bytecodeStream.hpp revision 9248:6ab7e19c9220 
1/*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25#ifndef SHARE_VM_INTERPRETER_BYTECODESTREAM_HPP
26#define SHARE_VM_INTERPRETER_BYTECODESTREAM_HPP
27
28#include "interpreter/bytecode.hpp"
29#include "memory/allocation.hpp"
30#include "oops/method.hpp"
31#include "runtime/handles.inline.hpp"
32#include "utilities/bytes.hpp"
33
34// A BytecodeStream is used for fast iteration over the bytecodes
35// of a Method*.
36//
37// Usage:
38//
39// BytecodeStream s(method);
40// Bytecodes::Code c;
41// while ((c = s.next()) >= 0) {
42//   ...
43// }
44
45// A RawBytecodeStream is a simple version of BytecodeStream.
46// It is used ONLY when we know the bytecodes haven't been rewritten
47// yet, such as in the rewriter or the verifier.
48
49// Here is the common base class for both RawBytecodeStream and BytecodeStream:
50class BaseBytecodeStream: StackObj {
51 protected:
52  // stream buffer
53  methodHandle    _method;                       // read from method directly
54
55  // reading position
56  int             _bci;                          // bci if current bytecode
57  int             _next_bci;                     // bci of next bytecode
58  int             _end_bci;                      // bci after the current iteration interval
59
60  // last bytecode read
61  Bytecodes::Code _raw_code;
62  bool            _is_wide;
63  bool            _is_raw;                       // false in 'cooked' BytecodeStream
64
65  // Construction
66  BaseBytecodeStream(const methodHandle& method) : _method(method) {
67    set_interval(0, _method->code_size());
68    _is_raw = false;
69  }
70
71 public:
72  // Iteration control
73  void set_interval(int beg_bci, int end_bci) {
74    // iterate over the interval [beg_bci, end_bci)
75    assert(0 <= beg_bci && beg_bci <= method()->code_size(), "illegal beg_bci");
76    assert(0 <= end_bci && end_bci <= method()->code_size(), "illegal end_bci");
77    // setup of iteration pointers
78    _bci      = beg_bci;
79    _next_bci = beg_bci;
80    _end_bci  = end_bci;
81  }
82  void set_start   (int beg_bci) {
83    set_interval(beg_bci, _method->code_size());
84  }
85
86  bool is_raw() const { return _is_raw; }
87
88  // Stream attributes
89  methodHandle    method() const                 { return _method; }
90
91  int             bci() const                    { return _bci; }
92  int             next_bci() const               { return _next_bci; }
93  int             end_bci() const                { return _end_bci; }
94
95  Bytecodes::Code raw_code() const               { return _raw_code; }
96  bool            is_wide() const                { return _is_wide; }
97  int             instruction_size() const       { return (_next_bci - _bci); }
98  bool            is_last_bytecode() const       { return _next_bci >= _end_bci; }
99
100  address         bcp() const                    { return method()->code_base() + _bci; }
101  Bytecode        bytecode() const               { return Bytecode(_method(), bcp()); }
102
103  // State changes
104  void            set_next_bci(int bci)          { assert(0 <= bci && bci <= method()->code_size(), "illegal bci"); _next_bci = bci; }
105
106  // Bytecode-specific attributes
107  int             dest() const                   { return bci() + bytecode().get_offset_s2(raw_code()); }
108  int             dest_w() const                 { return bci() + bytecode().get_offset_s4(raw_code()); }
109
110  // One-byte indices.
111  int             get_index_u1() const           { assert_raw_index_size(1); return *(jubyte*)(bcp()+1); }
112
113 protected:
114  void assert_raw_index_size(int size) const NOT_DEBUG_RETURN;
115  void assert_raw_stream(bool want_raw) const NOT_DEBUG_RETURN;
116};
117
118class RawBytecodeStream: public BaseBytecodeStream {
119 public:
120  // Construction
121  RawBytecodeStream(const methodHandle& method) : BaseBytecodeStream(method) {
122    _is_raw = true;
123  }
124
125 public:
126  // Iteration
127  // Use raw_next() rather than next() for faster method reference
128  Bytecodes::Code raw_next() {
129    Bytecodes::Code code;
130    // set reading position
131    _bci = _next_bci;
132    assert(!is_last_bytecode(), "caller should check is_last_bytecode()");
133
134    address bcp = this->bcp();
135    code        = Bytecodes::code_or_bp_at(bcp);
136
137    // set next bytecode position
138    int l = Bytecodes::length_for(code);
139    if (l > 0 && (_bci + l) <= _end_bci) {
140      assert(code != Bytecodes::_wide && code != Bytecodes::_tableswitch
141             && code != Bytecodes::_lookupswitch, "can't be special bytecode");
142      _is_wide = false;
143      _next_bci += l;
144      _raw_code = code;
145      return code;
146    } else {
147      return raw_next_special(code);
148    }
149  }
150  Bytecodes::Code raw_next_special(Bytecodes::Code code);
151
152  // Unsigned indices, widening, with no swapping of bytes
153  int             get_index() const          { return (is_wide()) ? get_index_u2_raw(bcp() + 2) : get_index_u1(); }
154  // Get an unsigned 2-byte index, with no swapping of bytes.
155  int             get_index_u2() const       { assert(!is_wide(), ""); return get_index_u2_raw(bcp() + 1);  }
156
157 private:
158  int get_index_u2_raw(address p) const {
159    assert_raw_index_size(2); assert_raw_stream(true);
160    return Bytes::get_Java_u2(p);
161  }
162};
163
164// In BytecodeStream, non-java bytecodes will be translated into the
165// corresponding java bytecodes.
166
167class BytecodeStream: public BaseBytecodeStream {
168  Bytecodes::Code _code;
169
170 public:
171  // Construction
172  BytecodeStream(const methodHandle& method) : BaseBytecodeStream(method) { }
173
174  // Iteration
175  Bytecodes::Code next() {
176    Bytecodes::Code raw_code, code;
177    // set reading position
178    _bci = _next_bci;
179    if (is_last_bytecode()) {
180      // indicate end of bytecode stream
181      raw_code = code = Bytecodes::_illegal;
182    } else {
183      // get bytecode
184      address bcp = this->bcp();
185      raw_code = Bytecodes::code_at(_method(), bcp);
186      code = Bytecodes::java_code(raw_code);
187      // set next bytecode position
188      //
189      // note that we cannot advance before having the
190      // tty bytecode otherwise the stepping is wrong!
191      // (carefull: length_for(...) must be used first!)
192      int l = Bytecodes::length_for(code);
193      if (l == 0) l = Bytecodes::length_at(_method(), bcp);
194      _next_bci  += l;
195      assert(_bci < _next_bci, "length must be > 0");
196      // set attributes
197      _is_wide      = false;
198      // check for special (uncommon) cases
199      if (code == Bytecodes::_wide) {
200        raw_code = (Bytecodes::Code)bcp[1];
201        code = raw_code;  // wide BCs are always Java-normal
202        _is_wide = true;
203      }
204      assert(Bytecodes::is_java_code(code), "sanity check");
205    }
206    _raw_code = raw_code;
207    _code = code;
208    return _code;
209  }
210
211  bool            is_active_breakpoint() const   { return Bytecodes::is_active_breakpoint_at(bcp()); }
212  Bytecodes::Code code() const                   { return _code; }
213
214  // Unsigned indices, widening
215  int             get_index() const              { return is_wide() ? bytecode().get_index_u2(raw_code(), true) : get_index_u1(); }
216  // Get an unsigned 2-byte index, swapping the bytes if necessary.
217  int             get_index_u2() const           { assert_raw_stream(false);
218                                                   return bytecode().get_index_u2(raw_code(), false); }
219  // Get an unsigned 2-byte index in native order.
220  int             get_index_u2_cpcache() const   { assert_raw_stream(false);
221                                                   return bytecode().get_index_u2_cpcache(raw_code()); }
222  int             get_index_u4() const           { assert_raw_stream(false);
223                                                   return bytecode().get_index_u4(raw_code()); }
224  bool            has_index_u4() const           { return bytecode().has_index_u4(raw_code()); }
225};
226
227#endif // SHARE_VM_INTERPRETER_BYTECODESTREAM_HPP
228