1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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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
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 {
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 {
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
149
150public:
151 ImplicitExceptionTable( ) : _size(0), _len(0), _data(0) { }
152 // (run-time) construction from nmethod
153 ImplicitExceptionTable( const CompiledMethod *nm );
154
155 void set_size( uint size );
156 void append( uint exec_off, uint cont_off );
157
158#if INCLUDE_JVMCI
159 void add_deoptimize(uint exec_off) {
160 // Use the same offset as a marker value for deoptimization
161 append(exec_off, exec_off);
162 }
163#endif
164
165 // Returns the offset to continue execution at. If the returned
166 // value equals exec_off then the dispatch is expected to be a
167 // deoptimization instead.
168 uint continuation_offset( uint exec_off ) const;
169
170 uint len() const { return _len; }
171
172 uint get_exec_offset(uint i) { assert(i < _len, "oob"); return *adr(i); }
173 uint get_cont_offset(uint i) { assert(i < _len, "oob"); return *(adr(i) + 1); }
174
175 int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * sizeof(implicit_null_entry)); }
176
177 void copy_to(nmethod* nm);
178 void copy_bytes_to(address addr, int size);
179 void print(address base) const;
180 void verify(nmethod *nm) const;
181};
182
183#endif // SHARE_CODE_EXCEPTIONHANDLERTABLE_HPP
184