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.
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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:
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
57 int len() const { return _bci; } // for entry at subtable begin
58 int bci() const { return _bci; }
59 int pco() const { return _pco; }
60 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
117 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;
145 implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; }
146 ReallocMark _nesting; // assertion check for reallocations
147 public:
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
156 uint len() const { return _len; }
157 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