414 lines
14 KiB
C++
414 lines
14 KiB
C++
/*
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* Copyright (c) 2006, 2012, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "memory/allocation.inline.hpp"
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#include "opto/connode.hpp"
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#include "opto/convertnode.hpp"
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#include "opto/loopnode.hpp"
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#include "opto/opaquenode.hpp"
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#include "opto/rootnode.hpp"
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//================= Loop Unswitching =====================
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//
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// orig: transformed:
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// if (invariant-test) then
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// predicate predicate
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// loop loop
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// stmt1 stmt1
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// if (invariant-test) then stmt2
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// stmt2 stmt4
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// else endloop
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// stmt3 else
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// endif predicate [clone]
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// stmt4 loop [clone]
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// endloop stmt1 [clone]
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// stmt3
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// stmt4 [clone]
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// endloop
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// endif
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//
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// Note: the "else" clause may be empty
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//------------------------------policy_unswitching-----------------------------
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// Return TRUE or FALSE if the loop should be unswitched
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// (ie. clone loop with an invariant test that does not exit the loop)
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bool IdealLoopTree::policy_unswitching( PhaseIdealLoop *phase ) const {
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if( !LoopUnswitching ) {
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return false;
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}
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if (!_head->is_Loop()) {
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return false;
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}
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// check for vectorized loops, any unswitching was already applied
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if (_head->is_CountedLoop() && _head->as_CountedLoop()->do_unroll_only()) {
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return false;
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}
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int nodes_left = phase->C->max_node_limit() - phase->C->live_nodes();
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if ((int)(2 * _body.size()) > nodes_left) {
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return false; // Too speculative if running low on nodes.
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}
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LoopNode* head = _head->as_Loop();
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if (head->unswitch_count() + 1 > head->unswitch_max()) {
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return false;
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}
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return phase->find_unswitching_candidate(this) != NULL;
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}
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//------------------------------find_unswitching_candidate-----------------------------
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// Find candidate "if" for unswitching
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IfNode* PhaseIdealLoop::find_unswitching_candidate(const IdealLoopTree *loop) const {
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// Find first invariant test that doesn't exit the loop
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LoopNode *head = loop->_head->as_Loop();
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IfNode* unswitch_iff = NULL;
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Node* n = head->in(LoopNode::LoopBackControl);
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while (n != head) {
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Node* n_dom = idom(n);
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if (n->is_Region()) {
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if (n_dom->is_If()) {
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IfNode* iff = n_dom->as_If();
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if (iff->in(1)->is_Bool()) {
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BoolNode* bol = iff->in(1)->as_Bool();
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if (bol->in(1)->is_Cmp()) {
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// If condition is invariant and not a loop exit,
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// then found reason to unswitch.
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if (loop->is_invariant(bol) && !loop->is_loop_exit(iff)) {
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unswitch_iff = iff;
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}
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}
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}
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}
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}
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n = n_dom;
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}
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return unswitch_iff;
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}
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//------------------------------do_unswitching-----------------------------
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// Clone loop with an invariant test (that does not exit) and
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// insert a clone of the test that selects which version to
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// execute.
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void PhaseIdealLoop::do_unswitching (IdealLoopTree *loop, Node_List &old_new) {
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// Find first invariant test that doesn't exit the loop
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LoopNode *head = loop->_head->as_Loop();
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IfNode* unswitch_iff = find_unswitching_candidate((const IdealLoopTree *)loop);
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assert(unswitch_iff != NULL, "should be at least one");
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#ifndef PRODUCT
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if (TraceLoopOpts) {
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tty->print("Unswitch %d ", head->unswitch_count()+1);
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loop->dump_head();
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}
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#endif
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// Need to revert back to normal loop
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if (head->is_CountedLoop() && !head->as_CountedLoop()->is_normal_loop()) {
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head->as_CountedLoop()->set_normal_loop();
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}
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ProjNode* proj_true = create_slow_version_of_loop(loop, old_new, unswitch_iff->Opcode());
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#ifdef ASSERT
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Node* uniqc = proj_true->unique_ctrl_out();
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Node* entry = head->in(LoopNode::EntryControl);
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Node* predicate = find_predicate(entry);
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if (predicate != NULL && UseLoopPredicate) {
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// We may have two predicates, find first.
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entry = find_predicate(entry->in(0)->in(0));
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if (entry != NULL) predicate = entry;
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}
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if (predicate != NULL) predicate = predicate->in(0);
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assert(proj_true->is_IfTrue() &&
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(predicate == NULL && uniqc == head ||
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predicate != NULL && uniqc == predicate), "by construction");
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#endif
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// Increment unswitch count
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LoopNode* head_clone = old_new[head->_idx]->as_Loop();
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int nct = head->unswitch_count() + 1;
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head->set_unswitch_count(nct);
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head_clone->set_unswitch_count(nct);
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// Add test to new "if" outside of loop
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IfNode* invar_iff = proj_true->in(0)->as_If();
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Node* invar_iff_c = invar_iff->in(0);
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BoolNode* bol = unswitch_iff->in(1)->as_Bool();
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invar_iff->set_req(1, bol);
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invar_iff->_prob = unswitch_iff->_prob;
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ProjNode* proj_false = invar_iff->proj_out(0)->as_Proj();
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// Hoist invariant casts out of each loop to the appropriate
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// control projection.
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Node_List worklist;
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for (DUIterator_Fast imax, i = unswitch_iff->fast_outs(imax); i < imax; i++) {
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ProjNode* proj= unswitch_iff->fast_out(i)->as_Proj();
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// Copy to a worklist for easier manipulation
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for (DUIterator_Fast jmax, j = proj->fast_outs(jmax); j < jmax; j++) {
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Node* use = proj->fast_out(j);
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if (use->Opcode() == Op_CheckCastPP && loop->is_invariant(use->in(1))) {
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worklist.push(use);
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}
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}
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ProjNode* invar_proj = invar_iff->proj_out(proj->_con)->as_Proj();
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while (worklist.size() > 0) {
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Node* use = worklist.pop();
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Node* nuse = use->clone();
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nuse->set_req(0, invar_proj);
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_igvn.replace_input_of(use, 1, nuse);
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register_new_node(nuse, invar_proj);
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// Same for the clone
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Node* use_clone = old_new[use->_idx];
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_igvn.replace_input_of(use_clone, 1, nuse);
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}
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}
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// Hardwire the control paths in the loops into if(true) and if(false)
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_igvn.rehash_node_delayed(unswitch_iff);
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short_circuit_if(unswitch_iff, proj_true);
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IfNode* unswitch_iff_clone = old_new[unswitch_iff->_idx]->as_If();
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_igvn.rehash_node_delayed(unswitch_iff_clone);
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short_circuit_if(unswitch_iff_clone, proj_false);
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// Reoptimize loops
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loop->record_for_igvn();
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for(int i = loop->_body.size() - 1; i >= 0 ; i--) {
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Node *n = loop->_body[i];
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Node *n_clone = old_new[n->_idx];
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_igvn._worklist.push(n_clone);
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}
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#ifndef PRODUCT
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if (TraceLoopUnswitching) {
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tty->print_cr("Loop unswitching orig: %d @ %d new: %d @ %d",
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head->_idx, unswitch_iff->_idx,
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old_new[head->_idx]->_idx, unswitch_iff_clone->_idx);
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}
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#endif
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C->set_major_progress();
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}
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//-------------------------create_slow_version_of_loop------------------------
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// Create a slow version of the loop by cloning the loop
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// and inserting an if to select fast-slow versions.
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// Return control projection of the entry to the fast version.
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ProjNode* PhaseIdealLoop::create_slow_version_of_loop(IdealLoopTree *loop,
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Node_List &old_new,
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int opcode) {
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LoopNode* head = loop->_head->as_Loop();
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bool counted_loop = head->is_CountedLoop();
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Node* entry = head->in(LoopNode::EntryControl);
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_igvn.rehash_node_delayed(entry);
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IdealLoopTree* outer_loop = loop->_parent;
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Node *cont = _igvn.intcon(1);
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set_ctrl(cont, C->root());
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Node* opq = new Opaque1Node(C, cont);
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register_node(opq, outer_loop, entry, dom_depth(entry));
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Node *bol = new Conv2BNode(opq);
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register_node(bol, outer_loop, entry, dom_depth(entry));
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IfNode* iff = (opcode == Op_RangeCheck) ? new RangeCheckNode(entry, bol, PROB_MAX, COUNT_UNKNOWN) :
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new IfNode(entry, bol, PROB_MAX, COUNT_UNKNOWN);
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register_node(iff, outer_loop, entry, dom_depth(entry));
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ProjNode* iffast = new IfTrueNode(iff);
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register_node(iffast, outer_loop, iff, dom_depth(iff));
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ProjNode* ifslow = new IfFalseNode(iff);
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register_node(ifslow, outer_loop, iff, dom_depth(iff));
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// Clone the loop body. The clone becomes the fast loop. The
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// original pre-header will (illegally) have 3 control users
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// (old & new loops & new if).
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clone_loop(loop, old_new, dom_depth(head), iff);
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assert(old_new[head->_idx]->is_Loop(), "" );
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// Fast (true) control
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Node* iffast_pred = clone_loop_predicates(entry, iffast, !counted_loop);
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_igvn.replace_input_of(head, LoopNode::EntryControl, iffast_pred);
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set_idom(head, iffast_pred, dom_depth(head));
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// Slow (false) control
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Node* ifslow_pred = clone_loop_predicates(entry, ifslow, !counted_loop);
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LoopNode* slow_head = old_new[head->_idx]->as_Loop();
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_igvn.replace_input_of(slow_head, LoopNode::EntryControl, ifslow_pred);
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set_idom(slow_head, ifslow_pred, dom_depth(slow_head));
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recompute_dom_depth();
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return iffast;
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}
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LoopNode* PhaseIdealLoop::create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk) {
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Node_List old_new;
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LoopNode* head = loop->_head->as_Loop();
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bool counted_loop = head->is_CountedLoop();
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Node* entry = head->in(LoopNode::EntryControl);
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_igvn.rehash_node_delayed(entry);
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IdealLoopTree* outer_loop = loop->_parent;
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ConINode* const_1 = _igvn.intcon(1);
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set_ctrl(const_1, C->root());
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IfNode* iff = new IfNode(entry, const_1, PROB_MAX, COUNT_UNKNOWN);
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register_node(iff, outer_loop, entry, dom_depth(entry));
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ProjNode* iffast = new IfTrueNode(iff);
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register_node(iffast, outer_loop, iff, dom_depth(iff));
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ProjNode* ifslow = new IfFalseNode(iff);
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register_node(ifslow, outer_loop, iff, dom_depth(iff));
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// Clone the loop body. The clone becomes the fast loop. The
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// original pre-header will (illegally) have 3 control users
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// (old & new loops & new if).
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clone_loop(loop, old_new, dom_depth(head), iff);
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assert(old_new[head->_idx]->is_Loop(), "" );
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LoopNode* slow_head = old_new[head->_idx]->as_Loop();
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#ifndef PRODUCT
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if (TraceLoopOpts) {
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tty->print_cr("PhaseIdealLoop::create_reserve_version_of_loop:");
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tty->print("\t iff = %d, ", iff->_idx); iff->dump();
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tty->print("\t iffast = %d, ", iffast->_idx); iffast->dump();
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tty->print("\t ifslow = %d, ", ifslow->_idx); ifslow->dump();
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tty->print("\t before replace_input_of: head = %d, ", head->_idx); head->dump();
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tty->print("\t before replace_input_of: slow_head = %d, ", slow_head->_idx); slow_head->dump();
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}
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#endif
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// Fast (true) control
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_igvn.replace_input_of(head, LoopNode::EntryControl, iffast);
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// Slow (false) control
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_igvn.replace_input_of(slow_head, LoopNode::EntryControl, ifslow);
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recompute_dom_depth();
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lk->set_iff(iff);
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#ifndef PRODUCT
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if (TraceLoopOpts ) {
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tty->print("\t after replace_input_of: head = %d, ", head->_idx); head->dump();
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tty->print("\t after replace_input_of: slow_head = %d, ", slow_head->_idx); slow_head->dump();
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}
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#endif
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return slow_head->as_Loop();
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}
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CountedLoopReserveKit::CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active = true) :
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_phase(phase),
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_lpt(loop),
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_lp(NULL),
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_iff(NULL),
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_lp_reserved(NULL),
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_has_reserved(false),
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_use_new(false),
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_active(active)
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{
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create_reserve();
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};
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CountedLoopReserveKit::~CountedLoopReserveKit() {
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if (!_active) {
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return;
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}
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if (_has_reserved && !_use_new) {
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// intcon(0)->iff-node reverts CF to the reserved copy
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ConINode* const_0 = _phase->_igvn.intcon(0);
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_phase->set_ctrl(const_0, _phase->C->root());
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_iff->set_req(1, const_0);
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#ifndef PRODUCT
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if (TraceLoopOpts) {
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tty->print_cr("CountedLoopReserveKit::~CountedLoopReserveKit()");
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tty->print("\t discard loop %d and revert to the reserved loop clone %d: ", _lp->_idx, _lp_reserved->_idx);
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_lp_reserved->dump();
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}
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#endif
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}
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}
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bool CountedLoopReserveKit::create_reserve() {
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if (!_active) {
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return false;
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}
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if(!_lpt->_head->is_CountedLoop()) {
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if (TraceLoopOpts) {
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tty->print_cr("CountedLoopReserveKit::create_reserve: %d not counted loop", _lpt->_head->_idx);
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}
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return false;
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}
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CountedLoopNode *cl = _lpt->_head->as_CountedLoop();
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if (!cl->is_valid_counted_loop()) {
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if (TraceLoopOpts) {
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tty->print_cr("CountedLoopReserveKit::create_reserve: %d not valid counted loop", cl->_idx);
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}
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return false; // skip malformed counted loop
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}
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if (!cl->is_main_loop()) {
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bool loop_not_canonical = true;
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if (cl->is_post_loop() && (cl->slp_max_unroll() > 0)) {
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loop_not_canonical = false;
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}
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// only reject some loop forms
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if (loop_not_canonical) {
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if (TraceLoopOpts) {
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tty->print_cr("CountedLoopReserveKit::create_reserve: %d not canonical loop", cl->_idx);
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}
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return false; // skip normal, pre, and post (conditionally) loops
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}
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}
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_lp = _lpt->_head->as_Loop();
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_lp_reserved = _phase->create_reserve_version_of_loop(_lpt, this);
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if (!_lp_reserved->is_CountedLoop()) {
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return false;
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}
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Node* ifslow_pred = _lp_reserved->as_CountedLoop()->in(LoopNode::EntryControl);
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if (!ifslow_pred->is_IfFalse()) {
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return false;
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}
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Node* iff = ifslow_pred->in(0);
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if (!iff->is_If() || iff != _iff) {
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return false;
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}
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if (iff->in(1)->Opcode() != Op_ConI) {
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return false;
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}
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return _has_reserved = true;
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}
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