--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/c1/c1_ValueMap.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,434 @@
+/*
+ * Copyright 1999-2005 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+#include "incls/_precompiled.incl"
+#include "incls/_c1_ValueMap.cpp.incl"
+
+
+#ifndef PRODUCT
+
+ int ValueMap::_number_of_finds = 0;
+ int ValueMap::_number_of_hits = 0;
+ int ValueMap::_number_of_kills = 0;
+
+ #define TRACE_VALUE_NUMBERING(code) if (PrintValueNumbering) { code; }
+
+#else
+
+ #define TRACE_VALUE_NUMBERING(code)
+
+#endif
+
+
+ValueMap::ValueMap()
+ : _nesting(0)
+ , _entries(ValueMapInitialSize, NULL)
+ , _killed_values()
+ , _entry_count(0)
+{
+ NOT_PRODUCT(reset_statistics());
+}
+
+
+ValueMap::ValueMap(ValueMap* old)
+ : _nesting(old->_nesting + 1)
+ , _entries(old->_entries.length())
+ , _killed_values()
+ , _entry_count(old->_entry_count)
+{
+ for (int i = size() - 1; i >= 0; i--) {
+ _entries.at_put(i, old->entry_at(i));
+ }
+ _killed_values.set_from(&old->_killed_values);
+}
+
+
+void ValueMap::increase_table_size() {
+ int old_size = size();
+ int new_size = old_size * 2 + 1;
+
+ ValueMapEntryList worklist(8);
+ ValueMapEntryArray new_entries(new_size, NULL);
+ int new_entry_count = 0;
+
+ TRACE_VALUE_NUMBERING(tty->print_cr("increasing table size from %d to %d", old_size, new_size));
+
+ for (int i = old_size - 1; i >= 0; i--) {
+ ValueMapEntry* entry;
+ for (entry = entry_at(i); entry != NULL; entry = entry->next()) {
+ if (!is_killed(entry->value())) {
+ worklist.push(entry);
+ }
+ }
+
+ while (!worklist.is_empty()) {
+ entry = worklist.pop();
+ int new_index = entry_index(entry->hash(), new_size);
+
+ if (entry->nesting() != nesting() && new_entries.at(new_index) != entry->next()) {
+ // changing entries with a lower nesting than the current nesting of the table
+ // is not allowed because then the same entry is contained in multiple value maps.
+ // clone entry when next-pointer must be changed
+ entry = new ValueMapEntry(entry->hash(), entry->value(), entry->nesting(), NULL);
+ }
+ entry->set_next(new_entries.at(new_index));
+ new_entries.at_put(new_index, entry);
+ new_entry_count++;
+ }
+ }
+
+ _entries = new_entries;
+ _entry_count = new_entry_count;
+}
+
+
+Value ValueMap::find_insert(Value x) {
+ const intx hash = x->hash();
+ if (hash != 0) {
+ // 0 hash means: exclude from value numbering
+ NOT_PRODUCT(_number_of_finds++);
+
+ for (ValueMapEntry* entry = entry_at(entry_index(hash, size())); entry != NULL; entry = entry->next()) {
+ if (entry->hash() == hash) {
+ Value f = entry->value();
+
+ if (!is_killed(f) && f->is_equal(x)) {
+ NOT_PRODUCT(_number_of_hits++);
+ 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()));
+
+ if (entry->nesting() != nesting() && f->as_Constant() == NULL) {
+ // non-constant values of of another block must be pinned,
+ // otherwise it is possible that they are not evaluated
+ f->pin(Instruction::PinGlobalValueNumbering);
+ }
+
+ return f;
+
+ }
+ }
+ }
+
+ // x not found, so insert it
+ if (entry_count() >= size_threshold()) {
+ increase_table_size();
+ }
+ int idx = entry_index(hash, size());
+ _entries.at_put(idx, new ValueMapEntry(hash, x, nesting(), entry_at(idx)));
+ _entry_count++;
+
+ 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()));
+ }
+
+ return x;
+}
+
+
+#define GENERIC_KILL_VALUE(must_kill_implementation) \
+ NOT_PRODUCT(_number_of_kills++); \
+ \
+ for (int i = size() - 1; i >= 0; i--) { \
+ ValueMapEntry* prev_entry = NULL; \
+ for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) { \
+ Value value = entry->value(); \
+ \
+ must_kill_implementation(must_kill, entry, value) \
+ \
+ if (must_kill) { \
+ kill_value(value); \
+ \
+ if (prev_entry == NULL) { \
+ _entries.at_put(i, entry->next()); \
+ _entry_count--; \
+ } else if (prev_entry->nesting() == nesting()) { \
+ prev_entry->set_next(entry->next()); \
+ _entry_count--; \
+ } else { \
+ prev_entry = entry; \
+ } \
+ \
+ 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())); \
+ } else { \
+ prev_entry = entry; \
+ } \
+ } \
+ } \
+
+#define MUST_KILL_MEMORY(must_kill, entry, value) \
+ bool must_kill = value->as_LoadField() != NULL || value->as_LoadIndexed() != NULL;
+
+#define MUST_KILL_ARRAY(must_kill, entry, value) \
+ bool must_kill = value->as_LoadIndexed() != NULL \
+ && value->type()->tag() == type->tag();
+
+#define MUST_KILL_FIELD(must_kill, entry, value) \
+ /* ciField's are not unique; must compare their contents */ \
+ LoadField* lf = value->as_LoadField(); \
+ bool must_kill = lf != NULL \
+ && lf->field()->holder() == field->holder() \
+ && lf->field()->offset() == field->offset();
+
+#define MUST_KILL_EXCEPTION(must_kill, entry, value) \
+ assert(entry->nesting() < nesting(), "must not find bigger nesting than current"); \
+ bool must_kill = (entry->nesting() == nesting() - 1);
+
+
+void ValueMap::kill_memory() {
+ GENERIC_KILL_VALUE(MUST_KILL_MEMORY);
+}
+
+void ValueMap::kill_array(ValueType* type) {
+ GENERIC_KILL_VALUE(MUST_KILL_ARRAY);
+}
+
+void ValueMap::kill_field(ciField* field) {
+ GENERIC_KILL_VALUE(MUST_KILL_FIELD);
+}
+
+void ValueMap::kill_exception() {
+ GENERIC_KILL_VALUE(MUST_KILL_EXCEPTION);
+}
+
+
+void ValueMap::kill_map(ValueMap* map) {
+ assert(is_global_value_numbering(), "only for global value numbering");
+ _killed_values.set_union(&map->_killed_values);
+}
+
+void ValueMap::kill_all() {
+ assert(is_local_value_numbering(), "only for local value numbering");
+ for (int i = size() - 1; i >= 0; i--) {
+ _entries.at_put(i, NULL);
+ }
+ _entry_count = 0;
+}
+
+
+#ifndef PRODUCT
+
+void ValueMap::print() {
+ tty->print_cr("(size %d, entries %d, nesting %d)", size(), entry_count(), nesting());
+
+ int entries = 0;
+ for (int i = 0; i < size(); i++) {
+ if (entry_at(i) != NULL) {
+ tty->print(" %2d: ", i);
+ for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) {
+ Value value = entry->value();
+ tty->print("%s %c%d (%s%d) -> ", value->name(), value->type()->tchar(), value->id(), is_killed(value) ? "x" : "", entry->nesting());
+ entries++;
+ }
+ tty->print_cr("NULL");
+ }
+ }
+
+ _killed_values.print();
+ assert(entry_count() == entries, "entry_count incorrect");
+}
+
+void ValueMap::reset_statistics() {
+ _number_of_finds = 0;
+ _number_of_hits = 0;
+ _number_of_kills = 0;
+}
+
+void ValueMap::print_statistics() {
+ float hit_rate = 0;
+ if (_number_of_finds != 0) {
+ hit_rate = (float)_number_of_hits / _number_of_finds;
+ }
+
+ tty->print_cr("finds:%3d hits:%3d kills:%3d hit rate: %1.4f", _number_of_finds, _number_of_hits, _number_of_kills, hit_rate);
+}
+
+#endif
+
+
+
+class ShortLoopOptimizer : public ValueNumberingVisitor {
+ private:
+ GlobalValueNumbering* _gvn;
+ BlockList _loop_blocks;
+ bool _too_complicated_loop;
+
+ // simplified access to methods of GlobalValueNumbering
+ ValueMap* current_map() { return _gvn->current_map(); }
+ ValueMap* value_map_of(BlockBegin* block) { return _gvn->value_map_of(block); }
+
+ // implementation for abstract methods of ValueNumberingVisitor
+ void kill_memory() { _too_complicated_loop = true; }
+ void kill_field(ciField* field) { current_map()->kill_field(field); };
+ void kill_array(ValueType* type) { current_map()->kill_array(type); };
+
+ public:
+ ShortLoopOptimizer(GlobalValueNumbering* gvn)
+ : _gvn(gvn)
+ , _loop_blocks(ValueMapMaxLoopSize)
+ , _too_complicated_loop(false)
+ {
+ }
+
+ bool process(BlockBegin* loop_header);
+};
+
+
+bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
+ TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block"));
+
+ _too_complicated_loop = false;
+ _loop_blocks.clear();
+ _loop_blocks.append(loop_header);
+
+ for (int i = 0; i < _loop_blocks.length(); i++) {
+ BlockBegin* block = _loop_blocks.at(i);
+ TRACE_VALUE_NUMBERING(tty->print_cr("processing loop block B%d", block->block_id()));
+
+ if (block->is_set(BlockBegin::exception_entry_flag)) {
+ // this would be too complicated
+ return false;
+ }
+
+ // add predecessors to worklist
+ for (int j = block->number_of_preds() - 1; j >= 0; j--) {
+ BlockBegin* pred = block->pred_at(j);
+
+ ValueMap* pred_map = value_map_of(pred);
+ if (pred_map != NULL) {
+ current_map()->kill_map(pred_map);
+ } else if (!_loop_blocks.contains(pred)) {
+ if (_loop_blocks.length() >= ValueMapMaxLoopSize) {
+ return false;
+ }
+ _loop_blocks.append(pred);
+ }
+ }
+
+ // use the instruction visitor for killing values
+ for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
+ instr->visit(this);
+ if (_too_complicated_loop) {
+ return false;
+ }
+ }
+ }
+
+ TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized"));
+ return true;
+}
+
+
+GlobalValueNumbering::GlobalValueNumbering(IR* ir)
+ : _current_map(NULL)
+ , _value_maps(ir->linear_scan_order()->length(), NULL)
+{
+ TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering"));
+
+ ShortLoopOptimizer short_loop_optimizer(this);
+ int subst_count = 0;
+
+ BlockList* blocks = ir->linear_scan_order();
+ int num_blocks = blocks->length();
+
+ BlockBegin* start_block = blocks->at(0);
+ assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block");
+ assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions");
+
+ // initial, empty value map with nesting 0
+ set_value_map_of(start_block, new ValueMap());
+
+ for (int i = 1; i < num_blocks; i++) {
+ BlockBegin* block = blocks->at(i);
+ TRACE_VALUE_NUMBERING(tty->print_cr("**** processing block B%d", block->block_id()));
+
+ int num_preds = block->number_of_preds();
+ assert(num_preds > 0, "block must have predecessors");
+
+ BlockBegin* dominator = block->dominator();
+ assert(dominator != NULL, "dominator must exist");
+ assert(value_map_of(dominator) != NULL, "value map of dominator must exist");
+
+ // create new value map with increased nesting
+ _current_map = new ValueMap(value_map_of(dominator));
+
+ if (num_preds == 1) {
+ assert(dominator == block->pred_at(0), "dominator must be equal to predecessor");
+ // nothing to do here
+
+ } else if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) {
+ // block has incoming backward branches -> try to optimize short loops
+ if (!short_loop_optimizer.process(block)) {
+ // loop is too complicated, so kill all memory loads because there might be
+ // stores to them in the loop
+ current_map()->kill_memory();
+ }
+
+ } else {
+ // only incoming forward branches that are already processed
+ for (int j = 0; j < num_preds; j++) {
+ BlockBegin* pred = block->pred_at(j);
+ ValueMap* pred_map = value_map_of(pred);
+
+ if (pred_map != NULL) {
+ // propagate killed values of the predecessor to this block
+ current_map()->kill_map(value_map_of(pred));
+ } else {
+ // kill all memory loads because predecessor not yet processed
+ // (this can happen with non-natural loops and OSR-compiles)
+ current_map()->kill_memory();
+ }
+ }
+ }
+
+ if (block->is_set(BlockBegin::exception_entry_flag)) {
+ current_map()->kill_exception();
+ }
+
+ TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print());
+
+ // visit all instructions of this block
+ for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
+ assert(!instr->has_subst(), "substitution already set");
+
+ // check if instruction kills any values
+ instr->visit(this);
+
+ if (instr->hash() != 0) {
+ Value f = current_map()->find_insert(instr);
+ if (f != instr) {
+ assert(!f->has_subst(), "can't have a substitution");
+ instr->set_subst(f);
+ subst_count++;
+ }
+ }
+ }
+
+ // remember value map for successors
+ set_value_map_of(block, current_map());
+ }
+
+ if (subst_count != 0) {
+ SubstitutionResolver resolver(ir);
+ }
+
+ TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics());
+}