1 /*
   2  * Copyright (c) 2003, 2009, 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 // An constMethodOop represents portions of a Java method which
  26 // do not vary.
  27 //
  28 // Memory layout (each line represents a word). Note that most
  29 // applications load thousands of methods, so keeping the size of this
  30 // structure small has a big impact on footprint.
  31 //
  32 // |------------------------------------------------------|
  33 // | header                                               |
  34 // | klass                                                |
  35 // |------------------------------------------------------|
  36 // | fingerprint 1                                        |
  37 // | fingerprint 2                                        |
  38 // | method                         (oop)                 |
  39 // | stackmap_data                  (oop)                 |
  40 // | exception_table                (oop)                 |
  41 // | constMethod_size                                     |
  42 // | interp_kind  | flags    | code_size                  |
  43 // | name index              | signature index            |
  44 // | method_idnum            | generic_signature_index    |
  45 // |------------------------------------------------------|
  46 // |                                                      |
  47 // | byte codes                                           |
  48 // |                                                      |
  49 // |------------------------------------------------------|
  50 // | compressed linenumber table                          |
  51 // |  (see class CompressedLineNumberReadStream)          |
  52 // |  (note that length is unknown until decompressed)    |
  53 // |  (access flags bit tells whether table is present)   |
  54 // |  (indexed from start of constMethodOop)              |
  55 // |  (elements not necessarily sorted!)                  |
  56 // |------------------------------------------------------|
  57 // | localvariable table elements + length (length last)  |
  58 // |  (length is u2, elements are 6-tuples of u2)         |
  59 // |  (see class LocalVariableTableElement)               |
  60 // |  (access flags bit tells whether table is present)   |
  61 // |  (indexed from end of contMethodOop)                 |
  62 // |------------------------------------------------------|
  63 // | checked exceptions elements + length (length last)   |
  64 // |  (length is u2, elements are u2)                     |
  65 // |  (see class CheckedExceptionElement)                 |
  66 // |  (access flags bit tells whether table is present)   |
  67 // |  (indexed from end of constMethodOop)                |
  68 // |------------------------------------------------------|
  69 
  70 
  71 // Utitily class decribing elements in checked exceptions table inlined in methodOop.
  72 class CheckedExceptionElement VALUE_OBJ_CLASS_SPEC {
  73  public:
  74   u2 class_cp_index;
  75 };
  76 
  77 
  78 // Utitily class decribing elements in local variable table inlined in methodOop.
  79 class LocalVariableTableElement VALUE_OBJ_CLASS_SPEC {
  80  public:
  81   u2 start_bci;
  82   u2 length;
  83   u2 name_cp_index;
  84   u2 descriptor_cp_index;
  85   u2 signature_cp_index;
  86   u2 slot;
  87 };
  88 
  89 
  90 class constMethodOopDesc : public oopDesc {
  91   friend class constMethodKlass;
  92   friend class VMStructs;
  93 private:
  94   enum {
  95     _has_linenumber_table = 1,
  96     _has_checked_exceptions = 2,
  97     _has_localvariable_table = 4
  98   };
  99 
 100   // Bit vector of signature
 101   // Callers interpret 0=not initialized yet and
 102   // -1=too many args to fix, must parse the slow way.
 103   // The real initial value is special to account for nonatomicity of 64 bit
 104   // loads and stores.  This value may updated and read without a lock by
 105   // multiple threads, so is volatile.
 106   volatile uint64_t _fingerprint;
 107   volatile bool     _is_conc_safe; // if true, safe for concurrent GC processing
 108 
 109 public:
 110   oop* oop_block_beg() const { return adr_method(); }
 111   oop* oop_block_end() const { return adr_exception_table() + 1; }
 112 
 113 private:
 114   //
 115   // The oop block.  See comment in klass.hpp before making changes.
 116   //
 117 
 118   // Backpointer to non-const methodOop (needed for some JVMTI operations)
 119   methodOop         _method;
 120 
 121   // Raw stackmap data for the method
 122   typeArrayOop      _stackmap_data;
 123 
 124   // The exception handler table. 4-tuples of ints [start_pc, end_pc,
 125   // handler_pc, catch_type index] For methods with no exceptions the
 126   // table is pointing to Universe::the_empty_int_array
 127   typeArrayOop      _exception_table;
 128 
 129   //
 130   // End of the oop block.
 131   //
 132 
 133   int               _constMethod_size;
 134   jbyte             _interpreter_kind;
 135   jbyte             _flags;
 136 
 137   // Size of Java bytecodes allocated immediately after methodOop.
 138   u2                _code_size;
 139   u2                _name_index;                 // Method name (index in constant pool)
 140   u2                _signature_index;            // Method signature (index in constant pool)
 141   u2                _method_idnum;               // unique identification number for the method within the class
 142                                                  // initially corresponds to the index into the methods array.
 143                                                  // but this may change with redefinition
 144   u2                _generic_signature_index;    // Generic signature (index in constant pool, 0 if absent)
 145 
 146 public:
 147   // Inlined tables
 148   void set_inlined_tables_length(int checked_exceptions_len,
 149                                  int compressed_line_number_size,
 150                                  int localvariable_table_len);
 151 
 152   bool has_linenumber_table() const
 153     { return (_flags & _has_linenumber_table) != 0; }
 154 
 155   bool has_checked_exceptions() const
 156     { return (_flags & _has_checked_exceptions) != 0; }
 157 
 158   bool has_localvariable_table() const
 159     { return (_flags & _has_localvariable_table) != 0; }
 160 
 161   void set_interpreter_kind(int kind)      { _interpreter_kind = kind; }
 162   int  interpreter_kind(void) const        { return _interpreter_kind; }
 163 
 164   // backpointer to non-const methodOop
 165   methodOop method() const                 { return _method; }
 166   void set_method(methodOop m)             { oop_store_without_check((oop*)&_method, (oop) m); }
 167 
 168 
 169   // stackmap table data
 170   typeArrayOop stackmap_data() const { return _stackmap_data; }
 171   void set_stackmap_data(typeArrayOop sd) {
 172     oop_store_without_check((oop*)&_stackmap_data, (oop)sd);
 173   }
 174   bool has_stackmap_table() const { return _stackmap_data != NULL; }
 175 
 176   // exception handler table
 177   typeArrayOop exception_table() const           { return _exception_table; }
 178   void set_exception_table(typeArrayOop e)       { oop_store_without_check((oop*) &_exception_table, (oop) e); }
 179   bool has_exception_handler() const             { return exception_table() != NULL && exception_table()->length() > 0; }
 180 
 181   void init_fingerprint() {
 182     const uint64_t initval = CONST64(0x8000000000000000);
 183     _fingerprint = initval;
 184   }
 185 
 186   uint64_t fingerprint() const                   {
 187     // Since reads aren't atomic for 64 bits, if any of the high or low order
 188     // word is the initial value, return 0.  See init_fingerprint for initval.
 189     uint high_fp = (uint)(_fingerprint >> 32);
 190     if ((int) _fingerprint == 0 || high_fp == 0x80000000) {
 191       return 0L;
 192     } else {
 193       return _fingerprint;
 194     }
 195   }
 196 
 197   uint64_t set_fingerprint(uint64_t new_fingerprint) {
 198 #ifdef ASSERT
 199     // Assert only valid if complete/valid 64 bit _fingerprint value is read.
 200     uint64_t oldfp = fingerprint();
 201 #endif // ASSERT
 202     _fingerprint = new_fingerprint;
 203     assert(oldfp == 0L || new_fingerprint == oldfp,
 204            "fingerprint cannot change");
 205     assert(((new_fingerprint >> 32) != 0x80000000) && (int)new_fingerprint !=0,
 206            "fingerprint should call init to set initial value");
 207     return new_fingerprint;
 208   }
 209 
 210   // name
 211   int name_index() const                         { return _name_index; }
 212   void set_name_index(int index)                 { _name_index = index; }
 213 
 214   // signature
 215   int signature_index() const                    { return _signature_index; }
 216   void set_signature_index(int index)            { _signature_index = index; }
 217 
 218   // generics support
 219   int generic_signature_index() const            { return _generic_signature_index; }
 220   void set_generic_signature_index(int index)    { _generic_signature_index = index; }
 221 
 222   // Sizing
 223   static int header_size() {
 224     return sizeof(constMethodOopDesc)/HeapWordSize;
 225   }
 226 
 227   // Object size needed
 228   static int object_size(int code_size, int compressed_line_number_size,
 229                          int local_variable_table_length,
 230                          int checked_exceptions_length);
 231 
 232   int object_size() const                 { return _constMethod_size; }
 233   void set_constMethod_size(int size)     { _constMethod_size = size; }
 234   // Is object parsable by gc
 235   bool object_is_parsable()               { return object_size() > 0; }
 236 
 237   // code size
 238   int code_size() const                          { return _code_size; }
 239   void set_code_size(int size) {
 240     assert(max_method_code_size < (1 << 16),
 241            "u2 is too small to hold method code size in general");
 242     assert(0 <= size && size <= max_method_code_size, "invalid code size");
 243     _code_size = size;
 244   }
 245 
 246   // linenumber table - note that length is unknown until decompression,
 247   // see class CompressedLineNumberReadStream.
 248   u_char* compressed_linenumber_table() const;         // not preserved by gc
 249   u2* checked_exceptions_length_addr() const;
 250   u2* localvariable_table_length_addr() const;
 251 
 252   // checked exceptions
 253   int checked_exceptions_length() const;
 254   CheckedExceptionElement* checked_exceptions_start() const;
 255 
 256   // localvariable table
 257   int localvariable_table_length() const;
 258   LocalVariableTableElement* localvariable_table_start() const;
 259 
 260   // byte codes
 261   void    set_code(address code) {
 262     if (code_size() > 0) {
 263       memcpy(code_base(), code, code_size());
 264     }
 265   }
 266   address code_base() const            { return (address) (this+1); }
 267   address code_end() const             { return code_base() + code_size(); }
 268   bool    contains(address bcp) const  { return code_base() <= bcp
 269                                                      && bcp < code_end(); }
 270   // Offset to bytecodes
 271   static ByteSize codes_offset()
 272                             { return in_ByteSize(sizeof(constMethodOopDesc)); }
 273 
 274   // interpreter support
 275   static ByteSize exception_table_offset()
 276                { return byte_offset_of(constMethodOopDesc, _exception_table); }
 277 
 278   // Garbage collection support
 279   oop*  adr_method() const             { return (oop*)&_method;          }
 280   oop*  adr_stackmap_data() const      { return (oop*)&_stackmap_data;   }
 281   oop*  adr_exception_table() const    { return (oop*)&_exception_table; }
 282   bool is_conc_safe() { return _is_conc_safe; }
 283   void set_is_conc_safe(bool v) { _is_conc_safe = v; }
 284 
 285   // Unique id for the method
 286   static const u2 MAX_IDNUM;
 287   static const u2 UNSET_IDNUM;
 288   u2 method_idnum() const                        { return _method_idnum; }
 289   void set_method_idnum(u2 idnum)                { _method_idnum = idnum; }
 290 
 291 private:
 292   // Since the size of the compressed line number table is unknown, the
 293   // offsets of the other variable sized sections are computed backwards
 294   // from the end of the constMethodOop.
 295 
 296   // First byte after constMethodOop
 297   address constMethod_end() const
 298                           { return (address)((oop*)this + _constMethod_size); }
 299 
 300   // Last short in constMethodOop
 301   u2* last_u2_element() const
 302                                          { return (u2*)constMethod_end() - 1; }
 303 };