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 /*

  * Copyright (c) 2003, 2010, 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.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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 #ifndef SHARE_VM_CLASSFILE_STACKMAPTABLE_HPP

 #define SHARE_VM_CLASSFILE_STACKMAPTABLE_HPP

 #include "classfile/stackMapFrame.hpp"

 #include "memory/allocation.hpp"

 #include "oops/constantPoolOop.hpp"

 #include "oops/methodOop.hpp"

 #include "utilities/globalDefinitions.hpp"

 #ifdef TARGET_ARCH_x86

 # include "bytes_x86.hpp"

 #endif

 #ifdef TARGET_ARCH_sparc

 # include "bytes_sparc.hpp"

 #endif

 #ifdef TARGET_ARCH_zero

 # include "bytes_zero.hpp"

 #endif

 class StackMapReader;

 // StackMapTable class is the StackMap table used by type checker

 class StackMapTable : public StackObj {

  private:

   // Logically, the _frame_count (as well as many fields in the StackFrame)

   // should be a u2, but if we defined the variable as that type it will

   // be difficult to detect/recover from overflow or underflow conditions.

   // Widening the type and making it signed will help detect these.

   int32_t              _code_length;

   int32_t              _frame_count;     // Stackmap frame count

   StackMapFrame**       _frame_array;

  public:

   StackMapTable(StackMapReader* reader, StackMapFrame* init_frame,

                 u2 max_locals, u2 max_stack,

                 char* code_data, int code_len, TRAPS);

   inline int32_t get_frame_count() const { return _frame_count; }

   inline int get_offset(int index) const {

     return _frame_array[index]->offset();

   }

   // Match and/or update current_frame to the frame in stackmap table with

   // specified offset. Return true if the two frames match.

   bool match_stackmap(

     StackMapFrame* current_frame, int32_t offset,

     bool match, bool update, TRAPS) const;

   // Match and/or update current_frame to the frame in stackmap table with

   // specified offset and frame index. Return true if the two frames match.

   bool match_stackmap(

     StackMapFrame* current_frame, int32_t offset, int32_t frame_index,

     bool match, bool update, TRAPS) const;

   // Check jump instructions. Make sure there are no uninitialized

   // instances on backward branch.

   void check_jump_target(StackMapFrame* frame, int32_t target, TRAPS) const;

   // The following methods are only used inside this class.

   // Returns the frame array index where the frame with offset is stored.

   int get_index_from_offset(int32_t offset) const;

   // Make sure that there's no uninitialized object exist on backward branch.

   void check_new_object(

     const StackMapFrame* frame, int32_t target, TRAPS) const;

   // Debugging

   void print() const PRODUCT_RETURN;

 };

 class StackMapStream : StackObj {

  private:

   typeArrayHandle _data;

   int _index;

  public:

   StackMapStream(typeArrayHandle ah)

     : _data(ah), _index(0) {

   }

   u1 get_u1(TRAPS) {

     if (_data == NULL || _index >= _data->length()) {

       stackmap_format_error("access beyond the end of attribute", CHECK_0);

     }

     return _data->byte_at(_index++);

   }

   u2 get_u2(TRAPS) {

     if (_data == NULL || _index >= _data->length() - 1) {

       stackmap_format_error("access beyond the end of attribute", CHECK_0);

     }

     u2 res = Bytes::get_Java_u2((u1*)_data->byte_at_addr(_index));

     _index += 2;

     return res;

   }

   bool at_end() {

     return (_data == NULL) || (_index == _data->length());

   }

   static void stackmap_format_error(const char* msg, TRAPS);

 };

 class StackMapReader : StackObj {

  private:

   // information about the class and method

   constantPoolHandle  _cp;

   ClassVerifier* _verifier;

   StackMapStream* _stream;

   char* _code_data;

   int32_t _code_length;

   // information get from the attribute

   int32_t  _frame_count;       // frame count

   int32_t chop(VerificationType* locals, int32_t length, int32_t chops);

   VerificationType parse_verification_type(u1* flags, TRAPS);

   void check_verification_type_array_size(

       int32_t size, int32_t max_size, TRAPS) {

     if (size < 0 || size > max_size) {

       // Since this error could be caused someone rewriting the method

       // but not knowing to update the stackmap data, we call the the

       // verifier's error method, which may not throw an exception and

       // failover to the old verifier instead.

       _verifier->class_format_error(

         "StackMapTable format error: bad type array size");

     }

   }

   enum {

     SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,

     SAME_EXTENDED = 251,

     FULL = 255

   };

  public:

   // Constructor

   StackMapReader(ClassVerifier* v, StackMapStream* stream, char* code_data,

                  int32_t code_len, TRAPS) :

                  _verifier(v), _stream(stream),

                  _code_data(code_data), _code_length(code_len) {

     methodHandle m = v->method();

     if (m->has_stackmap_table()) {

       _cp = constantPoolHandle(THREAD, m->constants());

       _frame_count = _stream->get_u2(CHECK);

     } else {

       // There's no stackmap table present. Frame count and size are 0.

       _frame_count = 0;

     }

   }

   inline int32_t get_frame_count() const                { return _frame_count; }

   StackMapFrame* next(StackMapFrame* pre_frame, bool first,

                       u2 max_locals, u2 max_stack, TRAPS);

   void check_end(TRAPS) {

     if (!_stream->at_end()) {

       StackMapStream::stackmap_format_error("wrong attribute size", CHECK);

     }

   }

 };

 #endif // SHARE_VM_CLASSFILE_STACKMAPTABLE_HPP