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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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#ifndef SHARE_VM_CLASSFILE_VERIFICATIONTYPE_HPP

#define SHARE_VM_CLASSFILE_VERIFICATIONTYPE_HPP

#include "classfile/systemDictionary.hpp"

#include "oops/instanceKlass.hpp"

#include "oops/oop.hpp"

#include "oops/symbol.hpp"

#include "runtime/handles.hpp"

#include "runtime/signature.hpp"

enum {

  // As specifed in the JVM spec

  ITEM_Top = 0,

  ITEM_Integer = 1,

  ITEM_Float = 2,

  ITEM_Double = 3,

  ITEM_Long = 4,

  ITEM_Null = 5,

  ITEM_UninitializedThis = 6,

  ITEM_Object = 7,

  ITEM_Uninitialized = 8,

  ITEM_Bogus = (uint)-1

};

class ClassVerifier;

class VerificationType {

  private:

    // Least significant bits of _handle are always 0, so we use these as

    // the indicator that the _handle is valid.  Otherwise, the _data field

    // contains encoded data (as specified below).  Should the VM change

    // and the lower bits on oops aren't 0, the assert in the constructor

    // will catch this and we'll have to add a descriminator tag to this

    // structure.

    union {

      Symbol*   _sym;

      uintptr_t _data;

    } _u;

    enum {

      // These rest are not found in classfiles, but used by the verifier

      ITEM_Boolean = 9, ITEM_Byte, ITEM_Short, ITEM_Char,

      ITEM_Long_2nd, ITEM_Double_2nd

    };

    // Enum for the _data field

    enum {

      // Bottom two bits determine if the type is a reference, primitive,

      // uninitialized or a query-type.

      TypeMask           = 0x00000003,

      // Topmost types encoding

      Reference          = 0x0,        // _sym contains the name

      Primitive          = 0x1,        // see below for primitive list

      Uninitialized      = 0x2,        // 0x00ffff00 contains bci

      TypeQuery          = 0x3,        // Meta-types used for category testing

      // Utility flags

      ReferenceFlag      = 0x00,       // For reference query types

      Category1Flag      = 0x01,       // One-word values

      Category2Flag      = 0x02,       // First word of a two-word value

      Category2_2ndFlag  = 0x04,       // Second word of a two-word value

      // special reference values

      Null               = 0x00000000, // A reference with a 0 sym is null

      // Primitives categories (the second byte determines the category)

      Category1          = (Category1Flag     << 1 * BitsPerByte) | Primitive,

      Category2          = (Category2Flag     << 1 * BitsPerByte) | Primitive,

      Category2_2nd      = (Category2_2ndFlag << 1 * BitsPerByte) | Primitive,

      // Primitive values (type descriminator stored in most-signifcant bytes)

      // Bogus needs the " | Primitive".  Else, is_reference(Bogus) returns TRUE.

      Bogus              = (ITEM_Bogus      << 2 * BitsPerByte) | Primitive,

      Boolean            = (ITEM_Boolean    << 2 * BitsPerByte) | Category1,

      Byte               = (ITEM_Byte       << 2 * BitsPerByte) | Category1,

      Short              = (ITEM_Short      << 2 * BitsPerByte) | Category1,

      Char               = (ITEM_Char       << 2 * BitsPerByte) | Category1,

      Integer            = (ITEM_Integer    << 2 * BitsPerByte) | Category1,

      Float              = (ITEM_Float      << 2 * BitsPerByte) | Category1,

      Long               = (ITEM_Long       << 2 * BitsPerByte) | Category2,

      Double             = (ITEM_Double     << 2 * BitsPerByte) | Category2,

      Long_2nd           = (ITEM_Long_2nd   << 2 * BitsPerByte) | Category2_2nd,

      Double_2nd         = (ITEM_Double_2nd << 2 * BitsPerByte) | Category2_2nd,

      // Used by Uninitialized (second and third bytes hold the bci)

      BciMask            = 0xffff << 1 * BitsPerByte,

      BciForThis         = ((u2)-1),   // A bci of -1 is an Unintialized-This

      // Query values

      ReferenceQuery     = (ReferenceFlag     << 1 * BitsPerByte) | TypeQuery,

      Category1Query     = (Category1Flag     << 1 * BitsPerByte) | TypeQuery,

      Category2Query     = (Category2Flag     << 1 * BitsPerByte) | TypeQuery,

      Category2_2ndQuery = (Category2_2ndFlag << 1 * BitsPerByte) | TypeQuery

    };

  VerificationType(uintptr_t raw_data) {

    _u._data = raw_data;

  }

 public:

  VerificationType() { *this = bogus_type(); }

  // Create verification types

  static VerificationType bogus_type() { return VerificationType(Bogus); }

  static VerificationType top_type() { return bogus_type(); } // alias

  static VerificationType null_type() { return VerificationType(Null); }

  static VerificationType integer_type() { return VerificationType(Integer); }

  static VerificationType float_type() { return VerificationType(Float); }

  static VerificationType long_type() { return VerificationType(Long); }

  static VerificationType long2_type() { return VerificationType(Long_2nd); }

  static VerificationType double_type() { return VerificationType(Double); }

  static VerificationType boolean_type() { return VerificationType(Boolean); }

  static VerificationType byte_type() { return VerificationType(Byte); }

  static VerificationType char_type() { return VerificationType(Char); }

  static VerificationType short_type() { return VerificationType(Short); }

  static VerificationType double2_type()

    { return VerificationType(Double_2nd); }

  // "check" types are used for queries.  A "check" type is not assignable

  // to anything, but the specified types are assignable to a "check".  For

  // example, any category1 primitive is assignable to category1_check and

  // any reference is assignable to reference_check.

  static VerificationType reference_check()

    { return VerificationType(ReferenceQuery); }

  static VerificationType category1_check()

    { return VerificationType(Category1Query); }

  static VerificationType category2_check()

    { return VerificationType(Category2Query); }

  static VerificationType category2_2nd_check()

    { return VerificationType(Category2_2ndQuery); }

  // For reference types, store the actual Symbol

  static VerificationType reference_type(Symbol* sh) {

      assert(((uintptr_t)sh & 0x3) == 0, "Symbols must be aligned");

      // If the above assert fails in the future because oop* isn't aligned,

      // then this type encoding system will have to change to have a tag value

      // to descriminate between oops and primitives.

      return VerificationType((uintptr_t)sh);

  }

  static VerificationType uninitialized_type(u2 bci)

    { return VerificationType(bci << 1 * BitsPerByte | Uninitialized); }

  static VerificationType uninitialized_this_type()

    { return uninitialized_type(BciForThis); }

  // Create based on u1 read from classfile

  static VerificationType from_tag(u1 tag);

  bool is_bogus() const     { return (_u._data == Bogus); }

  bool is_null() const      { return (_u._data == Null); }

  bool is_boolean() const   { return (_u._data == Boolean); }

  bool is_byte() const      { return (_u._data == Byte); }

  bool is_char() const      { return (_u._data == Char); }

  bool is_short() const     { return (_u._data == Short); }

  bool is_integer() const   { return (_u._data == Integer); }

  bool is_long() const      { return (_u._data == Long); }

  bool is_float() const     { return (_u._data == Float); }

  bool is_double() const    { return (_u._data == Double); }

  bool is_long2() const     { return (_u._data == Long_2nd); }

  bool is_double2() const   { return (_u._data == Double_2nd); }

  bool is_reference() const { return ((_u._data & TypeMask) == Reference); }

  bool is_category1() const {

    // This should return true for all one-word types, which are category1

    // primitives, and references (including uninitialized refs).  Though

    // the 'query' types should technically return 'false' here, if we

    // allow this to return true, we can perform the test using only

    // 2 operations rather than 8 (3 masks, 3 compares and 2 logical 'ands').

    // Since noone should call this on a query type anyway, this is ok.

    assert(!is_check(), "Must not be a check type (wrong value returned)");

    return ((_u._data & Category1) != Primitive);

    // should only return false if it's a primitive, and the category1 flag

    // is not set.

  }

  bool is_category2() const { return ((_u._data & Category2) == Category2); }

  bool is_category2_2nd() const {

    return ((_u._data & Category2_2nd) == Category2_2nd);

  }

  bool is_reference_check() const { return _u._data == ReferenceQuery; }

  bool is_category1_check() const { return _u._data == Category1Query; }

  bool is_category2_check() const { return _u._data == Category2Query; }

  bool is_category2_2nd_check() const { return _u._data == Category2_2ndQuery; }

  bool is_check() const { return (_u._data & TypeQuery) == TypeQuery; }

  bool is_x_array(char sig) const {

    return is_null() || (is_array() && (name()->byte_at(1) == sig));

  }

  bool is_int_array() const { return is_x_array('I'); }

  bool is_byte_array() const { return is_x_array('B'); }

  bool is_bool_array() const { return is_x_array('Z'); }

  bool is_char_array() const { return is_x_array('C'); }

  bool is_short_array() const { return is_x_array('S'); }

  bool is_long_array() const { return is_x_array('J'); }

  bool is_float_array() const { return is_x_array('F'); }

  bool is_double_array() const { return is_x_array('D'); }

  bool is_object_array() const { return is_x_array('L'); }

  bool is_array_array() const { return is_x_array('['); }

  bool is_reference_array() const

    { return is_object_array() || is_array_array(); }

  bool is_object() const

    { return (is_reference() && !is_null() && name()->utf8_length() >= 1 &&

              name()->byte_at(0) != '['); }

  bool is_array() const

    { return (is_reference() && !is_null() && name()->utf8_length() >= 2 &&

              name()->byte_at(0) == '['); }

  bool is_uninitialized() const

    { return ((_u._data & Uninitialized) == Uninitialized); }

  bool is_uninitialized_this() const

    { return is_uninitialized() && bci() == BciForThis; }

  VerificationType to_category2_2nd() const {

    assert(is_category2(), "Must be a double word");

    return VerificationType(is_long() ? Long_2nd : Double_2nd);

  }

  u2 bci() const {

    assert(is_uninitialized(), "Must be uninitialized type");

    return ((_u._data & BciMask) >> 1 * BitsPerByte);

  }

  Symbol* name() const {

    assert(is_reference() && !is_null(), "Must be a non-null reference");

    return _u._sym;

  }

  bool equals(const VerificationType& t) const {

    return (_u._data == t._u._data ||

      (is_reference() && t.is_reference() && !is_null() && !t.is_null() &&

       name() == t.name()));

  }

  bool operator ==(const VerificationType& t) const {

    return equals(t);

  }

  bool operator !=(const VerificationType& t) const {

    return !equals(t);

  }

  // The whole point of this type system - check to see if one type

  // is assignable to another.  Returns true if one can assign 'from' to

  // this.

  bool is_assignable_from(

      const VerificationType& from, ClassVerifier* context,

      bool from_field_is_protected, TRAPS) const {

    if (equals(from) || is_bogus()) {

      return true;

    } else {

      switch(_u._data) {

        case Category1Query:

          return from.is_category1();

        case Category2Query:

          return from.is_category2();

        case Category2_2ndQuery:

          return from.is_category2_2nd();

        case ReferenceQuery:

          return from.is_reference() || from.is_uninitialized();

        case Boolean:

        case Byte:

        case Char:

        case Short:

          // An int can be assigned to boolean, byte, char or short values.

          return from.is_integer();

        default:

          if (is_reference() && from.is_reference()) {

            return is_reference_assignable_from(from, context,

                                                from_field_is_protected,

                                                THREAD);

          } else {

            return false;

          }

      }

    }

  }

  // Check to see if one array component type is assignable to another.

  // Same as is_assignable_from() except int primitives must be identical.

  bool is_component_assignable_from(

      const VerificationType& from, ClassVerifier* context,

      bool from_field_is_protected, TRAPS) const {

    if (equals(from) || is_bogus()) {

      return true;

    } else {

      switch(_u._data) {

        case Boolean:

        case Byte:

        case Char:

        case Short:

          return false;

        default:

          return is_assignable_from(from, context, from_field_is_protected, CHECK_false);

      }

    }

  }

  VerificationType get_component(ClassVerifier* context, TRAPS) const;

  int dimensions() const {

    assert(is_array(), "Must be an array");

    int index = 0;

    while (name()->byte_at(index) == '[') index++;

    return index;

  }

  void print_on(outputStream* st) const;

 private:

  bool is_reference_assignable_from(

    const VerificationType&, ClassVerifier*, bool from_field_is_protected,

    TRAPS) const;

 public:

  static bool resolve_and_check_assignability(InstanceKlass* klass, Symbol* name,

                                              Symbol* from_name, bool from_field_is_protected,

                                              bool from_is_array, bool from_is_object,

                                              TRAPS);

};

#endif // SHARE_VM_CLASSFILE_VERIFICATIONTYPE_HPP