1 /*
2 * Copyright (c) 1999, 2010, 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 class ValueMapEntry: public CompilationResourceObj {
26 private:
27 intx _hash;
28 Value _value;
29 int _nesting;
30 ValueMapEntry* _next;
31
32 public:
33 ValueMapEntry(intx hash, Value value, int nesting, ValueMapEntry* next)
34 : _hash(hash)
35 , _value(value)
36 , _nesting(nesting)
37 , _next(next)
38 {
39 }
40
41 intx hash() { return _hash; }
42 Value value() { return _value; }
43 int nesting() { return _nesting; }
44 ValueMapEntry* next() { return _next; }
45
46 void set_next(ValueMapEntry* next) { _next = next; }
47 };
48
49 define_array(ValueMapEntryArray, ValueMapEntry*)
50 define_stack(ValueMapEntryList, ValueMapEntryArray)
51
52 // ValueMap implements nested hash tables for value numbering. It
53 // maintains a set _killed_values which represents the instructions
54 // which have been killed so far and an array of linked lists of
55 // ValueMapEntries names _entries. Each ValueMapEntry has a nesting
56 // which indicates what ValueMap nesting it belongs to. Higher
57 // nesting values are always before lower values in the linked list.
58 // This allows cloning of parent ValueMaps by simply copying the heads
59 // of the list. _entry_count represents the number of reachable
60 // entries in the ValueMap. A ValueMap is only allowed to mutate
61 // ValueMapEntries with the same nesting level. Adding or removing
62 // entries at the current nesting level requires updating
63 // _entry_count. Elements in the parent's list that get killed can be
64 // skipped if they are at the head of the list by simply moving to the
65 // next element in the list and decrementing _entry_count.
66
67 class ValueMap: public CompilationResourceObj {
68 private:
69 int _nesting;
70 ValueMapEntryArray _entries;
71 ValueSet _killed_values;
72 int _entry_count;
73
74 int nesting() { return _nesting; }
75 bool is_local_value_numbering() { return _nesting == 0; }
76 bool is_global_value_numbering() { return _nesting > 0; }
77
78 int entry_count() { return _entry_count; }
79 int size() { return _entries.length(); }
80 ValueMapEntry* entry_at(int i) { return _entries.at(i); }
81
82 // calculates the index of a hash value in a hash table of size n
83 int entry_index(intx hash, int n) { return (unsigned int)hash % n; }
84
85 // if entry_count > size_threshold, the size of the hash table is increased
86 int size_threshold() { return size(); }
87
88 // management of the killed-bitset for global value numbering
89 void kill_value(Value v) { if (is_global_value_numbering()) _killed_values.put(v); }
90 bool is_killed(Value v) { if (is_global_value_numbering()) return _killed_values.contains(v); else return false; }
91
92 // helper functions
93 void increase_table_size();
94
95 #ifndef PRODUCT
96 static int _number_of_finds;
97 static int _number_of_hits;
98 static int _number_of_kills;
99 #endif // PRODUCT
100
101 public:
102 // creation
103 ValueMap(); // empty value map
104 ValueMap(ValueMap* old); // value map with increased nesting
105
106 // manipulation
107 Value find_insert(Value x);
108
109 void kill_memory();
110 void kill_field(ciField* field);
111 void kill_array(ValueType* type);
112 void kill_exception();
113 void kill_map(ValueMap* map);
114 void kill_all();
115
116 #ifndef PRODUCT
117 // debugging/printing
118 void print();
119
120 static void reset_statistics();
121 static void print_statistics();
122 #endif
123 };
124
125 define_array(ValueMapArray, ValueMap*)
126
127
128 class ValueNumberingVisitor: public InstructionVisitor {
129 protected:
130 // called by visitor functions for instructions that kill values
131 virtual void kill_memory() = 0;
132 virtual void kill_field(ciField* field) = 0;
133 virtual void kill_array(ValueType* type) = 0;
134
135 // visitor functions
136 void do_StoreField (StoreField* x) {
137 if (!x->is_initialized()) {
138 kill_memory();
139 } else {
140 kill_field(x->field());
141 }
142 }
143 void do_StoreIndexed (StoreIndexed* x) { kill_array(x->type()); }
144 void do_MonitorEnter (MonitorEnter* x) { kill_memory(); }
145 void do_MonitorExit (MonitorExit* x) { kill_memory(); }
146 void do_Invoke (Invoke* x) { kill_memory(); }
147 void do_UnsafePutRaw (UnsafePutRaw* x) { kill_memory(); }
148 void do_UnsafePutObject(UnsafePutObject* x) { kill_memory(); }
149 void do_Intrinsic (Intrinsic* x) { if (!x->preserves_state()) kill_memory(); }
150
151 void do_Phi (Phi* x) { /* nothing to do */ }
152 void do_Local (Local* x) { /* nothing to do */ }
153 void do_Constant (Constant* x) { /* nothing to do */ }
154 void do_LoadField (LoadField* x) {
155 if (!x->is_initialized()) {
156 kill_memory();
157 }
158 }
159 void do_ArrayLength (ArrayLength* x) { /* nothing to do */ }
160 void do_LoadIndexed (LoadIndexed* x) { /* nothing to do */ }
161 void do_NegateOp (NegateOp* x) { /* nothing to do */ }
162 void do_ArithmeticOp (ArithmeticOp* x) { /* nothing to do */ }
163 void do_ShiftOp (ShiftOp* x) { /* nothing to do */ }
164 void do_LogicOp (LogicOp* x) { /* nothing to do */ }
165 void do_CompareOp (CompareOp* x) { /* nothing to do */ }
166 void do_IfOp (IfOp* x) { /* nothing to do */ }
167 void do_Convert (Convert* x) { /* nothing to do */ }
168 void do_NullCheck (NullCheck* x) { /* nothing to do */ }
169 void do_NewInstance (NewInstance* x) { /* nothing to do */ }
170 void do_NewTypeArray (NewTypeArray* x) { /* nothing to do */ }
171 void do_NewObjectArray (NewObjectArray* x) { /* nothing to do */ }
172 void do_NewMultiArray (NewMultiArray* x) { /* nothing to do */ }
173 void do_CheckCast (CheckCast* x) { /* nothing to do */ }
174 void do_InstanceOf (InstanceOf* x) { /* nothing to do */ }
175 void do_BlockBegin (BlockBegin* x) { /* nothing to do */ }
176 void do_Goto (Goto* x) { /* nothing to do */ }
177 void do_If (If* x) { /* nothing to do */ }
178 void do_IfInstanceOf (IfInstanceOf* x) { /* nothing to do */ }
179 void do_TableSwitch (TableSwitch* x) { /* nothing to do */ }
180 void do_LookupSwitch (LookupSwitch* x) { /* nothing to do */ }
181 void do_Return (Return* x) { /* nothing to do */ }
182 void do_Throw (Throw* x) { /* nothing to do */ }
183 void do_Base (Base* x) { /* nothing to do */ }
184 void do_OsrEntry (OsrEntry* x) { /* nothing to do */ }
185 void do_ExceptionObject(ExceptionObject* x) { /* nothing to do */ }
186 void do_RoundFP (RoundFP* x) { /* nothing to do */ }
187 void do_UnsafeGetRaw (UnsafeGetRaw* x) { /* nothing to do */ }
188 void do_ProfileInvoke (ProfileInvoke* x) { /* nothing to do */ };
189 void do_UnsafeGetObject(UnsafeGetObject* x) { /* nothing to do */ }
190 void do_UnsafePrefetchRead (UnsafePrefetchRead* x) { /* nothing to do */ }
191 void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) { /* nothing to do */ }
192 void do_ProfileCall (ProfileCall* x) { /* nothing to do */ }
193 };
194
195
196 class ValueNumberingEffects: public ValueNumberingVisitor {
197 private:
198 ValueMap* _map;
199
200 public:
201 // implementation for abstract methods of ValueNumberingVisitor
202 void kill_memory() { _map->kill_memory(); }
203 void kill_field(ciField* field) { _map->kill_field(field); }
204 void kill_array(ValueType* type) { _map->kill_array(type); }
205
206 ValueNumberingEffects(ValueMap* map): _map(map) {}
207 };
208
209
210 class GlobalValueNumbering: public ValueNumberingVisitor {
211 private:
212 ValueMap* _current_map; // value map of current block
213 ValueMapArray _value_maps; // list of value maps for all blocks
214
215 public:
216 // accessors
217 ValueMap* current_map() { return _current_map; }
218 ValueMap* value_map_of(BlockBegin* block) { return _value_maps.at(block->linear_scan_number()); }
219 void set_value_map_of(BlockBegin* block, ValueMap* map) { assert(value_map_of(block) == NULL, ""); _value_maps.at_put(block->linear_scan_number(), map); }
220
221 // implementation for abstract methods of ValueNumberingVisitor
222 void kill_memory() { current_map()->kill_memory(); }
223 void kill_field(ciField* field) { current_map()->kill_field(field); }
224 void kill_array(ValueType* type) { current_map()->kill_array(type); }
225
226 // main entry point that performs global value numbering
227 GlobalValueNumbering(IR* ir);
228 };