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src/share/vm/c1/c1_ValueMap.cpp@f067b4e0e04b
src/share/vm/c1/c1_ValueMap.cpp
Wed, 01 Feb 2012 10:36:58 +0100
- author
- roland
- date
- Wed, 01 Feb 2012 10:36:58 +0100
- changeset 3498
- f067b4e0e04b
- parent 2314
- f95d63e2154a
- child 4005
- 0bfcb7a3e12d
- permissions
- -rw-r--r--
7090976: Eclipse/CDT causes a JVM crash while indexing C++ code
Summary: too optimistic inlining decision confuses local value numbering.
Reviewed-by: never
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 */
25 #include "precompiled.hpp"
26 #include "c1/c1_Canonicalizer.hpp"
27 #include "c1/c1_IR.hpp"
28 #include "c1/c1_ValueMap.hpp"
29 #include "utilities/bitMap.inline.hpp"
32 #ifndef PRODUCT
34 int ValueMap::_number_of_finds = 0;
35 int ValueMap::_number_of_hits = 0;
36 int ValueMap::_number_of_kills = 0;
38 #define TRACE_VALUE_NUMBERING(code) if (PrintValueNumbering) { code; }
40 #else
42 #define TRACE_VALUE_NUMBERING(code)
44 #endif
47 ValueMap::ValueMap()
48 : _nesting(0)
49 , _entries(ValueMapInitialSize, NULL)
50 , _killed_values()
51 , _entry_count(0)
52 {
53 NOT_PRODUCT(reset_statistics());
54 }
57 ValueMap::ValueMap(ValueMap* old)
58 : _nesting(old->_nesting + 1)
59 , _entries(old->_entries.length())
60 , _killed_values()
61 , _entry_count(old->_entry_count)
62 {
63 for (int i = size() - 1; i >= 0; i--) {
64 _entries.at_put(i, old->entry_at(i));
65 }
66 _killed_values.set_from(&old->_killed_values);
67 }
70 void ValueMap::increase_table_size() {
71 int old_size = size();
72 int new_size = old_size * 2 + 1;
74 ValueMapEntryList worklist(8);
75 ValueMapEntryArray new_entries(new_size, NULL);
76 int new_entry_count = 0;
78 TRACE_VALUE_NUMBERING(tty->print_cr("increasing table size from %d to %d", old_size, new_size));
80 for (int i = old_size - 1; i >= 0; i--) {
81 ValueMapEntry* entry;
82 for (entry = entry_at(i); entry != NULL; entry = entry->next()) {
83 if (!is_killed(entry->value())) {
84 worklist.push(entry);
85 }
86 }
88 while (!worklist.is_empty()) {
89 entry = worklist.pop();
90 int new_index = entry_index(entry->hash(), new_size);
92 if (entry->nesting() != nesting() && new_entries.at(new_index) != entry->next()) {
93 // changing entries with a lower nesting than the current nesting of the table
94 // is not allowed because then the same entry is contained in multiple value maps.
95 // clone entry when next-pointer must be changed
96 entry = new ValueMapEntry(entry->hash(), entry->value(), entry->nesting(), NULL);
97 }
98 entry->set_next(new_entries.at(new_index));
99 new_entries.at_put(new_index, entry);
100 new_entry_count++;
101 }
102 }
104 _entries = new_entries;
105 _entry_count = new_entry_count;
106 }
109 Value ValueMap::find_insert(Value x) {
110 const intx hash = x->hash();
111 if (hash != 0) {
112 // 0 hash means: exclude from value numbering
113 NOT_PRODUCT(_number_of_finds++);
115 for (ValueMapEntry* entry = entry_at(entry_index(hash, size())); entry != NULL; entry = entry->next()) {
116 if (entry->hash() == hash) {
117 Value f = entry->value();
119 if (!is_killed(f) && f->is_equal(x)) {
120 NOT_PRODUCT(_number_of_hits++);
121 TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: %s %c%d equal to %c%d (size %d, entries %d, nesting-diff %d)", x->name(), x->type()->tchar(), x->id(), f->type()->tchar(), f->id(), size(), entry_count(), nesting() - entry->nesting()));
123 if (entry->nesting() != nesting() && f->as_Constant() == NULL) {
124 // non-constant values of of another block must be pinned,
125 // otherwise it is possible that they are not evaluated
126 f->pin(Instruction::PinGlobalValueNumbering);
127 }
128 assert(x->type()->tag() == f->type()->tag(), "should have same type");
130 return f;
132 }
133 }
134 }
136 // x not found, so insert it
137 if (entry_count() >= size_threshold()) {
138 increase_table_size();
139 }
140 int idx = entry_index(hash, size());
141 _entries.at_put(idx, new ValueMapEntry(hash, x, nesting(), entry_at(idx)));
142 _entry_count++;
144 TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: insert %s %c%d (size %d, entries %d, nesting %d)", x->name(), x->type()->tchar(), x->id(), size(), entry_count(), nesting()));
145 }
147 return x;
148 }
151 #define GENERIC_KILL_VALUE(must_kill_implementation) \
152 NOT_PRODUCT(_number_of_kills++); \
153 \
154 for (int i = size() - 1; i >= 0; i--) { \
155 ValueMapEntry* prev_entry = NULL; \
156 for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) { \
157 Value value = entry->value(); \
158 \
159 must_kill_implementation(must_kill, entry, value) \
160 \
161 if (must_kill) { \
162 kill_value(value); \
163 \
164 if (prev_entry == NULL) { \
165 _entries.at_put(i, entry->next()); \
166 _entry_count--; \
167 } else if (prev_entry->nesting() == nesting()) { \
168 prev_entry->set_next(entry->next()); \
169 _entry_count--; \
170 } else { \
171 prev_entry = entry; \
172 } \
173 \
174 TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: killed %s %c%d (size %d, entries %d, nesting-diff %d)", value->name(), value->type()->tchar(), value->id(), size(), entry_count(), nesting() - entry->nesting())); \
175 } else { \
176 prev_entry = entry; \
177 } \
178 } \
179 } \
181 #define MUST_KILL_MEMORY(must_kill, entry, value) \
182 bool must_kill = value->as_LoadField() != NULL || value->as_LoadIndexed() != NULL;
184 #define MUST_KILL_ARRAY(must_kill, entry, value) \
185 bool must_kill = value->as_LoadIndexed() != NULL \
186 && value->type()->tag() == type->tag();
188 #define MUST_KILL_FIELD(must_kill, entry, value) \
189 /* ciField's are not unique; must compare their contents */ \
190 LoadField* lf = value->as_LoadField(); \
191 bool must_kill = lf != NULL \
192 && lf->field()->holder() == field->holder() \
193 && lf->field()->offset() == field->offset();
195 #define MUST_KILL_EXCEPTION(must_kill, entry, value) \
196 assert(entry->nesting() < nesting(), "must not find bigger nesting than current"); \
197 bool must_kill = (entry->nesting() == nesting() - 1);
200 void ValueMap::kill_memory() {
201 GENERIC_KILL_VALUE(MUST_KILL_MEMORY);
202 }
204 void ValueMap::kill_array(ValueType* type) {
205 GENERIC_KILL_VALUE(MUST_KILL_ARRAY);
206 }
208 void ValueMap::kill_field(ciField* field) {
209 GENERIC_KILL_VALUE(MUST_KILL_FIELD);
210 }
212 void ValueMap::kill_exception() {
213 GENERIC_KILL_VALUE(MUST_KILL_EXCEPTION);
214 }
217 void ValueMap::kill_map(ValueMap* map) {
218 assert(is_global_value_numbering(), "only for global value numbering");
219 _killed_values.set_union(&map->_killed_values);
220 }
222 void ValueMap::kill_all() {
223 assert(is_local_value_numbering(), "only for local value numbering");
224 for (int i = size() - 1; i >= 0; i--) {
225 _entries.at_put(i, NULL);
226 }
227 _entry_count = 0;
228 }
231 #ifndef PRODUCT
233 void ValueMap::print() {
234 tty->print_cr("(size %d, entries %d, nesting %d)", size(), entry_count(), nesting());
236 int entries = 0;
237 for (int i = 0; i < size(); i++) {
238 if (entry_at(i) != NULL) {
239 tty->print(" %2d: ", i);
240 for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) {
241 Value value = entry->value();
242 tty->print("%s %c%d (%s%d) -> ", value->name(), value->type()->tchar(), value->id(), is_killed(value) ? "x" : "", entry->nesting());
243 entries++;
244 }
245 tty->print_cr("NULL");
246 }
247 }
249 _killed_values.print();
250 assert(entry_count() == entries, "entry_count incorrect");
251 }
253 void ValueMap::reset_statistics() {
254 _number_of_finds = 0;
255 _number_of_hits = 0;
256 _number_of_kills = 0;
257 }
259 void ValueMap::print_statistics() {
260 float hit_rate = 0;
261 if (_number_of_finds != 0) {
262 hit_rate = (float)_number_of_hits / _number_of_finds;
263 }
265 tty->print_cr("finds:%3d hits:%3d kills:%3d hit rate: %1.4f", _number_of_finds, _number_of_hits, _number_of_kills, hit_rate);
266 }
268 #endif
272 class ShortLoopOptimizer : public ValueNumberingVisitor {
273 private:
274 GlobalValueNumbering* _gvn;
275 BlockList _loop_blocks;
276 bool _too_complicated_loop;
278 // simplified access to methods of GlobalValueNumbering
279 ValueMap* current_map() { return _gvn->current_map(); }
280 ValueMap* value_map_of(BlockBegin* block) { return _gvn->value_map_of(block); }
282 // implementation for abstract methods of ValueNumberingVisitor
283 void kill_memory() { _too_complicated_loop = true; }
284 void kill_field(ciField* field) { current_map()->kill_field(field); };
285 void kill_array(ValueType* type) { current_map()->kill_array(type); };
287 public:
288 ShortLoopOptimizer(GlobalValueNumbering* gvn)
289 : _gvn(gvn)
290 , _loop_blocks(ValueMapMaxLoopSize)
291 , _too_complicated_loop(false)
292 {
293 }
295 bool process(BlockBegin* loop_header);
296 };
299 bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
300 TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block"));
302 _too_complicated_loop = false;
303 _loop_blocks.clear();
304 _loop_blocks.append(loop_header);
306 for (int i = 0; i < _loop_blocks.length(); i++) {
307 BlockBegin* block = _loop_blocks.at(i);
308 TRACE_VALUE_NUMBERING(tty->print_cr("processing loop block B%d", block->block_id()));
310 if (block->is_set(BlockBegin::exception_entry_flag)) {
311 // this would be too complicated
312 return false;
313 }
315 // add predecessors to worklist
316 for (int j = block->number_of_preds() - 1; j >= 0; j--) {
317 BlockBegin* pred = block->pred_at(j);
319 ValueMap* pred_map = value_map_of(pred);
320 if (pred_map != NULL) {
321 current_map()->kill_map(pred_map);
322 } else if (!_loop_blocks.contains(pred)) {
323 if (_loop_blocks.length() >= ValueMapMaxLoopSize) {
324 return false;
325 }
326 _loop_blocks.append(pred);
327 }
328 }
330 // use the instruction visitor for killing values
331 for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
332 instr->visit(this);
333 if (_too_complicated_loop) {
334 return false;
335 }
336 }
337 }
339 TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized"));
340 return true;
341 }
344 GlobalValueNumbering::GlobalValueNumbering(IR* ir)
345 : _current_map(NULL)
346 , _value_maps(ir->linear_scan_order()->length(), NULL)
347 {
348 TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering"));
350 ShortLoopOptimizer short_loop_optimizer(this);
351 int subst_count = 0;
353 BlockList* blocks = ir->linear_scan_order();
354 int num_blocks = blocks->length();
356 BlockBegin* start_block = blocks->at(0);
357 assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block");
358 assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions");
360 // initial, empty value map with nesting 0
361 set_value_map_of(start_block, new ValueMap());
363 for (int i = 1; i < num_blocks; i++) {
364 BlockBegin* block = blocks->at(i);
365 TRACE_VALUE_NUMBERING(tty->print_cr("**** processing block B%d", block->block_id()));
367 int num_preds = block->number_of_preds();
368 assert(num_preds > 0, "block must have predecessors");
370 BlockBegin* dominator = block->dominator();
371 assert(dominator != NULL, "dominator must exist");
372 assert(value_map_of(dominator) != NULL, "value map of dominator must exist");
374 // create new value map with increased nesting
375 _current_map = new ValueMap(value_map_of(dominator));
377 if (num_preds == 1) {
378 assert(dominator == block->pred_at(0), "dominator must be equal to predecessor");
379 // nothing to do here
381 } else if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) {
382 // block has incoming backward branches -> try to optimize short loops
383 if (!short_loop_optimizer.process(block)) {
384 // loop is too complicated, so kill all memory loads because there might be
385 // stores to them in the loop
386 current_map()->kill_memory();
387 }
389 } else {
390 // only incoming forward branches that are already processed
391 for (int j = 0; j < num_preds; j++) {
392 BlockBegin* pred = block->pred_at(j);
393 ValueMap* pred_map = value_map_of(pred);
395 if (pred_map != NULL) {
396 // propagate killed values of the predecessor to this block
397 current_map()->kill_map(value_map_of(pred));
398 } else {
399 // kill all memory loads because predecessor not yet processed
400 // (this can happen with non-natural loops and OSR-compiles)
401 current_map()->kill_memory();
402 }
403 }
404 }
406 if (block->is_set(BlockBegin::exception_entry_flag)) {
407 current_map()->kill_exception();
408 }
410 TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print());
412 // visit all instructions of this block
413 for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
414 assert(!instr->has_subst(), "substitution already set");
416 // check if instruction kills any values
417 instr->visit(this);
419 if (instr->hash() != 0) {
420 Value f = current_map()->find_insert(instr);
421 if (f != instr) {
422 assert(!f->has_subst(), "can't have a substitution");
423 instr->set_subst(f);
424 subst_count++;
425 }
426 }
427 }
429 // remember value map for successors
430 set_value_map_of(block, current_map());
431 }
433 if (subst_count != 0) {
434 SubstitutionResolver resolver(ir);
435 }
437 TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics());
438 }
