1 /*
2 * Copyright (c) 1998, 2024, 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.
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23 */
24
25 #ifndef SHARE_CODE_EXCEPTIONHANDLERTABLE_HPP
26 #define SHARE_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:
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
58 int len() const { return _bci; } // for entry at subtable begin
59 int bci() const { return _bci; }
60 int pco() const { return _pco; }
61 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 friend class SCCache;
88 friend class SCCReader;
89
90 private:
91 HandlerTableEntry* _table; // the table
92 int _length; // the current length of the table
93 int _size; // the number of allocated entries
94 ReallocMark _nesting; // assertion check for reallocations
95
96 int length() const { return _length; }
97 void set_length(int length) { _length = length; }
98 public:
99 // add the entry & grow the table if needed
100 void add_entry(HandlerTableEntry entry);
101 HandlerTableEntry* subtable_for(int catch_pco) const;
102
103 // (compile-time) construction within compiler
104 ExceptionHandlerTable(int initial_size = 8);
105
106 // (run-time) construction from nmethod
107 ExceptionHandlerTable(const nmethod* nm);
108
109 // (compile-time) add entries
110 void add_subtable(
111 int catch_pco, // the pc offset for the CatchNode
112 GrowableArray<intptr_t>* handler_bcis, // the exception handler entry point bcis
113 GrowableArray<intptr_t>* scope_depths_from_top_scope,
114 // if representing exception handlers in multiple
115 // inlined scopes, indicates which scope relative to
116 // the youngest/innermost one in which we are performing
117 // the lookup; zero (or null GrowableArray) indicates
118 // innermost scope
119 GrowableArray<intptr_t>* handler_pcos // pc offsets for the compiled handlers
120 );
121
122 HandlerTableEntry* table() const { return _table; }
123 // nmethod support
124 int size_in_bytes() const { return align_up(_length * (int)sizeof(HandlerTableEntry), oopSize); }
125 void copy_to(nmethod* nm);
126 void copy_bytes_to(address addr);
127
128 // lookup
129 HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const;
130
131 // debugging
132 void print_subtable(HandlerTableEntry* t, address base = nullptr) const;
133 void print(address base = nullptr) const;
134 void print_subtable_for(int catch_pco) const;
135 };
136
137
138 // ----------------------------------------------------------------------------
139 // Implicit null exception tables. Maps an exception PC offset to a
140 // continuation PC offset. During construction it's a variable sized
141 // array with a max size and current length. When stored inside an
142 // nmethod a zero length table takes no space. This is detected by
143 // nul_chk_table_size() == 0. Otherwise the table has a length word
144 // followed by pairs of <excp-offset, const-offset>.
145
146 // Use 32-bit representation for offsets
147 typedef uint implicit_null_entry;
148
149 class ImplicitExceptionTable {
150 friend class SCCache;
151 friend class SCCReader;
152 private:
153 uint _size;
154 uint _len;
155 implicit_null_entry *_data;
156 implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; }
157 ReallocMark _nesting; // assertion check for reallocations
158
159 void set_len(int length) { _len = length; }
160
161 public:
162 ImplicitExceptionTable( ) : _size(0), _len(0), _data(nullptr) { }
163 // (run-time) construction from nmethod
164 ImplicitExceptionTable(const nmethod *nm);
165
166 void set_size( uint size );
167 void append( uint exec_off, uint cont_off );
168
169 #if INCLUDE_JVMCI
170 void add_deoptimize(uint exec_off) {
171 // Use the same offset as a marker value for deoptimization
172 append(exec_off, exec_off);
173 }
174 #endif
175
176 // Returns the offset to continue execution at. If the returned
177 // value equals exec_off then the dispatch is expected to be a
178 // deoptimization instead.
179 uint continuation_offset( uint exec_off ) const;
180
181 uint len() const { return _len; }
182
183 implicit_null_entry* data() const { return _data; }
184
185 uint get_exec_offset(uint i) { assert(i < _len, "oob"); return *adr(i); }
186 uint get_cont_offset(uint i) { assert(i < _len, "oob"); return *(adr(i) + 1); }
187
188 int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * (int)sizeof(implicit_null_entry)); }
189
190 void copy_to(nmethod* nm);
191 void copy_bytes_to(address addr, int size);
192 void print(address base) const;
193 void verify(nmethod *nm) const;
194 };
195
196 #endif // SHARE_CODE_EXCEPTIONHANDLERTABLE_HPP