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/*
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* Copyright 2000-2007 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/_loopTransform.cpp.incl"
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//------------------------------is_loop_exit-----------------------------------
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// Given an IfNode, return the loop-exiting projection or NULL if both
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// arms remain in the loop.
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Node *IdealLoopTree::is_loop_exit(Node *iff) const {
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if( iff->outcnt() != 2 ) return NULL; // Ignore partially dead tests
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PhaseIdealLoop *phase = _phase;
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// Test is an IfNode, has 2 projections. If BOTH are in the loop
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// we need loop unswitching instead of peeling.
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if( !is_member(phase->get_loop( iff->raw_out(0) )) )
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return iff->raw_out(0);
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if( !is_member(phase->get_loop( iff->raw_out(1) )) )
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return iff->raw_out(1);
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return NULL;
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}
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//=============================================================================
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//------------------------------record_for_igvn----------------------------
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// Put loop body on igvn work list
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void IdealLoopTree::record_for_igvn() {
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for( uint i = 0; i < _body.size(); i++ ) {
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Node *n = _body.at(i);
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_phase->_igvn._worklist.push(n);
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}
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}
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//------------------------------compute_profile_trip_cnt----------------------------
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// Compute loop trip count from profile data as
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// (backedge_count + loop_exit_count) / loop_exit_count
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void IdealLoopTree::compute_profile_trip_cnt( PhaseIdealLoop *phase ) {
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if (!_head->is_CountedLoop()) {
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return;
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}
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CountedLoopNode* head = _head->as_CountedLoop();
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if (head->profile_trip_cnt() != COUNT_UNKNOWN) {
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return; // Already computed
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}
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float trip_cnt = (float)max_jint; // default is big
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Node* back = head->in(LoopNode::LoopBackControl);
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while (back != head) {
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if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
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back->in(0) &&
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back->in(0)->is_If() &&
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back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN &&
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back->in(0)->as_If()->_prob != PROB_UNKNOWN) {
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break;
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}
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back = phase->idom(back);
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}
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if (back != head) {
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assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
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back->in(0), "if-projection exists");
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IfNode* back_if = back->in(0)->as_If();
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float loop_back_cnt = back_if->_fcnt * back_if->_prob;
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// Now compute a loop exit count
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float loop_exit_cnt = 0.0f;
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for( uint i = 0; i < _body.size(); i++ ) {
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Node *n = _body[i];
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if( n->is_If() ) {
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IfNode *iff = n->as_If();
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if( iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN ) {
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Node *exit = is_loop_exit(iff);
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if( exit ) {
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float exit_prob = iff->_prob;
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if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob;
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if (exit_prob > PROB_MIN) {
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float exit_cnt = iff->_fcnt * exit_prob;
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loop_exit_cnt += exit_cnt;
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}
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}
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}
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}
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}
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if (loop_exit_cnt > 0.0f) {
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trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt;
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} else {
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// No exit count so use
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trip_cnt = loop_back_cnt;
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}
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}
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#ifndef PRODUCT
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if (TraceProfileTripCount) {
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tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt);
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}
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#endif
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head->set_profile_trip_cnt(trip_cnt);
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}
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//---------------------is_invariant_addition-----------------------------
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// Return nonzero index of invariant operand for an Add or Sub
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// of (nonconstant) invariant and variant values. Helper for reassoicate_invariants.
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int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) {
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int op = n->Opcode();
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if (op == Op_AddI || op == Op_SubI) {
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bool in1_invar = this->is_invariant(n->in(1));
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bool in2_invar = this->is_invariant(n->in(2));
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if (in1_invar && !in2_invar) return 1;
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if (!in1_invar && in2_invar) return 2;
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}
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return 0;
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}
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//---------------------reassociate_add_sub-----------------------------
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// Reassociate invariant add and subtract expressions:
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//
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// inv1 + (x + inv2) => ( inv1 + inv2) + x
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// (x + inv2) + inv1 => ( inv1 + inv2) + x
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// inv1 + (x - inv2) => ( inv1 - inv2) + x
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// inv1 - (inv2 - x) => ( inv1 - inv2) + x
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// (x + inv2) - inv1 => (-inv1 + inv2) + x
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// (x - inv2) + inv1 => ( inv1 - inv2) + x
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// (x - inv2) - inv1 => (-inv1 - inv2) + x
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// inv1 + (inv2 - x) => ( inv1 + inv2) - x
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// inv1 - (x - inv2) => ( inv1 + inv2) - x
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// (inv2 - x) + inv1 => ( inv1 + inv2) - x
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// (inv2 - x) - inv1 => (-inv1 + inv2) - x
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// inv1 - (x + inv2) => ( inv1 - inv2) - x
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//
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Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) {
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if (!n1->is_Add() && !n1->is_Sub() || n1->outcnt() == 0) return NULL;
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if (is_invariant(n1)) return NULL;
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int inv1_idx = is_invariant_addition(n1, phase);
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if (!inv1_idx) return NULL;
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// Don't mess with add of constant (igvn moves them to expression tree root.)
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if (n1->is_Add() && n1->in(2)->is_Con()) return NULL;
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Node* inv1 = n1->in(inv1_idx);
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Node* n2 = n1->in(3 - inv1_idx);
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int inv2_idx = is_invariant_addition(n2, phase);
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if (!inv2_idx) return NULL;
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Node* x = n2->in(3 - inv2_idx);
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Node* inv2 = n2->in(inv2_idx);
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bool neg_x = n2->is_Sub() && inv2_idx == 1;
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bool neg_inv2 = n2->is_Sub() && inv2_idx == 2;
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bool neg_inv1 = n1->is_Sub() && inv1_idx == 2;
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if (n1->is_Sub() && inv1_idx == 1) {
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neg_x = !neg_x;
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neg_inv2 = !neg_inv2;
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}
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Node* inv1_c = phase->get_ctrl(inv1);
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Node* inv2_c = phase->get_ctrl(inv2);
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Node* n_inv1;
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if (neg_inv1) {
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Node *zero = phase->_igvn.intcon(0);
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phase->set_ctrl(zero, phase->C->root());
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n_inv1 = new (phase->C, 3) SubINode(zero, inv1);
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phase->register_new_node(n_inv1, inv1_c);
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} else {
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n_inv1 = inv1;
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}
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Node* inv;
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if (neg_inv2) {
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inv = new (phase->C, 3) SubINode(n_inv1, inv2);
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} else {
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inv = new (phase->C, 3) AddINode(n_inv1, inv2);
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}
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phase->register_new_node(inv, phase->get_early_ctrl(inv));
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Node* addx;
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if (neg_x) {
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addx = new (phase->C, 3) SubINode(inv, x);
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} else {
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addx = new (phase->C, 3) AddINode(x, inv);
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}
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phase->register_new_node(addx, phase->get_ctrl(x));
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phase->_igvn.hash_delete(n1);
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phase->_igvn.subsume_node(n1, addx);
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return addx;
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}
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//---------------------reassociate_invariants-----------------------------
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// Reassociate invariant expressions:
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void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) {
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for (int i = _body.size() - 1; i >= 0; i--) {
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Node *n = _body.at(i);
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for (int j = 0; j < 5; j++) {
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Node* nn = reassociate_add_sub(n, phase);
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if (nn == NULL) break;
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n = nn; // again
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};
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}
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}
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//------------------------------policy_peeling---------------------------------
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// Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
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// make some loop-invariant test (usually a null-check) happen before the loop.
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bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const {
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Node *test = ((IdealLoopTree*)this)->tail();
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int body_size = ((IdealLoopTree*)this)->_body.size();
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int uniq = phase->C->unique();
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// Peeling does loop cloning which can result in O(N^2) node construction
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if( body_size > 255 /* Prevent overflow for large body_size */
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|| (body_size * body_size + uniq > MaxNodeLimit) ) {
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return false; // too large to safely clone
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}
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while( test != _head ) { // Scan till run off top of loop
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if( test->is_If() ) { // Test?
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Node *ctrl = phase->get_ctrl(test->in(1));
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if (ctrl->is_top())
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return false; // Found dead test on live IF? No peeling!
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// Standard IF only has one input value to check for loop invariance
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assert( test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
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// Condition is not a member of this loop?
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if( !is_member(phase->get_loop(ctrl)) &&
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is_loop_exit(test) )
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return true; // Found reason to peel!
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}
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// Walk up dominators to loop _head looking for test which is
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// executed on every path thru loop.
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test = phase->idom(test);
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}
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return false;
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}
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//------------------------------peeled_dom_test_elim---------------------------
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// If we got the effect of peeling, either by actually peeling or by making
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// a pre-loop which must execute at least once, we can remove all
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// loop-invariant dominated tests in the main body.
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void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) {
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bool progress = true;
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while( progress ) {
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progress = false; // Reset for next iteration
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Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail();
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Node *test = prev->in(0);
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while( test != loop->_head ) { // Scan till run off top of loop
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int p_op = prev->Opcode();
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if( (p_op == Op_IfFalse || p_op == Op_IfTrue) &&
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test->is_If() && // Test?
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!test->in(1)->is_Con() && // And not already obvious?
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// Condition is not a member of this loop?
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!loop->is_member(get_loop(get_ctrl(test->in(1))))){
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// Walk loop body looking for instances of this test
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for( uint i = 0; i < loop->_body.size(); i++ ) {
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Node *n = loop->_body.at(i);
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if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) {
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// IfNode was dominated by version in peeled loop body
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progress = true;
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dominated_by( old_new[prev->_idx], n );
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}
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}
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}
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prev = test;
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test = idom(test);
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} // End of scan tests in loop
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} // End of while( progress )
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}
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//------------------------------do_peeling-------------------------------------
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// Peel the first iteration of the given loop.
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// Step 1: Clone the loop body. The clone becomes the peeled iteration.
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// The pre-loop illegally has 2 control users (old & new loops).
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// Step 2: Make the old-loop fall-in edges point to the peeled iteration.
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// Do this by making the old-loop fall-in edges act as if they came
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// around the loopback from the prior iteration (follow the old-loop
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// backedges) and then map to the new peeled iteration. This leaves
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// the pre-loop with only 1 user (the new peeled iteration), but the
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// peeled-loop backedge has 2 users.
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// Step 3: Cut the backedge on the clone (so its not a loop) and remove the
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// extra backedge user.
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void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
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C->set_major_progress();
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// Peeling a 'main' loop in a pre/main/post situation obfuscates the
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// 'pre' loop from the main and the 'pre' can no longer have it's
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// iterations adjusted. Therefore, we need to declare this loop as
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// no longer a 'main' loop; it will need new pre and post loops before
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// we can do further RCE.
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Node *h = loop->_head;
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if( h->is_CountedLoop() ) {
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CountedLoopNode *cl = h->as_CountedLoop();
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assert(cl->trip_count() > 0, "peeling a fully unrolled loop");
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cl->set_trip_count(cl->trip_count() - 1);
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if( cl->is_main_loop() ) {
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cl->set_normal_loop();
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#ifndef PRODUCT
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if( PrintOpto && VerifyLoopOptimizations ) {
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tty->print("Peeling a 'main' loop; resetting to 'normal' ");
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loop->dump_head();
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}
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#endif
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}
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}
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// Step 1: Clone the loop body. The clone becomes the peeled iteration.
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// The pre-loop illegally has 2 control users (old & new loops).
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clone_loop( loop, old_new, dom_depth(loop->_head) );
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// Step 2: Make the old-loop fall-in edges point to the peeled iteration.
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// Do this by making the old-loop fall-in edges act as if they came
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// around the loopback from the prior iteration (follow the old-loop
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// backedges) and then map to the new peeled iteration. This leaves
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// the pre-loop with only 1 user (the new peeled iteration), but the
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// peeled-loop backedge has 2 users.
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for (DUIterator_Fast jmax, j = loop->_head->fast_outs(jmax); j < jmax; j++) {
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Node* old = loop->_head->fast_out(j);
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if( old->in(0) == loop->_head && old->req() == 3 &&
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(old->is_Loop() || old->is_Phi()) ) {
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Node *new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
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if( !new_exit_value ) // Backedge value is ALSO loop invariant?
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// Then loop body backedge value remains the same.
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new_exit_value = old->in(LoopNode::LoopBackControl);
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_igvn.hash_delete(old);
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old->set_req(LoopNode::EntryControl, new_exit_value);
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}
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}
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// Step 3: Cut the backedge on the clone (so its not a loop) and remove the
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// extra backedge user.
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Node *nnn = old_new[loop->_head->_idx];
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_igvn.hash_delete(nnn);
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nnn->set_req(LoopNode::LoopBackControl, C->top());
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for (DUIterator_Fast j2max, j2 = nnn->fast_outs(j2max); j2 < j2max; j2++) {
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Node* use = nnn->fast_out(j2);
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if( use->in(0) == nnn && use->req() == 3 && use->is_Phi() ) {
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_igvn.hash_delete(use);
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|
351 |
use->set_req(LoopNode::LoopBackControl, C->top());
|
|
352 |
}
|
|
353 |
}
|
|
354 |
|
|
355 |
|
|
356 |
// Step 4: Correct dom-depth info. Set to loop-head depth.
|
|
357 |
int dd = dom_depth(loop->_head);
|
|
358 |
set_idom(loop->_head, loop->_head->in(1), dd);
|
|
359 |
for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
|
|
360 |
Node *old = loop->_body.at(j3);
|
|
361 |
Node *nnn = old_new[old->_idx];
|
|
362 |
if (!has_ctrl(nnn))
|
|
363 |
set_idom(nnn, idom(nnn), dd-1);
|
|
364 |
// While we're at it, remove any SafePoints from the peeled code
|
|
365 |
if( old->Opcode() == Op_SafePoint ) {
|
|
366 |
Node *nnn = old_new[old->_idx];
|
|
367 |
lazy_replace(nnn,nnn->in(TypeFunc::Control));
|
|
368 |
}
|
|
369 |
}
|
|
370 |
|
|
371 |
// Now force out all loop-invariant dominating tests. The optimizer
|
|
372 |
// finds some, but we _know_ they are all useless.
|
|
373 |
peeled_dom_test_elim(loop,old_new);
|
|
374 |
|
|
375 |
loop->record_for_igvn();
|
|
376 |
}
|
|
377 |
|
|
378 |
//------------------------------policy_maximally_unroll------------------------
|
|
379 |
// Return exact loop trip count, or 0 if not maximally unrolling
|
|
380 |
bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const {
|
|
381 |
CountedLoopNode *cl = _head->as_CountedLoop();
|
|
382 |
assert( cl->is_normal_loop(), "" );
|
|
383 |
|
|
384 |
Node *init_n = cl->init_trip();
|
|
385 |
Node *limit_n = cl->limit();
|
|
386 |
|
|
387 |
// Non-constant bounds
|
|
388 |
if( init_n == NULL || !init_n->is_Con() ||
|
|
389 |
limit_n == NULL || !limit_n->is_Con() ||
|
|
390 |
// protect against stride not being a constant
|
|
391 |
!cl->stride_is_con() ) {
|
|
392 |
return false;
|
|
393 |
}
|
|
394 |
int init = init_n->get_int();
|
|
395 |
int limit = limit_n->get_int();
|
|
396 |
int span = limit - init;
|
|
397 |
int stride = cl->stride_con();
|
|
398 |
|
|
399 |
if (init >= limit || stride > span) {
|
|
400 |
// return a false (no maximally unroll) and the regular unroll/peel
|
|
401 |
// route will make a small mess which CCP will fold away.
|
|
402 |
return false;
|
|
403 |
}
|
|
404 |
uint trip_count = span/stride; // trip_count can be greater than 2 Gig.
|
|
405 |
assert( (int)trip_count*stride == span, "must divide evenly" );
|
|
406 |
|
|
407 |
// Real policy: if we maximally unroll, does it get too big?
|
|
408 |
// Allow the unrolled mess to get larger than standard loop
|
|
409 |
// size. After all, it will no longer be a loop.
|
|
410 |
uint body_size = _body.size();
|
|
411 |
uint unroll_limit = (uint)LoopUnrollLimit * 4;
|
|
412 |
assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
|
|
413 |
cl->set_trip_count(trip_count);
|
|
414 |
if( trip_count <= unroll_limit && body_size <= unroll_limit ) {
|
|
415 |
uint new_body_size = body_size * trip_count;
|
|
416 |
if (new_body_size <= unroll_limit &&
|
|
417 |
body_size == new_body_size / trip_count &&
|
|
418 |
// Unrolling can result in a large amount of node construction
|
|
419 |
new_body_size < MaxNodeLimit - phase->C->unique()) {
|
|
420 |
return true; // maximally unroll
|
|
421 |
}
|
|
422 |
}
|
|
423 |
|
|
424 |
return false; // Do not maximally unroll
|
|
425 |
}
|
|
426 |
|
|
427 |
|
|
428 |
//------------------------------policy_unroll----------------------------------
|
|
429 |
// Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
|
|
430 |
// the loop is a CountedLoop and the body is small enough.
|
|
431 |
bool IdealLoopTree::policy_unroll( PhaseIdealLoop *phase ) const {
|
|
432 |
|
|
433 |
CountedLoopNode *cl = _head->as_CountedLoop();
|
|
434 |
assert( cl->is_normal_loop() || cl->is_main_loop(), "" );
|
|
435 |
|
|
436 |
// protect against stride not being a constant
|
|
437 |
if( !cl->stride_is_con() ) return false;
|
|
438 |
|
|
439 |
// protect against over-unrolling
|
|
440 |
if( cl->trip_count() <= 1 ) return false;
|
|
441 |
|
|
442 |
int future_unroll_ct = cl->unrolled_count() * 2;
|
|
443 |
|
|
444 |
// Don't unroll if the next round of unrolling would push us
|
|
445 |
// over the expected trip count of the loop. One is subtracted
|
|
446 |
// from the expected trip count because the pre-loop normally
|
|
447 |
// executes 1 iteration.
|
|
448 |
if (UnrollLimitForProfileCheck > 0 &&
|
|
449 |
cl->profile_trip_cnt() != COUNT_UNKNOWN &&
|
|
450 |
future_unroll_ct > UnrollLimitForProfileCheck &&
|
|
451 |
(float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) {
|
|
452 |
return false;
|
|
453 |
}
|
|
454 |
|
|
455 |
// When unroll count is greater than LoopUnrollMin, don't unroll if:
|
|
456 |
// the residual iterations are more than 10% of the trip count
|
|
457 |
// and rounds of "unroll,optimize" are not making significant progress
|
|
458 |
// Progress defined as current size less than 20% larger than previous size.
|
|
459 |
if (UseSuperWord && cl->node_count_before_unroll() > 0 &&
|
|
460 |
future_unroll_ct > LoopUnrollMin &&
|
|
461 |
(future_unroll_ct - 1) * 10.0 > cl->profile_trip_cnt() &&
|
|
462 |
1.2 * cl->node_count_before_unroll() < (double)_body.size()) {
|
|
463 |
return false;
|
|
464 |
}
|
|
465 |
|
|
466 |
Node *init_n = cl->init_trip();
|
|
467 |
Node *limit_n = cl->limit();
|
|
468 |
// Non-constant bounds.
|
|
469 |
// Protect against over-unrolling when init or/and limit are not constant
|
|
470 |
// (so that trip_count's init value is maxint) but iv range is known.
|
|
471 |
if( init_n == NULL || !init_n->is_Con() ||
|
|
472 |
limit_n == NULL || !limit_n->is_Con() ) {
|
|
473 |
Node* phi = cl->phi();
|
|
474 |
if( phi != NULL ) {
|
|
475 |
assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
|
|
476 |
const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
|
|
477 |
int next_stride = cl->stride_con() * 2; // stride after this unroll
|
|
478 |
if( next_stride > 0 ) {
|
|
479 |
if( iv_type->_lo + next_stride <= iv_type->_lo || // overflow
|
|
480 |
iv_type->_lo + next_stride > iv_type->_hi ) {
|
|
481 |
return false; // over-unrolling
|
|
482 |
}
|
|
483 |
} else if( next_stride < 0 ) {
|
|
484 |
if( iv_type->_hi + next_stride >= iv_type->_hi || // overflow
|
|
485 |
iv_type->_hi + next_stride < iv_type->_lo ) {
|
|
486 |
return false; // over-unrolling
|
|
487 |
}
|
|
488 |
}
|
|
489 |
}
|
|
490 |
}
|
|
491 |
|
|
492 |
// Adjust body_size to determine if we unroll or not
|
|
493 |
uint body_size = _body.size();
|
|
494 |
// Key test to unroll CaffeineMark's Logic test
|
|
495 |
int xors_in_loop = 0;
|
|
496 |
// Also count ModL, DivL and MulL which expand mightly
|
|
497 |
for( uint k = 0; k < _body.size(); k++ ) {
|
|
498 |
switch( _body.at(k)->Opcode() ) {
|
|
499 |
case Op_XorI: xors_in_loop++; break; // CaffeineMark's Logic test
|
|
500 |
case Op_ModL: body_size += 30; break;
|
|
501 |
case Op_DivL: body_size += 30; break;
|
|
502 |
case Op_MulL: body_size += 10; break;
|
|
503 |
}
|
|
504 |
}
|
|
505 |
|
|
506 |
// Check for being too big
|
|
507 |
if( body_size > (uint)LoopUnrollLimit ) {
|
|
508 |
if( xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true;
|
|
509 |
// Normal case: loop too big
|
|
510 |
return false;
|
|
511 |
}
|
|
512 |
|
|
513 |
// Check for stride being a small enough constant
|
|
514 |
if( abs(cl->stride_con()) > (1<<3) ) return false;
|
|
515 |
|
|
516 |
// Unroll once! (Each trip will soon do double iterations)
|
|
517 |
return true;
|
|
518 |
}
|
|
519 |
|
|
520 |
//------------------------------policy_align-----------------------------------
|
|
521 |
// Return TRUE or FALSE if the loop should be cache-line aligned. Gather the
|
|
522 |
// expression that does the alignment. Note that only one array base can be
|
|
523 |
// aligned in a loop (unless the VM guarentees mutual alignment). Note that
|
|
524 |
// if we vectorize short memory ops into longer memory ops, we may want to
|
|
525 |
// increase alignment.
|
|
526 |
bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const {
|
|
527 |
return false;
|
|
528 |
}
|
|
529 |
|
|
530 |
//------------------------------policy_range_check-----------------------------
|
|
531 |
// Return TRUE or FALSE if the loop should be range-check-eliminated.
|
|
532 |
// Actually we do iteration-splitting, a more powerful form of RCE.
|
|
533 |
bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
|
|
534 |
if( !RangeCheckElimination ) return false;
|
|
535 |
|
|
536 |
CountedLoopNode *cl = _head->as_CountedLoop();
|
|
537 |
// If we unrolled with no intention of doing RCE and we later
|
|
538 |
// changed our minds, we got no pre-loop. Either we need to
|
|
539 |
// make a new pre-loop, or we gotta disallow RCE.
|
|
540 |
if( cl->is_main_no_pre_loop() ) return false; // Disallowed for now.
|
|
541 |
Node *trip_counter = cl->phi();
|
|
542 |
|
|
543 |
// Check loop body for tests of trip-counter plus loop-invariant vs
|
|
544 |
// loop-invariant.
|
|
545 |
for( uint i = 0; i < _body.size(); i++ ) {
|
|
546 |
Node *iff = _body[i];
|
|
547 |
if( iff->Opcode() == Op_If ) { // Test?
|
|
548 |
|
|
549 |
// Comparing trip+off vs limit
|
|
550 |
Node *bol = iff->in(1);
|
|
551 |
if( bol->req() != 2 ) continue; // dead constant test
|
|
552 |
Node *cmp = bol->in(1);
|
|
553 |
|
|
554 |
Node *rc_exp = cmp->in(1);
|
|
555 |
Node *limit = cmp->in(2);
|
|
556 |
|
|
557 |
Node *limit_c = phase->get_ctrl(limit);
|
|
558 |
if( limit_c == phase->C->top() )
|
|
559 |
return false; // Found dead test on live IF? No RCE!
|
|
560 |
if( is_member(phase->get_loop(limit_c) ) ) {
|
|
561 |
// Compare might have operands swapped; commute them
|
|
562 |
rc_exp = cmp->in(2);
|
|
563 |
limit = cmp->in(1);
|
|
564 |
limit_c = phase->get_ctrl(limit);
|
|
565 |
if( is_member(phase->get_loop(limit_c) ) )
|
|
566 |
continue; // Both inputs are loop varying; cannot RCE
|
|
567 |
}
|
|
568 |
|
|
569 |
if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) {
|
|
570 |
continue;
|
|
571 |
}
|
|
572 |
// Yeah! Found a test like 'trip+off vs limit'
|
|
573 |
// Test is an IfNode, has 2 projections. If BOTH are in the loop
|
|
574 |
// we need loop unswitching instead of iteration splitting.
|
|
575 |
if( is_loop_exit(iff) )
|
|
576 |
return true; // Found reason to split iterations
|
|
577 |
} // End of is IF
|
|
578 |
}
|
|
579 |
|
|
580 |
return false;
|
|
581 |
}
|
|
582 |
|
|
583 |
//------------------------------policy_peel_only-------------------------------
|
|
584 |
// Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful
|
|
585 |
// for unrolling loops with NO array accesses.
|
|
586 |
bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const {
|
|
587 |
|
|
588 |
for( uint i = 0; i < _body.size(); i++ )
|
|
589 |
if( _body[i]->is_Mem() )
|
|
590 |
return false;
|
|
591 |
|
|
592 |
// No memory accesses at all!
|
|
593 |
return true;
|
|
594 |
}
|
|
595 |
|
|
596 |
//------------------------------clone_up_backedge_goo--------------------------
|
|
597 |
// If Node n lives in the back_ctrl block and cannot float, we clone a private
|
|
598 |
// version of n in preheader_ctrl block and return that, otherwise return n.
|
|
599 |
Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n ) {
|
|
600 |
if( get_ctrl(n) != back_ctrl ) return n;
|
|
601 |
|
|
602 |
Node *x = NULL; // If required, a clone of 'n'
|
|
603 |
// Check for 'n' being pinned in the backedge.
|
|
604 |
if( n->in(0) && n->in(0) == back_ctrl ) {
|
|
605 |
x = n->clone(); // Clone a copy of 'n' to preheader
|
|
606 |
x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader
|
|
607 |
}
|
|
608 |
|
|
609 |
// Recursive fixup any other input edges into x.
|
|
610 |
// If there are no changes we can just return 'n', otherwise
|
|
611 |
// we need to clone a private copy and change it.
|
|
612 |
for( uint i = 1; i < n->req(); i++ ) {
|
|
613 |
Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i) );
|
|
614 |
if( g != n->in(i) ) {
|
|
615 |
if( !x )
|
|
616 |
x = n->clone();
|
|
617 |
x->set_req(i, g);
|
|
618 |
}
|
|
619 |
}
|
|
620 |
if( x ) { // x can legally float to pre-header location
|
|
621 |
register_new_node( x, preheader_ctrl );
|
|
622 |
return x;
|
|
623 |
} else { // raise n to cover LCA of uses
|
|
624 |
set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) );
|
|
625 |
}
|
|
626 |
return n;
|
|
627 |
}
|
|
628 |
|
|
629 |
//------------------------------insert_pre_post_loops--------------------------
|
|
630 |
// Insert pre and post loops. If peel_only is set, the pre-loop can not have
|
|
631 |
// more iterations added. It acts as a 'peel' only, no lower-bound RCE, no
|
|
632 |
// alignment. Useful to unroll loops that do no array accesses.
|
|
633 |
void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) {
|
|
634 |
|
|
635 |
C->set_major_progress();
|
|
636 |
|
|
637 |
// Find common pieces of the loop being guarded with pre & post loops
|
|
638 |
CountedLoopNode *main_head = loop->_head->as_CountedLoop();
|
|
639 |
assert( main_head->is_normal_loop(), "" );
|
|
640 |
CountedLoopEndNode *main_end = main_head->loopexit();
|
|
641 |
assert( main_end->outcnt() == 2, "1 true, 1 false path only" );
|
|
642 |
uint dd_main_head = dom_depth(main_head);
|
|
643 |
uint max = main_head->outcnt();
|
|
644 |
|
|
645 |
Node *pre_header= main_head->in(LoopNode::EntryControl);
|
|
646 |
Node *init = main_head->init_trip();
|
|
647 |
Node *incr = main_end ->incr();
|
|
648 |
Node *limit = main_end ->limit();
|
|
649 |
Node *stride = main_end ->stride();
|
|
650 |
Node *cmp = main_end ->cmp_node();
|
|
651 |
BoolTest::mask b_test = main_end->test_trip();
|
|
652 |
|
|
653 |
// Need only 1 user of 'bol' because I will be hacking the loop bounds.
|
|
654 |
Node *bol = main_end->in(CountedLoopEndNode::TestValue);
|
|
655 |
if( bol->outcnt() != 1 ) {
|
|
656 |
bol = bol->clone();
|
|
657 |
register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl));
|
|
658 |
_igvn.hash_delete(main_end);
|
|
659 |
main_end->set_req(CountedLoopEndNode::TestValue, bol);
|
|
660 |
}
|
|
661 |
// Need only 1 user of 'cmp' because I will be hacking the loop bounds.
|
|
662 |
if( cmp->outcnt() != 1 ) {
|
|
663 |
cmp = cmp->clone();
|
|
664 |
register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl));
|
|
665 |
_igvn.hash_delete(bol);
|
|
666 |
bol->set_req(1, cmp);
|
|
667 |
}
|
|
668 |
|
|
669 |
//------------------------------
|
|
670 |
// Step A: Create Post-Loop.
|
|
671 |
Node* main_exit = main_end->proj_out(false);
|
|
672 |
assert( main_exit->Opcode() == Op_IfFalse, "" );
|
|
673 |
int dd_main_exit = dom_depth(main_exit);
|
|
674 |
|
|
675 |
// Step A1: Clone the loop body. The clone becomes the post-loop. The main
|
|
676 |
// loop pre-header illegally has 2 control users (old & new loops).
|
|
677 |
clone_loop( loop, old_new, dd_main_exit );
|
|
678 |
assert( old_new[main_end ->_idx]->Opcode() == Op_CountedLoopEnd, "" );
|
|
679 |
CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop();
|
|
680 |
post_head->set_post_loop(main_head);
|
|
681 |
|
|
682 |
// Build the main-loop normal exit.
|
|
683 |
IfFalseNode *new_main_exit = new (C, 1) IfFalseNode(main_end);
|
|
684 |
_igvn.register_new_node_with_optimizer( new_main_exit );
|
|
685 |
set_idom(new_main_exit, main_end, dd_main_exit );
|
|
686 |
set_loop(new_main_exit, loop->_parent);
|
|
687 |
|
|
688 |
// Step A2: Build a zero-trip guard for the post-loop. After leaving the
|
|
689 |
// main-loop, the post-loop may not execute at all. We 'opaque' the incr
|
|
690 |
// (the main-loop trip-counter exit value) because we will be changing
|
|
691 |
// the exit value (via unrolling) so we cannot constant-fold away the zero
|
|
692 |
// trip guard until all unrolling is done.
|
|
693 |
Node *zer_opaq = new (C, 2) Opaque1Node(incr);
|
|
694 |
Node *zer_cmp = new (C, 3) CmpINode( zer_opaq, limit );
|
|
695 |
Node *zer_bol = new (C, 2) BoolNode( zer_cmp, b_test );
|
|
696 |
register_new_node( zer_opaq, new_main_exit );
|
|
697 |
register_new_node( zer_cmp , new_main_exit );
|
|
698 |
register_new_node( zer_bol , new_main_exit );
|
|
699 |
|
|
700 |
// Build the IfNode
|
|
701 |
IfNode *zer_iff = new (C, 2) IfNode( new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN );
|
|
702 |
_igvn.register_new_node_with_optimizer( zer_iff );
|
|
703 |
set_idom(zer_iff, new_main_exit, dd_main_exit);
|
|
704 |
set_loop(zer_iff, loop->_parent);
|
|
705 |
|
|
706 |
// Plug in the false-path, taken if we need to skip post-loop
|
|
707 |
_igvn.hash_delete( main_exit );
|
|
708 |
main_exit->set_req(0, zer_iff);
|
|
709 |
_igvn._worklist.push(main_exit);
|
|
710 |
set_idom(main_exit, zer_iff, dd_main_exit);
|
|
711 |
set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
|
|
712 |
// Make the true-path, must enter the post loop
|
|
713 |
Node *zer_taken = new (C, 1) IfTrueNode( zer_iff );
|
|
714 |
_igvn.register_new_node_with_optimizer( zer_taken );
|
|
715 |
set_idom(zer_taken, zer_iff, dd_main_exit);
|
|
716 |
set_loop(zer_taken, loop->_parent);
|
|
717 |
// Plug in the true path
|
|
718 |
_igvn.hash_delete( post_head );
|
|
719 |
post_head->set_req(LoopNode::EntryControl, zer_taken);
|
|
720 |
set_idom(post_head, zer_taken, dd_main_exit);
|
|
721 |
|
|
722 |
// Step A3: Make the fall-in values to the post-loop come from the
|
|
723 |
// fall-out values of the main-loop.
|
|
724 |
for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
|
|
725 |
Node* main_phi = main_head->fast_out(i);
|
|
726 |
if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0 ) {
|
|
727 |
Node *post_phi = old_new[main_phi->_idx];
|
|
728 |
Node *fallmain = clone_up_backedge_goo(main_head->back_control(),
|
|
729 |
post_head->init_control(),
|
|
730 |
main_phi->in(LoopNode::LoopBackControl));
|
|
731 |
_igvn.hash_delete(post_phi);
|
|
732 |
post_phi->set_req( LoopNode::EntryControl, fallmain );
|
|
733 |
}
|
|
734 |
}
|
|
735 |
|
|
736 |
// Update local caches for next stanza
|
|
737 |
main_exit = new_main_exit;
|
|
738 |
|
|
739 |
|
|
740 |
//------------------------------
|
|
741 |
// Step B: Create Pre-Loop.
|
|
742 |
|
|
743 |
// Step B1: Clone the loop body. The clone becomes the pre-loop. The main
|
|
744 |
// loop pre-header illegally has 2 control users (old & new loops).
|
|
745 |
clone_loop( loop, old_new, dd_main_head );
|
|
746 |
CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop();
|
|
747 |
CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
|
|
748 |
pre_head->set_pre_loop(main_head);
|
|
749 |
Node *pre_incr = old_new[incr->_idx];
|
|
750 |
|
|
751 |
// Find the pre-loop normal exit.
|
|
752 |
Node* pre_exit = pre_end->proj_out(false);
|
|
753 |
assert( pre_exit->Opcode() == Op_IfFalse, "" );
|
|
754 |
IfFalseNode *new_pre_exit = new (C, 1) IfFalseNode(pre_end);
|
|
755 |
_igvn.register_new_node_with_optimizer( new_pre_exit );
|
|
756 |
set_idom(new_pre_exit, pre_end, dd_main_head);
|
|
757 |
set_loop(new_pre_exit, loop->_parent);
|
|
758 |
|
|
759 |
// Step B2: Build a zero-trip guard for the main-loop. After leaving the
|
|
760 |
// pre-loop, the main-loop may not execute at all. Later in life this
|
|
761 |
// zero-trip guard will become the minimum-trip guard when we unroll
|
|
762 |
// the main-loop.
|
|
763 |
Node *min_opaq = new (C, 2) Opaque1Node(limit);
|
|
764 |
Node *min_cmp = new (C, 3) CmpINode( pre_incr, min_opaq );
|
|
765 |
Node *min_bol = new (C, 2) BoolNode( min_cmp, b_test );
|
|
766 |
register_new_node( min_opaq, new_pre_exit );
|
|
767 |
register_new_node( min_cmp , new_pre_exit );
|
|
768 |
register_new_node( min_bol , new_pre_exit );
|
|
769 |
|
|
770 |
// Build the IfNode
|
|
771 |
IfNode *min_iff = new (C, 2) IfNode( new_pre_exit, min_bol, PROB_FAIR, COUNT_UNKNOWN );
|
|
772 |
_igvn.register_new_node_with_optimizer( min_iff );
|
|
773 |
set_idom(min_iff, new_pre_exit, dd_main_head);
|
|
774 |
set_loop(min_iff, loop->_parent);
|
|
775 |
|
|
776 |
// Plug in the false-path, taken if we need to skip main-loop
|
|
777 |
_igvn.hash_delete( pre_exit );
|
|
778 |
pre_exit->set_req(0, min_iff);
|
|
779 |
set_idom(pre_exit, min_iff, dd_main_head);
|
|
780 |
set_idom(pre_exit->unique_out(), min_iff, dd_main_head);
|
|
781 |
// Make the true-path, must enter the main loop
|
|
782 |
Node *min_taken = new (C, 1) IfTrueNode( min_iff );
|
|
783 |
_igvn.register_new_node_with_optimizer( min_taken );
|
|
784 |
set_idom(min_taken, min_iff, dd_main_head);
|
|
785 |
set_loop(min_taken, loop->_parent);
|
|
786 |
// Plug in the true path
|
|
787 |
_igvn.hash_delete( main_head );
|
|
788 |
main_head->set_req(LoopNode::EntryControl, min_taken);
|
|
789 |
set_idom(main_head, min_taken, dd_main_head);
|
|
790 |
|
|
791 |
// Step B3: Make the fall-in values to the main-loop come from the
|
|
792 |
// fall-out values of the pre-loop.
|
|
793 |
for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
|
|
794 |
Node* main_phi = main_head->fast_out(i2);
|
|
795 |
if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) {
|
|
796 |
Node *pre_phi = old_new[main_phi->_idx];
|
|
797 |
Node *fallpre = clone_up_backedge_goo(pre_head->back_control(),
|
|
798 |
main_head->init_control(),
|
|
799 |
pre_phi->in(LoopNode::LoopBackControl));
|
|
800 |
_igvn.hash_delete(main_phi);
|
|
801 |
main_phi->set_req( LoopNode::EntryControl, fallpre );
|
|
802 |
}
|
|
803 |
}
|
|
804 |
|
|
805 |
// Step B4: Shorten the pre-loop to run only 1 iteration (for now).
|
|
806 |
// RCE and alignment may change this later.
|
|
807 |
Node *cmp_end = pre_end->cmp_node();
|
|
808 |
assert( cmp_end->in(2) == limit, "" );
|
|
809 |
Node *pre_limit = new (C, 3) AddINode( init, stride );
|
|
810 |
|
|
811 |
// Save the original loop limit in this Opaque1 node for
|
|
812 |
// use by range check elimination.
|
|
813 |
Node *pre_opaq = new (C, 3) Opaque1Node(pre_limit, limit);
|
|
814 |
|
|
815 |
register_new_node( pre_limit, pre_head->in(0) );
|
|
816 |
register_new_node( pre_opaq , pre_head->in(0) );
|
|
817 |
|
|
818 |
// Since no other users of pre-loop compare, I can hack limit directly
|
|
819 |
assert( cmp_end->outcnt() == 1, "no other users" );
|
|
820 |
_igvn.hash_delete(cmp_end);
|
|
821 |
cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq);
|
|
822 |
|
|
823 |
// Special case for not-equal loop bounds:
|
|
824 |
// Change pre loop test, main loop test, and the
|
|
825 |
// main loop guard test to use lt or gt depending on stride
|
|
826 |
// direction:
|
|
827 |
// positive stride use <
|
|
828 |
// negative stride use >
|
|
829 |
|
|
830 |
if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
|
|
831 |
|
|
832 |
BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
|
|
833 |
// Modify pre loop end condition
|
|
834 |
Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool();
|
|
835 |
BoolNode* new_bol0 = new (C, 2) BoolNode(pre_bol->in(1), new_test);
|
|
836 |
register_new_node( new_bol0, pre_head->in(0) );
|
|
837 |
_igvn.hash_delete(pre_end);
|
|
838 |
pre_end->set_req(CountedLoopEndNode::TestValue, new_bol0);
|
|
839 |
// Modify main loop guard condition
|
|
840 |
assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay");
|
|
841 |
BoolNode* new_bol1 = new (C, 2) BoolNode(min_bol->in(1), new_test);
|
|
842 |
register_new_node( new_bol1, new_pre_exit );
|
|
843 |
_igvn.hash_delete(min_iff);
|
|
844 |
min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1);
|
|
845 |
// Modify main loop end condition
|
|
846 |
BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool();
|
|
847 |
BoolNode* new_bol2 = new (C, 2) BoolNode(main_bol->in(1), new_test);
|
|
848 |
register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) );
|
|
849 |
_igvn.hash_delete(main_end);
|
|
850 |
main_end->set_req(CountedLoopEndNode::TestValue, new_bol2);
|
|
851 |
}
|
|
852 |
|
|
853 |
// Flag main loop
|
|
854 |
main_head->set_main_loop();
|
|
855 |
if( peel_only ) main_head->set_main_no_pre_loop();
|
|
856 |
|
|
857 |
// It's difficult to be precise about the trip-counts
|
|
858 |
// for the pre/post loops. They are usually very short,
|
|
859 |
// so guess that 4 trips is a reasonable value.
|
|
860 |
post_head->set_profile_trip_cnt(4.0);
|
|
861 |
pre_head->set_profile_trip_cnt(4.0);
|
|
862 |
|
|
863 |
// Now force out all loop-invariant dominating tests. The optimizer
|
|
864 |
// finds some, but we _know_ they are all useless.
|
|
865 |
peeled_dom_test_elim(loop,old_new);
|
|
866 |
}
|
|
867 |
|
|
868 |
//------------------------------is_invariant-----------------------------
|
|
869 |
// Return true if n is invariant
|
|
870 |
bool IdealLoopTree::is_invariant(Node* n) const {
|
|
871 |
Node *n_c = _phase->get_ctrl(n);
|
|
872 |
if (n_c->is_top()) return false;
|
|
873 |
return !is_member(_phase->get_loop(n_c));
|
|
874 |
}
|
|
875 |
|
|
876 |
|
|
877 |
//------------------------------do_unroll--------------------------------------
|
|
878 |
// Unroll the loop body one step - make each trip do 2 iterations.
|
|
879 |
void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) {
|
|
880 |
assert( LoopUnrollLimit, "" );
|
|
881 |
#ifndef PRODUCT
|
|
882 |
if( PrintOpto && VerifyLoopOptimizations ) {
|
|
883 |
tty->print("Unrolling ");
|
|
884 |
loop->dump_head();
|
|
885 |
}
|
|
886 |
#endif
|
|
887 |
CountedLoopNode *loop_head = loop->_head->as_CountedLoop();
|
|
888 |
CountedLoopEndNode *loop_end = loop_head->loopexit();
|
|
889 |
assert( loop_end, "" );
|
|
890 |
|
|
891 |
// Remember loop node count before unrolling to detect
|
|
892 |
// if rounds of unroll,optimize are making progress
|
|
893 |
loop_head->set_node_count_before_unroll(loop->_body.size());
|
|
894 |
|
|
895 |
Node *ctrl = loop_head->in(LoopNode::EntryControl);
|
|
896 |
Node *limit = loop_head->limit();
|
|
897 |
Node *init = loop_head->init_trip();
|
|
898 |
Node *strid = loop_head->stride();
|
|
899 |
|
|
900 |
Node *opaq = NULL;
|
|
901 |
if( adjust_min_trip ) { // If not maximally unrolling, need adjustment
|
|
902 |
assert( loop_head->is_main_loop(), "" );
|
|
903 |
assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
|
|
904 |
Node *iff = ctrl->in(0);
|
|
905 |
assert( iff->Opcode() == Op_If, "" );
|
|
906 |
Node *bol = iff->in(1);
|
|
907 |
assert( bol->Opcode() == Op_Bool, "" );
|
|
908 |
Node *cmp = bol->in(1);
|
|
909 |
assert( cmp->Opcode() == Op_CmpI, "" );
|
|
910 |
opaq = cmp->in(2);
|
|
911 |
// Occasionally it's possible for a pre-loop Opaque1 node to be
|
|
912 |
// optimized away and then another round of loop opts attempted.
|
|
913 |
// We can not optimize this particular loop in that case.
|
|
914 |
if( opaq->Opcode() != Op_Opaque1 )
|
|
915 |
return; // Cannot find pre-loop! Bail out!
|
|
916 |
}
|
|
917 |
|
|
918 |
C->set_major_progress();
|
|
919 |
|
|
920 |
// Adjust max trip count. The trip count is intentionally rounded
|
|
921 |
// down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
|
|
922 |
// the main, unrolled, part of the loop will never execute as it is protected
|
|
923 |
// by the min-trip test. See bug 4834191 for a case where we over-unrolled
|
|
924 |
// and later determined that part of the unrolled loop was dead.
|
|
925 |
loop_head->set_trip_count(loop_head->trip_count() / 2);
|
|
926 |
|
|
927 |
// Double the count of original iterations in the unrolled loop body.
|
|
928 |
loop_head->double_unrolled_count();
|
|
929 |
|
|
930 |
// -----------
|
|
931 |
// Step 2: Cut back the trip counter for an unroll amount of 2.
|
|
932 |
// Loop will normally trip (limit - init)/stride_con. Since it's a
|
|
933 |
// CountedLoop this is exact (stride divides limit-init exactly).
|
|
934 |
// We are going to double the loop body, so we want to knock off any
|
|
935 |
// odd iteration: (trip_cnt & ~1). Then back compute a new limit.
|
|
936 |
Node *span = new (C, 3) SubINode( limit, init );
|
|
937 |
register_new_node( span, ctrl );
|
|
938 |
Node *trip = new (C, 3) DivINode( 0, span, strid );
|
|
939 |
register_new_node( trip, ctrl );
|
|
940 |
Node *mtwo = _igvn.intcon(-2);
|
|
941 |
set_ctrl(mtwo, C->root());
|
|
942 |
Node *rond = new (C, 3) AndINode( trip, mtwo );
|
|
943 |
register_new_node( rond, ctrl );
|
|
944 |
Node *spn2 = new (C, 3) MulINode( rond, strid );
|
|
945 |
register_new_node( spn2, ctrl );
|
|
946 |
Node *lim2 = new (C, 3) AddINode( spn2, init );
|
|
947 |
register_new_node( lim2, ctrl );
|
|
948 |
|
|
949 |
// Hammer in the new limit
|
|
950 |
Node *ctrl2 = loop_end->in(0);
|
|
951 |
Node *cmp2 = new (C, 3) CmpINode( loop_head->incr(), lim2 );
|
|
952 |
register_new_node( cmp2, ctrl2 );
|
|
953 |
Node *bol2 = new (C, 2) BoolNode( cmp2, loop_end->test_trip() );
|
|
954 |
register_new_node( bol2, ctrl2 );
|
|
955 |
_igvn.hash_delete(loop_end);
|
|
956 |
loop_end->set_req(CountedLoopEndNode::TestValue, bol2);
|
|
957 |
|
|
958 |
// Step 3: Find the min-trip test guaranteed before a 'main' loop.
|
|
959 |
// Make it a 1-trip test (means at least 2 trips).
|
|
960 |
if( adjust_min_trip ) {
|
|
961 |
// Guard test uses an 'opaque' node which is not shared. Hence I
|
|
962 |
// can edit it's inputs directly. Hammer in the new limit for the
|
|
963 |
// minimum-trip guard.
|
|
964 |
assert( opaq->outcnt() == 1, "" );
|
|
965 |
_igvn.hash_delete(opaq);
|
|
966 |
opaq->set_req(1, lim2);
|
|
967 |
}
|
|
968 |
|
|
969 |
// ---------
|
|
970 |
// Step 4: Clone the loop body. Move it inside the loop. This loop body
|
|
971 |
// represents the odd iterations; since the loop trips an even number of
|
|
972 |
// times its backedge is never taken. Kill the backedge.
|
|
973 |
uint dd = dom_depth(loop_head);
|
|
974 |
clone_loop( loop, old_new, dd );
|
|
975 |
|
|
976 |
// Make backedges of the clone equal to backedges of the original.
|
|
977 |
// Make the fall-in from the original come from the fall-out of the clone.
|
|
978 |
for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) {
|
|
979 |
Node* phi = loop_head->fast_out(j);
|
|
980 |
if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) {
|
|
981 |
Node *newphi = old_new[phi->_idx];
|
|
982 |
_igvn.hash_delete( phi );
|
|
983 |
_igvn.hash_delete( newphi );
|
|
984 |
|
|
985 |
phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl));
|
|
986 |
newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl));
|
|
987 |
phi ->set_req(LoopNode::LoopBackControl, C->top());
|
|
988 |
}
|
|
989 |
}
|
|
990 |
Node *clone_head = old_new[loop_head->_idx];
|
|
991 |
_igvn.hash_delete( clone_head );
|
|
992 |
loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl));
|
|
993 |
clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl));
|
|
994 |
loop_head ->set_req(LoopNode::LoopBackControl, C->top());
|
|
995 |
loop->_head = clone_head; // New loop header
|
|
996 |
|
|
997 |
set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd);
|
|
998 |
set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd);
|
|
999 |
|
|
1000 |
// Kill the clone's backedge
|
|
1001 |
Node *newcle = old_new[loop_end->_idx];
|
|
1002 |
_igvn.hash_delete( newcle );
|
|
1003 |
Node *one = _igvn.intcon(1);
|
|
1004 |
set_ctrl(one, C->root());
|
|
1005 |
newcle->set_req(1, one);
|
|
1006 |
// Force clone into same loop body
|
|
1007 |
uint max = loop->_body.size();
|
|
1008 |
for( uint k = 0; k < max; k++ ) {
|
|
1009 |
Node *old = loop->_body.at(k);
|
|
1010 |
Node *nnn = old_new[old->_idx];
|
|
1011 |
loop->_body.push(nnn);
|
|
1012 |
if (!has_ctrl(old))
|
|
1013 |
set_loop(nnn, loop);
|
|
1014 |
}
|
|
1015 |
}
|
|
1016 |
|
|
1017 |
//------------------------------do_maximally_unroll----------------------------
|
|
1018 |
|
|
1019 |
void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) {
|
|
1020 |
CountedLoopNode *cl = loop->_head->as_CountedLoop();
|
|
1021 |
assert( cl->trip_count() > 0, "");
|
|
1022 |
|
|
1023 |
// If loop is tripping an odd number of times, peel odd iteration
|
|
1024 |
if( (cl->trip_count() & 1) == 1 ) {
|
|
1025 |
do_peeling( loop, old_new );
|
|
1026 |
}
|
|
1027 |
|
|
1028 |
// Now its tripping an even number of times remaining. Double loop body.
|
|
1029 |
// Do not adjust pre-guards; they are not needed and do not exist.
|
|
1030 |
if( cl->trip_count() > 0 ) {
|
|
1031 |
do_unroll( loop, old_new, false );
|
|
1032 |
}
|
|
1033 |
}
|
|
1034 |
|
|
1035 |
//------------------------------dominates_backedge---------------------------------
|
|
1036 |
// Returns true if ctrl is executed on every complete iteration
|
|
1037 |
bool IdealLoopTree::dominates_backedge(Node* ctrl) {
|
|
1038 |
assert(ctrl->is_CFG(), "must be control");
|
|
1039 |
Node* backedge = _head->as_Loop()->in(LoopNode::LoopBackControl);
|
|
1040 |
return _phase->dom_lca_internal(ctrl, backedge) == ctrl;
|
|
1041 |
}
|
|
1042 |
|
|
1043 |
//------------------------------add_constraint---------------------------------
|
|
1044 |
// Constrain the main loop iterations so the condition:
|
|
1045 |
// scale_con * I + offset < limit
|
|
1046 |
// always holds true. That is, either increase the number of iterations in
|
|
1047 |
// the pre-loop or the post-loop until the condition holds true in the main
|
|
1048 |
// loop. Stride, scale, offset and limit are all loop invariant. Further,
|
|
1049 |
// stride and scale are constants (offset and limit often are).
|
|
1050 |
void PhaseIdealLoop::add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ) {
|
|
1051 |
|
|
1052 |
// Compute "I :: (limit-offset)/scale_con"
|
|
1053 |
Node *con = new (C, 3) SubINode( limit, offset );
|
|
1054 |
register_new_node( con, pre_ctrl );
|
|
1055 |
Node *scale = _igvn.intcon(scale_con);
|
|
1056 |
set_ctrl(scale, C->root());
|
|
1057 |
Node *X = new (C, 3) DivINode( 0, con, scale );
|
|
1058 |
register_new_node( X, pre_ctrl );
|
|
1059 |
|
|
1060 |
// For positive stride, the pre-loop limit always uses a MAX function
|
|
1061 |
// and the main loop a MIN function. For negative stride these are
|
|
1062 |
// reversed.
|
|
1063 |
|
|
1064 |
// Also for positive stride*scale the affine function is increasing, so the
|
|
1065 |
// pre-loop must check for underflow and the post-loop for overflow.
|
|
1066 |
// Negative stride*scale reverses this; pre-loop checks for overflow and
|
|
1067 |
// post-loop for underflow.
|
|
1068 |
if( stride_con*scale_con > 0 ) {
|
|
1069 |
// Compute I < (limit-offset)/scale_con
|
|
1070 |
// Adjust main-loop last iteration to be MIN/MAX(main_loop,X)
|
|
1071 |
*main_limit = (stride_con > 0)
|
|
1072 |
? (Node*)(new (C, 3) MinINode( *main_limit, X ))
|
|
1073 |
: (Node*)(new (C, 3) MaxINode( *main_limit, X ));
|
|
1074 |
register_new_node( *main_limit, pre_ctrl );
|
|
1075 |
|
|
1076 |
} else {
|
|
1077 |
// Compute (limit-offset)/scale_con + SGN(-scale_con) <= I
|
|
1078 |
// Add the negation of the main-loop constraint to the pre-loop.
|
|
1079 |
// See footnote [++] below for a derivation of the limit expression.
|
|
1080 |
Node *incr = _igvn.intcon(scale_con > 0 ? -1 : 1);
|
|
1081 |
set_ctrl(incr, C->root());
|
|
1082 |
Node *adj = new (C, 3) AddINode( X, incr );
|
|
1083 |
register_new_node( adj, pre_ctrl );
|
|
1084 |
*pre_limit = (scale_con > 0)
|
|
1085 |
? (Node*)new (C, 3) MinINode( *pre_limit, adj )
|
|
1086 |
: (Node*)new (C, 3) MaxINode( *pre_limit, adj );
|
|
1087 |
register_new_node( *pre_limit, pre_ctrl );
|
|
1088 |
|
|
1089 |
// [++] Here's the algebra that justifies the pre-loop limit expression:
|
|
1090 |
//
|
|
1091 |
// NOT( scale_con * I + offset < limit )
|
|
1092 |
// ==
|
|
1093 |
// scale_con * I + offset >= limit
|
|
1094 |
// ==
|
|
1095 |
// SGN(scale_con) * I >= (limit-offset)/|scale_con|
|
|
1096 |
// ==
|
|
1097 |
// (limit-offset)/|scale_con| <= I * SGN(scale_con)
|
|
1098 |
// ==
|
|
1099 |
// (limit-offset)/|scale_con|-1 < I * SGN(scale_con)
|
|
1100 |
// ==
|
|
1101 |
// ( if (scale_con > 0) /*common case*/
|
|
1102 |
// (limit-offset)/scale_con - 1 < I
|
|
1103 |
// else
|
|
1104 |
// (limit-offset)/scale_con + 1 > I
|
|
1105 |
// )
|
|
1106 |
// ( if (scale_con > 0) /*common case*/
|
|
1107 |
// (limit-offset)/scale_con + SGN(-scale_con) < I
|
|
1108 |
// else
|
|
1109 |
// (limit-offset)/scale_con + SGN(-scale_con) > I
|
|
1110 |
}
|
|
1111 |
}
|
|
1112 |
|
|
1113 |
|
|
1114 |
//------------------------------is_scaled_iv---------------------------------
|
|
1115 |
// Return true if exp is a constant times an induction var
|
|
1116 |
bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) {
|
|
1117 |
if (exp == iv) {
|
|
1118 |
if (p_scale != NULL) {
|
|
1119 |
*p_scale = 1;
|
|
1120 |
}
|
|
1121 |
return true;
|
|
1122 |
}
|
|
1123 |
int opc = exp->Opcode();
|
|
1124 |
if (opc == Op_MulI) {
|
|
1125 |
if (exp->in(1) == iv && exp->in(2)->is_Con()) {
|
|
1126 |
if (p_scale != NULL) {
|
|
1127 |
*p_scale = exp->in(2)->get_int();
|
|
1128 |
}
|
|
1129 |
return true;
|
|
1130 |
}
|
|
1131 |
if (exp->in(2) == iv && exp->in(1)->is_Con()) {
|
|
1132 |
if (p_scale != NULL) {
|
|
1133 |
*p_scale = exp->in(1)->get_int();
|
|
1134 |
}
|
|
1135 |
return true;
|
|
1136 |
}
|
|
1137 |
} else if (opc == Op_LShiftI) {
|
|
1138 |
if (exp->in(1) == iv && exp->in(2)->is_Con()) {
|
|
1139 |
if (p_scale != NULL) {
|
|
1140 |
*p_scale = 1 << exp->in(2)->get_int();
|
|
1141 |
}
|
|
1142 |
return true;
|
|
1143 |
}
|
|
1144 |
}
|
|
1145 |
return false;
|
|
1146 |
}
|
|
1147 |
|
|
1148 |
//-----------------------------is_scaled_iv_plus_offset------------------------------
|
|
1149 |
// Return true if exp is a simple induction variable expression: k1*iv + (invar + k2)
|
|
1150 |
bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) {
|
|
1151 |
if (is_scaled_iv(exp, iv, p_scale)) {
|
|
1152 |
if (p_offset != NULL) {
|
|
1153 |
Node *zero = _igvn.intcon(0);
|
|
1154 |
set_ctrl(zero, C->root());
|
|
1155 |
*p_offset = zero;
|
|
1156 |
}
|
|
1157 |
return true;
|
|
1158 |
}
|
|
1159 |
int opc = exp->Opcode();
|
|
1160 |
if (opc == Op_AddI) {
|
|
1161 |
if (is_scaled_iv(exp->in(1), iv, p_scale)) {
|
|
1162 |
if (p_offset != NULL) {
|
|
1163 |
*p_offset = exp->in(2);
|
|
1164 |
}
|
|
1165 |
return true;
|
|
1166 |
}
|
|
1167 |
if (exp->in(2)->is_Con()) {
|
|
1168 |
Node* offset2 = NULL;
|
|
1169 |
if (depth < 2 &&
|
|
1170 |
is_scaled_iv_plus_offset(exp->in(1), iv, p_scale,
|
|
1171 |
p_offset != NULL ? &offset2 : NULL, depth+1)) {
|
|
1172 |
if (p_offset != NULL) {
|
|
1173 |
Node *ctrl_off2 = get_ctrl(offset2);
|
|
1174 |
Node* offset = new (C, 3) AddINode(offset2, exp->in(2));
|
|
1175 |
register_new_node(offset, ctrl_off2);
|
|
1176 |
*p_offset = offset;
|
|
1177 |
}
|
|
1178 |
return true;
|
|
1179 |
}
|
|
1180 |
}
|
|
1181 |
} else if (opc == Op_SubI) {
|
|
1182 |
if (is_scaled_iv(exp->in(1), iv, p_scale)) {
|
|
1183 |
if (p_offset != NULL) {
|
|
1184 |
Node *zero = _igvn.intcon(0);
|
|
1185 |
set_ctrl(zero, C->root());
|
|
1186 |
Node *ctrl_off = get_ctrl(exp->in(2));
|
|
1187 |
Node* offset = new (C, 3) SubINode(zero, exp->in(2));
|
|
1188 |
register_new_node(offset, ctrl_off);
|
|
1189 |
*p_offset = offset;
|
|
1190 |
}
|
|
1191 |
return true;
|
|
1192 |
}
|
|
1193 |
if (is_scaled_iv(exp->in(2), iv, p_scale)) {
|
|
1194 |
if (p_offset != NULL) {
|
|
1195 |
*p_scale *= -1;
|
|
1196 |
*p_offset = exp->in(1);
|
|
1197 |
}
|
|
1198 |
return true;
|
|
1199 |
}
|
|
1200 |
}
|
|
1201 |
return false;
|
|
1202 |
}
|
|
1203 |
|
|
1204 |
//------------------------------do_range_check---------------------------------
|
|
1205 |
// Eliminate range-checks and other trip-counter vs loop-invariant tests.
|
|
1206 |
void PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) {
|
|
1207 |
#ifndef PRODUCT
|
|
1208 |
if( PrintOpto && VerifyLoopOptimizations ) {
|
|
1209 |
tty->print("Range Check Elimination ");
|
|
1210 |
loop->dump_head();
|
|
1211 |
}
|
|
1212 |
#endif
|
|
1213 |
assert( RangeCheckElimination, "" );
|
|
1214 |
CountedLoopNode *cl = loop->_head->as_CountedLoop();
|
|
1215 |
assert( cl->is_main_loop(), "" );
|
|
1216 |
|
|
1217 |
// Find the trip counter; we are iteration splitting based on it
|
|
1218 |
Node *trip_counter = cl->phi();
|
|
1219 |
// Find the main loop limit; we will trim it's iterations
|
|
1220 |
// to not ever trip end tests
|
|
1221 |
Node *main_limit = cl->limit();
|
|
1222 |
// Find the pre-loop limit; we will expand it's iterations to
|
|
1223 |
// not ever trip low tests.
|
|
1224 |
Node *ctrl = cl->in(LoopNode::EntryControl);
|
|
1225 |
assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
|
|
1226 |
Node *iffm = ctrl->in(0);
|
|
1227 |
assert( iffm->Opcode() == Op_If, "" );
|
|
1228 |
Node *p_f = iffm->in(0);
|
|
1229 |
assert( p_f->Opcode() == Op_IfFalse, "" );
|
|
1230 |
CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
|
|
1231 |
assert( pre_end->loopnode()->is_pre_loop(), "" );
|
|
1232 |
Node *pre_opaq1 = pre_end->limit();
|
|
1233 |
// Occasionally it's possible for a pre-loop Opaque1 node to be
|
|
1234 |
// optimized away and then another round of loop opts attempted.
|
|
1235 |
// We can not optimize this particular loop in that case.
|
|
1236 |
if( pre_opaq1->Opcode() != Op_Opaque1 )
|
|
1237 |
return;
|
|
1238 |
Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
|
|
1239 |
Node *pre_limit = pre_opaq->in(1);
|
|
1240 |
|
|
1241 |
// Where do we put new limit calculations
|
|
1242 |
Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
|
|
1243 |
|
|
1244 |
// Ensure the original loop limit is available from the
|
|
1245 |
// pre-loop Opaque1 node.
|
|
1246 |
Node *orig_limit = pre_opaq->original_loop_limit();
|
|
1247 |
if( orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP )
|
|
1248 |
return;
|
|
1249 |
|
|
1250 |
// Need to find the main-loop zero-trip guard
|
|
1251 |
Node *bolzm = iffm->in(1);
|
|
1252 |
assert( bolzm->Opcode() == Op_Bool, "" );
|
|
1253 |
Node *cmpzm = bolzm->in(1);
|
|
1254 |
assert( cmpzm->is_Cmp(), "" );
|
|
1255 |
Node *opqzm = cmpzm->in(2);
|
|
1256 |
if( opqzm->Opcode() != Op_Opaque1 )
|
|
1257 |
return;
|
|
1258 |
assert( opqzm->in(1) == main_limit, "do not understand situation" );
|
|
1259 |
|
|
1260 |
// Must know if its a count-up or count-down loop
|
|
1261 |
|
|
1262 |
// protect against stride not being a constant
|
|
1263 |
if ( !cl->stride_is_con() ) {
|
|
1264 |
return;
|
|
1265 |
}
|
|
1266 |
int stride_con = cl->stride_con();
|
|
1267 |
Node *zero = _igvn.intcon(0);
|
|
1268 |
Node *one = _igvn.intcon(1);
|
|
1269 |
set_ctrl(zero, C->root());
|
|
1270 |
set_ctrl(one, C->root());
|
|
1271 |
|
|
1272 |
// Range checks that do not dominate the loop backedge (ie.
|
|
1273 |
// conditionally executed) can lengthen the pre loop limit beyond
|
|
1274 |
// the original loop limit. To prevent this, the pre limit is
|
|
1275 |
// (for stride > 0) MINed with the original loop limit (MAXed
|
|
1276 |
// stride < 0) when some range_check (rc) is conditionally
|
|
1277 |
// executed.
|
|
1278 |
bool conditional_rc = false;
|
|
1279 |
|
|
1280 |
// Check loop body for tests of trip-counter plus loop-invariant vs
|
|
1281 |
// loop-invariant.
|
|
1282 |
for( uint i = 0; i < loop->_body.size(); i++ ) {
|
|
1283 |
Node *iff = loop->_body[i];
|
|
1284 |
if( iff->Opcode() == Op_If ) { // Test?
|
|
1285 |
|
|
1286 |
// Test is an IfNode, has 2 projections. If BOTH are in the loop
|
|
1287 |
// we need loop unswitching instead of iteration splitting.
|
|
1288 |
Node *exit = loop->is_loop_exit(iff);
|
|
1289 |
if( !exit ) continue;
|
|
1290 |
int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0;
|
|
1291 |
|
|
1292 |
// Get boolean condition to test
|
|
1293 |
Node *i1 = iff->in(1);
|
|
1294 |
if( !i1->is_Bool() ) continue;
|
|
1295 |
BoolNode *bol = i1->as_Bool();
|
|
1296 |
BoolTest b_test = bol->_test;
|
|
1297 |
// Flip sense of test if exit condition is flipped
|
|
1298 |
if( flip )
|
|
1299 |
b_test = b_test.negate();
|
|
1300 |
|
|
1301 |
// Get compare
|
|
1302 |
Node *cmp = bol->in(1);
|
|
1303 |
|
|
1304 |
// Look for trip_counter + offset vs limit
|
|
1305 |
Node *rc_exp = cmp->in(1);
|
|
1306 |
Node *limit = cmp->in(2);
|
|
1307 |
jint scale_con= 1; // Assume trip counter not scaled
|
|
1308 |
|
|
1309 |
Node *limit_c = get_ctrl(limit);
|
|
1310 |
if( loop->is_member(get_loop(limit_c) ) ) {
|
|
1311 |
// Compare might have operands swapped; commute them
|
|
1312 |
b_test = b_test.commute();
|
|
1313 |
rc_exp = cmp->in(2);
|
|
1314 |
limit = cmp->in(1);
|
|
1315 |
limit_c = get_ctrl(limit);
|
|
1316 |
if( loop->is_member(get_loop(limit_c) ) )
|
|
1317 |
continue; // Both inputs are loop varying; cannot RCE
|
|
1318 |
}
|
|
1319 |
// Here we know 'limit' is loop invariant
|
|
1320 |
|
|
1321 |
// 'limit' maybe pinned below the zero trip test (probably from a
|
|
1322 |
// previous round of rce), in which case, it can't be used in the
|
|
1323 |
// zero trip test expression which must occur before the zero test's if.
|
|
1324 |
if( limit_c == ctrl ) {
|
|
1325 |
continue; // Don't rce this check but continue looking for other candidates.
|
|
1326 |
}
|
|
1327 |
|
|
1328 |
// Check for scaled induction variable plus an offset
|
|
1329 |
Node *offset = NULL;
|
|
1330 |
|
|
1331 |
if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) {
|
|
1332 |
continue;
|
|
1333 |
}
|
|
1334 |
|
|
1335 |
Node *offset_c = get_ctrl(offset);
|
|
1336 |
if( loop->is_member( get_loop(offset_c) ) )
|
|
1337 |
continue; // Offset is not really loop invariant
|
|
1338 |
// Here we know 'offset' is loop invariant.
|
|
1339 |
|
|
1340 |
// As above for the 'limit', the 'offset' maybe pinned below the
|
|
1341 |
// zero trip test.
|
|
1342 |
if( offset_c == ctrl ) {
|
|
1343 |
continue; // Don't rce this check but continue looking for other candidates.
|
|
1344 |
}
|
|
1345 |
|
|
1346 |
// At this point we have the expression as:
|
|
1347 |
// scale_con * trip_counter + offset :: limit
|
|
1348 |
// where scale_con, offset and limit are loop invariant. Trip_counter
|
|
1349 |
// monotonically increases by stride_con, a constant. Both (or either)
|
|
1350 |
// stride_con and scale_con can be negative which will flip about the
|
|
1351 |
// sense of the test.
|
|
1352 |
|
|
1353 |
// Adjust pre and main loop limits to guard the correct iteration set
|
|
1354 |
if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests
|
|
1355 |
if( b_test._test == BoolTest::lt ) { // Range checks always use lt
|
|
1356 |
// The overflow limit: scale*I+offset < limit
|
|
1357 |
add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit );
|
|
1358 |
// The underflow limit: 0 <= scale*I+offset.
|
|
1359 |
// Some math yields: -scale*I-(offset+1) < 0
|
|
1360 |
Node *plus_one = new (C, 3) AddINode( offset, one );
|
|
1361 |
register_new_node( plus_one, pre_ctrl );
|
|
1362 |
Node *neg_offset = new (C, 3) SubINode( zero, plus_one );
|
|
1363 |
register_new_node( neg_offset, pre_ctrl );
|
|
1364 |
add_constraint( stride_con, -scale_con, neg_offset, zero, pre_ctrl, &pre_limit, &main_limit );
|
|
1365 |
if (!conditional_rc) {
|
|
1366 |
conditional_rc = !loop->dominates_backedge(iff);
|
|
1367 |
}
|
|
1368 |
} else {
|
|
1369 |
#ifndef PRODUCT
|
|
1370 |
if( PrintOpto )
|
|
1371 |
tty->print_cr("missed RCE opportunity");
|
|
1372 |
#endif
|
|
1373 |
continue; // In release mode, ignore it
|
|
1374 |
}
|
|
1375 |
} else { // Otherwise work on normal compares
|
|
1376 |
switch( b_test._test ) {
|
|
1377 |
case BoolTest::ge: // Convert X >= Y to -X <= -Y
|
|
1378 |
scale_con = -scale_con;
|
|
1379 |
offset = new (C, 3) SubINode( zero, offset );
|
|
1380 |
register_new_node( offset, pre_ctrl );
|
|
1381 |
limit = new (C, 3) SubINode( zero, limit );
|
|
1382 |
register_new_node( limit, pre_ctrl );
|
|
1383 |
// Fall into LE case
|
|
1384 |
case BoolTest::le: // Convert X <= Y to X < Y+1
|
|
1385 |
limit = new (C, 3) AddINode( limit, one );
|
|
1386 |
register_new_node( limit, pre_ctrl );
|
|
1387 |
// Fall into LT case
|
|
1388 |
case BoolTest::lt:
|
|
1389 |
add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit );
|
|
1390 |
if (!conditional_rc) {
|
|
1391 |
conditional_rc = !loop->dominates_backedge(iff);
|
|
1392 |
}
|
|
1393 |
break;
|
|
1394 |
default:
|
|
1395 |
#ifndef PRODUCT
|
|
1396 |
if( PrintOpto )
|
|
1397 |
tty->print_cr("missed RCE opportunity");
|
|
1398 |
#endif
|
|
1399 |
continue; // Unhandled case
|
|
1400 |
}
|
|
1401 |
}
|
|
1402 |
|
|
1403 |
// Kill the eliminated test
|
|
1404 |
C->set_major_progress();
|
|
1405 |
Node *kill_con = _igvn.intcon( 1-flip );
|
|
1406 |
set_ctrl(kill_con, C->root());
|
|
1407 |
_igvn.hash_delete(iff);
|
|
1408 |
iff->set_req(1, kill_con);
|
|
1409 |
_igvn._worklist.push(iff);
|
|
1410 |
// Find surviving projection
|
|
1411 |
assert(iff->is_If(), "");
|
|
1412 |
ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip);
|
|
1413 |
// Find loads off the surviving projection; remove their control edge
|
|
1414 |
for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
|
|
1415 |
Node* cd = dp->fast_out(i); // Control-dependent node
|
|
1416 |
if( cd->is_Load() ) { // Loads can now float around in the loop
|
|
1417 |
_igvn.hash_delete(cd);
|
|
1418 |
// Allow the load to float around in the loop, or before it
|
|
1419 |
// but NOT before the pre-loop.
|
|
1420 |
cd->set_req(0, ctrl); // ctrl, not NULL
|
|
1421 |
_igvn._worklist.push(cd);
|
|
1422 |
--i;
|
|
1423 |
--imax;
|
|
1424 |
}
|
|
1425 |
}
|
|
1426 |
|
|
1427 |
} // End of is IF
|
|
1428 |
|
|
1429 |
}
|
|
1430 |
|
|
1431 |
// Update loop limits
|
|
1432 |
if (conditional_rc) {
|
|
1433 |
pre_limit = (stride_con > 0) ? (Node*)new (C,3) MinINode(pre_limit, orig_limit)
|
|
1434 |
: (Node*)new (C,3) MaxINode(pre_limit, orig_limit);
|
|
1435 |
register_new_node(pre_limit, pre_ctrl);
|
|
1436 |
}
|
|
1437 |
_igvn.hash_delete(pre_opaq);
|
|
1438 |
pre_opaq->set_req(1, pre_limit);
|
|
1439 |
|
|
1440 |
// Note:: we are making the main loop limit no longer precise;
|
|
1441 |
// need to round up based on stride.
|
|
1442 |
if( stride_con != 1 && stride_con != -1 ) { // Cutout for common case
|
|
1443 |
// "Standard" round-up logic: ([main_limit-init+(y-1)]/y)*y+init
|
|
1444 |
// Hopefully, compiler will optimize for powers of 2.
|
|
1445 |
Node *ctrl = get_ctrl(main_limit);
|
|
1446 |
Node *stride = cl->stride();
|
|
1447 |
Node *init = cl->init_trip();
|
|
1448 |
Node *span = new (C, 3) SubINode(main_limit,init);
|
|
1449 |
register_new_node(span,ctrl);
|
|
1450 |
Node *rndup = _igvn.intcon(stride_con + ((stride_con>0)?-1:1));
|
|
1451 |
Node *add = new (C, 3) AddINode(span,rndup);
|
|
1452 |
register_new_node(add,ctrl);
|
|
1453 |
Node *div = new (C, 3) DivINode(0,add,stride);
|
|
1454 |
register_new_node(div,ctrl);
|
|
1455 |
Node *mul = new (C, 3) MulINode(div,stride);
|
|
1456 |
register_new_node(mul,ctrl);
|
|
1457 |
Node *newlim = new (C, 3) AddINode(mul,init);
|
|
1458 |
register_new_node(newlim,ctrl);
|
|
1459 |
main_limit = newlim;
|
|
1460 |
}
|
|
1461 |
|
|
1462 |
Node *main_cle = cl->loopexit();
|
|
1463 |
Node *main_bol = main_cle->in(1);
|
|
1464 |
// Hacking loop bounds; need private copies of exit test
|
|
1465 |
if( main_bol->outcnt() > 1 ) {// BoolNode shared?
|
|
1466 |
_igvn.hash_delete(main_cle);
|
|
1467 |
main_bol = main_bol->clone();// Clone a private BoolNode
|
|
1468 |
register_new_node( main_bol, main_cle->in(0) );
|
|
1469 |
main_cle->set_req(1,main_bol);
|
|
1470 |
}
|
|
1471 |
Node *main_cmp = main_bol->in(1);
|
|
1472 |
if( main_cmp->outcnt() > 1 ) { // CmpNode shared?
|
|
1473 |
_igvn.hash_delete(main_bol);
|
|
1474 |
main_cmp = main_cmp->clone();// Clone a private CmpNode
|
|
1475 |
register_new_node( main_cmp, main_cle->in(0) );
|
|
1476 |
main_bol->set_req(1,main_cmp);
|
|
1477 |
}
|
|
1478 |
// Hack the now-private loop bounds
|
|
1479 |
_igvn.hash_delete(main_cmp);
|
|
1480 |
main_cmp->set_req(2, main_limit);
|
|
1481 |
_igvn._worklist.push(main_cmp);
|
|
1482 |
// The OpaqueNode is unshared by design
|
|
1483 |
_igvn.hash_delete(opqzm);
|
|
1484 |
assert( opqzm->outcnt() == 1, "cannot hack shared node" );
|
|
1485 |
opqzm->set_req(1,main_limit);
|
|
1486 |
_igvn._worklist.push(opqzm);
|
|
1487 |
}
|
|
1488 |
|
|
1489 |
//------------------------------DCE_loop_body----------------------------------
|
|
1490 |
// Remove simplistic dead code from loop body
|
|
1491 |
void IdealLoopTree::DCE_loop_body() {
|
|
1492 |
for( uint i = 0; i < _body.size(); i++ )
|
|
1493 |
if( _body.at(i)->outcnt() == 0 )
|
|
1494 |
_body.map( i--, _body.pop() );
|
|
1495 |
}
|
|
1496 |
|
|
1497 |
|
|
1498 |
//------------------------------adjust_loop_exit_prob--------------------------
|
|
1499 |
// Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage.
|
|
1500 |
// Replace with a 1-in-10 exit guess.
|
|
1501 |
void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) {
|
|
1502 |
Node *test = tail();
|
|
1503 |
while( test != _head ) {
|
|
1504 |
uint top = test->Opcode();
|
|
1505 |
if( top == Op_IfTrue || top == Op_IfFalse ) {
|
|
1506 |
int test_con = ((ProjNode*)test)->_con;
|
|
1507 |
assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity");
|
|
1508 |
IfNode *iff = test->in(0)->as_If();
|
|
1509 |
if( iff->outcnt() == 2 ) { // Ignore dead tests
|
|
1510 |
Node *bol = iff->in(1);
|
|
1511 |
if( bol && bol->req() > 1 && bol->in(1) &&
|
|
1512 |
((bol->in(1)->Opcode() == Op_StorePConditional ) ||
|
|
1513 |
(bol->in(1)->Opcode() == Op_StoreLConditional ) ||
|
|
1514 |
(bol->in(1)->Opcode() == Op_CompareAndSwapI ) ||
|
|
1515 |
(bol->in(1)->Opcode() == Op_CompareAndSwapL ) ||
|
|
1516 |
(bol->in(1)->Opcode() == Op_CompareAndSwapP )))
|
|
1517 |
return; // Allocation loops RARELY take backedge
|
|
1518 |
// Find the OTHER exit path from the IF
|
|
1519 |
Node* ex = iff->proj_out(1-test_con);
|
|
1520 |
float p = iff->_prob;
|
|
1521 |
if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) {
|
|
1522 |
if( top == Op_IfTrue ) {
|
|
1523 |
if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) {
|
|
1524 |
iff->_prob = PROB_STATIC_FREQUENT;
|
|
1525 |
}
|
|
1526 |
} else {
|
|
1527 |
if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) {
|
|
1528 |
iff->_prob = PROB_STATIC_INFREQUENT;
|
|
1529 |
}
|
|
1530 |
}
|
|
1531 |
}
|
|
1532 |
}
|
|
1533 |
}
|
|
1534 |
test = phase->idom(test);
|
|
1535 |
}
|
|
1536 |
}
|
|
1537 |
|
|
1538 |
|
|
1539 |
//------------------------------policy_do_remove_empty_loop--------------------
|
|
1540 |
// Micro-benchmark spamming. Policy is to always remove empty loops.
|
|
1541 |
// The 'DO' part is to replace the trip counter with the value it will
|
|
1542 |
// have on the last iteration. This will break the loop.
|
|
1543 |
bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
|
|
1544 |
// Minimum size must be empty loop
|
|
1545 |
if( _body.size() > 7/*number of nodes in an empty loop*/ ) return false;
|
|
1546 |
|
|
1547 |
if( !_head->is_CountedLoop() ) return false; // Dead loop
|
|
1548 |
CountedLoopNode *cl = _head->as_CountedLoop();
|
|
1549 |
if( !cl->loopexit() ) return false; // Malformed loop
|
|
1550 |
if( !phase->is_member(this,phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue)) ) )
|
|
1551 |
return false; // Infinite loop
|
|
1552 |
#ifndef PRODUCT
|
|
1553 |
if( PrintOpto )
|
|
1554 |
tty->print_cr("Removing empty loop");
|
|
1555 |
#endif
|
|
1556 |
#ifdef ASSERT
|
|
1557 |
// Ensure only one phi which is the iv.
|
|
1558 |
Node* iv = NULL;
|
|
1559 |
for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
|
|
1560 |
Node* n = cl->fast_out(i);
|
|
1561 |
if (n->Opcode() == Op_Phi) {
|
|
1562 |
assert(iv == NULL, "Too many phis" );
|
|
1563 |
iv = n;
|
|
1564 |
}
|
|
1565 |
}
|
|
1566 |
assert(iv == cl->phi(), "Wrong phi" );
|
|
1567 |
#endif
|
|
1568 |
// Replace the phi at loop head with the final value of the last
|
|
1569 |
// iteration. Then the CountedLoopEnd will collapse (backedge never
|
|
1570 |
// taken) and all loop-invariant uses of the exit values will be correct.
|
|
1571 |
Node *phi = cl->phi();
|
|
1572 |
Node *final = new (phase->C, 3) SubINode( cl->limit(), cl->stride() );
|
|
1573 |
phase->register_new_node(final,cl->in(LoopNode::EntryControl));
|
|
1574 |
phase->_igvn.hash_delete(phi);
|
|
1575 |
phase->_igvn.subsume_node(phi,final);
|
|
1576 |
phase->C->set_major_progress();
|
|
1577 |
return true;
|
|
1578 |
}
|
|
1579 |
|
|
1580 |
|
|
1581 |
//=============================================================================
|
|
1582 |
//------------------------------iteration_split_impl---------------------------
|
|
1583 |
void IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) {
|
|
1584 |
// Check and remove empty loops (spam micro-benchmarks)
|
|
1585 |
if( policy_do_remove_empty_loop(phase) )
|
|
1586 |
return; // Here we removed an empty loop
|
|
1587 |
|
|
1588 |
bool should_peel = policy_peeling(phase); // Should we peel?
|
|
1589 |
|
|
1590 |
bool should_unswitch = policy_unswitching(phase);
|
|
1591 |
|
|
1592 |
// Non-counted loops may be peeled; exactly 1 iteration is peeled.
|
|
1593 |
// This removes loop-invariant tests (usually null checks).
|
|
1594 |
if( !_head->is_CountedLoop() ) { // Non-counted loop
|
|
1595 |
if (PartialPeelLoop && phase->partial_peel(this, old_new)) {
|
|
1596 |
return;
|
|
1597 |
}
|
|
1598 |
if( should_peel ) { // Should we peel?
|
|
1599 |
#ifndef PRODUCT
|
|
1600 |
if (PrintOpto) tty->print_cr("should_peel");
|
|
1601 |
#endif
|
|
1602 |
phase->do_peeling(this,old_new);
|
|
1603 |
} else if( should_unswitch ) {
|
|
1604 |
phase->do_unswitching(this, old_new);
|
|
1605 |
}
|
|
1606 |
return;
|
|
1607 |
}
|
|
1608 |
CountedLoopNode *cl = _head->as_CountedLoop();
|
|
1609 |
|
|
1610 |
if( !cl->loopexit() ) return; // Ignore various kinds of broken loops
|
|
1611 |
|
|
1612 |
// Do nothing special to pre- and post- loops
|
|
1613 |
if( cl->is_pre_loop() || cl->is_post_loop() ) return;
|
|
1614 |
|
|
1615 |
// Compute loop trip count from profile data
|
|
1616 |
compute_profile_trip_cnt(phase);
|
|
1617 |
|
|
1618 |
// Before attempting fancy unrolling, RCE or alignment, see if we want
|
|
1619 |
// to completely unroll this loop or do loop unswitching.
|
|
1620 |
if( cl->is_normal_loop() ) {
|
|
1621 |
bool should_maximally_unroll = policy_maximally_unroll(phase);
|
|
1622 |
if( should_maximally_unroll ) {
|
|
1623 |
// Here we did some unrolling and peeling. Eventually we will
|
|
1624 |
// completely unroll this loop and it will no longer be a loop.
|
|
1625 |
phase->do_maximally_unroll(this,old_new);
|
|
1626 |
return;
|
|
1627 |
}
|
|
1628 |
if (should_unswitch) {
|
|
1629 |
phase->do_unswitching(this, old_new);
|
|
1630 |
return;
|
|
1631 |
}
|
|
1632 |
}
|
|
1633 |
|
|
1634 |
|
|
1635 |
// Counted loops may be peeled, may need some iterations run up
|
|
1636 |
// front for RCE, and may want to align loop refs to a cache
|
|
1637 |
// line. Thus we clone a full loop up front whose trip count is
|
|
1638 |
// at least 1 (if peeling), but may be several more.
|
|
1639 |
|
|
1640 |
// The main loop will start cache-line aligned with at least 1
|
|
1641 |
// iteration of the unrolled body (zero-trip test required) and
|
|
1642 |
// will have some range checks removed.
|
|
1643 |
|
|
1644 |
// A post-loop will finish any odd iterations (leftover after
|
|
1645 |
// unrolling), plus any needed for RCE purposes.
|
|
1646 |
|
|
1647 |
bool should_unroll = policy_unroll(phase);
|
|
1648 |
|
|
1649 |
bool should_rce = policy_range_check(phase);
|
|
1650 |
|
|
1651 |
bool should_align = policy_align(phase);
|
|
1652 |
|
|
1653 |
// If not RCE'ing (iteration splitting) or Aligning, then we do not
|
|
1654 |
// need a pre-loop. We may still need to peel an initial iteration but
|
|
1655 |
// we will not be needing an unknown number of pre-iterations.
|
|
1656 |
//
|
|
1657 |
// Basically, if may_rce_align reports FALSE first time through,
|
|
1658 |
// we will not be able to later do RCE or Aligning on this loop.
|
|
1659 |
bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align;
|
|
1660 |
|
|
1661 |
// If we have any of these conditions (RCE, alignment, unrolling) met, then
|
|
1662 |
// we switch to the pre-/main-/post-loop model. This model also covers
|
|
1663 |
// peeling.
|
|
1664 |
if( should_rce || should_align || should_unroll ) {
|
|
1665 |
if( cl->is_normal_loop() ) // Convert to 'pre/main/post' loops
|
|
1666 |
phase->insert_pre_post_loops(this,old_new, !may_rce_align);
|
|
1667 |
|
|
1668 |
// Adjust the pre- and main-loop limits to let the pre and post loops run
|
|
1669 |
// with full checks, but the main-loop with no checks. Remove said
|
|
1670 |
// checks from the main body.
|
|
1671 |
if( should_rce )
|
|
1672 |
phase->do_range_check(this,old_new);
|
|
1673 |
|
|
1674 |
// Double loop body for unrolling. Adjust the minimum-trip test (will do
|
|
1675 |
// twice as many iterations as before) and the main body limit (only do
|
|
1676 |
// an even number of trips). If we are peeling, we might enable some RCE
|
|
1677 |
// and we'd rather unroll the post-RCE'd loop SO... do not unroll if
|
|
1678 |
// peeling.
|
|
1679 |
if( should_unroll && !should_peel )
|
|
1680 |
phase->do_unroll(this,old_new, true);
|
|
1681 |
|
|
1682 |
// Adjust the pre-loop limits to align the main body
|
|
1683 |
// iterations.
|
|
1684 |
if( should_align )
|
|
1685 |
Unimplemented();
|
|
1686 |
|
|
1687 |
} else { // Else we have an unchanged counted loop
|
|
1688 |
if( should_peel ) // Might want to peel but do nothing else
|
|
1689 |
phase->do_peeling(this,old_new);
|
|
1690 |
}
|
|
1691 |
}
|
|
1692 |
|
|
1693 |
|
|
1694 |
//=============================================================================
|
|
1695 |
//------------------------------iteration_split--------------------------------
|
|
1696 |
void IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) {
|
|
1697 |
// Recursively iteration split nested loops
|
|
1698 |
if( _child ) _child->iteration_split( phase, old_new );
|
|
1699 |
|
|
1700 |
// Clean out prior deadwood
|
|
1701 |
DCE_loop_body();
|
|
1702 |
|
|
1703 |
|
|
1704 |
// Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
|
|
1705 |
// Replace with a 1-in-10 exit guess.
|
|
1706 |
if( _parent /*not the root loop*/ &&
|
|
1707 |
!_irreducible &&
|
|
1708 |
// Also ignore the occasional dead backedge
|
|
1709 |
!tail()->is_top() ) {
|
|
1710 |
adjust_loop_exit_prob(phase);
|
|
1711 |
}
|
|
1712 |
|
|
1713 |
|
|
1714 |
// Gate unrolling, RCE and peeling efforts.
|
|
1715 |
if( !_child && // If not an inner loop, do not split
|
|
1716 |
!_irreducible &&
|
|
1717 |
!tail()->is_top() ) { // Also ignore the occasional dead backedge
|
|
1718 |
if (!_has_call) {
|
|
1719 |
iteration_split_impl( phase, old_new );
|
|
1720 |
} else if (policy_unswitching(phase)) {
|
|
1721 |
phase->do_unswitching(this, old_new);
|
|
1722 |
}
|
|
1723 |
}
|
|
1724 |
|
|
1725 |
// Minor offset re-organization to remove loop-fallout uses of
|
|
1726 |
// trip counter.
|
|
1727 |
if( _head->is_CountedLoop() ) phase->reorg_offsets( this );
|
|
1728 |
if( _next ) _next->iteration_split( phase, old_new );
|
|
1729 |
}
|