| /* |
| * Copyright (c) 2006, 2012, 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 "memory/allocation.inline.hpp" |
| #include "opto/connode.hpp" |
| #include "opto/loopnode.hpp" |
| #include "opto/rootnode.hpp" |
| |
| //================= Loop Unswitching ===================== |
| // |
| // orig: transformed: |
| // if (invariant-test) then |
| // predicate predicate |
| // loop loop |
| // stmt1 stmt1 |
| // if (invariant-test) then stmt2 |
| // stmt2 stmt4 |
| // else endloop |
| // stmt3 else |
| // endif predicate [clone] |
| // stmt4 loop [clone] |
| // endloop stmt1 [clone] |
| // stmt3 |
| // stmt4 [clone] |
| // endloop |
| // endif |
| // |
| // Note: the "else" clause may be empty |
| |
| //------------------------------policy_unswitching----------------------------- |
| // Return TRUE or FALSE if the loop should be unswitched |
| // (ie. clone loop with an invariant test that does not exit the loop) |
| bool IdealLoopTree::policy_unswitching( PhaseIdealLoop *phase ) const { |
| if( !LoopUnswitching ) { |
| return false; |
| } |
| if (!_head->is_Loop()) { |
| return false; |
| } |
| int nodes_left = phase->C->max_node_limit() - phase->C->live_nodes(); |
| if ((int)(2 * _body.size()) > nodes_left) { |
| return false; // Too speculative if running low on nodes. |
| } |
| LoopNode* head = _head->as_Loop(); |
| if (head->unswitch_count() + 1 > head->unswitch_max()) { |
| return false; |
| } |
| return phase->find_unswitching_candidate(this) != NULL; |
| } |
| |
| //------------------------------find_unswitching_candidate----------------------------- |
| // Find candidate "if" for unswitching |
| IfNode* PhaseIdealLoop::find_unswitching_candidate(const IdealLoopTree *loop) const { |
| |
| // Find first invariant test that doesn't exit the loop |
| LoopNode *head = loop->_head->as_Loop(); |
| IfNode* unswitch_iff = NULL; |
| Node* n = head->in(LoopNode::LoopBackControl); |
| while (n != head) { |
| Node* n_dom = idom(n); |
| if (n->is_Region()) { |
| if (n_dom->is_If()) { |
| IfNode* iff = n_dom->as_If(); |
| if (iff->in(1)->is_Bool()) { |
| BoolNode* bol = iff->in(1)->as_Bool(); |
| if (bol->in(1)->is_Cmp()) { |
| // If condition is invariant and not a loop exit, |
| // then found reason to unswitch. |
| if (loop->is_invariant(bol) && !loop->is_loop_exit(iff)) { |
| unswitch_iff = iff; |
| } |
| } |
| } |
| } |
| } |
| n = n_dom; |
| } |
| return unswitch_iff; |
| } |
| |
| //------------------------------do_unswitching----------------------------- |
| // Clone loop with an invariant test (that does not exit) and |
| // insert a clone of the test that selects which version to |
| // execute. |
| void PhaseIdealLoop::do_unswitching (IdealLoopTree *loop, Node_List &old_new) { |
| |
| // Find first invariant test that doesn't exit the loop |
| LoopNode *head = loop->_head->as_Loop(); |
| |
| IfNode* unswitch_iff = find_unswitching_candidate((const IdealLoopTree *)loop); |
| assert(unswitch_iff != NULL, "should be at least one"); |
| |
| #ifndef PRODUCT |
| if (TraceLoopOpts) { |
| tty->print("Unswitch %d ", head->unswitch_count()+1); |
| loop->dump_head(); |
| } |
| #endif |
| |
| // Need to revert back to normal loop |
| if (head->is_CountedLoop() && !head->as_CountedLoop()->is_normal_loop()) { |
| head->as_CountedLoop()->set_normal_loop(); |
| } |
| |
| ProjNode* proj_true = create_slow_version_of_loop(loop, old_new); |
| |
| #ifdef ASSERT |
| Node* uniqc = proj_true->unique_ctrl_out(); |
| Node* entry = head->in(LoopNode::EntryControl); |
| Node* predicate = find_predicate(entry); |
| if (predicate != NULL && LoopLimitCheck && UseLoopPredicate) { |
| // We may have two predicates, find first. |
| entry = find_predicate(entry->in(0)->in(0)); |
| if (entry != NULL) predicate = entry; |
| } |
| if (predicate != NULL) predicate = predicate->in(0); |
| assert(proj_true->is_IfTrue() && |
| (predicate == NULL && uniqc == head || |
| predicate != NULL && uniqc == predicate), "by construction"); |
| #endif |
| // Increment unswitch count |
| LoopNode* head_clone = old_new[head->_idx]->as_Loop(); |
| int nct = head->unswitch_count() + 1; |
| head->set_unswitch_count(nct); |
| head_clone->set_unswitch_count(nct); |
| |
| // Add test to new "if" outside of loop |
| IfNode* invar_iff = proj_true->in(0)->as_If(); |
| Node* invar_iff_c = invar_iff->in(0); |
| BoolNode* bol = unswitch_iff->in(1)->as_Bool(); |
| invar_iff->set_req(1, bol); |
| invar_iff->_prob = unswitch_iff->_prob; |
| |
| ProjNode* proj_false = invar_iff->proj_out(0)->as_Proj(); |
| |
| // Hoist invariant casts out of each loop to the appropriate |
| // control projection. |
| |
| Node_List worklist; |
| |
| for (DUIterator_Fast imax, i = unswitch_iff->fast_outs(imax); i < imax; i++) { |
| ProjNode* proj= unswitch_iff->fast_out(i)->as_Proj(); |
| // Copy to a worklist for easier manipulation |
| for (DUIterator_Fast jmax, j = proj->fast_outs(jmax); j < jmax; j++) { |
| Node* use = proj->fast_out(j); |
| if (use->Opcode() == Op_CheckCastPP && loop->is_invariant(use->in(1))) { |
| worklist.push(use); |
| } |
| } |
| ProjNode* invar_proj = invar_iff->proj_out(proj->_con)->as_Proj(); |
| while (worklist.size() > 0) { |
| Node* use = worklist.pop(); |
| Node* nuse = use->clone(); |
| nuse->set_req(0, invar_proj); |
| _igvn.replace_input_of(use, 1, nuse); |
| register_new_node(nuse, invar_proj); |
| // Same for the clone |
| Node* use_clone = old_new[use->_idx]; |
| _igvn.replace_input_of(use_clone, 1, nuse); |
| } |
| } |
| |
| // Hardwire the control paths in the loops into if(true) and if(false) |
| _igvn.rehash_node_delayed(unswitch_iff); |
| short_circuit_if(unswitch_iff, proj_true); |
| |
| IfNode* unswitch_iff_clone = old_new[unswitch_iff->_idx]->as_If(); |
| _igvn.rehash_node_delayed(unswitch_iff_clone); |
| short_circuit_if(unswitch_iff_clone, proj_false); |
| |
| // Reoptimize loops |
| loop->record_for_igvn(); |
| for(int i = loop->_body.size() - 1; i >= 0 ; i--) { |
| Node *n = loop->_body[i]; |
| Node *n_clone = old_new[n->_idx]; |
| _igvn._worklist.push(n_clone); |
| } |
| |
| #ifndef PRODUCT |
| if (TraceLoopUnswitching) { |
| tty->print_cr("Loop unswitching orig: %d @ %d new: %d @ %d", |
| head->_idx, unswitch_iff->_idx, |
| old_new[head->_idx]->_idx, unswitch_iff_clone->_idx); |
| } |
| #endif |
| |
| C->set_major_progress(); |
| } |
| |
| //-------------------------create_slow_version_of_loop------------------------ |
| // Create a slow version of the loop by cloning the loop |
| // and inserting an if to select fast-slow versions. |
| // Return control projection of the entry to the fast version. |
| ProjNode* PhaseIdealLoop::create_slow_version_of_loop(IdealLoopTree *loop, |
| Node_List &old_new) { |
| LoopNode* head = loop->_head->as_Loop(); |
| bool counted_loop = head->is_CountedLoop(); |
| Node* entry = head->in(LoopNode::EntryControl); |
| _igvn.rehash_node_delayed(entry); |
| IdealLoopTree* outer_loop = loop->_parent; |
| |
| Node *cont = _igvn.intcon(1); |
| set_ctrl(cont, C->root()); |
| Node* opq = new (C) Opaque1Node(C, cont); |
| register_node(opq, outer_loop, entry, dom_depth(entry)); |
| Node *bol = new (C) Conv2BNode(opq); |
| register_node(bol, outer_loop, entry, dom_depth(entry)); |
| IfNode* iff = new (C) IfNode(entry, bol, PROB_MAX, COUNT_UNKNOWN); |
| register_node(iff, outer_loop, entry, dom_depth(entry)); |
| ProjNode* iffast = new (C) IfTrueNode(iff); |
| register_node(iffast, outer_loop, iff, dom_depth(iff)); |
| ProjNode* ifslow = new (C) IfFalseNode(iff); |
| register_node(ifslow, outer_loop, iff, dom_depth(iff)); |
| |
| // Clone the loop body. The clone becomes the fast loop. The |
| // original pre-header will (illegally) have 3 control users |
| // (old & new loops & new if). |
| clone_loop(loop, old_new, dom_depth(head), iff); |
| assert(old_new[head->_idx]->is_Loop(), "" ); |
| |
| // Fast (true) control |
| Node* iffast_pred = clone_loop_predicates(entry, iffast, !counted_loop); |
| _igvn.replace_input_of(head, LoopNode::EntryControl, iffast_pred); |
| set_idom(head, iffast_pred, dom_depth(head)); |
| |
| // Slow (false) control |
| Node* ifslow_pred = clone_loop_predicates(entry, ifslow, !counted_loop); |
| LoopNode* slow_head = old_new[head->_idx]->as_Loop(); |
| _igvn.replace_input_of(slow_head, LoopNode::EntryControl, ifslow_pred); |
| set_idom(slow_head, ifslow_pred, dom_depth(slow_head)); |
| |
| recompute_dom_depth(); |
| |
| return iffast; |
| } |
