duke@435: /* xdono@631: * Copyright 2000-2008 Sun Microsystems, Inc. All Rights Reserved. duke@435: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. duke@435: * duke@435: * This code is free software; you can redistribute it and/or modify it duke@435: * under the terms of the GNU General Public License version 2 only, as duke@435: * published by the Free Software Foundation. duke@435: * duke@435: * This code is distributed in the hope that it will be useful, but WITHOUT duke@435: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or duke@435: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License duke@435: * version 2 for more details (a copy is included in the LICENSE file that duke@435: * accompanied this code). duke@435: * duke@435: * You should have received a copy of the GNU General Public License version duke@435: * 2 along with this work; if not, write to the Free Software Foundation, duke@435: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. duke@435: * duke@435: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, duke@435: * CA 95054 USA or visit www.sun.com if you need additional information or duke@435: * have any questions. duke@435: * duke@435: */ duke@435: duke@435: #include "incls/_precompiled.incl" duke@435: #include "incls/_loopTransform.cpp.incl" duke@435: duke@435: //------------------------------is_loop_exit----------------------------------- duke@435: // Given an IfNode, return the loop-exiting projection or NULL if both duke@435: // arms remain in the loop. duke@435: Node *IdealLoopTree::is_loop_exit(Node *iff) const { duke@435: if( iff->outcnt() != 2 ) return NULL; // Ignore partially dead tests duke@435: PhaseIdealLoop *phase = _phase; duke@435: // Test is an IfNode, has 2 projections. If BOTH are in the loop duke@435: // we need loop unswitching instead of peeling. duke@435: if( !is_member(phase->get_loop( iff->raw_out(0) )) ) duke@435: return iff->raw_out(0); duke@435: if( !is_member(phase->get_loop( iff->raw_out(1) )) ) duke@435: return iff->raw_out(1); duke@435: return NULL; duke@435: } duke@435: duke@435: duke@435: //============================================================================= duke@435: duke@435: duke@435: //------------------------------record_for_igvn---------------------------- duke@435: // Put loop body on igvn work list duke@435: void IdealLoopTree::record_for_igvn() { duke@435: for( uint i = 0; i < _body.size(); i++ ) { duke@435: Node *n = _body.at(i); duke@435: _phase->_igvn._worklist.push(n); duke@435: } duke@435: } duke@435: duke@435: //------------------------------compute_profile_trip_cnt---------------------------- duke@435: // Compute loop trip count from profile data as duke@435: // (backedge_count + loop_exit_count) / loop_exit_count duke@435: void IdealLoopTree::compute_profile_trip_cnt( PhaseIdealLoop *phase ) { duke@435: if (!_head->is_CountedLoop()) { duke@435: return; duke@435: } duke@435: CountedLoopNode* head = _head->as_CountedLoop(); duke@435: if (head->profile_trip_cnt() != COUNT_UNKNOWN) { duke@435: return; // Already computed duke@435: } duke@435: float trip_cnt = (float)max_jint; // default is big duke@435: duke@435: Node* back = head->in(LoopNode::LoopBackControl); duke@435: while (back != head) { duke@435: if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) && duke@435: back->in(0) && duke@435: back->in(0)->is_If() && duke@435: back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN && duke@435: back->in(0)->as_If()->_prob != PROB_UNKNOWN) { duke@435: break; duke@435: } duke@435: back = phase->idom(back); duke@435: } duke@435: if (back != head) { duke@435: assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) && duke@435: back->in(0), "if-projection exists"); duke@435: IfNode* back_if = back->in(0)->as_If(); duke@435: float loop_back_cnt = back_if->_fcnt * back_if->_prob; duke@435: duke@435: // Now compute a loop exit count duke@435: float loop_exit_cnt = 0.0f; duke@435: for( uint i = 0; i < _body.size(); i++ ) { duke@435: Node *n = _body[i]; duke@435: if( n->is_If() ) { duke@435: IfNode *iff = n->as_If(); duke@435: if( iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN ) { duke@435: Node *exit = is_loop_exit(iff); duke@435: if( exit ) { duke@435: float exit_prob = iff->_prob; duke@435: if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob; duke@435: if (exit_prob > PROB_MIN) { duke@435: float exit_cnt = iff->_fcnt * exit_prob; duke@435: loop_exit_cnt += exit_cnt; duke@435: } duke@435: } duke@435: } duke@435: } duke@435: } duke@435: if (loop_exit_cnt > 0.0f) { duke@435: trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt; duke@435: } else { duke@435: // No exit count so use duke@435: trip_cnt = loop_back_cnt; duke@435: } duke@435: } duke@435: #ifndef PRODUCT duke@435: if (TraceProfileTripCount) { duke@435: tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt); duke@435: } duke@435: #endif duke@435: head->set_profile_trip_cnt(trip_cnt); duke@435: } duke@435: duke@435: //---------------------is_invariant_addition----------------------------- duke@435: // Return nonzero index of invariant operand for an Add or Sub duke@435: // of (nonconstant) invariant and variant values. Helper for reassoicate_invariants. duke@435: int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) { duke@435: int op = n->Opcode(); duke@435: if (op == Op_AddI || op == Op_SubI) { duke@435: bool in1_invar = this->is_invariant(n->in(1)); duke@435: bool in2_invar = this->is_invariant(n->in(2)); duke@435: if (in1_invar && !in2_invar) return 1; duke@435: if (!in1_invar && in2_invar) return 2; duke@435: } duke@435: return 0; duke@435: } duke@435: duke@435: //---------------------reassociate_add_sub----------------------------- duke@435: // Reassociate invariant add and subtract expressions: duke@435: // duke@435: // inv1 + (x + inv2) => ( inv1 + inv2) + x duke@435: // (x + inv2) + inv1 => ( inv1 + inv2) + x duke@435: // inv1 + (x - inv2) => ( inv1 - inv2) + x duke@435: // inv1 - (inv2 - x) => ( inv1 - inv2) + x duke@435: // (x + inv2) - inv1 => (-inv1 + inv2) + x duke@435: // (x - inv2) + inv1 => ( inv1 - inv2) + x duke@435: // (x - inv2) - inv1 => (-inv1 - inv2) + x duke@435: // inv1 + (inv2 - x) => ( inv1 + inv2) - x duke@435: // inv1 - (x - inv2) => ( inv1 + inv2) - x duke@435: // (inv2 - x) + inv1 => ( inv1 + inv2) - x duke@435: // (inv2 - x) - inv1 => (-inv1 + inv2) - x duke@435: // inv1 - (x + inv2) => ( inv1 - inv2) - x duke@435: // duke@435: Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) { duke@435: if (!n1->is_Add() && !n1->is_Sub() || n1->outcnt() == 0) return NULL; duke@435: if (is_invariant(n1)) return NULL; duke@435: int inv1_idx = is_invariant_addition(n1, phase); duke@435: if (!inv1_idx) return NULL; duke@435: // Don't mess with add of constant (igvn moves them to expression tree root.) duke@435: if (n1->is_Add() && n1->in(2)->is_Con()) return NULL; duke@435: Node* inv1 = n1->in(inv1_idx); duke@435: Node* n2 = n1->in(3 - inv1_idx); duke@435: int inv2_idx = is_invariant_addition(n2, phase); duke@435: if (!inv2_idx) return NULL; duke@435: Node* x = n2->in(3 - inv2_idx); duke@435: Node* inv2 = n2->in(inv2_idx); duke@435: duke@435: bool neg_x = n2->is_Sub() && inv2_idx == 1; duke@435: bool neg_inv2 = n2->is_Sub() && inv2_idx == 2; duke@435: bool neg_inv1 = n1->is_Sub() && inv1_idx == 2; duke@435: if (n1->is_Sub() && inv1_idx == 1) { duke@435: neg_x = !neg_x; duke@435: neg_inv2 = !neg_inv2; duke@435: } duke@435: Node* inv1_c = phase->get_ctrl(inv1); duke@435: Node* inv2_c = phase->get_ctrl(inv2); duke@435: Node* n_inv1; duke@435: if (neg_inv1) { duke@435: Node *zero = phase->_igvn.intcon(0); duke@435: phase->set_ctrl(zero, phase->C->root()); duke@435: n_inv1 = new (phase->C, 3) SubINode(zero, inv1); duke@435: phase->register_new_node(n_inv1, inv1_c); duke@435: } else { duke@435: n_inv1 = inv1; duke@435: } duke@435: Node* inv; duke@435: if (neg_inv2) { duke@435: inv = new (phase->C, 3) SubINode(n_inv1, inv2); duke@435: } else { duke@435: inv = new (phase->C, 3) AddINode(n_inv1, inv2); duke@435: } duke@435: phase->register_new_node(inv, phase->get_early_ctrl(inv)); duke@435: duke@435: Node* addx; duke@435: if (neg_x) { duke@435: addx = new (phase->C, 3) SubINode(inv, x); duke@435: } else { duke@435: addx = new (phase->C, 3) AddINode(x, inv); duke@435: } duke@435: phase->register_new_node(addx, phase->get_ctrl(x)); duke@435: phase->_igvn.hash_delete(n1); duke@435: phase->_igvn.subsume_node(n1, addx); duke@435: return addx; duke@435: } duke@435: duke@435: //---------------------reassociate_invariants----------------------------- duke@435: // Reassociate invariant expressions: duke@435: void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) { duke@435: for (int i = _body.size() - 1; i >= 0; i--) { duke@435: Node *n = _body.at(i); duke@435: for (int j = 0; j < 5; j++) { duke@435: Node* nn = reassociate_add_sub(n, phase); duke@435: if (nn == NULL) break; duke@435: n = nn; // again duke@435: }; duke@435: } duke@435: } duke@435: duke@435: //------------------------------policy_peeling--------------------------------- duke@435: // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can duke@435: // make some loop-invariant test (usually a null-check) happen before the loop. duke@435: bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const { duke@435: Node *test = ((IdealLoopTree*)this)->tail(); duke@435: int body_size = ((IdealLoopTree*)this)->_body.size(); duke@435: int uniq = phase->C->unique(); duke@435: // Peeling does loop cloning which can result in O(N^2) node construction duke@435: if( body_size > 255 /* Prevent overflow for large body_size */ duke@435: || (body_size * body_size + uniq > MaxNodeLimit) ) { duke@435: return false; // too large to safely clone duke@435: } duke@435: while( test != _head ) { // Scan till run off top of loop duke@435: if( test->is_If() ) { // Test? duke@435: Node *ctrl = phase->get_ctrl(test->in(1)); duke@435: if (ctrl->is_top()) duke@435: return false; // Found dead test on live IF? No peeling! duke@435: // Standard IF only has one input value to check for loop invariance duke@435: assert( test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added"); duke@435: // Condition is not a member of this loop? duke@435: if( !is_member(phase->get_loop(ctrl)) && duke@435: is_loop_exit(test) ) duke@435: return true; // Found reason to peel! duke@435: } duke@435: // Walk up dominators to loop _head looking for test which is duke@435: // executed on every path thru loop. duke@435: test = phase->idom(test); duke@435: } duke@435: return false; duke@435: } duke@435: duke@435: //------------------------------peeled_dom_test_elim--------------------------- duke@435: // If we got the effect of peeling, either by actually peeling or by making duke@435: // a pre-loop which must execute at least once, we can remove all duke@435: // loop-invariant dominated tests in the main body. duke@435: void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) { duke@435: bool progress = true; duke@435: while( progress ) { duke@435: progress = false; // Reset for next iteration duke@435: Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail(); duke@435: Node *test = prev->in(0); duke@435: while( test != loop->_head ) { // Scan till run off top of loop duke@435: duke@435: int p_op = prev->Opcode(); duke@435: if( (p_op == Op_IfFalse || p_op == Op_IfTrue) && duke@435: test->is_If() && // Test? duke@435: !test->in(1)->is_Con() && // And not already obvious? duke@435: // Condition is not a member of this loop? duke@435: !loop->is_member(get_loop(get_ctrl(test->in(1))))){ duke@435: // Walk loop body looking for instances of this test duke@435: for( uint i = 0; i < loop->_body.size(); i++ ) { duke@435: Node *n = loop->_body.at(i); duke@435: if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) { duke@435: // IfNode was dominated by version in peeled loop body duke@435: progress = true; duke@435: dominated_by( old_new[prev->_idx], n ); duke@435: } duke@435: } duke@435: } duke@435: prev = test; duke@435: test = idom(test); duke@435: } // End of scan tests in loop duke@435: duke@435: } // End of while( progress ) duke@435: } duke@435: duke@435: //------------------------------do_peeling------------------------------------- duke@435: // Peel the first iteration of the given loop. duke@435: // Step 1: Clone the loop body. The clone becomes the peeled iteration. duke@435: // The pre-loop illegally has 2 control users (old & new loops). duke@435: // Step 2: Make the old-loop fall-in edges point to the peeled iteration. duke@435: // Do this by making the old-loop fall-in edges act as if they came duke@435: // around the loopback from the prior iteration (follow the old-loop duke@435: // backedges) and then map to the new peeled iteration. This leaves duke@435: // the pre-loop with only 1 user (the new peeled iteration), but the duke@435: // peeled-loop backedge has 2 users. duke@435: // Step 3: Cut the backedge on the clone (so its not a loop) and remove the duke@435: // extra backedge user. duke@435: void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) { duke@435: duke@435: C->set_major_progress(); duke@435: // Peeling a 'main' loop in a pre/main/post situation obfuscates the duke@435: // 'pre' loop from the main and the 'pre' can no longer have it's duke@435: // iterations adjusted. Therefore, we need to declare this loop as duke@435: // no longer a 'main' loop; it will need new pre and post loops before duke@435: // we can do further RCE. duke@435: Node *h = loop->_head; duke@435: if( h->is_CountedLoop() ) { duke@435: CountedLoopNode *cl = h->as_CountedLoop(); duke@435: assert(cl->trip_count() > 0, "peeling a fully unrolled loop"); duke@435: cl->set_trip_count(cl->trip_count() - 1); duke@435: if( cl->is_main_loop() ) { duke@435: cl->set_normal_loop(); duke@435: #ifndef PRODUCT duke@435: if( PrintOpto && VerifyLoopOptimizations ) { duke@435: tty->print("Peeling a 'main' loop; resetting to 'normal' "); duke@435: loop->dump_head(); duke@435: } duke@435: #endif duke@435: } duke@435: } duke@435: duke@435: // Step 1: Clone the loop body. The clone becomes the peeled iteration. duke@435: // The pre-loop illegally has 2 control users (old & new loops). duke@435: clone_loop( loop, old_new, dom_depth(loop->_head) ); duke@435: duke@435: duke@435: // Step 2: Make the old-loop fall-in edges point to the peeled iteration. duke@435: // Do this by making the old-loop fall-in edges act as if they came duke@435: // around the loopback from the prior iteration (follow the old-loop duke@435: // backedges) and then map to the new peeled iteration. This leaves duke@435: // the pre-loop with only 1 user (the new peeled iteration), but the duke@435: // peeled-loop backedge has 2 users. duke@435: for (DUIterator_Fast jmax, j = loop->_head->fast_outs(jmax); j < jmax; j++) { duke@435: Node* old = loop->_head->fast_out(j); duke@435: if( old->in(0) == loop->_head && old->req() == 3 && duke@435: (old->is_Loop() || old->is_Phi()) ) { duke@435: Node *new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx]; duke@435: if( !new_exit_value ) // Backedge value is ALSO loop invariant? duke@435: // Then loop body backedge value remains the same. duke@435: new_exit_value = old->in(LoopNode::LoopBackControl); duke@435: _igvn.hash_delete(old); duke@435: old->set_req(LoopNode::EntryControl, new_exit_value); duke@435: } duke@435: } duke@435: duke@435: duke@435: // Step 3: Cut the backedge on the clone (so its not a loop) and remove the duke@435: // extra backedge user. duke@435: Node *nnn = old_new[loop->_head->_idx]; duke@435: _igvn.hash_delete(nnn); duke@435: nnn->set_req(LoopNode::LoopBackControl, C->top()); duke@435: for (DUIterator_Fast j2max, j2 = nnn->fast_outs(j2max); j2 < j2max; j2++) { duke@435: Node* use = nnn->fast_out(j2); duke@435: if( use->in(0) == nnn && use->req() == 3 && use->is_Phi() ) { duke@435: _igvn.hash_delete(use); duke@435: use->set_req(LoopNode::LoopBackControl, C->top()); duke@435: } duke@435: } duke@435: duke@435: duke@435: // Step 4: Correct dom-depth info. Set to loop-head depth. duke@435: int dd = dom_depth(loop->_head); duke@435: set_idom(loop->_head, loop->_head->in(1), dd); duke@435: for (uint j3 = 0; j3 < loop->_body.size(); j3++) { duke@435: Node *old = loop->_body.at(j3); duke@435: Node *nnn = old_new[old->_idx]; duke@435: if (!has_ctrl(nnn)) duke@435: set_idom(nnn, idom(nnn), dd-1); duke@435: // While we're at it, remove any SafePoints from the peeled code duke@435: if( old->Opcode() == Op_SafePoint ) { duke@435: Node *nnn = old_new[old->_idx]; duke@435: lazy_replace(nnn,nnn->in(TypeFunc::Control)); duke@435: } duke@435: } duke@435: duke@435: // Now force out all loop-invariant dominating tests. The optimizer duke@435: // finds some, but we _know_ they are all useless. duke@435: peeled_dom_test_elim(loop,old_new); duke@435: duke@435: loop->record_for_igvn(); duke@435: } duke@435: duke@435: //------------------------------policy_maximally_unroll------------------------ duke@435: // Return exact loop trip count, or 0 if not maximally unrolling duke@435: bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const { duke@435: CountedLoopNode *cl = _head->as_CountedLoop(); duke@435: assert( cl->is_normal_loop(), "" ); duke@435: duke@435: Node *init_n = cl->init_trip(); duke@435: Node *limit_n = cl->limit(); duke@435: duke@435: // Non-constant bounds duke@435: if( init_n == NULL || !init_n->is_Con() || duke@435: limit_n == NULL || !limit_n->is_Con() || duke@435: // protect against stride not being a constant duke@435: !cl->stride_is_con() ) { duke@435: return false; duke@435: } duke@435: int init = init_n->get_int(); duke@435: int limit = limit_n->get_int(); duke@435: int span = limit - init; duke@435: int stride = cl->stride_con(); duke@435: duke@435: if (init >= limit || stride > span) { duke@435: // return a false (no maximally unroll) and the regular unroll/peel duke@435: // route will make a small mess which CCP will fold away. duke@435: return false; duke@435: } duke@435: uint trip_count = span/stride; // trip_count can be greater than 2 Gig. duke@435: assert( (int)trip_count*stride == span, "must divide evenly" ); duke@435: duke@435: // Real policy: if we maximally unroll, does it get too big? duke@435: // Allow the unrolled mess to get larger than standard loop duke@435: // size. After all, it will no longer be a loop. duke@435: uint body_size = _body.size(); duke@435: uint unroll_limit = (uint)LoopUnrollLimit * 4; duke@435: assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits"); duke@435: cl->set_trip_count(trip_count); duke@435: if( trip_count <= unroll_limit && body_size <= unroll_limit ) { duke@435: uint new_body_size = body_size * trip_count; duke@435: if (new_body_size <= unroll_limit && duke@435: body_size == new_body_size / trip_count && duke@435: // Unrolling can result in a large amount of node construction duke@435: new_body_size < MaxNodeLimit - phase->C->unique()) { duke@435: return true; // maximally unroll duke@435: } duke@435: } duke@435: duke@435: return false; // Do not maximally unroll duke@435: } duke@435: duke@435: duke@435: //------------------------------policy_unroll---------------------------------- duke@435: // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if duke@435: // the loop is a CountedLoop and the body is small enough. duke@435: bool IdealLoopTree::policy_unroll( PhaseIdealLoop *phase ) const { duke@435: duke@435: CountedLoopNode *cl = _head->as_CountedLoop(); duke@435: assert( cl->is_normal_loop() || cl->is_main_loop(), "" ); duke@435: duke@435: // protect against stride not being a constant duke@435: if( !cl->stride_is_con() ) return false; duke@435: duke@435: // protect against over-unrolling duke@435: if( cl->trip_count() <= 1 ) return false; duke@435: duke@435: int future_unroll_ct = cl->unrolled_count() * 2; duke@435: duke@435: // Don't unroll if the next round of unrolling would push us duke@435: // over the expected trip count of the loop. One is subtracted duke@435: // from the expected trip count because the pre-loop normally duke@435: // executes 1 iteration. duke@435: if (UnrollLimitForProfileCheck > 0 && duke@435: cl->profile_trip_cnt() != COUNT_UNKNOWN && duke@435: future_unroll_ct > UnrollLimitForProfileCheck && duke@435: (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) { duke@435: return false; duke@435: } duke@435: duke@435: // When unroll count is greater than LoopUnrollMin, don't unroll if: duke@435: // the residual iterations are more than 10% of the trip count duke@435: // and rounds of "unroll,optimize" are not making significant progress duke@435: // Progress defined as current size less than 20% larger than previous size. duke@435: if (UseSuperWord && cl->node_count_before_unroll() > 0 && duke@435: future_unroll_ct > LoopUnrollMin && duke@435: (future_unroll_ct - 1) * 10.0 > cl->profile_trip_cnt() && duke@435: 1.2 * cl->node_count_before_unroll() < (double)_body.size()) { duke@435: return false; duke@435: } duke@435: duke@435: Node *init_n = cl->init_trip(); duke@435: Node *limit_n = cl->limit(); duke@435: // Non-constant bounds. duke@435: // Protect against over-unrolling when init or/and limit are not constant duke@435: // (so that trip_count's init value is maxint) but iv range is known. duke@435: if( init_n == NULL || !init_n->is_Con() || duke@435: limit_n == NULL || !limit_n->is_Con() ) { duke@435: Node* phi = cl->phi(); duke@435: if( phi != NULL ) { duke@435: assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi."); duke@435: const TypeInt* iv_type = phase->_igvn.type(phi)->is_int(); duke@435: int next_stride = cl->stride_con() * 2; // stride after this unroll duke@435: if( next_stride > 0 ) { duke@435: if( iv_type->_lo + next_stride <= iv_type->_lo || // overflow duke@435: iv_type->_lo + next_stride > iv_type->_hi ) { duke@435: return false; // over-unrolling duke@435: } duke@435: } else if( next_stride < 0 ) { duke@435: if( iv_type->_hi + next_stride >= iv_type->_hi || // overflow duke@435: iv_type->_hi + next_stride < iv_type->_lo ) { duke@435: return false; // over-unrolling duke@435: } duke@435: } duke@435: } duke@435: } duke@435: duke@435: // Adjust body_size to determine if we unroll or not duke@435: uint body_size = _body.size(); duke@435: // Key test to unroll CaffeineMark's Logic test duke@435: int xors_in_loop = 0; duke@435: // Also count ModL, DivL and MulL which expand mightly duke@435: for( uint k = 0; k < _body.size(); k++ ) { duke@435: switch( _body.at(k)->Opcode() ) { duke@435: case Op_XorI: xors_in_loop++; break; // CaffeineMark's Logic test duke@435: case Op_ModL: body_size += 30; break; duke@435: case Op_DivL: body_size += 30; break; duke@435: case Op_MulL: body_size += 10; break; duke@435: } duke@435: } duke@435: duke@435: // Check for being too big duke@435: if( body_size > (uint)LoopUnrollLimit ) { duke@435: if( xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true; duke@435: // Normal case: loop too big duke@435: return false; duke@435: } duke@435: duke@435: // Check for stride being a small enough constant duke@435: if( abs(cl->stride_con()) > (1<<3) ) return false; duke@435: duke@435: // Unroll once! (Each trip will soon do double iterations) duke@435: return true; duke@435: } duke@435: duke@435: //------------------------------policy_align----------------------------------- duke@435: // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the duke@435: // expression that does the alignment. Note that only one array base can be duke@435: // aligned in a loop (unless the VM guarentees mutual alignment). Note that duke@435: // if we vectorize short memory ops into longer memory ops, we may want to duke@435: // increase alignment. duke@435: bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const { duke@435: return false; duke@435: } duke@435: duke@435: //------------------------------policy_range_check----------------------------- duke@435: // Return TRUE or FALSE if the loop should be range-check-eliminated. duke@435: // Actually we do iteration-splitting, a more powerful form of RCE. duke@435: bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const { duke@435: if( !RangeCheckElimination ) return false; duke@435: duke@435: CountedLoopNode *cl = _head->as_CountedLoop(); duke@435: // If we unrolled with no intention of doing RCE and we later duke@435: // changed our minds, we got no pre-loop. Either we need to duke@435: // make a new pre-loop, or we gotta disallow RCE. duke@435: if( cl->is_main_no_pre_loop() ) return false; // Disallowed for now. duke@435: Node *trip_counter = cl->phi(); duke@435: duke@435: // Check loop body for tests of trip-counter plus loop-invariant vs duke@435: // loop-invariant. duke@435: for( uint i = 0; i < _body.size(); i++ ) { duke@435: Node *iff = _body[i]; duke@435: if( iff->Opcode() == Op_If ) { // Test? duke@435: duke@435: // Comparing trip+off vs limit duke@435: Node *bol = iff->in(1); duke@435: if( bol->req() != 2 ) continue; // dead constant test duke@435: Node *cmp = bol->in(1); duke@435: duke@435: Node *rc_exp = cmp->in(1); duke@435: Node *limit = cmp->in(2); duke@435: duke@435: Node *limit_c = phase->get_ctrl(limit); duke@435: if( limit_c == phase->C->top() ) duke@435: return false; // Found dead test on live IF? No RCE! duke@435: if( is_member(phase->get_loop(limit_c) ) ) { duke@435: // Compare might have operands swapped; commute them duke@435: rc_exp = cmp->in(2); duke@435: limit = cmp->in(1); duke@435: limit_c = phase->get_ctrl(limit); duke@435: if( is_member(phase->get_loop(limit_c) ) ) duke@435: continue; // Both inputs are loop varying; cannot RCE duke@435: } duke@435: duke@435: if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) { duke@435: continue; duke@435: } duke@435: // Yeah! Found a test like 'trip+off vs limit' duke@435: // Test is an IfNode, has 2 projections. If BOTH are in the loop duke@435: // we need loop unswitching instead of iteration splitting. duke@435: if( is_loop_exit(iff) ) duke@435: return true; // Found reason to split iterations duke@435: } // End of is IF duke@435: } duke@435: duke@435: return false; duke@435: } duke@435: duke@435: //------------------------------policy_peel_only------------------------------- duke@435: // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful duke@435: // for unrolling loops with NO array accesses. duke@435: bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const { duke@435: duke@435: for( uint i = 0; i < _body.size(); i++ ) duke@435: if( _body[i]->is_Mem() ) duke@435: return false; duke@435: duke@435: // No memory accesses at all! duke@435: return true; duke@435: } duke@435: duke@435: //------------------------------clone_up_backedge_goo-------------------------- duke@435: // If Node n lives in the back_ctrl block and cannot float, we clone a private duke@435: // version of n in preheader_ctrl block and return that, otherwise return n. duke@435: Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n ) { duke@435: if( get_ctrl(n) != back_ctrl ) return n; duke@435: duke@435: Node *x = NULL; // If required, a clone of 'n' duke@435: // Check for 'n' being pinned in the backedge. duke@435: if( n->in(0) && n->in(0) == back_ctrl ) { duke@435: x = n->clone(); // Clone a copy of 'n' to preheader duke@435: x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader duke@435: } duke@435: duke@435: // Recursive fixup any other input edges into x. duke@435: // If there are no changes we can just return 'n', otherwise duke@435: // we need to clone a private copy and change it. duke@435: for( uint i = 1; i < n->req(); i++ ) { duke@435: Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i) ); duke@435: if( g != n->in(i) ) { duke@435: if( !x ) duke@435: x = n->clone(); duke@435: x->set_req(i, g); duke@435: } duke@435: } duke@435: if( x ) { // x can legally float to pre-header location duke@435: register_new_node( x, preheader_ctrl ); duke@435: return x; duke@435: } else { // raise n to cover LCA of uses duke@435: set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) ); duke@435: } duke@435: return n; duke@435: } duke@435: duke@435: //------------------------------insert_pre_post_loops-------------------------- duke@435: // Insert pre and post loops. If peel_only is set, the pre-loop can not have duke@435: // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no duke@435: // alignment. Useful to unroll loops that do no array accesses. duke@435: void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) { duke@435: duke@435: C->set_major_progress(); duke@435: duke@435: // Find common pieces of the loop being guarded with pre & post loops duke@435: CountedLoopNode *main_head = loop->_head->as_CountedLoop(); duke@435: assert( main_head->is_normal_loop(), "" ); duke@435: CountedLoopEndNode *main_end = main_head->loopexit(); duke@435: assert( main_end->outcnt() == 2, "1 true, 1 false path only" ); duke@435: uint dd_main_head = dom_depth(main_head); duke@435: uint max = main_head->outcnt(); duke@435: duke@435: Node *pre_header= main_head->in(LoopNode::EntryControl); duke@435: Node *init = main_head->init_trip(); duke@435: Node *incr = main_end ->incr(); duke@435: Node *limit = main_end ->limit(); duke@435: Node *stride = main_end ->stride(); duke@435: Node *cmp = main_end ->cmp_node(); duke@435: BoolTest::mask b_test = main_end->test_trip(); duke@435: duke@435: // Need only 1 user of 'bol' because I will be hacking the loop bounds. duke@435: Node *bol = main_end->in(CountedLoopEndNode::TestValue); duke@435: if( bol->outcnt() != 1 ) { duke@435: bol = bol->clone(); duke@435: register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl)); duke@435: _igvn.hash_delete(main_end); duke@435: main_end->set_req(CountedLoopEndNode::TestValue, bol); duke@435: } duke@435: // Need only 1 user of 'cmp' because I will be hacking the loop bounds. duke@435: if( cmp->outcnt() != 1 ) { duke@435: cmp = cmp->clone(); duke@435: register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl)); duke@435: _igvn.hash_delete(bol); duke@435: bol->set_req(1, cmp); duke@435: } duke@435: duke@435: //------------------------------ duke@435: // Step A: Create Post-Loop. duke@435: Node* main_exit = main_end->proj_out(false); duke@435: assert( main_exit->Opcode() == Op_IfFalse, "" ); duke@435: int dd_main_exit = dom_depth(main_exit); duke@435: duke@435: // Step A1: Clone the loop body. The clone becomes the post-loop. The main duke@435: // loop pre-header illegally has 2 control users (old & new loops). duke@435: clone_loop( loop, old_new, dd_main_exit ); duke@435: assert( old_new[main_end ->_idx]->Opcode() == Op_CountedLoopEnd, "" ); duke@435: CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop(); duke@435: post_head->set_post_loop(main_head); duke@435: duke@435: // Build the main-loop normal exit. duke@435: IfFalseNode *new_main_exit = new (C, 1) IfFalseNode(main_end); duke@435: _igvn.register_new_node_with_optimizer( new_main_exit ); duke@435: set_idom(new_main_exit, main_end, dd_main_exit ); duke@435: set_loop(new_main_exit, loop->_parent); duke@435: duke@435: // Step A2: Build a zero-trip guard for the post-loop. After leaving the duke@435: // main-loop, the post-loop may not execute at all. We 'opaque' the incr duke@435: // (the main-loop trip-counter exit value) because we will be changing duke@435: // the exit value (via unrolling) so we cannot constant-fold away the zero duke@435: // trip guard until all unrolling is done. kvn@651: Node *zer_opaq = new (C, 2) Opaque1Node(C, incr); duke@435: Node *zer_cmp = new (C, 3) CmpINode( zer_opaq, limit ); duke@435: Node *zer_bol = new (C, 2) BoolNode( zer_cmp, b_test ); duke@435: register_new_node( zer_opaq, new_main_exit ); duke@435: register_new_node( zer_cmp , new_main_exit ); duke@435: register_new_node( zer_bol , new_main_exit ); duke@435: duke@435: // Build the IfNode duke@435: IfNode *zer_iff = new (C, 2) IfNode( new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN ); duke@435: _igvn.register_new_node_with_optimizer( zer_iff ); duke@435: set_idom(zer_iff, new_main_exit, dd_main_exit); duke@435: set_loop(zer_iff, loop->_parent); duke@435: duke@435: // Plug in the false-path, taken if we need to skip post-loop duke@435: _igvn.hash_delete( main_exit ); duke@435: main_exit->set_req(0, zer_iff); duke@435: _igvn._worklist.push(main_exit); duke@435: set_idom(main_exit, zer_iff, dd_main_exit); duke@435: set_idom(main_exit->unique_out(), zer_iff, dd_main_exit); duke@435: // Make the true-path, must enter the post loop duke@435: Node *zer_taken = new (C, 1) IfTrueNode( zer_iff ); duke@435: _igvn.register_new_node_with_optimizer( zer_taken ); duke@435: set_idom(zer_taken, zer_iff, dd_main_exit); duke@435: set_loop(zer_taken, loop->_parent); duke@435: // Plug in the true path duke@435: _igvn.hash_delete( post_head ); duke@435: post_head->set_req(LoopNode::EntryControl, zer_taken); duke@435: set_idom(post_head, zer_taken, dd_main_exit); duke@435: duke@435: // Step A3: Make the fall-in values to the post-loop come from the duke@435: // fall-out values of the main-loop. duke@435: for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) { duke@435: Node* main_phi = main_head->fast_out(i); duke@435: if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0 ) { duke@435: Node *post_phi = old_new[main_phi->_idx]; duke@435: Node *fallmain = clone_up_backedge_goo(main_head->back_control(), duke@435: post_head->init_control(), duke@435: main_phi->in(LoopNode::LoopBackControl)); duke@435: _igvn.hash_delete(post_phi); duke@435: post_phi->set_req( LoopNode::EntryControl, fallmain ); duke@435: } duke@435: } duke@435: duke@435: // Update local caches for next stanza duke@435: main_exit = new_main_exit; duke@435: duke@435: duke@435: //------------------------------ duke@435: // Step B: Create Pre-Loop. duke@435: duke@435: // Step B1: Clone the loop body. The clone becomes the pre-loop. The main duke@435: // loop pre-header illegally has 2 control users (old & new loops). duke@435: clone_loop( loop, old_new, dd_main_head ); duke@435: CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop(); duke@435: CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd(); duke@435: pre_head->set_pre_loop(main_head); duke@435: Node *pre_incr = old_new[incr->_idx]; duke@435: duke@435: // Find the pre-loop normal exit. duke@435: Node* pre_exit = pre_end->proj_out(false); duke@435: assert( pre_exit->Opcode() == Op_IfFalse, "" ); duke@435: IfFalseNode *new_pre_exit = new (C, 1) IfFalseNode(pre_end); duke@435: _igvn.register_new_node_with_optimizer( new_pre_exit ); duke@435: set_idom(new_pre_exit, pre_end, dd_main_head); duke@435: set_loop(new_pre_exit, loop->_parent); duke@435: duke@435: // Step B2: Build a zero-trip guard for the main-loop. After leaving the duke@435: // pre-loop, the main-loop may not execute at all. Later in life this duke@435: // zero-trip guard will become the minimum-trip guard when we unroll duke@435: // the main-loop. kvn@651: Node *min_opaq = new (C, 2) Opaque1Node(C, limit); duke@435: Node *min_cmp = new (C, 3) CmpINode( pre_incr, min_opaq ); duke@435: Node *min_bol = new (C, 2) BoolNode( min_cmp, b_test ); duke@435: register_new_node( min_opaq, new_pre_exit ); duke@435: register_new_node( min_cmp , new_pre_exit ); duke@435: register_new_node( min_bol , new_pre_exit ); duke@435: duke@435: // Build the IfNode duke@435: IfNode *min_iff = new (C, 2) IfNode( new_pre_exit, min_bol, PROB_FAIR, COUNT_UNKNOWN ); duke@435: _igvn.register_new_node_with_optimizer( min_iff ); duke@435: set_idom(min_iff, new_pre_exit, dd_main_head); duke@435: set_loop(min_iff, loop->_parent); duke@435: duke@435: // Plug in the false-path, taken if we need to skip main-loop duke@435: _igvn.hash_delete( pre_exit ); duke@435: pre_exit->set_req(0, min_iff); duke@435: set_idom(pre_exit, min_iff, dd_main_head); duke@435: set_idom(pre_exit->unique_out(), min_iff, dd_main_head); duke@435: // Make the true-path, must enter the main loop duke@435: Node *min_taken = new (C, 1) IfTrueNode( min_iff ); duke@435: _igvn.register_new_node_with_optimizer( min_taken ); duke@435: set_idom(min_taken, min_iff, dd_main_head); duke@435: set_loop(min_taken, loop->_parent); duke@435: // Plug in the true path duke@435: _igvn.hash_delete( main_head ); duke@435: main_head->set_req(LoopNode::EntryControl, min_taken); duke@435: set_idom(main_head, min_taken, dd_main_head); duke@435: duke@435: // Step B3: Make the fall-in values to the main-loop come from the duke@435: // fall-out values of the pre-loop. duke@435: for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) { duke@435: Node* main_phi = main_head->fast_out(i2); duke@435: if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) { duke@435: Node *pre_phi = old_new[main_phi->_idx]; duke@435: Node *fallpre = clone_up_backedge_goo(pre_head->back_control(), duke@435: main_head->init_control(), duke@435: pre_phi->in(LoopNode::LoopBackControl)); duke@435: _igvn.hash_delete(main_phi); duke@435: main_phi->set_req( LoopNode::EntryControl, fallpre ); duke@435: } duke@435: } duke@435: duke@435: // Step B4: Shorten the pre-loop to run only 1 iteration (for now). duke@435: // RCE and alignment may change this later. duke@435: Node *cmp_end = pre_end->cmp_node(); duke@435: assert( cmp_end->in(2) == limit, "" ); duke@435: Node *pre_limit = new (C, 3) AddINode( init, stride ); duke@435: duke@435: // Save the original loop limit in this Opaque1 node for duke@435: // use by range check elimination. kvn@651: Node *pre_opaq = new (C, 3) Opaque1Node(C, pre_limit, limit); duke@435: duke@435: register_new_node( pre_limit, pre_head->in(0) ); duke@435: register_new_node( pre_opaq , pre_head->in(0) ); duke@435: duke@435: // Since no other users of pre-loop compare, I can hack limit directly duke@435: assert( cmp_end->outcnt() == 1, "no other users" ); duke@435: _igvn.hash_delete(cmp_end); duke@435: cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq); duke@435: duke@435: // Special case for not-equal loop bounds: duke@435: // Change pre loop test, main loop test, and the duke@435: // main loop guard test to use lt or gt depending on stride duke@435: // direction: duke@435: // positive stride use < duke@435: // negative stride use > duke@435: duke@435: if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) { duke@435: duke@435: BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt; duke@435: // Modify pre loop end condition duke@435: Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool(); duke@435: BoolNode* new_bol0 = new (C, 2) BoolNode(pre_bol->in(1), new_test); duke@435: register_new_node( new_bol0, pre_head->in(0) ); duke@435: _igvn.hash_delete(pre_end); duke@435: pre_end->set_req(CountedLoopEndNode::TestValue, new_bol0); duke@435: // Modify main loop guard condition duke@435: assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay"); duke@435: BoolNode* new_bol1 = new (C, 2) BoolNode(min_bol->in(1), new_test); duke@435: register_new_node( new_bol1, new_pre_exit ); duke@435: _igvn.hash_delete(min_iff); duke@435: min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1); duke@435: // Modify main loop end condition duke@435: BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool(); duke@435: BoolNode* new_bol2 = new (C, 2) BoolNode(main_bol->in(1), new_test); duke@435: register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) ); duke@435: _igvn.hash_delete(main_end); duke@435: main_end->set_req(CountedLoopEndNode::TestValue, new_bol2); duke@435: } duke@435: duke@435: // Flag main loop duke@435: main_head->set_main_loop(); duke@435: if( peel_only ) main_head->set_main_no_pre_loop(); duke@435: duke@435: // It's difficult to be precise about the trip-counts duke@435: // for the pre/post loops. They are usually very short, duke@435: // so guess that 4 trips is a reasonable value. duke@435: post_head->set_profile_trip_cnt(4.0); duke@435: pre_head->set_profile_trip_cnt(4.0); duke@435: duke@435: // Now force out all loop-invariant dominating tests. The optimizer duke@435: // finds some, but we _know_ they are all useless. duke@435: peeled_dom_test_elim(loop,old_new); duke@435: } duke@435: duke@435: //------------------------------is_invariant----------------------------- duke@435: // Return true if n is invariant duke@435: bool IdealLoopTree::is_invariant(Node* n) const { duke@435: Node *n_c = _phase->get_ctrl(n); duke@435: if (n_c->is_top()) return false; duke@435: return !is_member(_phase->get_loop(n_c)); duke@435: } duke@435: duke@435: duke@435: //------------------------------do_unroll-------------------------------------- duke@435: // Unroll the loop body one step - make each trip do 2 iterations. duke@435: void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) { duke@435: assert( LoopUnrollLimit, "" ); duke@435: #ifndef PRODUCT duke@435: if( PrintOpto && VerifyLoopOptimizations ) { duke@435: tty->print("Unrolling "); duke@435: loop->dump_head(); duke@435: } duke@435: #endif duke@435: CountedLoopNode *loop_head = loop->_head->as_CountedLoop(); duke@435: CountedLoopEndNode *loop_end = loop_head->loopexit(); duke@435: assert( loop_end, "" ); duke@435: duke@435: // Remember loop node count before unrolling to detect duke@435: // if rounds of unroll,optimize are making progress duke@435: loop_head->set_node_count_before_unroll(loop->_body.size()); duke@435: duke@435: Node *ctrl = loop_head->in(LoopNode::EntryControl); duke@435: Node *limit = loop_head->limit(); duke@435: Node *init = loop_head->init_trip(); duke@435: Node *strid = loop_head->stride(); duke@435: duke@435: Node *opaq = NULL; duke@435: if( adjust_min_trip ) { // If not maximally unrolling, need adjustment duke@435: assert( loop_head->is_main_loop(), "" ); duke@435: assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); duke@435: Node *iff = ctrl->in(0); duke@435: assert( iff->Opcode() == Op_If, "" ); duke@435: Node *bol = iff->in(1); duke@435: assert( bol->Opcode() == Op_Bool, "" ); duke@435: Node *cmp = bol->in(1); duke@435: assert( cmp->Opcode() == Op_CmpI, "" ); duke@435: opaq = cmp->in(2); duke@435: // Occasionally it's possible for a pre-loop Opaque1 node to be duke@435: // optimized away and then another round of loop opts attempted. duke@435: // We can not optimize this particular loop in that case. duke@435: if( opaq->Opcode() != Op_Opaque1 ) duke@435: return; // Cannot find pre-loop! Bail out! duke@435: } duke@435: duke@435: C->set_major_progress(); duke@435: duke@435: // Adjust max trip count. The trip count is intentionally rounded duke@435: // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll, duke@435: // the main, unrolled, part of the loop will never execute as it is protected duke@435: // by the min-trip test. See bug 4834191 for a case where we over-unrolled duke@435: // and later determined that part of the unrolled loop was dead. duke@435: loop_head->set_trip_count(loop_head->trip_count() / 2); duke@435: duke@435: // Double the count of original iterations in the unrolled loop body. duke@435: loop_head->double_unrolled_count(); duke@435: duke@435: // ----------- duke@435: // Step 2: Cut back the trip counter for an unroll amount of 2. duke@435: // Loop will normally trip (limit - init)/stride_con. Since it's a duke@435: // CountedLoop this is exact (stride divides limit-init exactly). duke@435: // We are going to double the loop body, so we want to knock off any duke@435: // odd iteration: (trip_cnt & ~1). Then back compute a new limit. duke@435: Node *span = new (C, 3) SubINode( limit, init ); duke@435: register_new_node( span, ctrl ); duke@435: Node *trip = new (C, 3) DivINode( 0, span, strid ); duke@435: register_new_node( trip, ctrl ); duke@435: Node *mtwo = _igvn.intcon(-2); duke@435: set_ctrl(mtwo, C->root()); duke@435: Node *rond = new (C, 3) AndINode( trip, mtwo ); duke@435: register_new_node( rond, ctrl ); duke@435: Node *spn2 = new (C, 3) MulINode( rond, strid ); duke@435: register_new_node( spn2, ctrl ); duke@435: Node *lim2 = new (C, 3) AddINode( spn2, init ); duke@435: register_new_node( lim2, ctrl ); duke@435: duke@435: // Hammer in the new limit duke@435: Node *ctrl2 = loop_end->in(0); duke@435: Node *cmp2 = new (C, 3) CmpINode( loop_head->incr(), lim2 ); duke@435: register_new_node( cmp2, ctrl2 ); duke@435: Node *bol2 = new (C, 2) BoolNode( cmp2, loop_end->test_trip() ); duke@435: register_new_node( bol2, ctrl2 ); duke@435: _igvn.hash_delete(loop_end); duke@435: loop_end->set_req(CountedLoopEndNode::TestValue, bol2); duke@435: duke@435: // Step 3: Find the min-trip test guaranteed before a 'main' loop. duke@435: // Make it a 1-trip test (means at least 2 trips). duke@435: if( adjust_min_trip ) { duke@435: // Guard test uses an 'opaque' node which is not shared. Hence I duke@435: // can edit it's inputs directly. Hammer in the new limit for the duke@435: // minimum-trip guard. duke@435: assert( opaq->outcnt() == 1, "" ); duke@435: _igvn.hash_delete(opaq); duke@435: opaq->set_req(1, lim2); duke@435: } duke@435: duke@435: // --------- duke@435: // Step 4: Clone the loop body. Move it inside the loop. This loop body duke@435: // represents the odd iterations; since the loop trips an even number of duke@435: // times its backedge is never taken. Kill the backedge. duke@435: uint dd = dom_depth(loop_head); duke@435: clone_loop( loop, old_new, dd ); duke@435: duke@435: // Make backedges of the clone equal to backedges of the original. duke@435: // Make the fall-in from the original come from the fall-out of the clone. duke@435: for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) { duke@435: Node* phi = loop_head->fast_out(j); duke@435: if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) { duke@435: Node *newphi = old_new[phi->_idx]; duke@435: _igvn.hash_delete( phi ); duke@435: _igvn.hash_delete( newphi ); duke@435: duke@435: phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl)); duke@435: newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl)); duke@435: phi ->set_req(LoopNode::LoopBackControl, C->top()); duke@435: } duke@435: } duke@435: Node *clone_head = old_new[loop_head->_idx]; duke@435: _igvn.hash_delete( clone_head ); duke@435: loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl)); duke@435: clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl)); duke@435: loop_head ->set_req(LoopNode::LoopBackControl, C->top()); duke@435: loop->_head = clone_head; // New loop header duke@435: duke@435: set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd); duke@435: set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd); duke@435: duke@435: // Kill the clone's backedge duke@435: Node *newcle = old_new[loop_end->_idx]; duke@435: _igvn.hash_delete( newcle ); duke@435: Node *one = _igvn.intcon(1); duke@435: set_ctrl(one, C->root()); duke@435: newcle->set_req(1, one); duke@435: // Force clone into same loop body duke@435: uint max = loop->_body.size(); duke@435: for( uint k = 0; k < max; k++ ) { duke@435: Node *old = loop->_body.at(k); duke@435: Node *nnn = old_new[old->_idx]; duke@435: loop->_body.push(nnn); duke@435: if (!has_ctrl(old)) duke@435: set_loop(nnn, loop); duke@435: } never@802: never@802: loop->record_for_igvn(); duke@435: } duke@435: duke@435: //------------------------------do_maximally_unroll---------------------------- duke@435: duke@435: void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) { duke@435: CountedLoopNode *cl = loop->_head->as_CountedLoop(); duke@435: assert( cl->trip_count() > 0, ""); duke@435: duke@435: // If loop is tripping an odd number of times, peel odd iteration duke@435: if( (cl->trip_count() & 1) == 1 ) { duke@435: do_peeling( loop, old_new ); duke@435: } duke@435: duke@435: // Now its tripping an even number of times remaining. Double loop body. duke@435: // Do not adjust pre-guards; they are not needed and do not exist. duke@435: if( cl->trip_count() > 0 ) { duke@435: do_unroll( loop, old_new, false ); duke@435: } duke@435: } duke@435: duke@435: //------------------------------dominates_backedge--------------------------------- duke@435: // Returns true if ctrl is executed on every complete iteration duke@435: bool IdealLoopTree::dominates_backedge(Node* ctrl) { duke@435: assert(ctrl->is_CFG(), "must be control"); duke@435: Node* backedge = _head->as_Loop()->in(LoopNode::LoopBackControl); duke@435: return _phase->dom_lca_internal(ctrl, backedge) == ctrl; duke@435: } duke@435: duke@435: //------------------------------add_constraint--------------------------------- duke@435: // Constrain the main loop iterations so the condition: duke@435: // scale_con * I + offset < limit duke@435: // always holds true. That is, either increase the number of iterations in duke@435: // the pre-loop or the post-loop until the condition holds true in the main duke@435: // loop. Stride, scale, offset and limit are all loop invariant. Further, duke@435: // stride and scale are constants (offset and limit often are). duke@435: void PhaseIdealLoop::add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ) { duke@435: duke@435: // Compute "I :: (limit-offset)/scale_con" duke@435: Node *con = new (C, 3) SubINode( limit, offset ); duke@435: register_new_node( con, pre_ctrl ); duke@435: Node *scale = _igvn.intcon(scale_con); duke@435: set_ctrl(scale, C->root()); duke@435: Node *X = new (C, 3) DivINode( 0, con, scale ); duke@435: register_new_node( X, pre_ctrl ); duke@435: duke@435: // For positive stride, the pre-loop limit always uses a MAX function duke@435: // and the main loop a MIN function. For negative stride these are duke@435: // reversed. duke@435: duke@435: // Also for positive stride*scale the affine function is increasing, so the duke@435: // pre-loop must check for underflow and the post-loop for overflow. duke@435: // Negative stride*scale reverses this; pre-loop checks for overflow and duke@435: // post-loop for underflow. duke@435: if( stride_con*scale_con > 0 ) { duke@435: // Compute I < (limit-offset)/scale_con duke@435: // Adjust main-loop last iteration to be MIN/MAX(main_loop,X) duke@435: *main_limit = (stride_con > 0) duke@435: ? (Node*)(new (C, 3) MinINode( *main_limit, X )) duke@435: : (Node*)(new (C, 3) MaxINode( *main_limit, X )); duke@435: register_new_node( *main_limit, pre_ctrl ); duke@435: duke@435: } else { duke@435: // Compute (limit-offset)/scale_con + SGN(-scale_con) <= I duke@435: // Add the negation of the main-loop constraint to the pre-loop. duke@435: // See footnote [++] below for a derivation of the limit expression. duke@435: Node *incr = _igvn.intcon(scale_con > 0 ? -1 : 1); duke@435: set_ctrl(incr, C->root()); duke@435: Node *adj = new (C, 3) AddINode( X, incr ); duke@435: register_new_node( adj, pre_ctrl ); duke@435: *pre_limit = (scale_con > 0) duke@435: ? (Node*)new (C, 3) MinINode( *pre_limit, adj ) duke@435: : (Node*)new (C, 3) MaxINode( *pre_limit, adj ); duke@435: register_new_node( *pre_limit, pre_ctrl ); duke@435: duke@435: // [++] Here's the algebra that justifies the pre-loop limit expression: duke@435: // duke@435: // NOT( scale_con * I + offset < limit ) duke@435: // == duke@435: // scale_con * I + offset >= limit duke@435: // == duke@435: // SGN(scale_con) * I >= (limit-offset)/|scale_con| duke@435: // == duke@435: // (limit-offset)/|scale_con| <= I * SGN(scale_con) duke@435: // == duke@435: // (limit-offset)/|scale_con|-1 < I * SGN(scale_con) duke@435: // == duke@435: // ( if (scale_con > 0) /*common case*/ duke@435: // (limit-offset)/scale_con - 1 < I duke@435: // else duke@435: // (limit-offset)/scale_con + 1 > I duke@435: // ) duke@435: // ( if (scale_con > 0) /*common case*/ duke@435: // (limit-offset)/scale_con + SGN(-scale_con) < I duke@435: // else duke@435: // (limit-offset)/scale_con + SGN(-scale_con) > I duke@435: } duke@435: } duke@435: duke@435: duke@435: //------------------------------is_scaled_iv--------------------------------- duke@435: // Return true if exp is a constant times an induction var duke@435: bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) { duke@435: if (exp == iv) { duke@435: if (p_scale != NULL) { duke@435: *p_scale = 1; duke@435: } duke@435: return true; duke@435: } duke@435: int opc = exp->Opcode(); duke@435: if (opc == Op_MulI) { duke@435: if (exp->in(1) == iv && exp->in(2)->is_Con()) { duke@435: if (p_scale != NULL) { duke@435: *p_scale = exp->in(2)->get_int(); duke@435: } duke@435: return true; duke@435: } duke@435: if (exp->in(2) == iv && exp->in(1)->is_Con()) { duke@435: if (p_scale != NULL) { duke@435: *p_scale = exp->in(1)->get_int(); duke@435: } duke@435: return true; duke@435: } duke@435: } else if (opc == Op_LShiftI) { duke@435: if (exp->in(1) == iv && exp->in(2)->is_Con()) { duke@435: if (p_scale != NULL) { duke@435: *p_scale = 1 << exp->in(2)->get_int(); duke@435: } duke@435: return true; duke@435: } duke@435: } duke@435: return false; duke@435: } duke@435: duke@435: //-----------------------------is_scaled_iv_plus_offset------------------------------ duke@435: // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2) duke@435: bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) { duke@435: if (is_scaled_iv(exp, iv, p_scale)) { duke@435: if (p_offset != NULL) { duke@435: Node *zero = _igvn.intcon(0); duke@435: set_ctrl(zero, C->root()); duke@435: *p_offset = zero; duke@435: } duke@435: return true; duke@435: } duke@435: int opc = exp->Opcode(); duke@435: if (opc == Op_AddI) { duke@435: if (is_scaled_iv(exp->in(1), iv, p_scale)) { duke@435: if (p_offset != NULL) { duke@435: *p_offset = exp->in(2); duke@435: } duke@435: return true; duke@435: } duke@435: if (exp->in(2)->is_Con()) { duke@435: Node* offset2 = NULL; duke@435: if (depth < 2 && duke@435: is_scaled_iv_plus_offset(exp->in(1), iv, p_scale, duke@435: p_offset != NULL ? &offset2 : NULL, depth+1)) { duke@435: if (p_offset != NULL) { duke@435: Node *ctrl_off2 = get_ctrl(offset2); duke@435: Node* offset = new (C, 3) AddINode(offset2, exp->in(2)); duke@435: register_new_node(offset, ctrl_off2); duke@435: *p_offset = offset; duke@435: } duke@435: return true; duke@435: } duke@435: } duke@435: } else if (opc == Op_SubI) { duke@435: if (is_scaled_iv(exp->in(1), iv, p_scale)) { duke@435: if (p_offset != NULL) { duke@435: Node *zero = _igvn.intcon(0); duke@435: set_ctrl(zero, C->root()); duke@435: Node *ctrl_off = get_ctrl(exp->in(2)); duke@435: Node* offset = new (C, 3) SubINode(zero, exp->in(2)); duke@435: register_new_node(offset, ctrl_off); duke@435: *p_offset = offset; duke@435: } duke@435: return true; duke@435: } duke@435: if (is_scaled_iv(exp->in(2), iv, p_scale)) { duke@435: if (p_offset != NULL) { duke@435: *p_scale *= -1; duke@435: *p_offset = exp->in(1); duke@435: } duke@435: return true; duke@435: } duke@435: } duke@435: return false; duke@435: } duke@435: duke@435: //------------------------------do_range_check--------------------------------- duke@435: // Eliminate range-checks and other trip-counter vs loop-invariant tests. duke@435: void PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) { duke@435: #ifndef PRODUCT duke@435: if( PrintOpto && VerifyLoopOptimizations ) { duke@435: tty->print("Range Check Elimination "); duke@435: loop->dump_head(); duke@435: } duke@435: #endif duke@435: assert( RangeCheckElimination, "" ); duke@435: CountedLoopNode *cl = loop->_head->as_CountedLoop(); duke@435: assert( cl->is_main_loop(), "" ); duke@435: duke@435: // Find the trip counter; we are iteration splitting based on it duke@435: Node *trip_counter = cl->phi(); duke@435: // Find the main loop limit; we will trim it's iterations duke@435: // to not ever trip end tests duke@435: Node *main_limit = cl->limit(); duke@435: // Find the pre-loop limit; we will expand it's iterations to duke@435: // not ever trip low tests. duke@435: Node *ctrl = cl->in(LoopNode::EntryControl); duke@435: assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); duke@435: Node *iffm = ctrl->in(0); duke@435: assert( iffm->Opcode() == Op_If, "" ); duke@435: Node *p_f = iffm->in(0); duke@435: assert( p_f->Opcode() == Op_IfFalse, "" ); duke@435: CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd(); duke@435: assert( pre_end->loopnode()->is_pre_loop(), "" ); duke@435: Node *pre_opaq1 = pre_end->limit(); duke@435: // Occasionally it's possible for a pre-loop Opaque1 node to be duke@435: // optimized away and then another round of loop opts attempted. duke@435: // We can not optimize this particular loop in that case. duke@435: if( pre_opaq1->Opcode() != Op_Opaque1 ) duke@435: return; duke@435: Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1; duke@435: Node *pre_limit = pre_opaq->in(1); duke@435: duke@435: // Where do we put new limit calculations duke@435: Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl); duke@435: duke@435: // Ensure the original loop limit is available from the duke@435: // pre-loop Opaque1 node. duke@435: Node *orig_limit = pre_opaq->original_loop_limit(); duke@435: if( orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP ) duke@435: return; duke@435: duke@435: // Need to find the main-loop zero-trip guard duke@435: Node *bolzm = iffm->in(1); duke@435: assert( bolzm->Opcode() == Op_Bool, "" ); duke@435: Node *cmpzm = bolzm->in(1); duke@435: assert( cmpzm->is_Cmp(), "" ); duke@435: Node *opqzm = cmpzm->in(2); duke@435: if( opqzm->Opcode() != Op_Opaque1 ) duke@435: return; duke@435: assert( opqzm->in(1) == main_limit, "do not understand situation" ); duke@435: duke@435: // Must know if its a count-up or count-down loop duke@435: duke@435: // protect against stride not being a constant duke@435: if ( !cl->stride_is_con() ) { duke@435: return; duke@435: } duke@435: int stride_con = cl->stride_con(); duke@435: Node *zero = _igvn.intcon(0); duke@435: Node *one = _igvn.intcon(1); duke@435: set_ctrl(zero, C->root()); duke@435: set_ctrl(one, C->root()); duke@435: duke@435: // Range checks that do not dominate the loop backedge (ie. duke@435: // conditionally executed) can lengthen the pre loop limit beyond duke@435: // the original loop limit. To prevent this, the pre limit is duke@435: // (for stride > 0) MINed with the original loop limit (MAXed duke@435: // stride < 0) when some range_check (rc) is conditionally duke@435: // executed. duke@435: bool conditional_rc = false; duke@435: duke@435: // Check loop body for tests of trip-counter plus loop-invariant vs duke@435: // loop-invariant. duke@435: for( uint i = 0; i < loop->_body.size(); i++ ) { duke@435: Node *iff = loop->_body[i]; duke@435: if( iff->Opcode() == Op_If ) { // Test? duke@435: duke@435: // Test is an IfNode, has 2 projections. If BOTH are in the loop duke@435: // we need loop unswitching instead of iteration splitting. duke@435: Node *exit = loop->is_loop_exit(iff); duke@435: if( !exit ) continue; duke@435: int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0; duke@435: duke@435: // Get boolean condition to test duke@435: Node *i1 = iff->in(1); duke@435: if( !i1->is_Bool() ) continue; duke@435: BoolNode *bol = i1->as_Bool(); duke@435: BoolTest b_test = bol->_test; duke@435: // Flip sense of test if exit condition is flipped duke@435: if( flip ) duke@435: b_test = b_test.negate(); duke@435: duke@435: // Get compare duke@435: Node *cmp = bol->in(1); duke@435: duke@435: // Look for trip_counter + offset vs limit duke@435: Node *rc_exp = cmp->in(1); duke@435: Node *limit = cmp->in(2); duke@435: jint scale_con= 1; // Assume trip counter not scaled duke@435: duke@435: Node *limit_c = get_ctrl(limit); duke@435: if( loop->is_member(get_loop(limit_c) ) ) { duke@435: // Compare might have operands swapped; commute them duke@435: b_test = b_test.commute(); duke@435: rc_exp = cmp->in(2); duke@435: limit = cmp->in(1); duke@435: limit_c = get_ctrl(limit); duke@435: if( loop->is_member(get_loop(limit_c) ) ) duke@435: continue; // Both inputs are loop varying; cannot RCE duke@435: } duke@435: // Here we know 'limit' is loop invariant duke@435: duke@435: // 'limit' maybe pinned below the zero trip test (probably from a duke@435: // previous round of rce), in which case, it can't be used in the duke@435: // zero trip test expression which must occur before the zero test's if. duke@435: if( limit_c == ctrl ) { duke@435: continue; // Don't rce this check but continue looking for other candidates. duke@435: } duke@435: duke@435: // Check for scaled induction variable plus an offset duke@435: Node *offset = NULL; duke@435: duke@435: if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) { duke@435: continue; duke@435: } duke@435: duke@435: Node *offset_c = get_ctrl(offset); duke@435: if( loop->is_member( get_loop(offset_c) ) ) duke@435: continue; // Offset is not really loop invariant duke@435: // Here we know 'offset' is loop invariant. duke@435: duke@435: // As above for the 'limit', the 'offset' maybe pinned below the duke@435: // zero trip test. duke@435: if( offset_c == ctrl ) { duke@435: continue; // Don't rce this check but continue looking for other candidates. duke@435: } duke@435: duke@435: // At this point we have the expression as: duke@435: // scale_con * trip_counter + offset :: limit duke@435: // where scale_con, offset and limit are loop invariant. Trip_counter duke@435: // monotonically increases by stride_con, a constant. Both (or either) duke@435: // stride_con and scale_con can be negative which will flip about the duke@435: // sense of the test. duke@435: duke@435: // Adjust pre and main loop limits to guard the correct iteration set duke@435: if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests duke@435: if( b_test._test == BoolTest::lt ) { // Range checks always use lt duke@435: // The overflow limit: scale*I+offset < limit duke@435: add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit ); duke@435: // The underflow limit: 0 <= scale*I+offset. duke@435: // Some math yields: -scale*I-(offset+1) < 0 duke@435: Node *plus_one = new (C, 3) AddINode( offset, one ); duke@435: register_new_node( plus_one, pre_ctrl ); duke@435: Node *neg_offset = new (C, 3) SubINode( zero, plus_one ); duke@435: register_new_node( neg_offset, pre_ctrl ); duke@435: add_constraint( stride_con, -scale_con, neg_offset, zero, pre_ctrl, &pre_limit, &main_limit ); duke@435: if (!conditional_rc) { duke@435: conditional_rc = !loop->dominates_backedge(iff); duke@435: } duke@435: } else { duke@435: #ifndef PRODUCT duke@435: if( PrintOpto ) duke@435: tty->print_cr("missed RCE opportunity"); duke@435: #endif duke@435: continue; // In release mode, ignore it duke@435: } duke@435: } else { // Otherwise work on normal compares duke@435: switch( b_test._test ) { duke@435: case BoolTest::ge: // Convert X >= Y to -X <= -Y duke@435: scale_con = -scale_con; duke@435: offset = new (C, 3) SubINode( zero, offset ); duke@435: register_new_node( offset, pre_ctrl ); duke@435: limit = new (C, 3) SubINode( zero, limit ); duke@435: register_new_node( limit, pre_ctrl ); duke@435: // Fall into LE case duke@435: case BoolTest::le: // Convert X <= Y to X < Y+1 duke@435: limit = new (C, 3) AddINode( limit, one ); duke@435: register_new_node( limit, pre_ctrl ); duke@435: // Fall into LT case duke@435: case BoolTest::lt: duke@435: add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit ); duke@435: if (!conditional_rc) { duke@435: conditional_rc = !loop->dominates_backedge(iff); duke@435: } duke@435: break; duke@435: default: duke@435: #ifndef PRODUCT duke@435: if( PrintOpto ) duke@435: tty->print_cr("missed RCE opportunity"); duke@435: #endif duke@435: continue; // Unhandled case duke@435: } duke@435: } duke@435: duke@435: // Kill the eliminated test duke@435: C->set_major_progress(); duke@435: Node *kill_con = _igvn.intcon( 1-flip ); duke@435: set_ctrl(kill_con, C->root()); duke@435: _igvn.hash_delete(iff); duke@435: iff->set_req(1, kill_con); duke@435: _igvn._worklist.push(iff); duke@435: // Find surviving projection duke@435: assert(iff->is_If(), ""); duke@435: ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip); duke@435: // Find loads off the surviving projection; remove their control edge duke@435: for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) { duke@435: Node* cd = dp->fast_out(i); // Control-dependent node duke@435: if( cd->is_Load() ) { // Loads can now float around in the loop duke@435: _igvn.hash_delete(cd); duke@435: // Allow the load to float around in the loop, or before it duke@435: // but NOT before the pre-loop. duke@435: cd->set_req(0, ctrl); // ctrl, not NULL duke@435: _igvn._worklist.push(cd); duke@435: --i; duke@435: --imax; duke@435: } duke@435: } duke@435: duke@435: } // End of is IF duke@435: duke@435: } duke@435: duke@435: // Update loop limits duke@435: if (conditional_rc) { duke@435: pre_limit = (stride_con > 0) ? (Node*)new (C,3) MinINode(pre_limit, orig_limit) duke@435: : (Node*)new (C,3) MaxINode(pre_limit, orig_limit); duke@435: register_new_node(pre_limit, pre_ctrl); duke@435: } duke@435: _igvn.hash_delete(pre_opaq); duke@435: pre_opaq->set_req(1, pre_limit); duke@435: duke@435: // Note:: we are making the main loop limit no longer precise; duke@435: // need to round up based on stride. duke@435: if( stride_con != 1 && stride_con != -1 ) { // Cutout for common case duke@435: // "Standard" round-up logic: ([main_limit-init+(y-1)]/y)*y+init duke@435: // Hopefully, compiler will optimize for powers of 2. duke@435: Node *ctrl = get_ctrl(main_limit); duke@435: Node *stride = cl->stride(); duke@435: Node *init = cl->init_trip(); duke@435: Node *span = new (C, 3) SubINode(main_limit,init); duke@435: register_new_node(span,ctrl); duke@435: Node *rndup = _igvn.intcon(stride_con + ((stride_con>0)?-1:1)); duke@435: Node *add = new (C, 3) AddINode(span,rndup); duke@435: register_new_node(add,ctrl); duke@435: Node *div = new (C, 3) DivINode(0,add,stride); duke@435: register_new_node(div,ctrl); duke@435: Node *mul = new (C, 3) MulINode(div,stride); duke@435: register_new_node(mul,ctrl); duke@435: Node *newlim = new (C, 3) AddINode(mul,init); duke@435: register_new_node(newlim,ctrl); duke@435: main_limit = newlim; duke@435: } duke@435: duke@435: Node *main_cle = cl->loopexit(); duke@435: Node *main_bol = main_cle->in(1); duke@435: // Hacking loop bounds; need private copies of exit test duke@435: if( main_bol->outcnt() > 1 ) {// BoolNode shared? duke@435: _igvn.hash_delete(main_cle); duke@435: main_bol = main_bol->clone();// Clone a private BoolNode duke@435: register_new_node( main_bol, main_cle->in(0) ); duke@435: main_cle->set_req(1,main_bol); duke@435: } duke@435: Node *main_cmp = main_bol->in(1); duke@435: if( main_cmp->outcnt() > 1 ) { // CmpNode shared? duke@435: _igvn.hash_delete(main_bol); duke@435: main_cmp = main_cmp->clone();// Clone a private CmpNode duke@435: register_new_node( main_cmp, main_cle->in(0) ); duke@435: main_bol->set_req(1,main_cmp); duke@435: } duke@435: // Hack the now-private loop bounds duke@435: _igvn.hash_delete(main_cmp); duke@435: main_cmp->set_req(2, main_limit); duke@435: _igvn._worklist.push(main_cmp); duke@435: // The OpaqueNode is unshared by design duke@435: _igvn.hash_delete(opqzm); duke@435: assert( opqzm->outcnt() == 1, "cannot hack shared node" ); duke@435: opqzm->set_req(1,main_limit); duke@435: _igvn._worklist.push(opqzm); duke@435: } duke@435: duke@435: //------------------------------DCE_loop_body---------------------------------- duke@435: // Remove simplistic dead code from loop body duke@435: void IdealLoopTree::DCE_loop_body() { duke@435: for( uint i = 0; i < _body.size(); i++ ) duke@435: if( _body.at(i)->outcnt() == 0 ) duke@435: _body.map( i--, _body.pop() ); duke@435: } duke@435: duke@435: duke@435: //------------------------------adjust_loop_exit_prob-------------------------- duke@435: // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage. duke@435: // Replace with a 1-in-10 exit guess. duke@435: void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) { duke@435: Node *test = tail(); duke@435: while( test != _head ) { duke@435: uint top = test->Opcode(); duke@435: if( top == Op_IfTrue || top == Op_IfFalse ) { duke@435: int test_con = ((ProjNode*)test)->_con; duke@435: assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity"); duke@435: IfNode *iff = test->in(0)->as_If(); duke@435: if( iff->outcnt() == 2 ) { // Ignore dead tests duke@435: Node *bol = iff->in(1); duke@435: if( bol && bol->req() > 1 && bol->in(1) && duke@435: ((bol->in(1)->Opcode() == Op_StorePConditional ) || duke@435: (bol->in(1)->Opcode() == Op_StoreLConditional ) || duke@435: (bol->in(1)->Opcode() == Op_CompareAndSwapI ) || duke@435: (bol->in(1)->Opcode() == Op_CompareAndSwapL ) || coleenp@548: (bol->in(1)->Opcode() == Op_CompareAndSwapP ) || coleenp@548: (bol->in(1)->Opcode() == Op_CompareAndSwapN ))) duke@435: return; // Allocation loops RARELY take backedge duke@435: // Find the OTHER exit path from the IF duke@435: Node* ex = iff->proj_out(1-test_con); duke@435: float p = iff->_prob; duke@435: if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) { duke@435: if( top == Op_IfTrue ) { duke@435: if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) { duke@435: iff->_prob = PROB_STATIC_FREQUENT; duke@435: } duke@435: } else { duke@435: if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) { duke@435: iff->_prob = PROB_STATIC_INFREQUENT; duke@435: } duke@435: } duke@435: } duke@435: } duke@435: } duke@435: test = phase->idom(test); duke@435: } duke@435: } duke@435: duke@435: duke@435: //------------------------------policy_do_remove_empty_loop-------------------- duke@435: // Micro-benchmark spamming. Policy is to always remove empty loops. duke@435: // The 'DO' part is to replace the trip counter with the value it will duke@435: // have on the last iteration. This will break the loop. duke@435: bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) { duke@435: // Minimum size must be empty loop duke@435: if( _body.size() > 7/*number of nodes in an empty loop*/ ) return false; duke@435: duke@435: if( !_head->is_CountedLoop() ) return false; // Dead loop duke@435: CountedLoopNode *cl = _head->as_CountedLoop(); duke@435: if( !cl->loopexit() ) return false; // Malformed loop duke@435: if( !phase->is_member(this,phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue)) ) ) duke@435: return false; // Infinite loop duke@435: #ifndef PRODUCT duke@435: if( PrintOpto ) duke@435: tty->print_cr("Removing empty loop"); duke@435: #endif duke@435: #ifdef ASSERT duke@435: // Ensure only one phi which is the iv. duke@435: Node* iv = NULL; duke@435: for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) { duke@435: Node* n = cl->fast_out(i); duke@435: if (n->Opcode() == Op_Phi) { duke@435: assert(iv == NULL, "Too many phis" ); duke@435: iv = n; duke@435: } duke@435: } duke@435: assert(iv == cl->phi(), "Wrong phi" ); duke@435: #endif duke@435: // Replace the phi at loop head with the final value of the last duke@435: // iteration. Then the CountedLoopEnd will collapse (backedge never duke@435: // taken) and all loop-invariant uses of the exit values will be correct. duke@435: Node *phi = cl->phi(); duke@435: Node *final = new (phase->C, 3) SubINode( cl->limit(), cl->stride() ); duke@435: phase->register_new_node(final,cl->in(LoopNode::EntryControl)); duke@435: phase->_igvn.hash_delete(phi); duke@435: phase->_igvn.subsume_node(phi,final); duke@435: phase->C->set_major_progress(); duke@435: return true; duke@435: } duke@435: duke@435: duke@435: //============================================================================= duke@435: //------------------------------iteration_split_impl--------------------------- duke@435: void IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) { duke@435: // Check and remove empty loops (spam micro-benchmarks) duke@435: if( policy_do_remove_empty_loop(phase) ) duke@435: return; // Here we removed an empty loop duke@435: duke@435: bool should_peel = policy_peeling(phase); // Should we peel? duke@435: duke@435: bool should_unswitch = policy_unswitching(phase); duke@435: duke@435: // Non-counted loops may be peeled; exactly 1 iteration is peeled. duke@435: // This removes loop-invariant tests (usually null checks). duke@435: if( !_head->is_CountedLoop() ) { // Non-counted loop duke@435: if (PartialPeelLoop && phase->partial_peel(this, old_new)) { duke@435: return; duke@435: } duke@435: if( should_peel ) { // Should we peel? duke@435: #ifndef PRODUCT duke@435: if (PrintOpto) tty->print_cr("should_peel"); duke@435: #endif duke@435: phase->do_peeling(this,old_new); duke@435: } else if( should_unswitch ) { duke@435: phase->do_unswitching(this, old_new); duke@435: } duke@435: return; duke@435: } duke@435: CountedLoopNode *cl = _head->as_CountedLoop(); duke@435: duke@435: if( !cl->loopexit() ) return; // Ignore various kinds of broken loops duke@435: duke@435: // Do nothing special to pre- and post- loops duke@435: if( cl->is_pre_loop() || cl->is_post_loop() ) return; duke@435: duke@435: // Compute loop trip count from profile data duke@435: compute_profile_trip_cnt(phase); duke@435: duke@435: // Before attempting fancy unrolling, RCE or alignment, see if we want duke@435: // to completely unroll this loop or do loop unswitching. duke@435: if( cl->is_normal_loop() ) { duke@435: bool should_maximally_unroll = policy_maximally_unroll(phase); duke@435: if( should_maximally_unroll ) { duke@435: // Here we did some unrolling and peeling. Eventually we will duke@435: // completely unroll this loop and it will no longer be a loop. duke@435: phase->do_maximally_unroll(this,old_new); duke@435: return; duke@435: } duke@435: if (should_unswitch) { duke@435: phase->do_unswitching(this, old_new); duke@435: return; duke@435: } duke@435: } duke@435: duke@435: duke@435: // Counted loops may be peeled, may need some iterations run up duke@435: // front for RCE, and may want to align loop refs to a cache duke@435: // line. Thus we clone a full loop up front whose trip count is duke@435: // at least 1 (if peeling), but may be several more. duke@435: duke@435: // The main loop will start cache-line aligned with at least 1 duke@435: // iteration of the unrolled body (zero-trip test required) and duke@435: // will have some range checks removed. duke@435: duke@435: // A post-loop will finish any odd iterations (leftover after duke@435: // unrolling), plus any needed for RCE purposes. duke@435: duke@435: bool should_unroll = policy_unroll(phase); duke@435: duke@435: bool should_rce = policy_range_check(phase); duke@435: duke@435: bool should_align = policy_align(phase); duke@435: duke@435: // If not RCE'ing (iteration splitting) or Aligning, then we do not duke@435: // need a pre-loop. We may still need to peel an initial iteration but duke@435: // we will not be needing an unknown number of pre-iterations. duke@435: // duke@435: // Basically, if may_rce_align reports FALSE first time through, duke@435: // we will not be able to later do RCE or Aligning on this loop. duke@435: bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align; duke@435: duke@435: // If we have any of these conditions (RCE, alignment, unrolling) met, then duke@435: // we switch to the pre-/main-/post-loop model. This model also covers duke@435: // peeling. duke@435: if( should_rce || should_align || should_unroll ) { duke@435: if( cl->is_normal_loop() ) // Convert to 'pre/main/post' loops duke@435: phase->insert_pre_post_loops(this,old_new, !may_rce_align); duke@435: duke@435: // Adjust the pre- and main-loop limits to let the pre and post loops run duke@435: // with full checks, but the main-loop with no checks. Remove said duke@435: // checks from the main body. duke@435: if( should_rce ) duke@435: phase->do_range_check(this,old_new); duke@435: duke@435: // Double loop body for unrolling. Adjust the minimum-trip test (will do duke@435: // twice as many iterations as before) and the main body limit (only do duke@435: // an even number of trips). If we are peeling, we might enable some RCE duke@435: // and we'd rather unroll the post-RCE'd loop SO... do not unroll if duke@435: // peeling. duke@435: if( should_unroll && !should_peel ) duke@435: phase->do_unroll(this,old_new, true); duke@435: duke@435: // Adjust the pre-loop limits to align the main body duke@435: // iterations. duke@435: if( should_align ) duke@435: Unimplemented(); duke@435: duke@435: } else { // Else we have an unchanged counted loop duke@435: if( should_peel ) // Might want to peel but do nothing else duke@435: phase->do_peeling(this,old_new); duke@435: } duke@435: } duke@435: duke@435: duke@435: //============================================================================= duke@435: //------------------------------iteration_split-------------------------------- duke@435: void IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) { duke@435: // Recursively iteration split nested loops duke@435: if( _child ) _child->iteration_split( phase, old_new ); duke@435: duke@435: // Clean out prior deadwood duke@435: DCE_loop_body(); duke@435: duke@435: duke@435: // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. duke@435: // Replace with a 1-in-10 exit guess. duke@435: if( _parent /*not the root loop*/ && duke@435: !_irreducible && duke@435: // Also ignore the occasional dead backedge duke@435: !tail()->is_top() ) { duke@435: adjust_loop_exit_prob(phase); duke@435: } duke@435: duke@435: duke@435: // Gate unrolling, RCE and peeling efforts. duke@435: if( !_child && // If not an inner loop, do not split duke@435: !_irreducible && kvn@474: _allow_optimizations && duke@435: !tail()->is_top() ) { // Also ignore the occasional dead backedge duke@435: if (!_has_call) { duke@435: iteration_split_impl( phase, old_new ); duke@435: } else if (policy_unswitching(phase)) { duke@435: phase->do_unswitching(this, old_new); duke@435: } duke@435: } duke@435: duke@435: // Minor offset re-organization to remove loop-fallout uses of duke@435: // trip counter. duke@435: if( _head->is_CountedLoop() ) phase->reorg_offsets( this ); duke@435: if( _next ) _next->iteration_split( phase, old_new ); duke@435: }