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