jdk8-mips64-public/hotspot: src/share/vm/c1/c1_ValueMap.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_ValueMap.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_ValueMap.cpp

Wed, 31 Aug 2011 16:46:11 -0700

author: never
date: Wed, 31 Aug 2011 16:46:11 -0700
changeset 3099: c124e2e7463e
parent 2314: f95d63e2154a
child 3498: f067b4e0e04b
permissions: -rw-r--r--

7083786: dead various dead chunks of code
Reviewed-by: iveresov, kvn

 /*
  * Copyright (c) 1999, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "c1/c1_Canonicalizer.hpp"
 #include "c1/c1_IR.hpp"
 #include "c1/c1_ValueMap.hpp"
 #include "utilities/bitMap.inline.hpp"
 #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());
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/c1/c1_ValueMap.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_ValueMap.cpp