/*

 * Copyright (c) 1999, 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

 * questions.

 *

 */

// 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;

  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;

  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_at(_bc_start); }

  Bytecode* next_bytecode() const { return Bytecode_at(_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:

  //     while( (bc = iter.next()) != 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?

  int get_index_u1() const {

    return bytecode()->get_index_u1(cur_bc_raw());

  }

  // Get a byte index following this bytecode.

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

  int get_index() const {

    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_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

  ciConstant get_constant();

  // 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();

  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];

  }

};