, offset, tp->speculative(), tp->inline_depth());
      case AnyNull:
-       return make( ptr, _elem, klass(), offset );
+       return make(ptr, _elem, klass(), offset, is_not_flat(), is_not_null_free(), is_null_free());
      case BotPTR:
      case NotNull:
        return TypePtr::make(AnyPtr, ptr, offset, tp->speculative(), tp->inline_depth());
      default: typerr(t);
      }

@@ -6316,23 +6766,38 @@
    //             A-bot         }
    //
  
    case AryKlassPtr: {  // Meet two KlassPtr types
      const TypeAryKlassPtr *tap = t->is_aryklassptr();
-     int off = meet_offset(tap->offset());
+     Offset off = meet_offset(tap->offset());
      const Type* elem = _elem->meet(tap->_elem);
- 
      PTR ptr = meet_ptr(tap->ptr());
      ciKlass* res_klass = nullptr;
      bool res_xk = false;
-     meet_aryptr(ptr, elem, this, tap, res_klass, res_xk);
+     bool res_flat = false;
+     bool res_not_flat = false;
+     bool res_not_null_free = false;
+     MeetResult res = meet_aryptr(ptr, elem, this, tap,
+                                  res_klass, res_xk, res_flat, res_not_flat, res_not_null_free);
      assert(res_xk == (ptr == Constant), "");
-     return make(ptr, elem, res_klass, off);
+     bool null_free = meet_null_free(tap->_null_free);
+     if (res == NOT_SUBTYPE) {
+       null_free = false;
+     } else if (res == SUBTYPE) {
+       if (above_centerline(tap->ptr()) && !above_centerline(this->ptr())) {
+         null_free = _null_free;
+       } else if (above_centerline(this->ptr()) && !above_centerline(tap->ptr())) {
+         null_free = tap->_null_free;
+       } else if (above_centerline(this->ptr()) && above_centerline(tap->ptr())) {
+         null_free = _null_free || tap->_null_free;
+       }
+     }
+     return make(ptr, elem, res_klass, off, res_not_flat, res_not_null_free, null_free);
    } // End of case KlassPtr
    case InstKlassPtr: {
      const TypeInstKlassPtr *tp = t->is_instklassptr();
-     int offset = meet_offset(tp->offset());
+     Offset offset = meet_offset(tp->offset());
      PTR ptr = meet_ptr(tp->ptr());
      const TypeInterfaces* interfaces = meet_interfaces(tp);
      const TypeInterfaces* tp_interfaces = tp->_interfaces;
      const TypeInterfaces* this_interfaces = _interfaces;
  

@@ -6342,16 +6807,16 @@
        // For instances when a subclass meets a superclass we fall
        // below the centerline when the superclass is exact. We need to
        // do the same here.
        if (tp->klass()->equals(ciEnv::current()->Object_klass()) && this_interfaces->contains(tp_interfaces) &&
            !tp->klass_is_exact()) {
-         return TypeAryKlassPtr::make(ptr, _elem, _klass, offset);
+         return TypeAryKlassPtr::make(ptr, _elem, _klass, offset, is_not_flat(), is_not_null_free(), is_null_free());
        } else {
          // cannot subclass, so the meet has to fall badly below the centerline
          ptr = NotNull;
          interfaces = this_interfaces->intersection_with(tp->_interfaces);
-         return TypeInstKlassPtr::make(ptr, ciEnv::current()->Object_klass(), interfaces, offset);
+         return TypeInstKlassPtr::make(ptr, ciEnv::current()->Object_klass(), interfaces, offset, false);
        }
      case Constant:
      case NotNull:
      case BotPTR:                // Fall down to object klass
        // LCA is object_klass, but if we subclass from the top we can do better

@@ -6362,19 +6827,19 @@
          // below the centerline when the superclass is exact. We need
          // to do the same here.
          if (tp->klass()->equals(ciEnv::current()->Object_klass()) && this_interfaces->contains(tp_interfaces) &&
              !tp->klass_is_exact()) {
            // that is, my array type is a subtype of 'tp' klass
-           return make(ptr, _elem, _klass, offset);
+           return make(ptr, _elem, _klass, offset, is_not_flat(), is_not_null_free(), is_null_free());
          }
        }
        // The other case cannot happen, since t cannot be a subtype of an array.
        // The meet falls down to Object class below centerline.
        if (ptr == Constant)
           ptr = NotNull;
        interfaces = this_interfaces->intersection_with(tp_interfaces);
-       return TypeInstKlassPtr::make(ptr, ciEnv::current()->Object_klass(), interfaces, offset);
+       return TypeInstKlassPtr::make(ptr, ciEnv::current()->Object_klass(), interfaces, offset, false);
      default: typerr(t);
      }
    }
  
    } // End of switch

@@ -6408,10 +6873,13 @@
    }
  
    const TypePtr* other_elem = other_ary->elem()->make_ptr();
    const TypePtr* this_elem = this_one->elem()->make_ptr();
    if (this_elem != nullptr && other_elem != nullptr) {
+     if (other->is_null_free() && !this_one->is_null_free()) {
+       return false; // A nullable array can't be a subtype of a null-free array
+     }
      return this_one->is_reference_type(this_elem)->is_java_subtype_of_helper(this_one->is_reference_type(other_elem), this_exact, other_exact);
    }
    if (this_elem == nullptr && other_elem == nullptr) {
      return this_one->klass()->is_subtype_of(other->klass());
    }

@@ -6500,21 +6968,21 @@
  }
  
  //------------------------------xdual------------------------------------------
  // Dual: compute field-by-field dual
  const Type    *TypeAryKlassPtr::xdual() const {
-   return new TypeAryKlassPtr(dual_ptr(), elem()->dual(), klass(), dual_offset());
+   return new TypeAryKlassPtr(dual_ptr(), elem()->dual(), klass(), dual_offset(), !is_not_flat(), !is_not_null_free(), dual_null_free());
  }
  
  // Is there a single ciKlass* that can represent that type?
  ciKlass* TypeAryKlassPtr::exact_klass_helper() const {
    if (elem()->isa_klassptr()) {
      ciKlass* k = elem()->is_klassptr()->exact_klass_helper();
      if (k == nullptr) {
        return nullptr;
      }
-     k = ciObjArrayKlass::make(k);
+     k = ciArrayKlass::make(k, _null_free);
      return k;
    }
  
    return klass();
  }

@@ -6557,17 +7025,19 @@
      if( _ptr == Constant ) st->print(":exact");
      break;
    default:
      break;
    }
- 
-   if( _offset ) {               // Dump offset, if any
-     if( _offset == OffsetBot )      { st->print("+any"); }
-     else if( _offset == OffsetTop ) { st->print("+unknown"); }
-     else                            { st->print("+%d", _offset); }
+   if (is_flat()) st->print(":flat");
+   if (_null_free) st->print(":null free");
+   if (Verbose) {
+     if (_not_flat) st->print(":not flat");
+     if (_not_null_free) st->print(":not null free");
    }
  
+   _offset.dump2(st);
+ 
    st->print(" *");
  }
  #endif
  
  const Type* TypeAryKlassPtr::base_element_type(int& dims) const {

@@ -6582,28 +7052,54 @@
  
  //=============================================================================
  // Convenience common pre-built types.
  
  //------------------------------make-------------------------------------------
- const TypeFunc *TypeFunc::make( const TypeTuple *domain, const TypeTuple *range ) {
-   return (TypeFunc*)(new TypeFunc(domain,range))->hashcons();
+ const TypeFunc *TypeFunc::make(const TypeTuple *domain_sig, const TypeTuple* domain_cc,
+                                const TypeTuple *range_sig, const TypeTuple *range_cc) {
+   return (TypeFunc*)(new TypeFunc(domain_sig, domain_cc, range_sig, range_cc))->hashcons();
+ }
+ 
+ const TypeFunc *TypeFunc::make(const TypeTuple *domain, const TypeTuple *range) {
+   return make(domain, domain, range, range);
+ }
+ 
+ //------------------------------osr_domain-----------------------------
+ const TypeTuple* osr_domain() {
+   const Type **fields = TypeTuple::fields(2);
+   fields[TypeFunc::Parms+0] = TypeRawPtr::BOTTOM;  // address of osr buffer
+   return TypeTuple::make(TypeFunc::Parms+1, fields);
  }
  
  //------------------------------make-------------------------------------------
- const TypeFunc *TypeFunc::make(ciMethod* method) {
+ const TypeFunc* TypeFunc::make(ciMethod* method, bool is_osr_compilation) {
    Compile* C = Compile::current();
-   const TypeFunc* tf = C->last_tf(method); // check cache
-   if (tf != nullptr)  return tf;  // The hit rate here is almost 50%.
-   const TypeTuple *domain;
-   if (method->is_static()) {
-     domain = TypeTuple::make_domain(nullptr, method->signature(), ignore_interfaces);
-   } else {
-     domain = TypeTuple::make_domain(method->holder(), method->signature(), ignore_interfaces);
+   const TypeFunc* tf = nullptr;
+   if (!is_osr_compilation) {
+     tf = C->last_tf(method); // check cache
+     if (tf != nullptr)  return tf;  // The hit rate here is almost 50%.
+   }
+   // Inline types are not passed/returned by reference, instead each field of
+   // the inline type is passed/returned as an argument. We maintain two views of
+   // the argument/return list here: one based on the signature (with an inline
+   // type argument/return as a single slot), one based on the actual calling
+   // convention (with an inline type argument/return as a list of its fields).
+   bool has_scalar_args = method->has_scalarized_args() && !is_osr_compilation;
+   // Fall back to the non-scalarized calling convention when compiling a call via a mismatching method
+   if (method != C->method() && method->get_Method()->mismatch()) {
+     has_scalar_args = false;
+   }
+   const TypeTuple* domain_sig = is_osr_compilation ? osr_domain() : TypeTuple::make_domain(method, ignore_interfaces, false);
+   const TypeTuple* domain_cc = has_scalar_args ? TypeTuple::make_domain(method, ignore_interfaces, true) : domain_sig;
+   ciSignature* sig = method->signature();
+   bool has_scalar_ret = !method->is_native() && sig->return_type()->is_inlinetype() && sig->return_type()->as_inline_klass()->can_be_returned_as_fields();
+   const TypeTuple* range_sig = TypeTuple::make_range(sig, ignore_interfaces, false);
+   const TypeTuple* range_cc = has_scalar_ret ? TypeTuple::make_range(sig, ignore_interfaces, true) : range_sig;
+   tf = TypeFunc::make(domain_sig, domain_cc, range_sig, range_cc);
+   if (!is_osr_compilation) {
+     C->set_last_tf(method, tf);  // fill cache
    }
-   const TypeTuple *range  = TypeTuple::make_range(method->signature(), ignore_interfaces);
-   tf = TypeFunc::make(domain, range);
-   C->set_last_tf(method, tf);  // fill cache
    return tf;
  }
  
  //------------------------------meet-------------------------------------------
  // Compute the MEET of two types.  It returns a new Type object.

@@ -6634,46 +7130,48 @@
  
  //------------------------------eq---------------------------------------------
  // Structural equality check for Type representations
  bool TypeFunc::eq( const Type *t ) const {
    const TypeFunc *a = (const TypeFunc*)t;
-   return _domain == a->_domain &&
-     _range == a->_range;
+   return _domain_sig == a->_domain_sig &&
+     _domain_cc == a->_domain_cc &&
+     _range_sig == a->_range_sig &&
+     _range_cc == a->_range_cc;
  }
  
  //------------------------------hash-------------------------------------------
  // Type-specific hashing function.
  uint TypeFunc::hash(void) const {
-   return (uint)(uintptr_t)_domain + (uint)(uintptr_t)_range;
+   return (uint)(intptr_t)_domain_sig + (uint)(intptr_t)_domain_cc + (uint)(intptr_t)_range_sig + (uint)(intptr_t)_range_cc;
  }
  
  //------------------------------dump2------------------------------------------
  // Dump Function Type
  #ifndef PRODUCT
  void TypeFunc::dump2( Dict &d, uint depth, outputStream *st ) const {
-   if( _range->cnt() <= Parms )
+   if( _range_sig->cnt() <= Parms )
      st->print("void");
    else {
      uint i;
-     for (i = Parms; i < _range->cnt()-1; i++) {
-       _range->field_at(i)->dump2(d,depth,st);
+     for (i = Parms; i < _range_sig->cnt()-1; i++) {
+       _range_sig->field_at(i)->dump2(d,depth,st);
        st->print("/");
      }
-     _range->field_at(i)->dump2(d,depth,st);
+     _range_sig->field_at(i)->dump2(d,depth,st);
    }
    st->print(" ");
    st->print("( ");
    if( !depth || d[this] ) {     // Check for recursive dump
      st->print("...)");
      return;
    }
    d.Insert((void*)this,(void*)this);    // Stop recursion
-   if (Parms < _domain->cnt())
-     _domain->field_at(Parms)->dump2(d,depth-1,st);
-   for (uint i = Parms+1; i < _domain->cnt(); i++) {
+   if (Parms < _domain_sig->cnt())
+     _domain_sig->field_at(Parms)->dump2(d,depth-1,st);
+   for (uint i = Parms+1; i < _domain_sig->cnt(); i++) {
      st->print(", ");
-     _domain->field_at(i)->dump2(d,depth-1,st);
+     _domain_sig->field_at(i)->dump2(d,depth-1,st);
    }
    st->print(" )");
  }
  #endif
  

@@ -6689,10 +7187,10 @@
    return false;                 // Never empty
  }
  
  
  BasicType TypeFunc::return_type() const{
-   if (range()->cnt() == TypeFunc::Parms) {
+   if (range_sig()->cnt() == TypeFunc::Parms) {
      return T_VOID;
    }
-   return range()->field_at(TypeFunc::Parms)->basic_type();
+   return range_sig()->field_at(TypeFunc::Parms)->basic_type();
  }
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