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 /*

  * Copyright (c) 1999, 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.

  *

  * 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_CI_CISTREAMS_HPP

 #define SHARE_VM_CI_CISTREAMS_HPP

 #include "ci/ciClassList.hpp"

 #include "ci/ciExceptionHandler.hpp"

 #include "ci/ciInstanceKlass.hpp"

 #include "ci/ciMethod.hpp"

 #include "interpreter/bytecode.hpp"

 // ciBytecodeStream

 //

 // The class is used to iterate over the bytecodes of a method.

 // It hides the details of constant pool structure/access by

 // providing accessors for constant pool items.  It returns only pure

 // Java bytecodes; VM-internal _fast bytecodes are translated back to

 // their original form during iteration.

 class ciBytecodeStream : StackObj {

 private:

   // Handling for the weird bytecodes

   Bytecodes::Code next_wide_or_table(Bytecodes::Code); // Handle _wide & complicated inline table

   static Bytecodes::Code check_java(Bytecodes::Code c) {

     assert(Bytecodes::is_java_code(c), "should not return _fast bytecodes");

     return c;

   }

   static Bytecodes::Code check_defined(Bytecodes::Code c) {

     assert(Bytecodes::is_defined(c), "");

     return c;

   }

   ciMethod* _method;           // the method

   ciInstanceKlass* _holder;

   ciCPCache* _cpcache;

   address _bc_start;            // Start of current bytecode for table

   address _was_wide;            // Address past last wide bytecode

   jint* _table_base;            // Aligned start of last table or switch

   address _start;                  // Start of bytecodes

   address _end;                    // Past end of bytecodes

   address _pc;                     // Current PC

   Bytecodes::Code _bc;             // Current bytecode

   Bytecodes::Code _raw_bc;         // Current bytecode, raw form

   void reset( address base, unsigned int size ) {

     _bc_start =_was_wide = 0;

     _start = _pc = base; _end = base + size;

     _cpcache = NULL;

   }

   void assert_wide(bool require_wide) const {

     if (require_wide)

          { assert(is_wide(),  "must be a wide instruction"); }

     else { assert(!is_wide(), "must not be a wide instruction"); }

   }

   Bytecode bytecode() const { return Bytecode(this, _bc_start); }

   Bytecode next_bytecode() const { return Bytecode(this, _pc); }

 public:

   // End-Of-Bytecodes

   static Bytecodes::Code EOBC() {

     return Bytecodes::_illegal;

   }

   ciBytecodeStream(ciMethod* m) {

     reset_to_method(m);

   }

   ciBytecodeStream() {

     reset_to_method(NULL);

   }

   ciMethod* method() const { return _method; }

   void reset_to_method(ciMethod* m) {

     _method = m;

     if (m == NULL) {

       _holder = NULL;

       reset(NULL, 0);

     } else {

       _holder = m->holder();

       reset(m->code(), m->code_size());

     }

   }

   void reset_to_bci( int bci );

   // Force the iterator to report a certain bci.

   void force_bci(int bci);

   void set_max_bci( int max ) {

     _end = _start + max;

   }

   address cur_bcp() const       { return _bc_start; }  // Returns bcp to current instruction

   int next_bci() const          { return _pc - _start; }

   int cur_bci() const           { return _bc_start - _start; }

   int instruction_size() const  { return _pc - _bc_start; }

   Bytecodes::Code cur_bc() const{ return check_java(_bc); }

   Bytecodes::Code cur_bc_raw() const { return check_defined(_raw_bc); }

   Bytecodes::Code next_bc()     { return Bytecodes::java_code((Bytecodes::Code)* _pc); }

   // Return current ByteCode and increment PC to next bytecode, skipping all

   // intermediate constants.  Returns EOBC at end.

   // Expected usage:

   //     ciBytecodeStream iter(m);

   //     while (iter.next() != ciBytecodeStream::EOBC()) { ... }

   Bytecodes::Code next() {

     _bc_start = _pc;                        // Capture start of bc

     if( _pc >= _end ) return EOBC();        // End-Of-Bytecodes

     // Fetch Java bytecode

     // All rewritten bytecodes maintain the size of original bytecode.

     _bc = Bytecodes::java_code(_raw_bc = (Bytecodes::Code)*_pc);

     int csize = Bytecodes::length_for(_bc); // Expected size

     _pc += csize;                           // Bump PC past bytecode

     if (csize == 0) {

       _bc = next_wide_or_table(_bc);

     }

     return check_java(_bc);

   }

   bool is_wide() const { return ( _pc == _was_wide ); }

   // Does this instruction contain an index which refes into the CP cache?

   bool has_cache_index() const { return Bytecodes::uses_cp_cache(cur_bc_raw()); }

   int get_index_u1() const {

     return bytecode().get_index_u1(cur_bc_raw());

   }

   int get_index_u1_cpcache() const {

     return bytecode().get_index_u1_cpcache(cur_bc_raw());

   }

   // Get a byte index following this bytecode.

   // If prefixed with a wide bytecode, get a wide index.

   int get_index() const {

     assert(!has_cache_index(), "else use cpcache variant");

     return (_pc == _was_wide)   // was widened?

       ? get_index_u2(true)      // yes, return wide index

       : get_index_u1();         // no, return narrow index

   }

   // Get 2-byte index (byte swapping depending on which bytecode)

   int get_index_u2(bool is_wide = false) const {

     return bytecode().get_index_u2(cur_bc_raw(), is_wide);

   }

   // Get 2-byte index in native byte order.  (Rewriter::rewrite makes these.)

   int get_index_u2_cpcache() const {

     return bytecode().get_index_u2_cpcache(cur_bc_raw());

   }

   // Get 4-byte index, for invokedynamic.

   int get_index_u4() const {

     return bytecode().get_index_u4(cur_bc_raw());

   }

   bool has_index_u4() const {

     return bytecode().has_index_u4(cur_bc_raw());

   }

   // Get dimensions byte (multinewarray)

   int get_dimensions() const { return *(unsigned char*)(_pc-1); }

   // Sign-extended index byte/short, no widening

   int get_constant_u1()                     const { return bytecode().get_constant_u1(instruction_size()-1, cur_bc_raw()); }

   int get_constant_u2(bool is_wide = false) const { return bytecode().get_constant_u2(instruction_size()-2, cur_bc_raw(), is_wide); }

   // Get a byte signed constant for "iinc".  Invalid for other bytecodes.

   // If prefixed with a wide bytecode, get a wide constant

   int get_iinc_con() const {return (_pc==_was_wide) ? (jshort) get_constant_u2(true) : (jbyte) get_constant_u1();}

   // 2-byte branch offset from current pc

   int get_dest() const {

     return cur_bci() + bytecode().get_offset_s2(cur_bc_raw());

   }

   // 2-byte branch offset from next pc

   int next_get_dest() const {

     assert(_pc < _end, "");

     return next_bci() + next_bytecode().get_offset_s2(Bytecodes::_ifeq);

   }

   // 4-byte branch offset from current pc

   int get_far_dest() const {

     return cur_bci() + bytecode().get_offset_s4(cur_bc_raw());

   }

   // For a lookup or switch table, return target destination

   int get_int_table( int index ) const {

     return Bytes::get_Java_u4((address)&_table_base[index]); }

   // For tableswitch - get length of offset part

   int get_tableswitch_length()  { return get_int_table(2)-get_int_table(1)+1; }

   int get_dest_table( int index ) const {

     return cur_bci() + get_int_table(index); }

   // --- Constant pool access ---

   int get_constant_raw_index() const;

   int get_constant_pool_index() const;

   int get_constant_cache_index() const;

   int get_field_index();

   int get_method_index();

   // If this bytecode is a new, newarray, multianewarray, instanceof,

   // or checkcast, get the referenced klass.

   ciKlass* get_klass(bool& will_link);

   int get_klass_index() const;

   // If this bytecode is one of the ldc variants, get the referenced

   // constant.  Do not attempt to resolve it, since that would require

   // execution of Java code.  If it is not resolved, return an unloaded

   // object (ciConstant.as_object()->is_loaded() == false).

   ciConstant get_constant();

   constantTag get_constant_pool_tag(int index) const;

   // True if the klass-using bytecode points to an unresolved klass

   bool is_unresolved_klass() const {

     constantTag tag = get_constant_pool_tag(get_klass_index());

     return tag.is_unresolved_klass();

   }

   // If this bytecode is one of get_field, get_static, put_field,

   // or put_static, get the referenced field.

   ciField* get_field(bool& will_link);

   ciInstanceKlass* get_declared_field_holder();

   int      get_field_holder_index();

   int      get_field_signature_index();

   // If this is a method invocation bytecode, get the invoked method.

   ciMethod* get_method(bool& will_link);

   ciKlass*  get_declared_method_holder();

   int       get_method_holder_index();

   int       get_method_signature_index();

   ciCPCache*  get_cpcache() const;

   ciCallSite* get_call_site();

 };

 // ciSignatureStream

 //

 // The class is used to iterate over the elements of a method signature.

 class ciSignatureStream : public StackObj {

 private:

   ciSignature* _sig;

   int    _pos;

 public:

   ciSignatureStream(ciSignature* signature) {

     _sig = signature;

     _pos = 0;

   }

   bool at_return_type() { return _pos == _sig->count(); }

   bool is_done() { return _pos > _sig->count(); }

   void next() {

     if (_pos <= _sig->count()) {

       _pos++;

     }

   }

   ciType* type() {

     if (at_return_type()) {

       return _sig->return_type();

     } else {

       return _sig->type_at(_pos);

     }

   }

 };

 // ciExceptionHandlerStream

 //

 // The class is used to iterate over the exception handlers of

 // a method.

 class ciExceptionHandlerStream : public StackObj {

 private:

   // The method whose handlers we are traversing

   ciMethod* _method;

   // Our current position in the list of handlers

   int        _pos;

   int        _end;

   ciInstanceKlass*  _exception_klass;

   int        _bci;

   bool       _is_exact;

 public:

   ciExceptionHandlerStream(ciMethod* method) {

     _method = method;

     // Force loading of method code and handlers.

     _method->code();

     _pos = 0;

     _end = _method->_handler_count;

     _exception_klass = NULL;

     _bci    = -1;

     _is_exact = false;

   }

   ciExceptionHandlerStream(ciMethod* method, int bci,

                            ciInstanceKlass* exception_klass = NULL,

                            bool is_exact = false) {

     _method = method;

     // Force loading of method code and handlers.

     _method->code();

     _pos = -1;

     _end = _method->_handler_count + 1; // include the rethrow handler

     _exception_klass = (exception_klass != NULL && exception_klass->is_loaded()

                           ? exception_klass

                           : NULL);

     _bci = bci;

     assert(_bci >= 0, "bci out of range");

     _is_exact = is_exact;

     next();

   }

   // These methods are currently implemented in an odd way.

   // Count the number of handlers the iterator has ever produced

   // or will ever produce.  Do not include the final rethrow handler.

   // That is, a trivial exception handler stream will have a count

   // of zero and produce just the rethrow handler.

   int count();

   // Count the number of handlers this stream will produce from now on.

   // Include the current handler, and the final rethrow handler.

   // The remaining count will be zero iff is_done() is true,

   int count_remaining();

   bool is_done() {

     return (_pos >= _end);

   }

   void next() {

     _pos++;

     if (_bci != -1) {

       // We are not iterating over all handlers...

       while (!is_done()) {

         ciExceptionHandler* handler = _method->_exception_handlers[_pos];

         if (handler->is_in_range(_bci)) {

           if (handler->is_catch_all()) {

             // Found final active catch block.

             _end = _pos+1;

             return;

           } else if (_exception_klass == NULL || !handler->catch_klass()->is_loaded()) {

             // We cannot do any type analysis here.  Must conservatively assume

             // catch block is reachable.

             return;

           } else if (_exception_klass->is_subtype_of(handler->catch_klass())) {

             // This catch clause will definitely catch the exception.

             // Final candidate.

             _end = _pos+1;

             return;

           } else if (!_is_exact &&

                      handler->catch_klass()->is_subtype_of(_exception_klass)) {

             // This catch block may be reachable.

             return;

           }

         }

         // The catch block was not pertinent.  Go on.

         _pos++;

       }

     } else {

       // This is an iteration over all handlers.

       return;

     }

   }

   ciExceptionHandler* handler() {

     return _method->_exception_handlers[_pos];

   }

 };

 // Implementation for declarations in bytecode.hpp

 Bytecode::Bytecode(const ciBytecodeStream* stream, address bcp): _bcp(bcp != NULL ? bcp : stream->cur_bcp()), _code(Bytecodes::code_at(NULL, addr_at(0))) {}

 Bytecode_lookupswitch::Bytecode_lookupswitch(const ciBytecodeStream* stream): Bytecode(stream) { verify(); }

 Bytecode_tableswitch::Bytecode_tableswitch(const ciBytecodeStream* stream): Bytecode(stream) { verify(); }

 #endif // SHARE_VM_CI_CISTREAMS_HPP