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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 "utilities/bytes.hpp"
32 
33 // A BytecodeStream is used for fast iteration over the bytecodes
34 // of a Method*.
35 //
36 // Usage:
37 //
38 // BytecodeStream s(method);
39 // Bytecodes::Code c;
40 // while ((c = s.next()) >= 0) {
41 //   ...
42 // }
43 
44 // A RawBytecodeStream is a simple version of BytecodeStream.
45 // It is used ONLY when we know the bytecodes haven't been rewritten
46 // yet, such as in the rewriter or the verifier.
47 
48 // Here is the common base class for both RawBytecodeStream and BytecodeStream:
49 class BaseBytecodeStream: StackObj {
50  protected:
51   // stream buffer
52   methodHandle    _method;                       // read from method directly
53 
54   // reading position
55   int             _bci;                          // bci if current bytecode
56   int             _next_bci;                     // bci of next bytecode
57   int             _end_bci;                      // bci after the current iteration interval
58 
59   // last bytecode read
60   Bytecodes::Code _raw_code;
61   bool            _is_wide;
62   bool            _is_raw;                       // false in 'cooked' BytecodeStream
63 
64   // Construction
65   BaseBytecodeStream(const methodHandle& method);
66 
67  public:
68   // Iteration control
set_interval(int beg_bci,int end_bci)69   void set_interval(int beg_bci, int end_bci) {
70     // iterate over the interval [beg_bci, end_bci)
71     assert(0 <= beg_bci && beg_bci <= method()->code_size(), "illegal beg_bci");
72     assert(0 <= end_bci && end_bci <= method()->code_size(), "illegal end_bci");
73     // setup of iteration pointers
74     _bci      = beg_bci;
75     _next_bci = beg_bci;
76     _end_bci  = end_bci;
77   }
set_start(int beg_bci)78   void set_start   (int beg_bci) {
79     set_interval(beg_bci, _method->code_size());
80   }
81 
is_raw() const82   bool is_raw() const { return _is_raw; }
83 
84   // Stream attributes
method() const85   const methodHandle& method() const             { return _method; }
86 
bci() const87   int             bci() const                    { return _bci; }
next_bci() const88   int             next_bci() const               { return _next_bci; }
end_bci() const89   int             end_bci() const                { return _end_bci; }
90 
raw_code() const91   Bytecodes::Code raw_code() const               { return _raw_code; }
is_wide() const92   bool            is_wide() const                { return _is_wide; }
instruction_size() const93   int             instruction_size() const       { return (_next_bci - _bci); }
is_last_bytecode() const94   bool            is_last_bytecode() const       { return _next_bci >= _end_bci; }
95 
bcp() const96   address         bcp() const                    { return method()->code_base() + _bci; }
bytecode() const97   Bytecode        bytecode() const               { return Bytecode(_method(), bcp()); }
98 
99   // State changes
set_next_bci(int bci)100   void            set_next_bci(int bci)          { assert(0 <= bci && bci <= method()->code_size(), "illegal bci"); _next_bci = bci; }
101 
102   // Bytecode-specific attributes
dest() const103   int             dest() const                   { return bci() + bytecode().get_offset_s2(raw_code()); }
dest_w() const104   int             dest_w() const                 { return bci() + bytecode().get_offset_s4(raw_code()); }
105 
106   // One-byte indices.
get_index_u1() const107   int             get_index_u1() const           { assert_raw_index_size(1); return *(jubyte*)(bcp()+1); }
108 
109  protected:
110   void assert_raw_index_size(int size) const NOT_DEBUG_RETURN;
111   void assert_raw_stream(bool want_raw) const NOT_DEBUG_RETURN;
112 };
113 
114 class RawBytecodeStream: public BaseBytecodeStream {
115  public:
116   // Construction
RawBytecodeStream(const methodHandle & method)117   RawBytecodeStream(const methodHandle& method) : BaseBytecodeStream(method) {
118     _is_raw = true;
119   }
120 
121  public:
122   // Iteration
123   // Use raw_next() rather than next() for faster method reference
raw_next()124   Bytecodes::Code raw_next() {
125     Bytecodes::Code code;
126     // set reading position
127     _bci = _next_bci;
128     assert(!is_last_bytecode(), "caller should check is_last_bytecode()");
129 
130     address bcp = this->bcp();
131     code        = Bytecodes::code_or_bp_at(bcp);
132 
133     // set next bytecode position
134     int len = Bytecodes::length_for(code);
135     if (len > 0 && (_bci <= _end_bci - len)) {
136       assert(code != Bytecodes::_wide && code != Bytecodes::_tableswitch
137              && code != Bytecodes::_lookupswitch, "can't be special bytecode");
138       _is_wide = false;
139       _next_bci += len;
140       if (_next_bci <= _bci) { // Check for integer overflow
141         code = Bytecodes::_illegal;
142       }
143       _raw_code = code;
144       return code;
145     } else {
146       return raw_next_special(code);
147     }
148   }
149   Bytecodes::Code raw_next_special(Bytecodes::Code code);
150 
151   // Unsigned indices, widening, with no swapping of bytes
get_index() const152   int             get_index() const          { return (is_wide()) ? get_index_u2_raw(bcp() + 2) : get_index_u1(); }
153   // Get an unsigned 2-byte index, with no swapping of bytes.
get_index_u2() const154   int             get_index_u2() const       { assert(!is_wide(), ""); return get_index_u2_raw(bcp() + 1);  }
155 
156  private:
get_index_u2_raw(address p) const157   int get_index_u2_raw(address p) const {
158     assert_raw_index_size(2); assert_raw_stream(true);
159     return Bytes::get_Java_u2(p);
160   }
161 };
162 
163 // In BytecodeStream, non-java bytecodes will be translated into the
164 // corresponding java bytecodes.
165 
166 class BytecodeStream: public BaseBytecodeStream {
167   Bytecodes::Code _code;
168 
169  public:
170   // Construction
BytecodeStream(const methodHandle & method)171   BytecodeStream(const methodHandle& method) : BaseBytecodeStream(method) { }
172 
173   // Iteration
next()174   Bytecodes::Code next() {
175     Bytecodes::Code raw_code, code;
176     // set reading position
177     _bci = _next_bci;
178     if (is_last_bytecode()) {
179       // indicate end of bytecode stream
180       raw_code = code = Bytecodes::_illegal;
181     } else {
182       // get bytecode
183       address bcp = this->bcp();
184       raw_code = Bytecodes::code_at(_method(), bcp);
185       code = Bytecodes::java_code(raw_code);
186       // set next bytecode position
187       //
188       // note that we cannot advance before having the
189       // tty bytecode otherwise the stepping is wrong!
190       // (carefull: length_for(...) must be used first!)
191       int len = Bytecodes::length_for(code);
192       if (len == 0) len = Bytecodes::length_at(_method(), bcp);
193       if (len <= 0 || (_bci > _end_bci - len) || (_bci - len >= _next_bci)) {
194         raw_code = code = Bytecodes::_illegal;
195       } else {
196         _next_bci  += len;
197         assert(_bci < _next_bci, "length must be > 0");
198         // set attributes
199         _is_wide      = false;
200         // check for special (uncommon) cases
201         if (code == Bytecodes::_wide) {
202           raw_code = (Bytecodes::Code)bcp[1];
203           code = raw_code;  // wide BCs are always Java-normal
204           _is_wide = true;
205         }
206         assert(Bytecodes::is_java_code(code), "sanity check");
207       }
208     }
209     _raw_code = raw_code;
210     _code = code;
211     return _code;
212   }
213 
is_active_breakpoint() const214   bool            is_active_breakpoint() const   { return Bytecodes::is_active_breakpoint_at(bcp()); }
code() const215   Bytecodes::Code code() const                   { return _code; }
216 
217   // Unsigned indices, widening
get_index() const218   int             get_index() const              { return is_wide() ? bytecode().get_index_u2(raw_code(), true) : get_index_u1(); }
219   // Get an unsigned 2-byte index, swapping the bytes if necessary.
get_index_u2() const220   int             get_index_u2() const           { assert_raw_stream(false);
221                                                    return bytecode().get_index_u2(raw_code(), false); }
222   // Get an unsigned 2-byte index in native order.
get_index_u2_cpcache() const223   int             get_index_u2_cpcache() const   { assert_raw_stream(false);
224                                                    return bytecode().get_index_u2_cpcache(raw_code()); }
get_index_u4() const225   int             get_index_u4() const           { assert_raw_stream(false);
226                                                    return bytecode().get_index_u4(raw_code()); }
has_index_u4() const227   bool            has_index_u4() const           { return bytecode().has_index_u4(raw_code()); }
228 };
229 
230 #endif // SHARE_VM_INTERPRETER_BYTECODESTREAM_HPP
231