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 };