1 /* 2 * Copyright (c) 1998, 2012, 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_CODE_EXCEPTIONHANDLERTABLE_HPP 26 #define SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP 27 28 #include "memory/allocation.hpp" 29 #include "oops/method.hpp" 30 31 // A HandlerTableEntry describes an individual entry of a subtable 32 // of ExceptionHandlerTable. An entry consists of a pair(bci, pco), 33 // where bci is the exception handler bci, and pco is the pc offset 34 // relative to the nmethod code start for the compiled exception 35 // handler corresponding to the (interpreted) exception handler 36 // starting at bci. 37 // 38 // The first HandlerTableEntry of each subtable holds the length 39 // and catch_pco for the subtable (the length is the number of 40 // subtable entries w/o header). 41 42 class HandlerTableEntry { 43 private: 44 int _bci; 45 int _pco; 46 int _scope_depth; 47 48 public: HandlerTableEntry(int bci,int pco,int scope_depth)49 HandlerTableEntry(int bci, int pco, int scope_depth) { 50 assert( 0 <= pco, "pco must be positive"); 51 assert( 0 <= scope_depth, "scope_depth must be positive"); 52 _bci = bci; 53 _pco = pco; 54 _scope_depth = scope_depth; 55 } 56 len() const57 int len() const { return _bci; } // for entry at subtable begin bci() const58 int bci() const { return _bci; } pco() const59 int pco() const { return _pco; } scope_depth() const60 int scope_depth() const { return _scope_depth; } 61 }; 62 63 64 // An ExceptionHandlerTable is an abstraction over a list of subtables 65 // of exception handlers for CatchNodes. Each subtable has a one-entry 66 // header holding length and catch_pco of the subtable, followed 67 // by 'length' entries for each exception handler that can be reached 68 // from the corresponding CatchNode. The catch_pco is the pc offset of 69 // the CatchNode in the corresponding nmethod. Empty subtables are dis- 70 // carded. 71 // 72 // Structure of the table: 73 // 74 // table = { subtable }. 75 // subtable = header entry { entry }. 76 // header = a pair (number of subtable entries, catch pc offset, [unused]) 77 // entry = a pair (handler bci, handler pc offset, scope depth) 78 // 79 // An ExceptionHandlerTable can be created from scratch, in which case 80 // it is possible to add subtables. It can also be created from an 81 // nmethod (for lookup purposes) in which case the table cannot be 82 // modified. 83 84 class nmethod; 85 class ExceptionHandlerTable VALUE_OBJ_CLASS_SPEC { 86 private: 87 HandlerTableEntry* _table; // the table 88 int _length; // the current length of the table 89 int _size; // the number of allocated entries 90 ReallocMark _nesting; // assertion check for reallocations 91 92 // add the entry & grow the table if needed 93 void add_entry(HandlerTableEntry entry); 94 HandlerTableEntry* subtable_for(int catch_pco) const; 95 96 public: 97 // (compile-time) construction within compiler 98 ExceptionHandlerTable(int initial_size = 8); 99 100 // (run-time) construction from nmethod 101 ExceptionHandlerTable(const nmethod* nm); 102 103 // (compile-time) add entries 104 void add_subtable( 105 int catch_pco, // the pc offset for the CatchNode 106 GrowableArray<intptr_t>* handler_bcis, // the exception handler entry point bcis 107 GrowableArray<intptr_t>* scope_depths_from_top_scope, 108 // if representing exception handlers in multiple 109 // inlined scopes, indicates which scope relative to 110 // the youngest/innermost one in which we are performing 111 // the lookup; zero (or null GrowableArray) indicates 112 // innermost scope 113 GrowableArray<intptr_t>* handler_pcos // pc offsets for the compiled handlers 114 ); 115 116 // nmethod support size_in_bytes() const117 int size_in_bytes() const { return round_to(_length * sizeof(HandlerTableEntry), oopSize); } 118 void copy_to(nmethod* nm); 119 120 // lookup 121 HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const; 122 123 // debugging 124 void print_subtable(HandlerTableEntry* t) const; 125 void print() const; 126 void print_subtable_for(int catch_pco) const; 127 }; 128 129 130 // ---------------------------------------------------------------------------- 131 // Implicit null exception tables. Maps an exception PC offset to a 132 // continuation PC offset. During construction it's a variable sized 133 // array with a max size and current length. When stored inside an 134 // nmethod a zero length table takes no space. This is detected by 135 // nul_chk_table_size() == 0. Otherwise the table has a length word 136 // followed by pairs of <excp-offset, const-offset>. 137 138 // Use 32-bit representation for offsets 139 typedef uint implicit_null_entry; 140 141 class ImplicitExceptionTable VALUE_OBJ_CLASS_SPEC { 142 uint _size; 143 uint _len; 144 implicit_null_entry *_data; adr(uint idx) const145 implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; } 146 ReallocMark _nesting; // assertion check for reallocations 147 public: ImplicitExceptionTable()148 ImplicitExceptionTable( ) : _data(0), _size(0), _len(0) { } 149 // (run-time) construction from nmethod 150 ImplicitExceptionTable( const nmethod *nm ); 151 152 void set_size( uint size ); 153 void append( uint exec_off, uint cont_off ); 154 uint at( uint exec_off ) const; 155 len() const156 uint len() const { return _len; } size_in_bytes() const157 int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * sizeof(implicit_null_entry)); } 158 159 void copy_to(nmethod* nm); 160 void print(address base) const; 161 void verify(nmethod *nm) const; 162 }; 163 164 #endif // SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP 165