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
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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
42class 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
84class nmethod;
85class 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 public:
93  // add the entry & grow the table if needed
94  void add_entry(HandlerTableEntry entry);
95  HandlerTableEntry* subtable_for(int catch_pco) const;
96
97  // (compile-time) construction within compiler
98  ExceptionHandlerTable(int initial_size = 8);
99
100  // (run-time) construction from nmethod
101  ExceptionHandlerTable(const CompiledMethod* 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(CompiledMethod* nm);
119  void copy_bytes_to(address addr);
120
121  // lookup
122  HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const;
123
124  // debugging
125  void print_subtable(HandlerTableEntry* t) const;
126  void print() const;
127  void print_subtable_for(int catch_pco) const;
128};
129
130
131// ----------------------------------------------------------------------------
132// Implicit null exception tables.  Maps an exception PC offset to a
133// continuation PC offset.  During construction it's a variable sized
134// array with a max size and current length.  When stored inside an
135// nmethod a zero length table takes no space.  This is detected by
136// nul_chk_table_size() == 0.  Otherwise the table has a length word
137// followed by pairs of <excp-offset, const-offset>.
138
139// Use 32-bit representation for offsets
140typedef  uint              implicit_null_entry;
141
142class ImplicitExceptionTable VALUE_OBJ_CLASS_SPEC {
143  uint _size;
144  uint _len;
145  implicit_null_entry *_data;
146  implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; }
147  ReallocMark          _nesting;  // assertion check for reallocations
148public:
149  ImplicitExceptionTable( ) :  _data(0), _size(0), _len(0) { }
150  // (run-time) construction from nmethod
151  ImplicitExceptionTable( const nmethod *nm );
152
153  void set_size( uint size );
154  void append( uint exec_off, uint cont_off );
155  uint at( uint exec_off ) const;
156
157  uint len() const { return _len; }
158  int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * sizeof(implicit_null_entry)); }
159
160  void copy_to(nmethod* nm);
161  void print(address base) const;
162  void verify(nmethod *nm) const;
163};
164
165#endif // SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP
166