GlobalValueNumbering::GlobalValueNumbering(IR* ir) : _current_map(NULL) , _value_maps(ir->linear_scan_order()->length(), NULL) , _compilation(ir->compilation()) { TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering")); ShortLoopOptimizer short_loop_optimizer(this); 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"); // method parameters are not linked in instructions list, so process them separateley for_each_state_value(start_block->state(), value, assert(value->as_Local() != NULL, "only method parameters allowed"); set_processed(value); );
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()); }