1 /*
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   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.
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   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  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  20  * or visit www.oracle.com if you need additional information or have any
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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 "runtime/handles.inline.hpp"
  32 #ifdef TARGET_ARCH_x86
  33 # include "bytes_x86.hpp"
  34 #endif
  35 #ifdef TARGET_ARCH_sparc
  36 # include "bytes_sparc.hpp"
  37 #endif
  38 #ifdef TARGET_ARCH_zero
  39 # include "bytes_zero.hpp"
  40 #endif
  41 #ifdef TARGET_ARCH_arm
  42 # include "bytes_arm.hpp"
  43 #endif
  44 #ifdef TARGET_ARCH_ppc
  45 # include "bytes_ppc.hpp"
  46 #endif
  47 #ifdef TARGET_ARCH_aarch32
  48 # include "bytes_aarch32.hpp"
  49 #endif
  50 
  51 // A BytecodeStream is used for fast iteration over the bytecodes
  52 // of a Method*.
  53 //
  54 // Usage:
  55 //
  56 // BytecodeStream s(method);
  57 // Bytecodes::Code c;
  58 // while ((c = s.next()) >= 0) {
  59 //   ...
  60 // }
  61 
  62 // A RawBytecodeStream is a simple version of BytecodeStream.
  63 // It is used ONLY when we know the bytecodes haven't been rewritten
  64 // yet, such as in the rewriter or the verifier.
  65 
  66 // Here is the common base class for both RawBytecodeStream and BytecodeStream:
  67 class BaseBytecodeStream: StackObj {
  68  protected:
  69   // stream buffer
  70   methodHandle    _method;                       // read from method directly
  71 
  72   // reading position
  73   int             _bci;                          // bci if current bytecode
  74   int             _next_bci;                     // bci of next bytecode
  75   int             _end_bci;                      // bci after the current iteration interval
  76 
  77   // last bytecode read
  78   Bytecodes::Code _raw_code;
  79   bool            _is_wide;
  80   bool            _is_raw;                       // false in 'cooked' BytecodeStream
  81 
  82   // Construction
  83   BaseBytecodeStream(methodHandle method) : _method(method) {
  84     set_interval(0, _method->code_size());
  85     _is_raw = false;
  86   }
  87 
  88  public:
  89   // Iteration control
  90   void set_interval(int beg_bci, int end_bci) {
  91     // iterate over the interval [beg_bci, end_bci)
  92     assert(0 <= beg_bci && beg_bci <= method()->code_size(), "illegal beg_bci");
  93     assert(0 <= end_bci && end_bci <= method()->code_size(), "illegal end_bci");
  94     // setup of iteration pointers
  95     _bci      = beg_bci;
  96     _next_bci = beg_bci;
  97     _end_bci  = end_bci;
  98   }
  99   void set_start   (int beg_bci) {
 100     set_interval(beg_bci, _method->code_size());
 101   }
 102 
 103   bool is_raw() const { return _is_raw; }
 104 
 105   // Stream attributes
 106   methodHandle    method() const                 { return _method; }
 107 
 108   int             bci() const                    { return _bci; }
 109   int             next_bci() const               { return _next_bci; }
 110   int             end_bci() const                { return _end_bci; }
 111 
 112   Bytecodes::Code raw_code() const               { return _raw_code; }
 113   bool            is_wide() const                { return _is_wide; }
 114   int             instruction_size() const       { return (_next_bci - _bci); }
 115   bool            is_last_bytecode() const       { return _next_bci >= _end_bci; }
 116 
 117   address         bcp() const                    { return method()->code_base() + _bci; }
 118   Bytecode        bytecode() const               { return Bytecode(_method(), bcp()); }
 119 
 120   // State changes
 121   void            set_next_bci(int bci)          { assert(0 <= bci && bci <= method()->code_size(), "illegal bci"); _next_bci = bci; }
 122 
 123   // Bytecode-specific attributes
 124   int             dest() const                   { return bci() + bytecode().get_offset_s2(raw_code()); }
 125   int             dest_w() const                 { return bci() + bytecode().get_offset_s4(raw_code()); }
 126 
 127   // One-byte indices.
 128   int             get_index_u1() const           { assert_raw_index_size(1); return *(jubyte*)(bcp()+1); }
 129 
 130  protected:
 131   void assert_raw_index_size(int size) const NOT_DEBUG_RETURN;
 132   void assert_raw_stream(bool want_raw) const NOT_DEBUG_RETURN;
 133 };
 134 
 135 class RawBytecodeStream: public BaseBytecodeStream {
 136  public:
 137   // Construction
 138   RawBytecodeStream(methodHandle method) : BaseBytecodeStream(method) {
 139     _is_raw = true;
 140   }
 141 
 142  public:
 143   // Iteration
 144   // Use raw_next() rather than next() for faster method reference
 145   Bytecodes::Code raw_next() {
 146     Bytecodes::Code code;
 147     // set reading position
 148     _bci = _next_bci;
 149     assert(!is_last_bytecode(), "caller should check is_last_bytecode()");
 150 
 151     address bcp = this->bcp();
 152     code        = Bytecodes::code_or_bp_at(bcp);
 153 
 154     // set next bytecode position
 155     int len = Bytecodes::length_for(code);
 156     if (len > 0 && (_bci <= _end_bci - len)) {
 157       assert(code != Bytecodes::_wide && code != Bytecodes::_tableswitch
 158              && code != Bytecodes::_lookupswitch, "can't be special bytecode");
 159       _is_wide = false;
 160       _next_bci += len;
 161       if (_next_bci <= _bci) { // Check for integer overflow
 162         code = Bytecodes::_illegal;
 163       }
 164       _raw_code = code;
 165       return code;
 166     } else {
 167       return raw_next_special(code);
 168     }
 169   }
 170   Bytecodes::Code raw_next_special(Bytecodes::Code code);
 171 
 172   // Unsigned indices, widening, with no swapping of bytes
 173   int             get_index() const          { return (is_wide()) ? get_index_u2_raw(bcp() + 2) : get_index_u1(); }
 174   // Get an unsigned 2-byte index, with no swapping of bytes.
 175   int             get_index_u2() const       { assert(!is_wide(), ""); return get_index_u2_raw(bcp() + 1);  }
 176 
 177  private:
 178   int get_index_u2_raw(address p) const {
 179     assert_raw_index_size(2); assert_raw_stream(true);
 180     return Bytes::get_Java_u2(p);
 181   }
 182 };
 183 
 184 // In BytecodeStream, non-java bytecodes will be translated into the
 185 // corresponding java bytecodes.
 186 
 187 class BytecodeStream: public BaseBytecodeStream {
 188   Bytecodes::Code _code;
 189 
 190  public:
 191   // Construction
 192   BytecodeStream(methodHandle method) : BaseBytecodeStream(method) { }
 193 
 194   // Iteration
 195   Bytecodes::Code next() {
 196     Bytecodes::Code raw_code, code;
 197     // set reading position
 198     _bci = _next_bci;
 199     if (is_last_bytecode()) {
 200       // indicate end of bytecode stream
 201       raw_code = code = Bytecodes::_illegal;
 202     } else {
 203       // get bytecode
 204       address bcp = this->bcp();
 205       raw_code = Bytecodes::code_at(_method(), bcp);
 206       code = Bytecodes::java_code(raw_code);
 207       // set next bytecode position
 208       //
 209       // note that we cannot advance before having the
 210       // tty bytecode otherwise the stepping is wrong!
 211       // (carefull: length_for(...) must be used first!)
 212       int len = Bytecodes::length_for(code);
 213       if (len == 0) len = Bytecodes::length_at(_method(), bcp);
 214       if (len <= 0 || (_bci > _end_bci - len) || (_bci - len >= _next_bci)) {
 215         raw_code = code = Bytecodes::_illegal;
 216       } else {
 217         _next_bci  += len;
 218         assert(_bci < _next_bci, "length must be > 0");
 219         // set attributes
 220         _is_wide      = false;
 221         // check for special (uncommon) cases
 222         if (code == Bytecodes::_wide) {
 223           raw_code = (Bytecodes::Code)bcp[1];
 224           code = raw_code;  // wide BCs are always Java-normal
 225           _is_wide = true;
 226         }
 227         assert(Bytecodes::is_java_code(code), "sanity check");
 228       }
 229     }
 230     _raw_code = raw_code;
 231     _code = code;
 232     return _code;
 233   }
 234 
 235   bool            is_active_breakpoint() const   { return Bytecodes::is_active_breakpoint_at(bcp()); }
 236   Bytecodes::Code code() const                   { return _code; }
 237 
 238   // Unsigned indices, widening
 239   int             get_index() const              { return is_wide() ? bytecode().get_index_u2(raw_code(), true) : get_index_u1(); }
 240   // Get an unsigned 2-byte index, swapping the bytes if necessary.
 241   int             get_index_u2() const           { assert_raw_stream(false);
 242                                                    return bytecode().get_index_u2(raw_code(), false); }
 243   // Get an unsigned 2-byte index in native order.
 244   int             get_index_u2_cpcache() const   { assert_raw_stream(false);
 245                                                    return bytecode().get_index_u2_cpcache(raw_code()); }
 246   int             get_index_u4() const           { assert_raw_stream(false);
 247                                                    return bytecode().get_index_u4(raw_code()); }
 248   bool            has_index_u4() const           { return bytecode().has_index_u4(raw_code()); }
 249 };
 250 
 251 #endif // SHARE_VM_INTERPRETER_BYTECODESTREAM_HPP