1/*
2 * Copyright (c) 1998, 2016, 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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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
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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#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
43class 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
85class nmethod;
86class ExceptionHandlerTable VALUE_OBJ_CLASS_SPEC {
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
118  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
141typedef  uint              implicit_null_entry;
142
143class ImplicitExceptionTable VALUE_OBJ_CLASS_SPEC {
144  uint _size;
145  uint _len;
146  implicit_null_entry *_data;
147  implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; }
148  ReallocMark          _nesting;  // assertion check for reallocations
149public:
150  ImplicitExceptionTable( ) :  _data(0), _size(0), _len(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
158  uint len() const { return _len; }
159  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