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 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.

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

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * 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_STACKMAPFRAME_HPP

#define SHARE_VM_CLASSFILE_STACKMAPFRAME_HPP

#include "classfile/verificationType.hpp"

#include "classfile/verifier.hpp"

#include "oops/methodOop.hpp"

#include "runtime/handles.hpp"

#include "runtime/signature.hpp"

#include "utilities/exceptions.hpp"

// A StackMapFrame represents one frame in the stack map attribute.

enum {

  FLAG_THIS_UNINIT = 0x01

};

class StackMapFrame : public ResourceObj {

 private:

  int32_t _offset;

  // See comment in StackMapTable about _frame_count about why these

  // fields are int32_t instead of u2.

  int32_t _locals_size;  // number of valid type elements in _locals

  int32_t _stack_size;   // number of valid type elements in _stack

  int32_t _max_locals;

  int32_t _max_stack;

  u1 _flags;

  VerificationType* _locals; // local variable type array

  VerificationType* _stack;  // operand stack type array

  ClassVerifier* _verifier;  // the verifier verifying this method

 public:

  // constructors

  // This constructor is used by the type checker to allocate frames

  // in type state, which have _max_locals and _max_stack array elements

  // in _locals and _stack.

  StackMapFrame(u2 max_locals, u2 max_stack, ClassVerifier* verifier);

  // This constructor is used to initialize stackmap frames in stackmap table,

  // which have _locals_size and _stack_size array elements in _locals and _stack.

  StackMapFrame(int32_t offset,

                u1 flags,

                u2 locals_size,

                u2 stack_size,

                u2 max_locals,

                u2 max_stack,

                VerificationType* locals,

                VerificationType* stack,

                ClassVerifier* v) : _offset(offset), _flags(flags),

                                    _locals_size(locals_size),

                                    _stack_size(stack_size),

                                    _max_locals(max_locals),

                                    _max_stack(max_stack),

                                    _locals(locals), _stack(stack),

                                    _verifier(v) { }

  inline void set_offset(int32_t offset)      { _offset = offset; }

  inline void set_verifier(ClassVerifier* v)  { _verifier = v; }

  inline void set_flags(u1 flags)             { _flags = flags; }

  inline void set_locals_size(u2 locals_size) { _locals_size = locals_size; }

  inline void set_stack_size(u2 stack_size)   { _stack_size = stack_size; }

  inline void clear_stack()                   { _stack_size = 0; }

  inline int32_t offset()   const             { return _offset; }

  inline ClassVerifier* verifier() const      { return _verifier; }

  inline u1 flags() const                     { return _flags; }

  inline int32_t locals_size() const          { return _locals_size; }

  inline VerificationType* locals() const     { return _locals; }

  inline int32_t stack_size() const           { return _stack_size; }

  inline VerificationType* stack() const      { return _stack; }

  inline int32_t max_locals() const           { return _max_locals; }

  inline int32_t max_stack() const            { return _max_stack; }

  inline bool flag_this_uninit() const        { return _flags & FLAG_THIS_UNINIT; }

  // Set locals and stack types to bogus

  inline void reset() {

    int32_t i;

    for (i = 0; i < _max_locals; i++) {

      _locals[i] = VerificationType::bogus_type();

    }

    for (i = 0; i < _max_stack; i++) {

      _stack[i] = VerificationType::bogus_type();

    }

  }

  // Return a StackMapFrame with the same local variable array and empty stack.

  // Stack array is allocate with unused one element.

  StackMapFrame* frame_in_exception_handler(u1 flags);

  // Set local variable type array based on m's signature.

  VerificationType set_locals_from_arg(

    const methodHandle m, VerificationType thisKlass, TRAPS);

  // Search local variable type array and stack type array.

  // Return true if an uninitialized object is found.

  bool has_new_object() const;

  // Search local variable type array and stack type array.

  // Set every element with type of old_object to new_object.

  void initialize_object(

    VerificationType old_object, VerificationType new_object);

  // Copy local variable type array in src into this local variable type array.

  void copy_locals(const StackMapFrame* src);

  // Copy stack type array in src into this stack type array.

  void copy_stack(const StackMapFrame* src);

  // Return true if this stack map frame is assignable to target.

  bool is_assignable_to(const StackMapFrame* target,

                        bool is_exception_handler, TRAPS) const;

  // Push type into stack type array.

  inline void push_stack(VerificationType type, TRAPS) {

    assert(!type.is_check(), "Must be a real type");

    if (_stack_size >= _max_stack) {

      verifier()->verify_error(_offset, "Operand stack overflow");

      return;

    }

    _stack[_stack_size++] = type;

  }

  inline void push_stack_2(

      VerificationType type1, VerificationType type2, TRAPS) {

    assert(type1.is_long() || type1.is_double(), "must be long/double");

    assert(type2.is_long2() || type2.is_double2(), "must be long/double_2");

    if (_stack_size >= _max_stack - 1) {

      verifier()->verify_error(_offset, "Operand stack overflow");

      return;

    }

    _stack[_stack_size++] = type1;

    _stack[_stack_size++] = type2;

  }

  // Pop and return the top type on stack without verifying.

  inline VerificationType pop_stack(TRAPS) {

    if (_stack_size <= 0) {

      verifier()->verify_error(_offset, "Operand stack underflow");

      return VerificationType::bogus_type();

    }

    // Put bogus type to indicate it's no longer valid.

    // Added to make it consistent with the other pop_stack method.

    VerificationType top = _stack[--_stack_size];

    NOT_PRODUCT( _stack[_stack_size] = VerificationType::bogus_type(); )

    return top;

  }

  // Pop and return the top type on stack type array after verifying it

  // is assignable to type.

  inline VerificationType pop_stack(VerificationType type, TRAPS) {

    if (_stack_size != 0) {

      VerificationType top = _stack[_stack_size - 1];

      bool subtype = type.is_assignable_from(

        top, verifier(), CHECK_(VerificationType::bogus_type()));

      if (subtype) {

        _stack_size --;

        NOT_PRODUCT( _stack[_stack_size] = VerificationType::bogus_type(); )

        return top;

      }

    }

    return pop_stack_ex(type, THREAD);

  }

  inline void pop_stack_2(

      VerificationType type1, VerificationType type2, TRAPS) {

    assert(type1.is_long2() || type1.is_double2(), "must be long/double");

    assert(type2.is_long() || type2.is_double(), "must be long/double_2");

    if (_stack_size >= 2) {

      VerificationType top1 = _stack[_stack_size - 1];

      bool subtype1 = type1.is_assignable_from(top1, verifier(), CHECK);

      VerificationType top2 = _stack[_stack_size - 2];

      bool subtype2 = type2.is_assignable_from(top2, verifier(), CHECK);

      if (subtype1 && subtype2) {

        _stack_size -= 2;

        NOT_PRODUCT( _stack[_stack_size] = VerificationType::bogus_type(); )

        NOT_PRODUCT( _stack[_stack_size+1] = VerificationType::bogus_type(); )

        return;

      }

    }

    pop_stack_ex(type1, THREAD);

    pop_stack_ex(type2, THREAD);

  }

  // Uncommon case that throws exceptions.

  VerificationType pop_stack_ex(VerificationType type, TRAPS);

  // Return the type at index in local variable array after verifying

  // it is assignable to type.

  VerificationType get_local(int32_t index, VerificationType type, TRAPS);

  // For long/double.

  void get_local_2(

    int32_t index, VerificationType type1, VerificationType type2, TRAPS);

  // Set element at index in local variable array to type.

  void set_local(int32_t index, VerificationType type, TRAPS);

  // For long/double.

  void set_local_2(

    int32_t index, VerificationType type1, VerificationType type2, TRAPS);

  // Private auxiliary method used only in is_assignable_to(StackMapFrame).

  // Returns true if src is assignable to target.

  bool is_assignable_to(

    VerificationType* src, VerificationType* target, int32_t len, TRAPS) const;

  bool has_flag_match_exception(const StackMapFrame* target) const;

  // Debugging

  void print() const PRODUCT_RETURN;

};

#endif // SHARE_VM_CLASSFILE_STACKMAPFRAME_HPP