1 /* 2 * Copyright (c) 1998, 2005, 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 // A HandlerTableEntry describes an individual entry of a subtable 26 // of ExceptionHandlerTable. An entry consists of a pair(bci, pco), 27 // where bci is the exception handler bci, and pco is the pc offset 28 // relative to the nmethod code start for the compiled exception 29 // handler corresponding to the (interpreted) exception handler 30 // starting at bci. 31 // 32 // The first HandlerTableEntry of each subtable holds the length 33 // and catch_pco for the subtable (the length is the number of 34 // subtable entries w/o header). 35 36 class HandlerTableEntry { 37 private: 38 int _bci; 39 int _pco; 40 int _scope_depth; 41 42 public: 43 HandlerTableEntry(int bci, int pco, int scope_depth) { 44 assert( 0 <= pco, "pco must be positive"); 45 assert( 0 <= scope_depth, "scope_depth must be positive"); 46 _bci = bci; 47 _pco = pco; 48 _scope_depth = scope_depth; 49 } 50 51 int len() const { return _bci; } // for entry at subtable begin 52 int bci() const { return _bci; } 53 int pco() const { return _pco; } 54 int scope_depth() const { return _scope_depth; } 55 }; 56 57 58 // An ExceptionHandlerTable is an abstraction over a list of subtables 59 // of exception handlers for CatchNodes. Each subtable has a one-entry 60 // header holding length and catch_pco of the subtable, followed 61 // by 'length' entries for each exception handler that can be reached 62 // from the corresponding CatchNode. The catch_pco is the pc offset of 63 // the CatchNode in the corresponding nmethod. Empty subtables are dis- 64 // carded. 65 // 66 // Structure of the table: 67 // 68 // table = { subtable }. 69 // subtable = header entry { entry }. 70 // header = a pair (number of subtable entries, catch pc offset, [unused]) 71 // entry = a pair (handler bci, handler pc offset, scope depth) 72 // 73 // An ExceptionHandlerTable can be created from scratch, in which case 74 // it is possible to add subtables. It can also be created from an 75 // nmethod (for lookup purposes) in which case the table cannot be 76 // modified. 77 78 class nmethod; 79 class ExceptionHandlerTable VALUE_OBJ_CLASS_SPEC { 80 private: 81 HandlerTableEntry* _table; // the table 82 int _length; // the current length of the table 83 int _size; // the number of allocated entries 84 ReallocMark _nesting; // assertion check for reallocations 85 86 // add the entry & grow the table if needed 87 void add_entry(HandlerTableEntry entry); 88 HandlerTableEntry* subtable_for(int catch_pco) const; 89 90 public: 91 // (compile-time) construction within compiler 92 ExceptionHandlerTable(int initial_size = 8); 93 94 // (run-time) construction from nmethod 95 ExceptionHandlerTable(const nmethod* nm); 96 97 // (compile-time) add entries 98 void add_subtable( 99 int catch_pco, // the pc offset for the CatchNode 100 GrowableArray<intptr_t>* handler_bcis, // the exception handler entry point bcis 101 GrowableArray<intptr_t>* scope_depths_from_top_scope, 102 // if representing exception handlers in multiple 103 // inlined scopes, indicates which scope relative to 104 // the youngest/innermost one in which we are performing 105 // the lookup; zero (or null GrowableArray) indicates 106 // innermost scope 107 GrowableArray<intptr_t>* handler_pcos // pc offsets for the compiled handlers 108 ); 109 110 // nmethod support 111 int size_in_bytes() const { return round_to(_length * sizeof(HandlerTableEntry), oopSize); } 112 void copy_to(nmethod* nm); 113 114 // lookup 115 HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const; 116 117 // debugging 118 void print_subtable(HandlerTableEntry* t) const; 119 void print() const; 120 void print_subtable_for(int catch_pco) const; 121 }; 122 123 124 // ---------------------------------------------------------------------------- 125 // Implicit null exception tables. Maps an exception PC offset to a 126 // continuation PC offset. During construction it's a variable sized 127 // array with a max size and current length. When stored inside an 128 // nmethod a zero length table takes no space. This is detected by 129 // nul_chk_table_size() == 0. Otherwise the table has a length word 130 // followed by pairs of <excp-offset, const-offset>. 131 132 // Use 32-bit representation for offsets 133 typedef uint implicit_null_entry; 134 135 class ImplicitExceptionTable VALUE_OBJ_CLASS_SPEC { 136 uint _size; 137 uint _len; 138 implicit_null_entry *_data; 139 implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; } 140 ReallocMark _nesting; // assertion check for reallocations 141 public: 142 ImplicitExceptionTable( ) : _data(0), _size(0), _len(0) { } 143 // (run-time) construction from nmethod 144 ImplicitExceptionTable( const nmethod *nm ); 145 146 void set_size( uint size ); 147 void append( uint exec_off, uint cont_off ); 148 uint at( uint exec_off ) const; 149 150 uint len() const { return _len; } 151 int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * sizeof(implicit_null_entry)); } 152 153 void copy_to(nmethod* nm); 154 void print(address base) const; 155 void verify(nmethod *nm) const; 156 };