1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/c1/c1_ValueMap.cpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,434 @@
1.4 +/*
1.5 + * Copyright 1999-2005 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "incls/_precompiled.incl"
1.29 +#include "incls/_c1_ValueMap.cpp.incl"
1.30 +
1.31 +
1.32 +#ifndef PRODUCT
1.33 +
1.34 + int ValueMap::_number_of_finds = 0;
1.35 + int ValueMap::_number_of_hits = 0;
1.36 + int ValueMap::_number_of_kills = 0;
1.37 +
1.38 + #define TRACE_VALUE_NUMBERING(code) if (PrintValueNumbering) { code; }
1.39 +
1.40 +#else
1.41 +
1.42 + #define TRACE_VALUE_NUMBERING(code)
1.43 +
1.44 +#endif
1.45 +
1.46 +
1.47 +ValueMap::ValueMap()
1.48 + : _nesting(0)
1.49 + , _entries(ValueMapInitialSize, NULL)
1.50 + , _killed_values()
1.51 + , _entry_count(0)
1.52 +{
1.53 + NOT_PRODUCT(reset_statistics());
1.54 +}
1.55 +
1.56 +
1.57 +ValueMap::ValueMap(ValueMap* old)
1.58 + : _nesting(old->_nesting + 1)
1.59 + , _entries(old->_entries.length())
1.60 + , _killed_values()
1.61 + , _entry_count(old->_entry_count)
1.62 +{
1.63 + for (int i = size() - 1; i >= 0; i--) {
1.64 + _entries.at_put(i, old->entry_at(i));
1.65 + }
1.66 + _killed_values.set_from(&old->_killed_values);
1.67 +}
1.68 +
1.69 +
1.70 +void ValueMap::increase_table_size() {
1.71 + int old_size = size();
1.72 + int new_size = old_size * 2 + 1;
1.73 +
1.74 + ValueMapEntryList worklist(8);
1.75 + ValueMapEntryArray new_entries(new_size, NULL);
1.76 + int new_entry_count = 0;
1.77 +
1.78 + TRACE_VALUE_NUMBERING(tty->print_cr("increasing table size from %d to %d", old_size, new_size));
1.79 +
1.80 + for (int i = old_size - 1; i >= 0; i--) {
1.81 + ValueMapEntry* entry;
1.82 + for (entry = entry_at(i); entry != NULL; entry = entry->next()) {
1.83 + if (!is_killed(entry->value())) {
1.84 + worklist.push(entry);
1.85 + }
1.86 + }
1.87 +
1.88 + while (!worklist.is_empty()) {
1.89 + entry = worklist.pop();
1.90 + int new_index = entry_index(entry->hash(), new_size);
1.91 +
1.92 + if (entry->nesting() != nesting() && new_entries.at(new_index) != entry->next()) {
1.93 + // changing entries with a lower nesting than the current nesting of the table
1.94 + // is not allowed because then the same entry is contained in multiple value maps.
1.95 + // clone entry when next-pointer must be changed
1.96 + entry = new ValueMapEntry(entry->hash(), entry->value(), entry->nesting(), NULL);
1.97 + }
1.98 + entry->set_next(new_entries.at(new_index));
1.99 + new_entries.at_put(new_index, entry);
1.100 + new_entry_count++;
1.101 + }
1.102 + }
1.103 +
1.104 + _entries = new_entries;
1.105 + _entry_count = new_entry_count;
1.106 +}
1.107 +
1.108 +
1.109 +Value ValueMap::find_insert(Value x) {
1.110 + const intx hash = x->hash();
1.111 + if (hash != 0) {
1.112 + // 0 hash means: exclude from value numbering
1.113 + NOT_PRODUCT(_number_of_finds++);
1.114 +
1.115 + for (ValueMapEntry* entry = entry_at(entry_index(hash, size())); entry != NULL; entry = entry->next()) {
1.116 + if (entry->hash() == hash) {
1.117 + Value f = entry->value();
1.118 +
1.119 + if (!is_killed(f) && f->is_equal(x)) {
1.120 + NOT_PRODUCT(_number_of_hits++);
1.121 + 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()));
1.122 +
1.123 + if (entry->nesting() != nesting() && f->as_Constant() == NULL) {
1.124 + // non-constant values of of another block must be pinned,
1.125 + // otherwise it is possible that they are not evaluated
1.126 + f->pin(Instruction::PinGlobalValueNumbering);
1.127 + }
1.128 +
1.129 + return f;
1.130 +
1.131 + }
1.132 + }
1.133 + }
1.134 +
1.135 + // x not found, so insert it
1.136 + if (entry_count() >= size_threshold()) {
1.137 + increase_table_size();
1.138 + }
1.139 + int idx = entry_index(hash, size());
1.140 + _entries.at_put(idx, new ValueMapEntry(hash, x, nesting(), entry_at(idx)));
1.141 + _entry_count++;
1.142 +
1.143 + 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()));
1.144 + }
1.145 +
1.146 + return x;
1.147 +}
1.148 +
1.149 +
1.150 +#define GENERIC_KILL_VALUE(must_kill_implementation) \
1.151 + NOT_PRODUCT(_number_of_kills++); \
1.152 + \
1.153 + for (int i = size() - 1; i >= 0; i--) { \
1.154 + ValueMapEntry* prev_entry = NULL; \
1.155 + for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) { \
1.156 + Value value = entry->value(); \
1.157 + \
1.158 + must_kill_implementation(must_kill, entry, value) \
1.159 + \
1.160 + if (must_kill) { \
1.161 + kill_value(value); \
1.162 + \
1.163 + if (prev_entry == NULL) { \
1.164 + _entries.at_put(i, entry->next()); \
1.165 + _entry_count--; \
1.166 + } else if (prev_entry->nesting() == nesting()) { \
1.167 + prev_entry->set_next(entry->next()); \
1.168 + _entry_count--; \
1.169 + } else { \
1.170 + prev_entry = entry; \
1.171 + } \
1.172 + \
1.173 + 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())); \
1.174 + } else { \
1.175 + prev_entry = entry; \
1.176 + } \
1.177 + } \
1.178 + } \
1.179 +
1.180 +#define MUST_KILL_MEMORY(must_kill, entry, value) \
1.181 + bool must_kill = value->as_LoadField() != NULL || value->as_LoadIndexed() != NULL;
1.182 +
1.183 +#define MUST_KILL_ARRAY(must_kill, entry, value) \
1.184 + bool must_kill = value->as_LoadIndexed() != NULL \
1.185 + && value->type()->tag() == type->tag();
1.186 +
1.187 +#define MUST_KILL_FIELD(must_kill, entry, value) \
1.188 + /* ciField's are not unique; must compare their contents */ \
1.189 + LoadField* lf = value->as_LoadField(); \
1.190 + bool must_kill = lf != NULL \
1.191 + && lf->field()->holder() == field->holder() \
1.192 + && lf->field()->offset() == field->offset();
1.193 +
1.194 +#define MUST_KILL_EXCEPTION(must_kill, entry, value) \
1.195 + assert(entry->nesting() < nesting(), "must not find bigger nesting than current"); \
1.196 + bool must_kill = (entry->nesting() == nesting() - 1);
1.197 +
1.198 +
1.199 +void ValueMap::kill_memory() {
1.200 + GENERIC_KILL_VALUE(MUST_KILL_MEMORY);
1.201 +}
1.202 +
1.203 +void ValueMap::kill_array(ValueType* type) {
1.204 + GENERIC_KILL_VALUE(MUST_KILL_ARRAY);
1.205 +}
1.206 +
1.207 +void ValueMap::kill_field(ciField* field) {
1.208 + GENERIC_KILL_VALUE(MUST_KILL_FIELD);
1.209 +}
1.210 +
1.211 +void ValueMap::kill_exception() {
1.212 + GENERIC_KILL_VALUE(MUST_KILL_EXCEPTION);
1.213 +}
1.214 +
1.215 +
1.216 +void ValueMap::kill_map(ValueMap* map) {
1.217 + assert(is_global_value_numbering(), "only for global value numbering");
1.218 + _killed_values.set_union(&map->_killed_values);
1.219 +}
1.220 +
1.221 +void ValueMap::kill_all() {
1.222 + assert(is_local_value_numbering(), "only for local value numbering");
1.223 + for (int i = size() - 1; i >= 0; i--) {
1.224 + _entries.at_put(i, NULL);
1.225 + }
1.226 + _entry_count = 0;
1.227 +}
1.228 +
1.229 +
1.230 +#ifndef PRODUCT
1.231 +
1.232 +void ValueMap::print() {
1.233 + tty->print_cr("(size %d, entries %d, nesting %d)", size(), entry_count(), nesting());
1.234 +
1.235 + int entries = 0;
1.236 + for (int i = 0; i < size(); i++) {
1.237 + if (entry_at(i) != NULL) {
1.238 + tty->print(" %2d: ", i);
1.239 + for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) {
1.240 + Value value = entry->value();
1.241 + tty->print("%s %c%d (%s%d) -> ", value->name(), value->type()->tchar(), value->id(), is_killed(value) ? "x" : "", entry->nesting());
1.242 + entries++;
1.243 + }
1.244 + tty->print_cr("NULL");
1.245 + }
1.246 + }
1.247 +
1.248 + _killed_values.print();
1.249 + assert(entry_count() == entries, "entry_count incorrect");
1.250 +}
1.251 +
1.252 +void ValueMap::reset_statistics() {
1.253 + _number_of_finds = 0;
1.254 + _number_of_hits = 0;
1.255 + _number_of_kills = 0;
1.256 +}
1.257 +
1.258 +void ValueMap::print_statistics() {
1.259 + float hit_rate = 0;
1.260 + if (_number_of_finds != 0) {
1.261 + hit_rate = (float)_number_of_hits / _number_of_finds;
1.262 + }
1.263 +
1.264 + tty->print_cr("finds:%3d hits:%3d kills:%3d hit rate: %1.4f", _number_of_finds, _number_of_hits, _number_of_kills, hit_rate);
1.265 +}
1.266 +
1.267 +#endif
1.268 +
1.269 +
1.270 +
1.271 +class ShortLoopOptimizer : public ValueNumberingVisitor {
1.272 + private:
1.273 + GlobalValueNumbering* _gvn;
1.274 + BlockList _loop_blocks;
1.275 + bool _too_complicated_loop;
1.276 +
1.277 + // simplified access to methods of GlobalValueNumbering
1.278 + ValueMap* current_map() { return _gvn->current_map(); }
1.279 + ValueMap* value_map_of(BlockBegin* block) { return _gvn->value_map_of(block); }
1.280 +
1.281 + // implementation for abstract methods of ValueNumberingVisitor
1.282 + void kill_memory() { _too_complicated_loop = true; }
1.283 + void kill_field(ciField* field) { current_map()->kill_field(field); };
1.284 + void kill_array(ValueType* type) { current_map()->kill_array(type); };
1.285 +
1.286 + public:
1.287 + ShortLoopOptimizer(GlobalValueNumbering* gvn)
1.288 + : _gvn(gvn)
1.289 + , _loop_blocks(ValueMapMaxLoopSize)
1.290 + , _too_complicated_loop(false)
1.291 + {
1.292 + }
1.293 +
1.294 + bool process(BlockBegin* loop_header);
1.295 +};
1.296 +
1.297 +
1.298 +bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
1.299 + TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block"));
1.300 +
1.301 + _too_complicated_loop = false;
1.302 + _loop_blocks.clear();
1.303 + _loop_blocks.append(loop_header);
1.304 +
1.305 + for (int i = 0; i < _loop_blocks.length(); i++) {
1.306 + BlockBegin* block = _loop_blocks.at(i);
1.307 + TRACE_VALUE_NUMBERING(tty->print_cr("processing loop block B%d", block->block_id()));
1.308 +
1.309 + if (block->is_set(BlockBegin::exception_entry_flag)) {
1.310 + // this would be too complicated
1.311 + return false;
1.312 + }
1.313 +
1.314 + // add predecessors to worklist
1.315 + for (int j = block->number_of_preds() - 1; j >= 0; j--) {
1.316 + BlockBegin* pred = block->pred_at(j);
1.317 +
1.318 + ValueMap* pred_map = value_map_of(pred);
1.319 + if (pred_map != NULL) {
1.320 + current_map()->kill_map(pred_map);
1.321 + } else if (!_loop_blocks.contains(pred)) {
1.322 + if (_loop_blocks.length() >= ValueMapMaxLoopSize) {
1.323 + return false;
1.324 + }
1.325 + _loop_blocks.append(pred);
1.326 + }
1.327 + }
1.328 +
1.329 + // use the instruction visitor for killing values
1.330 + for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
1.331 + instr->visit(this);
1.332 + if (_too_complicated_loop) {
1.333 + return false;
1.334 + }
1.335 + }
1.336 + }
1.337 +
1.338 + TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized"));
1.339 + return true;
1.340 +}
1.341 +
1.342 +
1.343 +GlobalValueNumbering::GlobalValueNumbering(IR* ir)
1.344 + : _current_map(NULL)
1.345 + , _value_maps(ir->linear_scan_order()->length(), NULL)
1.346 +{
1.347 + TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering"));
1.348 +
1.349 + ShortLoopOptimizer short_loop_optimizer(this);
1.350 + int subst_count = 0;
1.351 +
1.352 + BlockList* blocks = ir->linear_scan_order();
1.353 + int num_blocks = blocks->length();
1.354 +
1.355 + BlockBegin* start_block = blocks->at(0);
1.356 + assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block");
1.357 + assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions");
1.358 +
1.359 + // initial, empty value map with nesting 0
1.360 + set_value_map_of(start_block, new ValueMap());
1.361 +
1.362 + for (int i = 1; i < num_blocks; i++) {
1.363 + BlockBegin* block = blocks->at(i);
1.364 + TRACE_VALUE_NUMBERING(tty->print_cr("**** processing block B%d", block->block_id()));
1.365 +
1.366 + int num_preds = block->number_of_preds();
1.367 + assert(num_preds > 0, "block must have predecessors");
1.368 +
1.369 + BlockBegin* dominator = block->dominator();
1.370 + assert(dominator != NULL, "dominator must exist");
1.371 + assert(value_map_of(dominator) != NULL, "value map of dominator must exist");
1.372 +
1.373 + // create new value map with increased nesting
1.374 + _current_map = new ValueMap(value_map_of(dominator));
1.375 +
1.376 + if (num_preds == 1) {
1.377 + assert(dominator == block->pred_at(0), "dominator must be equal to predecessor");
1.378 + // nothing to do here
1.379 +
1.380 + } else if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) {
1.381 + // block has incoming backward branches -> try to optimize short loops
1.382 + if (!short_loop_optimizer.process(block)) {
1.383 + // loop is too complicated, so kill all memory loads because there might be
1.384 + // stores to them in the loop
1.385 + current_map()->kill_memory();
1.386 + }
1.387 +
1.388 + } else {
1.389 + // only incoming forward branches that are already processed
1.390 + for (int j = 0; j < num_preds; j++) {
1.391 + BlockBegin* pred = block->pred_at(j);
1.392 + ValueMap* pred_map = value_map_of(pred);
1.393 +
1.394 + if (pred_map != NULL) {
1.395 + // propagate killed values of the predecessor to this block
1.396 + current_map()->kill_map(value_map_of(pred));
1.397 + } else {
1.398 + // kill all memory loads because predecessor not yet processed
1.399 + // (this can happen with non-natural loops and OSR-compiles)
1.400 + current_map()->kill_memory();
1.401 + }
1.402 + }
1.403 + }
1.404 +
1.405 + if (block->is_set(BlockBegin::exception_entry_flag)) {
1.406 + current_map()->kill_exception();
1.407 + }
1.408 +
1.409 + TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print());
1.410 +
1.411 + // visit all instructions of this block
1.412 + for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
1.413 + assert(!instr->has_subst(), "substitution already set");
1.414 +
1.415 + // check if instruction kills any values
1.416 + instr->visit(this);
1.417 +
1.418 + if (instr->hash() != 0) {
1.419 + Value f = current_map()->find_insert(instr);
1.420 + if (f != instr) {
1.421 + assert(!f->has_subst(), "can't have a substitution");
1.422 + instr->set_subst(f);
1.423 + subst_count++;
1.424 + }
1.425 + }
1.426 + }
1.427 +
1.428 + // remember value map for successors
1.429 + set_value_map_of(block, current_map());
1.430 + }
1.431 +
1.432 + if (subst_count != 0) {
1.433 + SubstitutionResolver resolver(ir);
1.434 + }
1.435 +
1.436 + TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics());
1.437 +}
