1 /* 2 * Copyright (c) 1998, 2018, 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 #include "utilities/align.hpp" 31 32 // A HandlerTableEntry describes an individual entry of a subtable 33 // of ExceptionHandlerTable. An entry consists of a pair(bci, pco), 34 // where bci is the exception handler bci, and pco is the pc offset 35 // relative to the nmethod code start for the compiled exception 36 // handler corresponding to the (interpreted) exception handler 37 // starting at bci. 38 // 39 // The first HandlerTableEntry of each subtable holds the length 40 // and catch_pco for the subtable (the length is the number of 41 // subtable entries w/o header). 42 43 class HandlerTableEntry { 44 private: 45 int _bci; 46 int _pco; 47 int _scope_depth; 48 49 public: HandlerTableEntry(int bci,int pco,int scope_depth)50 HandlerTableEntry(int bci, int pco, int scope_depth) { 51 assert( 0 <= pco, "pco must be positive"); 52 assert( 0 <= scope_depth, "scope_depth must be positive"); 53 _bci = bci; 54 _pco = pco; 55 _scope_depth = scope_depth; 56 } 57 len() const58 int len() const { return _bci; } // for entry at subtable begin bci() const59 int bci() const { return _bci; } pco() const60 int pco() const { return _pco; } scope_depth() const61 int scope_depth() const { return _scope_depth; } 62 }; 63 64 65 // An ExceptionHandlerTable is an abstraction over a list of subtables 66 // of exception handlers for CatchNodes. Each subtable has a one-entry 67 // header holding length and catch_pco of the subtable, followed 68 // by 'length' entries for each exception handler that can be reached 69 // from the corresponding CatchNode. The catch_pco is the pc offset of 70 // the CatchNode in the corresponding nmethod. Empty subtables are dis- 71 // carded. 72 // 73 // Structure of the table: 74 // 75 // table = { subtable }. 76 // subtable = header entry { entry }. 77 // header = a pair (number of subtable entries, catch pc offset, [unused]) 78 // entry = a pair (handler bci, handler pc offset, scope depth) 79 // 80 // An ExceptionHandlerTable can be created from scratch, in which case 81 // it is possible to add subtables. It can also be created from an 82 // nmethod (for lookup purposes) in which case the table cannot be 83 // modified. 84 85 class nmethod; 86 class ExceptionHandlerTable { 87 private: 88 HandlerTableEntry* _table; // the table 89 int _length; // the current length of the table 90 int _size; // the number of allocated entries 91 ReallocMark _nesting; // assertion check for reallocations 92 93 public: 94 // add the entry & grow the table if needed 95 void add_entry(HandlerTableEntry entry); 96 HandlerTableEntry* subtable_for(int catch_pco) const; 97 98 // (compile-time) construction within compiler 99 ExceptionHandlerTable(int initial_size = 8); 100 101 // (run-time) construction from nmethod 102 ExceptionHandlerTable(const CompiledMethod* nm); 103 104 // (compile-time) add entries 105 void add_subtable( 106 int catch_pco, // the pc offset for the CatchNode 107 GrowableArray<intptr_t>* handler_bcis, // the exception handler entry point bcis 108 GrowableArray<intptr_t>* scope_depths_from_top_scope, 109 // if representing exception handlers in multiple 110 // inlined scopes, indicates which scope relative to 111 // the youngest/innermost one in which we are performing 112 // the lookup; zero (or null GrowableArray) indicates 113 // innermost scope 114 GrowableArray<intptr_t>* handler_pcos // pc offsets for the compiled handlers 115 ); 116 117 // nmethod support size_in_bytes() const118 int size_in_bytes() const { return align_up(_length * (int)sizeof(HandlerTableEntry), oopSize); } 119 void copy_to(CompiledMethod* nm); 120 void copy_bytes_to(address addr); 121 122 // lookup 123 HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const; 124 125 // debugging 126 void print_subtable(HandlerTableEntry* t) const; 127 void print() const; 128 void print_subtable_for(int catch_pco) const; 129 }; 130 131 132 // ---------------------------------------------------------------------------- 133 // Implicit null exception tables. Maps an exception PC offset to a 134 // continuation PC offset. During construction it's a variable sized 135 // array with a max size and current length. When stored inside an 136 // nmethod a zero length table takes no space. This is detected by 137 // nul_chk_table_size() == 0. Otherwise the table has a length word 138 // followed by pairs of <excp-offset, const-offset>. 139 140 // Use 32-bit representation for offsets 141 typedef uint implicit_null_entry; 142 143 class ImplicitExceptionTable { 144 uint _size; 145 uint _len; 146 implicit_null_entry *_data; adr(uint idx) const147 implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; } 148 ReallocMark _nesting; // assertion check for reallocations 149 public: ImplicitExceptionTable()150 ImplicitExceptionTable( ) : _size(0), _len(0), _data(0) { } 151 // (run-time) construction from nmethod 152 ImplicitExceptionTable( const nmethod *nm ); 153 154 void set_size( uint size ); 155 void append( uint exec_off, uint cont_off ); 156 uint at( uint exec_off ) const; 157 len() const158 uint len() const { return _len; } size_in_bytes() const159 int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * sizeof(implicit_null_entry)); } 160 161 void copy_to(nmethod* nm); 162 void print(address base) const; 163 void verify(nmethod *nm) const; 164 }; 165 166 #endif // SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP 167