Mercurial > hg > truffle
diff src/share/vm/opto/loopnode.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ff5961f4c095 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/opto/loopnode.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,2886 @@ +/* + * Copyright 1998-2007 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +#include "incls/_precompiled.incl" +#include "incls/_loopnode.cpp.incl" + +//============================================================================= +//------------------------------is_loop_iv------------------------------------- +// Determine if a node is Counted loop induction variable. +// The method is declared in node.hpp. +const Node* Node::is_loop_iv() const { + if (this->is_Phi() && !this->as_Phi()->is_copy() && + this->as_Phi()->region()->is_CountedLoop() && + this->as_Phi()->region()->as_CountedLoop()->phi() == this) { + return this; + } else { + return NULL; + } +} + +//============================================================================= +//------------------------------dump_spec-------------------------------------- +// Dump special per-node info +#ifndef PRODUCT +void LoopNode::dump_spec(outputStream *st) const { + if( is_inner_loop () ) st->print( "inner " ); + if( is_partial_peel_loop () ) st->print( "partial_peel " ); + if( partial_peel_has_failed () ) st->print( "partial_peel_failed " ); +} +#endif + +//------------------------------get_early_ctrl--------------------------------- +// Compute earliest legal control +Node *PhaseIdealLoop::get_early_ctrl( Node *n ) { + assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" ); + uint i; + Node *early; + if( n->in(0) ) { + early = n->in(0); + if( !early->is_CFG() ) // Might be a non-CFG multi-def + early = get_ctrl(early); // So treat input as a straight data input + i = 1; + } else { + early = get_ctrl(n->in(1)); + i = 2; + } + uint e_d = dom_depth(early); + assert( early, "" ); + for( ; i < n->req(); i++ ) { + Node *cin = get_ctrl(n->in(i)); + assert( cin, "" ); + // Keep deepest dominator depth + uint c_d = dom_depth(cin); + if( c_d > e_d ) { // Deeper guy? + early = cin; // Keep deepest found so far + e_d = c_d; + } else if( c_d == e_d && // Same depth? + early != cin ) { // If not equal, must use slower algorithm + // If same depth but not equal, one _must_ dominate the other + // and we want the deeper (i.e., dominated) guy. + Node *n1 = early; + Node *n2 = cin; + while( 1 ) { + n1 = idom(n1); // Walk up until break cycle + n2 = idom(n2); + if( n1 == cin || // Walked early up to cin + dom_depth(n2) < c_d ) + break; // early is deeper; keep him + if( n2 == early || // Walked cin up to early + dom_depth(n1) < c_d ) { + early = cin; // cin is deeper; keep him + break; + } + } + e_d = dom_depth(early); // Reset depth register cache + } + } + + // Return earliest legal location + assert(early == find_non_split_ctrl(early), "unexpected early control"); + + return early; +} + +//------------------------------set_early_ctrl--------------------------------- +// Set earliest legal control +void PhaseIdealLoop::set_early_ctrl( Node *n ) { + Node *early = get_early_ctrl(n); + + // Record earliest legal location + set_ctrl(n, early); +} + +//------------------------------set_subtree_ctrl------------------------------- +// set missing _ctrl entries on new nodes +void PhaseIdealLoop::set_subtree_ctrl( Node *n ) { + // Already set? Get out. + if( _nodes[n->_idx] ) return; + // Recursively set _nodes array to indicate where the Node goes + uint i; + for( i = 0; i < n->req(); ++i ) { + Node *m = n->in(i); + if( m && m != C->root() ) + set_subtree_ctrl( m ); + } + + // Fixup self + set_early_ctrl( n ); +} + +//------------------------------is_counted_loop-------------------------------- +Node *PhaseIdealLoop::is_counted_loop( Node *x, IdealLoopTree *loop ) { + PhaseGVN *gvn = &_igvn; + + // Counted loop head must be a good RegionNode with only 3 not NULL + // control input edges: Self, Entry, LoopBack. + if ( x->in(LoopNode::Self) == NULL || x->req() != 3 ) + return NULL; + + Node *init_control = x->in(LoopNode::EntryControl); + Node *back_control = x->in(LoopNode::LoopBackControl); + if( init_control == NULL || back_control == NULL ) // Partially dead + return NULL; + // Must also check for TOP when looking for a dead loop + if( init_control->is_top() || back_control->is_top() ) + return NULL; + + // Allow funny placement of Safepoint + if( back_control->Opcode() == Op_SafePoint ) + back_control = back_control->in(TypeFunc::Control); + + // Controlling test for loop + Node *iftrue = back_control; + uint iftrue_op = iftrue->Opcode(); + if( iftrue_op != Op_IfTrue && + iftrue_op != Op_IfFalse ) + // I have a weird back-control. Probably the loop-exit test is in + // the middle of the loop and I am looking at some trailing control-flow + // merge point. To fix this I would have to partially peel the loop. + return NULL; // Obscure back-control + + // Get boolean guarding loop-back test + Node *iff = iftrue->in(0); + if( get_loop(iff) != loop || !iff->in(1)->is_Bool() ) return NULL; + BoolNode *test = iff->in(1)->as_Bool(); + BoolTest::mask bt = test->_test._test; + float cl_prob = iff->as_If()->_prob; + if( iftrue_op == Op_IfFalse ) { + bt = BoolTest(bt).negate(); + cl_prob = 1.0 - cl_prob; + } + // Get backedge compare + Node *cmp = test->in(1); + int cmp_op = cmp->Opcode(); + if( cmp_op != Op_CmpI ) + return NULL; // Avoid pointer & float compares + + // Find the trip-counter increment & limit. Limit must be loop invariant. + Node *incr = cmp->in(1); + Node *limit = cmp->in(2); + + // --------- + // need 'loop()' test to tell if limit is loop invariant + // --------- + + if( !is_member( loop, get_ctrl(incr) ) ) { // Swapped trip counter and limit? + Node *tmp = incr; // Then reverse order into the CmpI + incr = limit; + limit = tmp; + bt = BoolTest(bt).commute(); // And commute the exit test + } + if( is_member( loop, get_ctrl(limit) ) ) // Limit must loop-invariant + return NULL; + + // Trip-counter increment must be commutative & associative. + uint incr_op = incr->Opcode(); + if( incr_op == Op_Phi && incr->req() == 3 ) { + incr = incr->in(2); // Assume incr is on backedge of Phi + incr_op = incr->Opcode(); + } + Node* trunc1 = NULL; + Node* trunc2 = NULL; + const TypeInt* iv_trunc_t = NULL; + if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) { + return NULL; // Funny increment opcode + } + + // Get merge point + Node *xphi = incr->in(1); + Node *stride = incr->in(2); + if( !stride->is_Con() ) { // Oops, swap these + if( !xphi->is_Con() ) // Is the other guy a constant? + return NULL; // Nope, unknown stride, bail out + Node *tmp = xphi; // 'incr' is commutative, so ok to swap + xphi = stride; + stride = tmp; + } + //if( loop(xphi) != l) return NULL;// Merge point is in inner loop?? + if( !xphi->is_Phi() ) return NULL; // Too much math on the trip counter + PhiNode *phi = xphi->as_Phi(); + + // Stride must be constant + const Type *stride_t = stride->bottom_type(); + int stride_con = stride_t->is_int()->get_con(); + assert( stride_con, "missed some peephole opt" ); + + // Phi must be of loop header; backedge must wrap to increment + if( phi->region() != x ) return NULL; + if( trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr || + trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1 ) { + return NULL; + } + Node *init_trip = phi->in(LoopNode::EntryControl); + //if (!init_trip->is_Con()) return NULL; // avoid rolling over MAXINT/MININT + + // If iv trunc type is smaller than int, check for possible wrap. + if (!TypeInt::INT->higher_equal(iv_trunc_t)) { + assert(trunc1 != NULL, "must have found some truncation"); + + // Get a better type for the phi (filtered thru if's) + const TypeInt* phi_ft = filtered_type(phi); + + // Can iv take on a value that will wrap? + // + // Ensure iv's limit is not within "stride" of the wrap value. + // + // Example for "short" type + // Truncation ensures value is in the range -32768..32767 (iv_trunc_t) + // If the stride is +10, then the last value of the induction + // variable before the increment (phi_ft->_hi) must be + // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to + // ensure no truncation occurs after the increment. + + if (stride_con > 0) { + if (iv_trunc_t->_hi - phi_ft->_hi < stride_con || + iv_trunc_t->_lo > phi_ft->_lo) { + return NULL; // truncation may occur + } + } else if (stride_con < 0) { + if (iv_trunc_t->_lo - phi_ft->_lo > stride_con || + iv_trunc_t->_hi < phi_ft->_hi) { + return NULL; // truncation may occur + } + } + // No possibility of wrap so truncation can be discarded + // Promote iv type to Int + } else { + assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int"); + } + + // ================================================= + // ---- SUCCESS! Found A Trip-Counted Loop! ----- + // + // Canonicalize the condition on the test. If we can exactly determine + // the trip-counter exit value, then set limit to that value and use + // a '!=' test. Otherwise use conditon '<' for count-up loops and + // '>' for count-down loops. If the condition is inverted and we will + // be rolling through MININT to MAXINT, then bail out. + + C->print_method("Before CountedLoop", 3); + + // Check for SafePoint on backedge and remove + Node *sfpt = x->in(LoopNode::LoopBackControl); + if( sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) { + lazy_replace( sfpt, iftrue ); + loop->_tail = iftrue; + } + + + // If compare points to incr, we are ok. Otherwise the compare + // can directly point to the phi; in this case adjust the compare so that + // it points to the incr by adusting the limit. + if( cmp->in(1) == phi || cmp->in(2) == phi ) + limit = gvn->transform(new (C, 3) AddINode(limit,stride)); + + // trip-count for +-tive stride should be: (limit - init_trip + stride - 1)/stride. + // Final value for iterator should be: trip_count * stride + init_trip. + const Type *limit_t = limit->bottom_type(); + const Type *init_t = init_trip->bottom_type(); + Node *one_p = gvn->intcon( 1); + Node *one_m = gvn->intcon(-1); + + Node *trip_count = NULL; + Node *hook = new (C, 6) Node(6); + switch( bt ) { + case BoolTest::eq: + return NULL; // Bail out, but this loop trips at most twice! + case BoolTest::ne: // Ahh, the case we desire + if( stride_con == 1 ) + trip_count = gvn->transform(new (C, 3) SubINode(limit,init_trip)); + else if( stride_con == -1 ) + trip_count = gvn->transform(new (C, 3) SubINode(init_trip,limit)); + else + return NULL; // Odd stride; must prove we hit limit exactly + set_subtree_ctrl( trip_count ); + //_loop.map(trip_count->_idx,loop(limit)); + break; + case BoolTest::le: // Maybe convert to '<' case + limit = gvn->transform(new (C, 3) AddINode(limit,one_p)); + set_subtree_ctrl( limit ); + hook->init_req(4, limit); + + bt = BoolTest::lt; + // Make the new limit be in the same loop nest as the old limit + //_loop.map(limit->_idx,limit_loop); + // Fall into next case + case BoolTest::lt: { // Maybe convert to '!=' case + if( stride_con < 0 ) return NULL; // Count down loop rolls through MAXINT + Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip)); + set_subtree_ctrl( range ); + hook->init_req(0, range); + + Node *bias = gvn->transform(new (C, 3) AddINode(range,stride)); + set_subtree_ctrl( bias ); + hook->init_req(1, bias); + + Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_m)); + set_subtree_ctrl( bias1 ); + hook->init_req(2, bias1); + + trip_count = gvn->transform(new (C, 3) DivINode(0,bias1,stride)); + set_subtree_ctrl( trip_count ); + hook->init_req(3, trip_count); + break; + } + + case BoolTest::ge: // Maybe convert to '>' case + limit = gvn->transform(new (C, 3) AddINode(limit,one_m)); + set_subtree_ctrl( limit ); + hook->init_req(4 ,limit); + + bt = BoolTest::gt; + // Make the new limit be in the same loop nest as the old limit + //_loop.map(limit->_idx,limit_loop); + // Fall into next case + case BoolTest::gt: { // Maybe convert to '!=' case + if( stride_con > 0 ) return NULL; // count up loop rolls through MININT + Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip)); + set_subtree_ctrl( range ); + hook->init_req(0, range); + + Node *bias = gvn->transform(new (C, 3) AddINode(range,stride)); + set_subtree_ctrl( bias ); + hook->init_req(1, bias); + + Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_p)); + set_subtree_ctrl( bias1 ); + hook->init_req(2, bias1); + + trip_count = gvn->transform(new (C, 3) DivINode(0,bias1,stride)); + set_subtree_ctrl( trip_count ); + hook->init_req(3, trip_count); + break; + } + } + + Node *span = gvn->transform(new (C, 3) MulINode(trip_count,stride)); + set_subtree_ctrl( span ); + hook->init_req(5, span); + + limit = gvn->transform(new (C, 3) AddINode(span,init_trip)); + set_subtree_ctrl( limit ); + + // Build a canonical trip test. + // Clone code, as old values may be in use. + incr = incr->clone(); + incr->set_req(1,phi); + incr->set_req(2,stride); + incr = _igvn.register_new_node_with_optimizer(incr); + set_early_ctrl( incr ); + _igvn.hash_delete(phi); + phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn ); + + // If phi type is more restrictive than Int, raise to + // Int to prevent (almost) infinite recursion in igvn + // which can only handle integer types for constants or minint..maxint. + if (!TypeInt::INT->higher_equal(phi->bottom_type())) { + Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT); + nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl)); + nphi = _igvn.register_new_node_with_optimizer(nphi); + set_ctrl(nphi, get_ctrl(phi)); + _igvn.subsume_node(phi, nphi); + phi = nphi->as_Phi(); + } + cmp = cmp->clone(); + cmp->set_req(1,incr); + cmp->set_req(2,limit); + cmp = _igvn.register_new_node_with_optimizer(cmp); + set_ctrl(cmp, iff->in(0)); + + Node *tmp = test->clone(); + assert( tmp->is_Bool(), "" ); + test = (BoolNode*)tmp; + (*(BoolTest*)&test->_test)._test = bt; //BoolTest::ne; + test->set_req(1,cmp); + _igvn.register_new_node_with_optimizer(test); + set_ctrl(test, iff->in(0)); + // If the exit test is dead, STOP! + if( test == NULL ) return NULL; + _igvn.hash_delete(iff); + iff->set_req_X( 1, test, &_igvn ); + + // Replace the old IfNode with a new LoopEndNode + Node *lex = _igvn.register_new_node_with_optimizer(new (C, 2) CountedLoopEndNode( iff->in(0), iff->in(1), cl_prob, iff->as_If()->_fcnt )); + IfNode *le = lex->as_If(); + uint dd = dom_depth(iff); + set_idom(le, le->in(0), dd); // Update dominance for loop exit + set_loop(le, loop); + + // Get the loop-exit control + Node *if_f = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue)); + + // Need to swap loop-exit and loop-back control? + if( iftrue_op == Op_IfFalse ) { + Node *ift2=_igvn.register_new_node_with_optimizer(new (C, 1) IfTrueNode (le)); + Node *iff2=_igvn.register_new_node_with_optimizer(new (C, 1) IfFalseNode(le)); + + loop->_tail = back_control = ift2; + set_loop(ift2, loop); + set_loop(iff2, get_loop(if_f)); + + // Lazy update of 'get_ctrl' mechanism. + lazy_replace_proj( if_f , iff2 ); + lazy_replace_proj( iftrue, ift2 ); + + // Swap names + if_f = iff2; + iftrue = ift2; + } else { + _igvn.hash_delete(if_f ); + _igvn.hash_delete(iftrue); + if_f ->set_req_X( 0, le, &_igvn ); + iftrue->set_req_X( 0, le, &_igvn ); + } + + set_idom(iftrue, le, dd+1); + set_idom(if_f, le, dd+1); + + // Now setup a new CountedLoopNode to replace the existing LoopNode + CountedLoopNode *l = new (C, 3) CountedLoopNode(init_control, back_control); + // The following assert is approximately true, and defines the intention + // of can_be_counted_loop. It fails, however, because phase->type + // is not yet initialized for this loop and its parts. + //assert(l->can_be_counted_loop(this), "sanity"); + _igvn.register_new_node_with_optimizer(l); + set_loop(l, loop); + loop->_head = l; + // Fix all data nodes placed at the old loop head. + // Uses the lazy-update mechanism of 'get_ctrl'. + lazy_replace( x, l ); + set_idom(l, init_control, dom_depth(x)); + + // Check for immediately preceeding SafePoint and remove + Node *sfpt2 = le->in(0); + if( sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2)) + lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control)); + + // Free up intermediate goo + _igvn.remove_dead_node(hook); + + C->print_method("After CountedLoop", 3); + + // Return trip counter + return trip_count; +} + + +//------------------------------Ideal------------------------------------------ +// Return a node which is more "ideal" than the current node. +// Attempt to convert into a counted-loop. +Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) { + if (!can_be_counted_loop(phase)) { + phase->C->set_major_progress(); + } + return RegionNode::Ideal(phase, can_reshape); +} + + +//============================================================================= +//------------------------------Ideal------------------------------------------ +// Return a node which is more "ideal" than the current node. +// Attempt to convert into a counted-loop. +Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) { + return RegionNode::Ideal(phase, can_reshape); +} + +//------------------------------dump_spec-------------------------------------- +// Dump special per-node info +#ifndef PRODUCT +void CountedLoopNode::dump_spec(outputStream *st) const { + LoopNode::dump_spec(st); + if( stride_is_con() ) { + st->print("stride: %d ",stride_con()); + } else { + st->print("stride: not constant "); + } + if( is_pre_loop () ) st->print("pre of N%d" , _main_idx ); + if( is_main_loop() ) st->print("main of N%d", _idx ); + if( is_post_loop() ) st->print("post of N%d", _main_idx ); +} +#endif + +//============================================================================= +int CountedLoopEndNode::stride_con() const { + return stride()->bottom_type()->is_int()->get_con(); +} + + +//----------------------match_incr_with_optional_truncation-------------------- +// Match increment with optional truncation: +// CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16 +// Return NULL for failure. Success returns the increment node. +Node* CountedLoopNode::match_incr_with_optional_truncation( + Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) { + // Quick cutouts: + if (expr == NULL || expr->req() != 3) return false; + + Node *t1 = NULL; + Node *t2 = NULL; + const TypeInt* trunc_t = TypeInt::INT; + Node* n1 = expr; + int n1op = n1->Opcode(); + + // Try to strip (n1 & M) or (n1 << N >> N) from n1. + if (n1op == Op_AndI && + n1->in(2)->is_Con() && + n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) { + // %%% This check should match any mask of 2**K-1. + t1 = n1; + n1 = t1->in(1); + n1op = n1->Opcode(); + trunc_t = TypeInt::CHAR; + } else if (n1op == Op_RShiftI && + n1->in(1) != NULL && + n1->in(1)->Opcode() == Op_LShiftI && + n1->in(2) == n1->in(1)->in(2) && + n1->in(2)->is_Con()) { + jint shift = n1->in(2)->bottom_type()->is_int()->get_con(); + // %%% This check should match any shift in [1..31]. + if (shift == 16 || shift == 8) { + t1 = n1; + t2 = t1->in(1); + n1 = t2->in(1); + n1op = n1->Opcode(); + if (shift == 16) { + trunc_t = TypeInt::SHORT; + } else if (shift == 8) { + trunc_t = TypeInt::BYTE; + } + } + } + + // If (maybe after stripping) it is an AddI, we won: + if (n1op == Op_AddI) { + *trunc1 = t1; + *trunc2 = t2; + *trunc_type = trunc_t; + return n1; + } + + // failed + return NULL; +} + + +//------------------------------filtered_type-------------------------------- +// Return a type based on condition control flow +// A successful return will be a type that is restricted due +// to a series of dominating if-tests, such as: +// if (i < 10) { +// if (i > 0) { +// here: "i" type is [1..10) +// } +// } +// or a control flow merge +// if (i < 10) { +// do { +// phi( , ) -- at top of loop type is [min_int..10) +// i = ? +// } while ( i < 10) +// +const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) { + assert(n && n->bottom_type()->is_int(), "must be int"); + const TypeInt* filtered_t = NULL; + if (!n->is_Phi()) { + assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control"); + filtered_t = filtered_type_from_dominators(n, n_ctrl); + + } else { + Node* phi = n->as_Phi(); + Node* region = phi->in(0); + assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region"); + if (region && region != C->top()) { + for (uint i = 1; i < phi->req(); i++) { + Node* val = phi->in(i); + Node* use_c = region->in(i); + const TypeInt* val_t = filtered_type_from_dominators(val, use_c); + if (val_t != NULL) { + if (filtered_t == NULL) { + filtered_t = val_t; + } else { + filtered_t = filtered_t->meet(val_t)->is_int(); + } + } + } + } + } + const TypeInt* n_t = _igvn.type(n)->is_int(); + if (filtered_t != NULL) { + n_t = n_t->join(filtered_t)->is_int(); + } + return n_t; +} + + +//------------------------------filtered_type_from_dominators-------------------------------- +// Return a possibly more restrictive type for val based on condition control flow of dominators +const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) { + if (val->is_Con()) { + return val->bottom_type()->is_int(); + } + uint if_limit = 10; // Max number of dominating if's visited + const TypeInt* rtn_t = NULL; + + if (use_ctrl && use_ctrl != C->top()) { + Node* val_ctrl = get_ctrl(val); + uint val_dom_depth = dom_depth(val_ctrl); + Node* pred = use_ctrl; + uint if_cnt = 0; + while (if_cnt < if_limit) { + if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) { + if_cnt++; + const TypeInt* if_t = filtered_type_at_if(val, pred); + if (if_t != NULL) { + if (rtn_t == NULL) { + rtn_t = if_t; + } else { + rtn_t = rtn_t->join(if_t)->is_int(); + } + } + } + pred = idom(pred); + if (pred == NULL || pred == C->top()) { + break; + } + // Stop if going beyond definition block of val + if (dom_depth(pred) < val_dom_depth) { + break; + } + } + } + return rtn_t; +} + + +//------------------------------filtered_type_at_if-------------------------------- +// Return a possibly more restrictive type for val based on condition control flow for an if +const TypeInt* PhaseIdealLoop::filtered_type_at_if( Node* val, Node *if_proj) { + assert(if_proj && + (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection"); + if (if_proj->in(0) && if_proj->in(0)->is_If()) { + IfNode* iff = if_proj->in(0)->as_If(); + if (iff->in(1) && iff->in(1)->is_Bool()) { + BoolNode* bol = iff->in(1)->as_Bool(); + if (bol->in(1) && bol->in(1)->is_Cmp()) { + const CmpNode* cmp = bol->in(1)->as_Cmp(); + if (cmp->in(1) == val) { + const TypeInt* cmp2_t = _igvn.type(cmp->in(2))->isa_int(); + if (cmp2_t != NULL) { + jint lo = cmp2_t->_lo; + jint hi = cmp2_t->_hi; + BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate(); + switch (msk) { + case BoolTest::ne: + // Can't refine type + return NULL; + case BoolTest::eq: + return cmp2_t; + case BoolTest::lt: + lo = TypeInt::INT->_lo; + if (hi - 1 < hi) { + hi = hi - 1; + } + break; + case BoolTest::le: + lo = TypeInt::INT->_lo; + break; + case BoolTest::gt: + if (lo + 1 > lo) { + lo = lo + 1; + } + hi = TypeInt::INT->_hi; + break; + case BoolTest::ge: + // lo unchanged + hi = TypeInt::INT->_hi; + break; + } + const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen); + return rtn_t; + } + } + } + } + } + return NULL; +} + +//------------------------------dump_spec-------------------------------------- +// Dump special per-node info +#ifndef PRODUCT +void CountedLoopEndNode::dump_spec(outputStream *st) const { + if( in(TestValue)->is_Bool() ) { + BoolTest bt( test_trip()); // Added this for g++. + + st->print("["); + bt.dump_on(st); + st->print("]"); + } + st->print(" "); + IfNode::dump_spec(st); +} +#endif + +//============================================================================= +//------------------------------is_member-------------------------------------- +// Is 'l' a member of 'this'? +int IdealLoopTree::is_member( const IdealLoopTree *l ) const { + while( l->_nest > _nest ) l = l->_parent; + return l == this; +} + +//------------------------------set_nest--------------------------------------- +// Set loop tree nesting depth. Accumulate _has_call bits. +int IdealLoopTree::set_nest( uint depth ) { + _nest = depth; + int bits = _has_call; + if( _child ) bits |= _child->set_nest(depth+1); + if( bits ) _has_call = 1; + if( _next ) bits |= _next ->set_nest(depth ); + return bits; +} + +//------------------------------split_fall_in---------------------------------- +// Split out multiple fall-in edges from the loop header. Move them to a +// private RegionNode before the loop. This becomes the loop landing pad. +void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) { + PhaseIterGVN &igvn = phase->_igvn; + uint i; + + // Make a new RegionNode to be the landing pad. + Node *landing_pad = new (phase->C, fall_in_cnt+1) RegionNode( fall_in_cnt+1 ); + phase->set_loop(landing_pad,_parent); + // Gather all the fall-in control paths into the landing pad + uint icnt = fall_in_cnt; + uint oreq = _head->req(); + for( i = oreq-1; i>0; i-- ) + if( !phase->is_member( this, _head->in(i) ) ) + landing_pad->set_req(icnt--,_head->in(i)); + + // Peel off PhiNode edges as well + for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { + Node *oj = _head->fast_out(j); + if( oj->is_Phi() ) { + PhiNode* old_phi = oj->as_Phi(); + assert( old_phi->region() == _head, "" ); + igvn.hash_delete(old_phi); // Yank from hash before hacking edges + Node *p = PhiNode::make_blank(landing_pad, old_phi); + uint icnt = fall_in_cnt; + for( i = oreq-1; i>0; i-- ) { + if( !phase->is_member( this, _head->in(i) ) ) { + p->init_req(icnt--, old_phi->in(i)); + // Go ahead and clean out old edges from old phi + old_phi->del_req(i); + } + } + // Search for CSE's here, because ZKM.jar does a lot of + // loop hackery and we need to be a little incremental + // with the CSE to avoid O(N^2) node blow-up. + Node *p2 = igvn.hash_find_insert(p); // Look for a CSE + if( p2 ) { // Found CSE + p->destruct(); // Recover useless new node + p = p2; // Use old node + } else { + igvn.register_new_node_with_optimizer(p, old_phi); + } + // Make old Phi refer to new Phi. + old_phi->add_req(p); + // Check for the special case of making the old phi useless and + // disappear it. In JavaGrande I have a case where this useless + // Phi is the loop limit and prevents recognizing a CountedLoop + // which in turn prevents removing an empty loop. + Node *id_old_phi = old_phi->Identity( &igvn ); + if( id_old_phi != old_phi ) { // Found a simple identity? + // Note that I cannot call 'subsume_node' here, because + // that will yank the edge from old_phi to the Region and + // I'm mid-iteration over the Region's uses. + for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) { + Node* use = old_phi->last_out(i); + igvn.hash_delete(use); + igvn._worklist.push(use); + uint uses_found = 0; + for (uint j = 0; j < use->len(); j++) { + if (use->in(j) == old_phi) { + if (j < use->req()) use->set_req (j, id_old_phi); + else use->set_prec(j, id_old_phi); + uses_found++; + } + } + i -= uses_found; // we deleted 1 or more copies of this edge + } + } + igvn._worklist.push(old_phi); + } + } + // Finally clean out the fall-in edges from the RegionNode + for( i = oreq-1; i>0; i-- ) { + if( !phase->is_member( this, _head->in(i) ) ) { + _head->del_req(i); + } + } + // Transform landing pad + igvn.register_new_node_with_optimizer(landing_pad, _head); + // Insert landing pad into the header + _head->add_req(landing_pad); +} + +//------------------------------split_outer_loop------------------------------- +// Split out the outermost loop from this shared header. +void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) { + PhaseIterGVN &igvn = phase->_igvn; + + // Find index of outermost loop; it should also be my tail. + uint outer_idx = 1; + while( _head->in(outer_idx) != _tail ) outer_idx++; + + // Make a LoopNode for the outermost loop. + Node *ctl = _head->in(LoopNode::EntryControl); + Node *outer = new (phase->C, 3) LoopNode( ctl, _head->in(outer_idx) ); + outer = igvn.register_new_node_with_optimizer(outer, _head); + phase->set_created_loop_node(); + // Outermost loop falls into '_head' loop + _head->set_req(LoopNode::EntryControl, outer); + _head->del_req(outer_idx); + // Split all the Phis up between '_head' loop and 'outer' loop. + for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { + Node *out = _head->fast_out(j); + if( out->is_Phi() ) { + PhiNode *old_phi = out->as_Phi(); + assert( old_phi->region() == _head, "" ); + Node *phi = PhiNode::make_blank(outer, old_phi); + phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl)); + phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx)); + phi = igvn.register_new_node_with_optimizer(phi, old_phi); + // Make old Phi point to new Phi on the fall-in path + igvn.hash_delete(old_phi); + old_phi->set_req(LoopNode::EntryControl, phi); + old_phi->del_req(outer_idx); + igvn._worklist.push(old_phi); + } + } + + // Use the new loop head instead of the old shared one + _head = outer; + phase->set_loop(_head, this); +} + +//------------------------------fix_parent------------------------------------- +static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) { + loop->_parent = parent; + if( loop->_child ) fix_parent( loop->_child, loop ); + if( loop->_next ) fix_parent( loop->_next , parent ); +} + +//------------------------------estimate_path_freq----------------------------- +static float estimate_path_freq( Node *n ) { + // Try to extract some path frequency info + IfNode *iff; + for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests + uint nop = n->Opcode(); + if( nop == Op_SafePoint ) { // Skip any safepoint + n = n->in(0); + continue; + } + if( nop == Op_CatchProj ) { // Get count from a prior call + // Assume call does not always throw exceptions: means the call-site + // count is also the frequency of the fall-through path. + assert( n->is_CatchProj(), "" ); + if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index ) + return 0.0f; // Assume call exception path is rare + Node *call = n->in(0)->in(0)->in(0); + assert( call->is_Call(), "expect a call here" ); + const JVMState *jvms = ((CallNode*)call)->jvms(); + ciMethodData* methodData = jvms->method()->method_data(); + if (!methodData->is_mature()) return 0.0f; // No call-site data + ciProfileData* data = methodData->bci_to_data(jvms->bci()); + if ((data == NULL) || !data->is_CounterData()) { + // no call profile available, try call's control input + n = n->in(0); + continue; + } + return data->as_CounterData()->count()/FreqCountInvocations; + } + // See if there's a gating IF test + Node *n_c = n->in(0); + if( !n_c->is_If() ) break; // No estimate available + iff = n_c->as_If(); + if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count? + // Compute how much count comes on this path + return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt; + // Have no count info. Skip dull uncommon-trap like branches. + if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) || + (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) ) + break; + // Skip through never-taken branch; look for a real loop exit. + n = iff->in(0); + } + return 0.0f; // No estimate available +} + +//------------------------------merge_many_backedges--------------------------- +// Merge all the backedges from the shared header into a private Region. +// Feed that region as the one backedge to this loop. +void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) { + uint i; + + // Scan for the top 2 hottest backedges + float hotcnt = 0.0f; + float warmcnt = 0.0f; + uint hot_idx = 0; + // Loop starts at 2 because slot 1 is the fall-in path + for( i = 2; i < _head->req(); i++ ) { + float cnt = estimate_path_freq(_head->in(i)); + if( cnt > hotcnt ) { // Grab hottest path + warmcnt = hotcnt; + hotcnt = cnt; + hot_idx = i; + } else if( cnt > warmcnt ) { // And 2nd hottest path + warmcnt = cnt; + } + } + + // See if the hottest backedge is worthy of being an inner loop + // by being much hotter than the next hottest backedge. + if( hotcnt <= 0.0001 || + hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge + + // Peel out the backedges into a private merge point; peel + // them all except optionally hot_idx. + PhaseIterGVN &igvn = phase->_igvn; + + Node *hot_tail = NULL; + // Make a Region for the merge point + Node *r = new (phase->C, 1) RegionNode(1); + for( i = 2; i < _head->req(); i++ ) { + if( i != hot_idx ) + r->add_req( _head->in(i) ); + else hot_tail = _head->in(i); + } + igvn.register_new_node_with_optimizer(r, _head); + // Plug region into end of loop _head, followed by hot_tail + while( _head->req() > 3 ) _head->del_req( _head->req()-1 ); + _head->set_req(2, r); + if( hot_idx ) _head->add_req(hot_tail); + + // Split all the Phis up between '_head' loop and the Region 'r' + for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { + Node *out = _head->fast_out(j); + if( out->is_Phi() ) { + PhiNode* n = out->as_Phi(); + igvn.hash_delete(n); // Delete from hash before hacking edges + Node *hot_phi = NULL; + Node *phi = new (phase->C, r->req()) PhiNode(r, n->type(), n->adr_type()); + // Check all inputs for the ones to peel out + uint j = 1; + for( uint i = 2; i < n->req(); i++ ) { + if( i != hot_idx ) + phi->set_req( j++, n->in(i) ); + else hot_phi = n->in(i); + } + // Register the phi but do not transform until whole place transforms + igvn.register_new_node_with_optimizer(phi, n); + // Add the merge phi to the old Phi + while( n->req() > 3 ) n->del_req( n->req()-1 ); + n->set_req(2, phi); + if( hot_idx ) n->add_req(hot_phi); + } + } + + + // Insert a new IdealLoopTree inserted below me. Turn it into a clone + // of self loop tree. Turn self into a loop headed by _head and with + // tail being the new merge point. + IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail ); + phase->set_loop(_tail,ilt); // Adjust tail + _tail = r; // Self's tail is new merge point + phase->set_loop(r,this); + ilt->_child = _child; // New guy has my children + _child = ilt; // Self has new guy as only child + ilt->_parent = this; // new guy has self for parent + ilt->_nest = _nest; // Same nesting depth (for now) + + // Starting with 'ilt', look for child loop trees using the same shared + // header. Flatten these out; they will no longer be loops in the end. + IdealLoopTree **pilt = &_child; + while( ilt ) { + if( ilt->_head == _head ) { + uint i; + for( i = 2; i < _head->req(); i++ ) + if( _head->in(i) == ilt->_tail ) + break; // Still a loop + if( i == _head->req() ) { // No longer a loop + // Flatten ilt. Hang ilt's "_next" list from the end of + // ilt's '_child' list. Move the ilt's _child up to replace ilt. + IdealLoopTree **cp = &ilt->_child; + while( *cp ) cp = &(*cp)->_next; // Find end of child list + *cp = ilt->_next; // Hang next list at end of child list + *pilt = ilt->_child; // Move child up to replace ilt + ilt->_head = NULL; // Flag as a loop UNIONED into parent + ilt = ilt->_child; // Repeat using new ilt + continue; // do not advance over ilt->_child + } + assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" ); + phase->set_loop(_head,ilt); + } + pilt = &ilt->_child; // Advance to next + ilt = *pilt; + } + + if( _child ) fix_parent( _child, this ); +} + +//------------------------------beautify_loops--------------------------------- +// Split shared headers and insert loop landing pads. +// Insert a LoopNode to replace the RegionNode. +// Return TRUE if loop tree is structurally changed. +bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) { + bool result = false; + // Cache parts in locals for easy + PhaseIterGVN &igvn = phase->_igvn; + + phase->C->print_method("Before beautify loops", 3); + + igvn.hash_delete(_head); // Yank from hash before hacking edges + + // Check for multiple fall-in paths. Peel off a landing pad if need be. + int fall_in_cnt = 0; + for( uint i = 1; i < _head->req(); i++ ) + if( !phase->is_member( this, _head->in(i) ) ) + fall_in_cnt++; + assert( fall_in_cnt, "at least 1 fall-in path" ); + if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins + split_fall_in( phase, fall_in_cnt ); + + // Swap inputs to the _head and all Phis to move the fall-in edge to + // the left. + fall_in_cnt = 1; + while( phase->is_member( this, _head->in(fall_in_cnt) ) ) + fall_in_cnt++; + if( fall_in_cnt > 1 ) { + // Since I am just swapping inputs I do not need to update def-use info + Node *tmp = _head->in(1); + _head->set_req( 1, _head->in(fall_in_cnt) ); + _head->set_req( fall_in_cnt, tmp ); + // Swap also all Phis + for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) { + Node* phi = _head->fast_out(i); + if( phi->is_Phi() ) { + igvn.hash_delete(phi); // Yank from hash before hacking edges + tmp = phi->in(1); + phi->set_req( 1, phi->in(fall_in_cnt) ); + phi->set_req( fall_in_cnt, tmp ); + } + } + } + assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" ); + assert( phase->is_member( this, _head->in(2) ), "right edge is loop" ); + + // If I am a shared header (multiple backedges), peel off the many + // backedges into a private merge point and use the merge point as + // the one true backedge. + if( _head->req() > 3 ) { + // Merge the many backedges into a single backedge. + merge_many_backedges( phase ); + result = true; + } + + // If I am a shared header (multiple backedges), peel off myself loop. + // I better be the outermost loop. + if( _head->req() > 3 ) { + split_outer_loop( phase ); + result = true; + + } else if( !_head->is_Loop() && !_irreducible ) { + // Make a new LoopNode to replace the old loop head + Node *l = new (phase->C, 3) LoopNode( _head->in(1), _head->in(2) ); + l = igvn.register_new_node_with_optimizer(l, _head); + phase->set_created_loop_node(); + // Go ahead and replace _head + phase->_igvn.subsume_node( _head, l ); + _head = l; + phase->set_loop(_head, this); + for (DUIterator_Fast imax, i = l->fast_outs(imax); i < imax; i++) + phase->_igvn.add_users_to_worklist(l->fast_out(i)); + } + + phase->C->print_method("After beautify loops", 3); + + // Now recursively beautify nested loops + if( _child ) result |= _child->beautify_loops( phase ); + if( _next ) result |= _next ->beautify_loops( phase ); + return result; +} + +//------------------------------allpaths_check_safepts---------------------------- +// Allpaths backwards scan from loop tail, terminating each path at first safepoint +// encountered. Helper for check_safepts. +void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) { + assert(stack.size() == 0, "empty stack"); + stack.push(_tail); + visited.Clear(); + visited.set(_tail->_idx); + while (stack.size() > 0) { + Node* n = stack.pop(); + if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) { + // Terminate this path + } else if (n->Opcode() == Op_SafePoint) { + if (_phase->get_loop(n) != this) { + if (_required_safept == NULL) _required_safept = new Node_List(); + _required_safept->push(n); // save the one closest to the tail + } + // Terminate this path + } else { + uint start = n->is_Region() ? 1 : 0; + uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1; + for (uint i = start; i < end; i++) { + Node* in = n->in(i); + assert(in->is_CFG(), "must be"); + if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) { + stack.push(in); + } + } + } + } +} + +//------------------------------check_safepts---------------------------- +// Given dominators, try to find loops with calls that must always be +// executed (call dominates loop tail). These loops do not need non-call +// safepoints (ncsfpt). +// +// A complication is that a safepoint in a inner loop may be needed +// by an outer loop. In the following, the inner loop sees it has a +// call (block 3) on every path from the head (block 2) to the +// backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint) +// in block 2, _but_ this leaves the outer loop without a safepoint. +// +// entry 0 +// | +// v +// outer 1,2 +->1 +// | | +// | v +// | 2<---+ ncsfpt in 2 +// |_/|\ | +// | v | +// inner 2,3 / 3 | call in 3 +// / | | +// v +--+ +// exit 4 +// +// +// This method creates a list (_required_safept) of ncsfpt nodes that must +// be protected is created for each loop. When a ncsfpt maybe deleted, it +// is first looked for in the lists for the outer loops of the current loop. +// +// The insights into the problem: +// A) counted loops are okay +// B) innermost loops are okay (only an inner loop can delete +// a ncsfpt needed by an outer loop) +// C) a loop is immune from an inner loop deleting a safepoint +// if the loop has a call on the idom-path +// D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the +// idom-path that is not in a nested loop +// E) otherwise, an ncsfpt on the idom-path that is nested in an inner +// loop needs to be prevented from deletion by an inner loop +// +// There are two analyses: +// 1) The first, and cheaper one, scans the loop body from +// tail to head following the idom (immediate dominator) +// chain, looking for the cases (C,D,E) above. +// Since inner loops are scanned before outer loops, there is summary +// information about inner loops. Inner loops can be skipped over +// when the tail of an inner loop is encountered. +// +// 2) The second, invoked if the first fails to find a call or ncsfpt on +// the idom path (which is rare), scans all predecessor control paths +// from the tail to the head, terminating a path when a call or sfpt +// is encountered, to find the ncsfpt's that are closest to the tail. +// +void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) { + // Bottom up traversal + IdealLoopTree* ch = _child; + while (ch != NULL) { + ch->check_safepts(visited, stack); + ch = ch->_next; + } + + if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) { + bool has_call = false; // call on dom-path + bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth + Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth + // Scan the dom-path nodes from tail to head + for (Node* n = tail(); n != _head; n = _phase->idom(n)) { + if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) { + has_call = true; + _has_sfpt = 1; // Then no need for a safept! + break; + } else if (n->Opcode() == Op_SafePoint) { + if (_phase->get_loop(n) == this) { + has_local_ncsfpt = true; + break; + } + if (nonlocal_ncsfpt == NULL) { + nonlocal_ncsfpt = n; // save the one closest to the tail + } + } else { + IdealLoopTree* nlpt = _phase->get_loop(n); + if (this != nlpt) { + // If at an inner loop tail, see if the inner loop has already + // recorded seeing a call on the dom-path (and stop.) If not, + // jump to the head of the inner loop. + assert(is_member(nlpt), "nested loop"); + Node* tail = nlpt->_tail; + if (tail->in(0)->is_If()) tail = tail->in(0); + if (n == tail) { + // If inner loop has call on dom-path, so does outer loop + if (nlpt->_has_sfpt) { + has_call = true; + _has_sfpt = 1; + break; + } + // Skip to head of inner loop + assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head"); + n = nlpt->_head; + } + } + } + } + // Record safept's that this loop needs preserved when an + // inner loop attempts to delete it's safepoints. + if (_child != NULL && !has_call && !has_local_ncsfpt) { + if (nonlocal_ncsfpt != NULL) { + if (_required_safept == NULL) _required_safept = new Node_List(); + _required_safept->push(nonlocal_ncsfpt); + } else { + // Failed to find a suitable safept on the dom-path. Now use + // an all paths walk from tail to head, looking for safepoints to preserve. + allpaths_check_safepts(visited, stack); + } + } + } +} + +//---------------------------is_deleteable_safept---------------------------- +// Is safept not required by an outer loop? +bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) { + assert(sfpt->Opcode() == Op_SafePoint, ""); + IdealLoopTree* lp = get_loop(sfpt)->_parent; + while (lp != NULL) { + Node_List* sfpts = lp->_required_safept; + if (sfpts != NULL) { + for (uint i = 0; i < sfpts->size(); i++) { + if (sfpt == sfpts->at(i)) + return false; + } + } + lp = lp->_parent; + } + return true; +} + +//------------------------------counted_loop----------------------------------- +// Convert to counted loops where possible +void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) { + + // For grins, set the inner-loop flag here + if( !_child ) { + if( _head->is_Loop() ) _head->as_Loop()->set_inner_loop(); + } + + if( _head->is_CountedLoop() || + phase->is_counted_loop( _head, this ) ) { + _has_sfpt = 1; // Indicate we do not need a safepoint here + + // Look for a safepoint to remove + for (Node* n = tail(); n != _head; n = phase->idom(n)) + if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this && + phase->is_deleteable_safept(n)) + phase->lazy_replace(n,n->in(TypeFunc::Control)); + + CountedLoopNode *cl = _head->as_CountedLoop(); + Node *incr = cl->incr(); + if( !incr ) return; // Dead loop? + Node *init = cl->init_trip(); + Node *phi = cl->phi(); + // protect against stride not being a constant + if( !cl->stride_is_con() ) return; + int stride_con = cl->stride_con(); + + // Look for induction variables + + // Visit all children, looking for Phis + for (DUIterator i = cl->outs(); cl->has_out(i); i++) { + Node *out = cl->out(i); + if (!out->is_Phi()) continue; // Looking for phis + PhiNode* phi2 = out->as_Phi(); + Node *incr2 = phi2->in( LoopNode::LoopBackControl ); + // Look for induction variables of the form: X += constant + if( phi2->region() != _head || + incr2->req() != 3 || + incr2->in(1) != phi2 || + incr2 == incr || + incr2->Opcode() != Op_AddI || + !incr2->in(2)->is_Con() ) + continue; + + // Check for parallel induction variable (parallel to trip counter) + // via an affine function. In particular, count-down loops with + // count-up array indices are common. We only RCE references off + // the trip-counter, so we need to convert all these to trip-counter + // expressions. + Node *init2 = phi2->in( LoopNode::EntryControl ); + int stride_con2 = incr2->in(2)->get_int(); + + // The general case here gets a little tricky. We want to find the + // GCD of all possible parallel IV's and make a new IV using this + // GCD for the loop. Then all possible IVs are simple multiples of + // the GCD. In practice, this will cover very few extra loops. + // Instead we require 'stride_con2' to be a multiple of 'stride_con', + // where +/-1 is the common case, but other integer multiples are + // also easy to handle. + int ratio_con = stride_con2/stride_con; + + if( ratio_con * stride_con == stride_con2 ) { // Check for exact + // Convert to using the trip counter. The parallel induction + // variable differs from the trip counter by a loop-invariant + // amount, the difference between their respective initial values. + // It is scaled by the 'ratio_con'. + Compile* C = phase->C; + Node* ratio = phase->_igvn.intcon(ratio_con); + phase->set_ctrl(ratio, C->root()); + Node* ratio_init = new (C, 3) MulINode(init, ratio); + phase->_igvn.register_new_node_with_optimizer(ratio_init, init); + phase->set_early_ctrl(ratio_init); + Node* diff = new (C, 3) SubINode(init2, ratio_init); + phase->_igvn.register_new_node_with_optimizer(diff, init2); + phase->set_early_ctrl(diff); + Node* ratio_idx = new (C, 3) MulINode(phi, ratio); + phase->_igvn.register_new_node_with_optimizer(ratio_idx, phi); + phase->set_ctrl(ratio_idx, cl); + Node* add = new (C, 3) AddINode(ratio_idx, diff); + phase->_igvn.register_new_node_with_optimizer(add); + phase->set_ctrl(add, cl); + phase->_igvn.hash_delete( phi2 ); + phase->_igvn.subsume_node( phi2, add ); + // Sometimes an induction variable is unused + if (add->outcnt() == 0) { + phase->_igvn.remove_dead_node(add); + } + --i; // deleted this phi; rescan starting with next position + continue; + } + } + } else if (_parent != NULL && !_irreducible) { + // Not a counted loop. + // Look for a safepoint on the idom-path to remove, preserving the first one + bool found = false; + Node* n = tail(); + for (; n != _head && !found; n = phase->idom(n)) { + if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this) + found = true; // Found one + } + // Skip past it and delete the others + for (; n != _head; n = phase->idom(n)) { + if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this && + phase->is_deleteable_safept(n)) + phase->lazy_replace(n,n->in(TypeFunc::Control)); + } + } + + // Recursively + if( _child ) _child->counted_loop( phase ); + if( _next ) _next ->counted_loop( phase ); +} + +#ifndef PRODUCT +//------------------------------dump_head-------------------------------------- +// Dump 1 liner for loop header info +void IdealLoopTree::dump_head( ) const { + for( uint i=0; i<_nest; i++ ) + tty->print(" "); + tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx); + if( _irreducible ) tty->print(" IRREDUCIBLE"); + if( _head->is_CountedLoop() ) { + CountedLoopNode *cl = _head->as_CountedLoop(); + tty->print(" counted"); + if( cl->is_pre_loop () ) tty->print(" pre" ); + if( cl->is_main_loop() ) tty->print(" main"); + if( cl->is_post_loop() ) tty->print(" post"); + } + tty->cr(); +} + +//------------------------------dump------------------------------------------- +// Dump loops by loop tree +void IdealLoopTree::dump( ) const { + dump_head(); + if( _child ) _child->dump(); + if( _next ) _next ->dump(); +} + +#endif + +//============================================================================= +//------------------------------PhaseIdealLoop--------------------------------- +// Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to +// its corresponding LoopNode. If 'optimize' is true, do some loop cleanups. +PhaseIdealLoop::PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me, bool do_split_ifs ) + : PhaseTransform(Ideal_Loop), + _igvn(igvn), + _dom_lca_tags(C->comp_arena()) { + // Reset major-progress flag for the driver's heuristics + C->clear_major_progress(); + +#ifndef PRODUCT + // Capture for later assert + uint unique = C->unique(); + _loop_invokes++; + _loop_work += unique; +#endif + + // True if the method has at least 1 irreducible loop + _has_irreducible_loops = false; + + _created_loop_node = false; + + Arena *a = Thread::current()->resource_area(); + VectorSet visited(a); + // Pre-grow the mapping from Nodes to IdealLoopTrees. + _nodes.map(C->unique(), NULL); + memset(_nodes.adr(), 0, wordSize * C->unique()); + + // Pre-build the top-level outermost loop tree entry + _ltree_root = new IdealLoopTree( this, C->root(), C->root() ); + // Do not need a safepoint at the top level + _ltree_root->_has_sfpt = 1; + + // Empty pre-order array + allocate_preorders(); + + // Build a loop tree on the fly. Build a mapping from CFG nodes to + // IdealLoopTree entries. Data nodes are NOT walked. + build_loop_tree(); + // Check for bailout, and return + if (C->failing()) { + return; + } + + // No loops after all + if( !_ltree_root->_child ) C->set_has_loops(false); + + // There should always be an outer loop containing the Root and Return nodes. + // If not, we have a degenerate empty program. Bail out in this case. + if (!has_node(C->root())) { + C->clear_major_progress(); + C->record_method_not_compilable("empty program detected during loop optimization"); + return; + } + + // Nothing to do, so get out + if( !C->has_loops() && !do_split_ifs && !verify_me) { + _igvn.optimize(); // Cleanup NeverBranches + return; + } + + // Set loop nesting depth + _ltree_root->set_nest( 0 ); + + // Split shared headers and insert loop landing pads. + // Do not bother doing this on the Root loop of course. + if( !verify_me && _ltree_root->_child ) { + if( _ltree_root->_child->beautify_loops( this ) ) { + // Re-build loop tree! + _ltree_root->_child = NULL; + _nodes.clear(); + reallocate_preorders(); + build_loop_tree(); + // Check for bailout, and return + if (C->failing()) { + return; + } + // Reset loop nesting depth + _ltree_root->set_nest( 0 ); + } + } + + // Build Dominators for elision of NULL checks & loop finding. + // Since nodes do not have a slot for immediate dominator, make + // a persistant side array for that info indexed on node->_idx. + _idom_size = C->unique(); + _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size ); + _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size ); + _dom_stk = NULL; // Allocated on demand in recompute_dom_depth + memset( _dom_depth, 0, _idom_size * sizeof(uint) ); + + Dominators(); + + // As a side effect, Dominators removed any unreachable CFG paths + // into RegionNodes. It doesn't do this test against Root, so + // we do it here. + for( uint i = 1; i < C->root()->req(); i++ ) { + if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root? + _igvn.hash_delete(C->root()); + C->root()->del_req(i); + _igvn._worklist.push(C->root()); + i--; // Rerun same iteration on compressed edges + } + } + + // Given dominators, try to find inner loops with calls that must + // always be executed (call dominates loop tail). These loops do + // not need a seperate safepoint. + Node_List cisstack(a); + _ltree_root->check_safepts(visited, cisstack); + + // Walk the DATA nodes and place into loops. Find earliest control + // node. For CFG nodes, the _nodes array starts out and remains + // holding the associated IdealLoopTree pointer. For DATA nodes, the + // _nodes array holds the earliest legal controlling CFG node. + + // Allocate stack with enough space to avoid frequent realloc + int stack_size = (C->unique() >> 1) + 16; // (unique>>1)+16 from Java2D stats + Node_Stack nstack( a, stack_size ); + + visited.Clear(); + Node_List worklist(a); + // Don't need C->root() on worklist since + // it will be processed among C->top() inputs + worklist.push( C->top() ); + visited.set( C->top()->_idx ); // Set C->top() as visited now + build_loop_early( visited, worklist, nstack, verify_me ); + + // Given early legal placement, try finding counted loops. This placement + // is good enough to discover most loop invariants. + if( !verify_me ) + _ltree_root->counted_loop( this ); + + // Find latest loop placement. Find ideal loop placement. + visited.Clear(); + init_dom_lca_tags(); + // Need C->root() on worklist when processing outs + worklist.push( C->root() ); + NOT_PRODUCT( C->verify_graph_edges(); ) + worklist.push( C->top() ); + build_loop_late( visited, worklist, nstack, verify_me ); + + // clear out the dead code + while(_deadlist.size()) { + igvn.remove_globally_dead_node(_deadlist.pop()); + } + +#ifndef PRODUCT + C->verify_graph_edges(); + if( verify_me ) { // Nested verify pass? + // Check to see if the verify mode is broken + assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?"); + return; + } + if( VerifyLoopOptimizations ) verify(); +#endif + + if (ReassociateInvariants) { + // Reassociate invariants and prep for split_thru_phi + for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { + IdealLoopTree* lpt = iter.current(); + if (!lpt->is_counted() || !lpt->is_inner()) continue; + + lpt->reassociate_invariants(this); + + // Because RCE opportunities can be masked by split_thru_phi, + // look for RCE candidates and inhibit split_thru_phi + // on just their loop-phi's for this pass of loop opts + if( SplitIfBlocks && do_split_ifs ) { + if (lpt->policy_range_check(this)) { + lpt->_rce_candidate = true; + } + } + } + } + + // Check for aggressive application of split-if and other transforms + // that require basic-block info (like cloning through Phi's) + if( SplitIfBlocks && do_split_ifs ) { + visited.Clear(); + split_if_with_blocks( visited, nstack ); + NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); ); + } + + // Perform iteration-splitting on inner loops. Split iterations to avoid + // range checks or one-shot null checks. + + // If split-if's didn't hack the graph too bad (no CFG changes) + // then do loop opts. + if( C->has_loops() && !C->major_progress() ) { + memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) ); + _ltree_root->_child->iteration_split( this, worklist ); + // No verify after peeling! GCM has hoisted code out of the loop. + // After peeling, the hoisted code could sink inside the peeled area. + // The peeling code does not try to recompute the best location for + // all the code before the peeled area, so the verify pass will always + // complain about it. + } + // Do verify graph edges in any case + NOT_PRODUCT( C->verify_graph_edges(); ); + + if( !do_split_ifs ) { + // We saw major progress in Split-If to get here. We forced a + // pass with unrolling and not split-if, however more split-if's + // might make progress. If the unrolling didn't make progress + // then the major-progress flag got cleared and we won't try + // another round of Split-If. In particular the ever-common + // instance-of/check-cast pattern requires at least 2 rounds of + // Split-If to clear out. + C->set_major_progress(); + } + + // Repeat loop optimizations if new loops were seen + if (created_loop_node()) { + C->set_major_progress(); + } + + // Convert scalar to superword operations + + if (UseSuperWord && C->has_loops() && !C->major_progress()) { + // SuperWord transform + SuperWord sw(this); + for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { + IdealLoopTree* lpt = iter.current(); + if (lpt->is_counted()) { + sw.transform_loop(lpt); + } + } + } + + // Cleanup any modified bits + _igvn.optimize(); + + // Do not repeat loop optimizations if irreducible loops are present + // by claiming no-progress. + if( _has_irreducible_loops ) + C->clear_major_progress(); +} + +#ifndef PRODUCT +//------------------------------print_statistics------------------------------- +int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes +int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique +void PhaseIdealLoop::print_statistics() { + tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work); +} + +//------------------------------verify----------------------------------------- +// Build a verify-only PhaseIdealLoop, and see that it agrees with me. +static int fail; // debug only, so its multi-thread dont care +void PhaseIdealLoop::verify() const { + int old_progress = C->major_progress(); + ResourceMark rm; + PhaseIdealLoop loop_verify( _igvn, this, false ); + VectorSet visited(Thread::current()->resource_area()); + + fail = 0; + verify_compare( C->root(), &loop_verify, visited ); + assert( fail == 0, "verify loops failed" ); + // Verify loop structure is the same + _ltree_root->verify_tree(loop_verify._ltree_root, NULL); + // Reset major-progress. It was cleared by creating a verify version of + // PhaseIdealLoop. + for( int i=0; i<old_progress; i++ ) + C->set_major_progress(); +} + +//------------------------------verify_compare--------------------------------- +// Make sure me and the given PhaseIdealLoop agree on key data structures +void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const { + if( !n ) return; + if( visited.test_set( n->_idx ) ) return; + if( !_nodes[n->_idx] ) { // Unreachable + assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" ); + return; + } + + uint i; + for( i = 0; i < n->req(); i++ ) + verify_compare( n->in(i), loop_verify, visited ); + + // Check the '_nodes' block/loop structure + i = n->_idx; + if( has_ctrl(n) ) { // We have control; verify has loop or ctrl + if( _nodes[i] != loop_verify->_nodes[i] && + get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) { + tty->print("Mismatched control setting for: "); + n->dump(); + if( fail++ > 10 ) return; + Node *c = get_ctrl_no_update(n); + tty->print("We have it as: "); + if( c->in(0) ) c->dump(); + else tty->print_cr("N%d",c->_idx); + tty->print("Verify thinks: "); + if( loop_verify->has_ctrl(n) ) + loop_verify->get_ctrl_no_update(n)->dump(); + else + loop_verify->get_loop_idx(n)->dump(); + tty->cr(); + } + } else { // We have a loop + IdealLoopTree *us = get_loop_idx(n); + if( loop_verify->has_ctrl(n) ) { + tty->print("Mismatched loop setting for: "); + n->dump(); + if( fail++ > 10 ) return; + tty->print("We have it as: "); + us->dump(); + tty->print("Verify thinks: "); + loop_verify->get_ctrl_no_update(n)->dump(); + tty->cr(); + } else if (!C->major_progress()) { + // Loop selection can be messed up if we did a major progress + // operation, like split-if. Do not verify in that case. + IdealLoopTree *them = loop_verify->get_loop_idx(n); + if( us->_head != them->_head || us->_tail != them->_tail ) { + tty->print("Unequals loops for: "); + n->dump(); + if( fail++ > 10 ) return; + tty->print("We have it as: "); + us->dump(); + tty->print("Verify thinks: "); + them->dump(); + tty->cr(); + } + } + } + + // Check for immediate dominators being equal + if( i >= _idom_size ) { + if( !n->is_CFG() ) return; + tty->print("CFG Node with no idom: "); + n->dump(); + return; + } + if( !n->is_CFG() ) return; + if( n == C->root() ) return; // No IDOM here + + assert(n->_idx == i, "sanity"); + Node *id = idom_no_update(n); + if( id != loop_verify->idom_no_update(n) ) { + tty->print("Unequals idoms for: "); + n->dump(); + if( fail++ > 10 ) return; + tty->print("We have it as: "); + id->dump(); + tty->print("Verify thinks: "); + loop_verify->idom_no_update(n)->dump(); + tty->cr(); + } + +} + +//------------------------------verify_tree------------------------------------ +// Verify that tree structures match. Because the CFG can change, siblings +// within the loop tree can be reordered. We attempt to deal with that by +// reordering the verify's loop tree if possible. +void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const { + assert( _parent == parent, "Badly formed loop tree" ); + + // Siblings not in same order? Attempt to re-order. + if( _head != loop->_head ) { + // Find _next pointer to update + IdealLoopTree **pp = &loop->_parent->_child; + while( *pp != loop ) + pp = &((*pp)->_next); + // Find proper sibling to be next + IdealLoopTree **nn = &loop->_next; + while( (*nn) && (*nn)->_head != _head ) + nn = &((*nn)->_next); + + // Check for no match. + if( !(*nn) ) { + // Annoyingly, irreducible loops can pick different headers + // after a major_progress operation, so the rest of the loop + // tree cannot be matched. + if (_irreducible && Compile::current()->major_progress()) return; + assert( 0, "failed to match loop tree" ); + } + + // Move (*nn) to (*pp) + IdealLoopTree *hit = *nn; + *nn = hit->_next; + hit->_next = loop; + *pp = loop; + loop = hit; + // Now try again to verify + } + + assert( _head == loop->_head , "mismatched loop head" ); + Node *tail = _tail; // Inline a non-updating version of + while( !tail->in(0) ) // the 'tail()' call. + tail = tail->in(1); + assert( tail == loop->_tail, "mismatched loop tail" ); + + // Counted loops that are guarded should be able to find their guards + if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) { + CountedLoopNode *cl = _head->as_CountedLoop(); + Node *init = cl->init_trip(); + Node *ctrl = cl->in(LoopNode::EntryControl); + assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); + Node *iff = ctrl->in(0); + assert( iff->Opcode() == Op_If, "" ); + Node *bol = iff->in(1); + assert( bol->Opcode() == Op_Bool, "" ); + Node *cmp = bol->in(1); + assert( cmp->Opcode() == Op_CmpI, "" ); + Node *add = cmp->in(1); + Node *opaq; + if( add->Opcode() == Op_Opaque1 ) { + opaq = add; + } else { + assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" ); + assert( add == init, "" ); + opaq = cmp->in(2); + } + assert( opaq->Opcode() == Op_Opaque1, "" ); + + } + + if (_child != NULL) _child->verify_tree(loop->_child, this); + if (_next != NULL) _next ->verify_tree(loop->_next, parent); + // Innermost loops need to verify loop bodies, + // but only if no 'major_progress' + int fail = 0; + if (!Compile::current()->major_progress() && _child == NULL) { + for( uint i = 0; i < _body.size(); i++ ) { + Node *n = _body.at(i); + if (n->outcnt() == 0) continue; // Ignore dead + uint j; + for( j = 0; j < loop->_body.size(); j++ ) + if( loop->_body.at(j) == n ) + break; + if( j == loop->_body.size() ) { // Not found in loop body + // Last ditch effort to avoid assertion: Its possible that we + // have some users (so outcnt not zero) but are still dead. + // Try to find from root. + if (Compile::current()->root()->find(n->_idx)) { + fail++; + tty->print("We have that verify does not: "); + n->dump(); + } + } + } + for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) { + Node *n = loop->_body.at(i2); + if (n->outcnt() == 0) continue; // Ignore dead + uint j; + for( j = 0; j < _body.size(); j++ ) + if( _body.at(j) == n ) + break; + if( j == _body.size() ) { // Not found in loop body + // Last ditch effort to avoid assertion: Its possible that we + // have some users (so outcnt not zero) but are still dead. + // Try to find from root. + if (Compile::current()->root()->find(n->_idx)) { + fail++; + tty->print("Verify has that we do not: "); + n->dump(); + } + } + } + assert( !fail, "loop body mismatch" ); + } +} + +#endif + +//------------------------------set_idom--------------------------------------- +void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) { + uint idx = d->_idx; + if (idx >= _idom_size) { + uint newsize = _idom_size<<1; + while( idx >= newsize ) { + newsize <<= 1; + } + _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize); + _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize); + memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) ); + _idom_size = newsize; + } + _idom[idx] = n; + _dom_depth[idx] = dom_depth; +} + +//------------------------------recompute_dom_depth--------------------------------------- +// The dominator tree is constructed with only parent pointers. +// This recomputes the depth in the tree by first tagging all +// nodes as "no depth yet" marker. The next pass then runs up +// the dom tree from each node marked "no depth yet", and computes +// the depth on the way back down. +void PhaseIdealLoop::recompute_dom_depth() { + uint no_depth_marker = C->unique(); + uint i; + // Initialize depth to "no depth yet" + for (i = 0; i < _idom_size; i++) { + if (_dom_depth[i] > 0 && _idom[i] != NULL) { + _dom_depth[i] = no_depth_marker; + } + } + if (_dom_stk == NULL) { + uint init_size = C->unique() / 100; // Guess that 1/100 is a reasonable initial size. + if (init_size < 10) init_size = 10; + _dom_stk = new (C->node_arena()) GrowableArray<uint>(C->node_arena(), init_size, 0, 0); + } + // Compute new depth for each node. + for (i = 0; i < _idom_size; i++) { + uint j = i; + // Run up the dom tree to find a node with a depth + while (_dom_depth[j] == no_depth_marker) { + _dom_stk->push(j); + j = _idom[j]->_idx; + } + // Compute the depth on the way back down this tree branch + uint dd = _dom_depth[j] + 1; + while (_dom_stk->length() > 0) { + uint j = _dom_stk->pop(); + _dom_depth[j] = dd; + dd++; + } + } +} + +//------------------------------sort------------------------------------------- +// Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the +// loop tree, not the root. +IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) { + if( !innermost ) return loop; // New innermost loop + + int loop_preorder = get_preorder(loop->_head); // Cache pre-order number + assert( loop_preorder, "not yet post-walked loop" ); + IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer + IdealLoopTree *l = *pp; // Do I go before or after 'l'? + + // Insert at start of list + while( l ) { // Insertion sort based on pre-order + if( l == loop ) return innermost; // Already on list! + int l_preorder = get_preorder(l->_head); // Cache pre-order number + assert( l_preorder, "not yet post-walked l" ); + // Check header pre-order number to figure proper nesting + if( loop_preorder > l_preorder ) + break; // End of insertion + // If headers tie (e.g., shared headers) check tail pre-order numbers. + // Since I split shared headers, you'd think this could not happen. + // BUT: I must first do the preorder numbering before I can discover I + // have shared headers, so the split headers all get the same preorder + // number as the RegionNode they split from. + if( loop_preorder == l_preorder && + get_preorder(loop->_tail) < get_preorder(l->_tail) ) + break; // Also check for shared headers (same pre#) + pp = &l->_parent; // Chain up list + l = *pp; + } + // Link into list + // Point predecessor to me + *pp = loop; + // Point me to successor + IdealLoopTree *p = loop->_parent; + loop->_parent = l; // Point me to successor + if( p ) sort( p, innermost ); // Insert my parents into list as well + return innermost; +} + +//------------------------------build_loop_tree-------------------------------- +// I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit +// bits. The _nodes[] array is mapped by Node index and holds a NULL for +// not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the +// tightest enclosing IdealLoopTree for post-walked. +// +// During my forward walk I do a short 1-layer lookahead to see if I can find +// a loop backedge with that doesn't have any work on the backedge. This +// helps me construct nested loops with shared headers better. +// +// Once I've done the forward recursion, I do the post-work. For each child +// I check to see if there is a backedge. Backedges define a loop! I +// insert an IdealLoopTree at the target of the backedge. +// +// During the post-work I also check to see if I have several children +// belonging to different loops. If so, then this Node is a decision point +// where control flow can choose to change loop nests. It is at this +// decision point where I can figure out how loops are nested. At this +// time I can properly order the different loop nests from my children. +// Note that there may not be any backedges at the decision point! +// +// Since the decision point can be far removed from the backedges, I can't +// order my loops at the time I discover them. Thus at the decision point +// I need to inspect loop header pre-order numbers to properly nest my +// loops. This means I need to sort my childrens' loops by pre-order. +// The sort is of size number-of-control-children, which generally limits +// it to size 2 (i.e., I just choose between my 2 target loops). +void PhaseIdealLoop::build_loop_tree() { + // Allocate stack of size C->unique()/2 to avoid frequent realloc + GrowableArray <Node *> bltstack(C->unique() >> 1); + Node *n = C->root(); + bltstack.push(n); + int pre_order = 1; + int stack_size; + + while ( ( stack_size = bltstack.length() ) != 0 ) { + n = bltstack.top(); // Leave node on stack + if ( !is_visited(n) ) { + // ---- Pre-pass Work ---- + // Pre-walked but not post-walked nodes need a pre_order number. + + set_preorder_visited( n, pre_order ); // set as visited + + // ---- Scan over children ---- + // Scan first over control projections that lead to loop headers. + // This helps us find inner-to-outer loops with shared headers better. + + // Scan children's children for loop headers. + for ( int i = n->outcnt() - 1; i >= 0; --i ) { + Node* m = n->raw_out(i); // Child + if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children + // Scan over children's children to find loop + for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { + Node* l = m->fast_out(j); + if( is_visited(l) && // Been visited? + !is_postvisited(l) && // But not post-visited + get_preorder(l) < pre_order ) { // And smaller pre-order + // Found! Scan the DFS down this path before doing other paths + bltstack.push(m); + break; + } + } + } + } + pre_order++; + } + else if ( !is_postvisited(n) ) { + // Note: build_loop_tree_impl() adds out edges on rare occasions, + // such as com.sun.rsasign.am::a. + // For non-recursive version, first, process current children. + // On next iteration, check if additional children were added. + for ( int k = n->outcnt() - 1; k >= 0; --k ) { + Node* u = n->raw_out(k); + if ( u->is_CFG() && !is_visited(u) ) { + bltstack.push(u); + } + } + if ( bltstack.length() == stack_size ) { + // There were no additional children, post visit node now + (void)bltstack.pop(); // Remove node from stack + pre_order = build_loop_tree_impl( n, pre_order ); + // Check for bailout + if (C->failing()) { + return; + } + // Check to grow _preorders[] array for the case when + // build_loop_tree_impl() adds new nodes. + check_grow_preorders(); + } + } + else { + (void)bltstack.pop(); // Remove post-visited node from stack + } + } +} + +//------------------------------build_loop_tree_impl--------------------------- +int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) { + // ---- Post-pass Work ---- + // Pre-walked but not post-walked nodes need a pre_order number. + + // Tightest enclosing loop for this Node + IdealLoopTree *innermost = NULL; + + // For all children, see if any edge is a backedge. If so, make a loop + // for it. Then find the tightest enclosing loop for the self Node. + for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { + Node* m = n->fast_out(i); // Child + if( n == m ) continue; // Ignore control self-cycles + if( !m->is_CFG() ) continue;// Ignore non-CFG edges + + IdealLoopTree *l; // Child's loop + if( !is_postvisited(m) ) { // Child visited but not post-visited? + // Found a backedge + assert( get_preorder(m) < pre_order, "should be backedge" ); + // Check for the RootNode, which is already a LoopNode and is allowed + // to have multiple "backedges". + if( m == C->root()) { // Found the root? + l = _ltree_root; // Root is the outermost LoopNode + } else { // Else found a nested loop + // Insert a LoopNode to mark this loop. + l = new IdealLoopTree(this, m, n); + } // End of Else found a nested loop + if( !has_loop(m) ) // If 'm' does not already have a loop set + set_loop(m, l); // Set loop header to loop now + + } else { // Else not a nested loop + if( !_nodes[m->_idx] ) continue; // Dead code has no loop + l = get_loop(m); // Get previously determined loop + // If successor is header of a loop (nest), move up-loop till it + // is a member of some outer enclosing loop. Since there are no + // shared headers (I've split them already) I only need to go up + // at most 1 level. + while( l && l->_head == m ) // Successor heads loop? + l = l->_parent; // Move up 1 for me + // If this loop is not properly parented, then this loop + // has no exit path out, i.e. its an infinite loop. + if( !l ) { + // Make loop "reachable" from root so the CFG is reachable. Basically + // insert a bogus loop exit that is never taken. 'm', the loop head, + // points to 'n', one (of possibly many) fall-in paths. There may be + // many backedges as well. + + // Here I set the loop to be the root loop. I could have, after + // inserting a bogus loop exit, restarted the recursion and found my + // new loop exit. This would make the infinite loop a first-class + // loop and it would then get properly optimized. What's the use of + // optimizing an infinite loop? + l = _ltree_root; // Oops, found infinite loop + + // Insert the NeverBranch between 'm' and it's control user. + NeverBranchNode *iff = new (C, 1) NeverBranchNode( m ); + _igvn.register_new_node_with_optimizer(iff); + set_loop(iff, l); + Node *if_t = new (C, 1) CProjNode( iff, 0 ); + _igvn.register_new_node_with_optimizer(if_t); + set_loop(if_t, l); + + Node* cfg = NULL; // Find the One True Control User of m + for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { + Node* x = m->fast_out(j); + if (x->is_CFG() && x != m && x != iff) + { cfg = x; break; } + } + assert(cfg != NULL, "must find the control user of m"); + uint k = 0; // Probably cfg->in(0) + while( cfg->in(k) != m ) k++; // But check incase cfg is a Region + cfg->set_req( k, if_t ); // Now point to NeverBranch + + // Now create the never-taken loop exit + Node *if_f = new (C, 1) CProjNode( iff, 1 ); + _igvn.register_new_node_with_optimizer(if_f); + set_loop(if_f, l); + // Find frame ptr for Halt. Relies on the optimizer + // V-N'ing. Easier and quicker than searching through + // the program structure. + Node *frame = new (C, 1) ParmNode( C->start(), TypeFunc::FramePtr ); + _igvn.register_new_node_with_optimizer(frame); + // Halt & Catch Fire + Node *halt = new (C, TypeFunc::Parms) HaltNode( if_f, frame ); + _igvn.register_new_node_with_optimizer(halt); + set_loop(halt, l); + C->root()->add_req(halt); + set_loop(C->root(), _ltree_root); + } + } + // Weeny check for irreducible. This child was already visited (this + // IS the post-work phase). Is this child's loop header post-visited + // as well? If so, then I found another entry into the loop. + while( is_postvisited(l->_head) ) { + // found irreducible + l->_irreducible = true; + l = l->_parent; + _has_irreducible_loops = true; + // Check for bad CFG here to prevent crash, and bailout of compile + if (l == NULL) { + C->record_method_not_compilable("unhandled CFG detected during loop optimization"); + return pre_order; + } + } + + // This Node might be a decision point for loops. It is only if + // it's children belong to several different loops. The sort call + // does a trivial amount of work if there is only 1 child or all + // children belong to the same loop. If however, the children + // belong to different loops, the sort call will properly set the + // _parent pointers to show how the loops nest. + // + // In any case, it returns the tightest enclosing loop. + innermost = sort( l, innermost ); + } + + // Def-use info will have some dead stuff; dead stuff will have no + // loop decided on. + + // Am I a loop header? If so fix up my parent's child and next ptrs. + if( innermost && innermost->_head == n ) { + assert( get_loop(n) == innermost, "" ); + IdealLoopTree *p = innermost->_parent; + IdealLoopTree *l = innermost; + while( p && l->_head == n ) { + l->_next = p->_child; // Put self on parents 'next child' + p->_child = l; // Make self as first child of parent + l = p; // Now walk up the parent chain + p = l->_parent; + } + } else { + // Note that it is possible for a LoopNode to reach here, if the + // backedge has been made unreachable (hence the LoopNode no longer + // denotes a Loop, and will eventually be removed). + + // Record tightest enclosing loop for self. Mark as post-visited. + set_loop(n, innermost); + // Also record has_call flag early on + if( innermost ) { + if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) { + // Do not count uncommon calls + if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) { + Node *iff = n->in(0)->in(0); + if( !iff->is_If() || + (n->in(0)->Opcode() == Op_IfFalse && + (1.0 - iff->as_If()->_prob) >= 0.01) || + (iff->as_If()->_prob >= 0.01) ) + innermost->_has_call = 1; + } + } + } + } + + // Flag as post-visited now + set_postvisited(n); + return pre_order; +} + + +//------------------------------build_loop_early------------------------------- +// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. +// First pass computes the earliest controlling node possible. This is the +// controlling input with the deepest dominating depth. +void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me ) { + while (worklist.size() != 0) { + // Use local variables nstack_top_n & nstack_top_i to cache values + // on nstack's top. + Node *nstack_top_n = worklist.pop(); + uint nstack_top_i = 0; +//while_nstack_nonempty: + while (true) { + // Get parent node and next input's index from stack's top. + Node *n = nstack_top_n; + uint i = nstack_top_i; + uint cnt = n->req(); // Count of inputs + if (i == 0) { // Pre-process the node. + if( has_node(n) && // Have either loop or control already? + !has_ctrl(n) ) { // Have loop picked out already? + // During "merge_many_backedges" we fold up several nested loops + // into a single loop. This makes the members of the original + // loop bodies pointing to dead loops; they need to move up + // to the new UNION'd larger loop. I set the _head field of these + // dead loops to NULL and the _parent field points to the owning + // loop. Shades of UNION-FIND algorithm. + IdealLoopTree *ilt; + while( !(ilt = get_loop(n))->_head ) { + // Normally I would use a set_loop here. But in this one special + // case, it is legal (and expected) to change what loop a Node + // belongs to. + _nodes.map(n->_idx, (Node*)(ilt->_parent) ); + } + // Remove safepoints ONLY if I've already seen I don't need one. + // (the old code here would yank a 2nd safepoint after seeing a + // first one, even though the 1st did not dominate in the loop body + // and thus could be avoided indefinitely) + if( !verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint && + is_deleteable_safept(n)) { + Node *in = n->in(TypeFunc::Control); + lazy_replace(n,in); // Pull safepoint now + // Carry on with the recursion "as if" we are walking + // only the control input + if( !visited.test_set( in->_idx ) ) { + worklist.push(in); // Visit this guy later, using worklist + } + // Get next node from nstack: + // - skip n's inputs processing by setting i > cnt; + // - we also will not call set_early_ctrl(n) since + // has_node(n) == true (see the condition above). + i = cnt + 1; + } + } + } // if (i == 0) + + // Visit all inputs + bool done = true; // Assume all n's inputs will be processed + while (i < cnt) { + Node *in = n->in(i); + ++i; + if (in == NULL) continue; + if (in->pinned() && !in->is_CFG()) + set_ctrl(in, in->in(0)); + int is_visited = visited.test_set( in->_idx ); + if (!has_node(in)) { // No controlling input yet? + assert( !in->is_CFG(), "CFG Node with no controlling input?" ); + assert( !is_visited, "visit only once" ); + nstack.push(n, i); // Save parent node and next input's index. + nstack_top_n = in; // Process current input now. + nstack_top_i = 0; + done = false; // Not all n's inputs processed. + break; // continue while_nstack_nonempty; + } else if (!is_visited) { + // This guy has a location picked out for him, but has not yet + // been visited. Happens to all CFG nodes, for instance. + // Visit him using the worklist instead of recursion, to break + // cycles. Since he has a location already we do not need to + // find his location before proceeding with the current Node. + worklist.push(in); // Visit this guy later, using worklist + } + } + if (done) { + // All of n's inputs have been processed, complete post-processing. + + // Compute earilest point this Node can go. + // CFG, Phi, pinned nodes already know their controlling input. + if (!has_node(n)) { + // Record earliest legal location + set_early_ctrl( n ); + } + if (nstack.is_empty()) { + // Finished all nodes on stack. + // Process next node on the worklist. + break; + } + // Get saved parent node and next input's index. + nstack_top_n = nstack.node(); + nstack_top_i = nstack.index(); + nstack.pop(); + } + } // while (true) + } +} + +//------------------------------dom_lca_internal-------------------------------- +// Pair-wise LCA +Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const { + if( !n1 ) return n2; // Handle NULL original LCA + assert( n1->is_CFG(), "" ); + assert( n2->is_CFG(), "" ); + // find LCA of all uses + uint d1 = dom_depth(n1); + uint d2 = dom_depth(n2); + while (n1 != n2) { + if (d1 > d2) { + n1 = idom(n1); + d1 = dom_depth(n1); + } else if (d1 < d2) { + n2 = idom(n2); + d2 = dom_depth(n2); + } else { + // Here d1 == d2. Due to edits of the dominator-tree, sections + // of the tree might have the same depth. These sections have + // to be searched more carefully. + + // Scan up all the n1's with equal depth, looking for n2. + Node *t1 = idom(n1); + while (dom_depth(t1) == d1) { + if (t1 == n2) return n2; + t1 = idom(t1); + } + // Scan up all the n2's with equal depth, looking for n1. + Node *t2 = idom(n2); + while (dom_depth(t2) == d2) { + if (t2 == n1) return n1; + t2 = idom(t2); + } + // Move up to a new dominator-depth value as well as up the dom-tree. + n1 = t1; + n2 = t2; + d1 = dom_depth(n1); + d2 = dom_depth(n2); + } + } + return n1; +} + +//------------------------------compute_idom----------------------------------- +// Locally compute IDOM using dom_lca call. Correct only if the incoming +// IDOMs are correct. +Node *PhaseIdealLoop::compute_idom( Node *region ) const { + assert( region->is_Region(), "" ); + Node *LCA = NULL; + for( uint i = 1; i < region->req(); i++ ) { + if( region->in(i) != C->top() ) + LCA = dom_lca( LCA, region->in(i) ); + } + return LCA; +} + +//------------------------------get_late_ctrl---------------------------------- +// Compute latest legal control. +Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) { + assert(early != NULL, "early control should not be NULL"); + + // Compute LCA over list of uses + Node *LCA = NULL; + for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) { + Node* c = n->fast_out(i); + if (_nodes[c->_idx] == NULL) + continue; // Skip the occasional dead node + if( c->is_Phi() ) { // For Phis, we must land above on the path + for( uint j=1; j<c->req(); j++ ) {// For all inputs + if( c->in(j) == n ) { // Found matching input? + Node *use = c->in(0)->in(j); + LCA = dom_lca_for_get_late_ctrl( LCA, use, n ); + } + } + } else { + // For CFG data-users, use is in the block just prior + Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0); + LCA = dom_lca_for_get_late_ctrl( LCA, use, n ); + } + } + + // if this is a load, check for anti-dependent stores + // We use a conservative algorithm to identify potential interfering + // instructions and for rescheduling the load. The users of the memory + // input of this load are examined. Any use which is not a load and is + // dominated by early is considered a potentially interfering store. + // This can produce false positives. + if (n->is_Load() && LCA != early) { + Node_List worklist; + + Node *mem = n->in(MemNode::Memory); + for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { + Node* s = mem->fast_out(i); + worklist.push(s); + } + while(worklist.size() != 0 && LCA != early) { + Node* s = worklist.pop(); + if (s->is_Load()) { + continue; + } else if (s->is_MergeMem()) { + for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) { + Node* s1 = s->fast_out(i); + worklist.push(s1); + } + } else { + Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0); + assert(sctrl != NULL || s->outcnt() == 0, "must have control"); + if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) { + LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n); + } + } + } + } + + assert(LCA == find_non_split_ctrl(LCA), "unexpected late control"); + return LCA; +} + +// true if CFG node d dominates CFG node n +bool PhaseIdealLoop::is_dominator(Node *d, Node *n) { + if (d == n) + return true; + assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes"); + uint dd = dom_depth(d); + while (dom_depth(n) >= dd) { + if (n == d) + return true; + n = idom(n); + } + return false; +} + +//------------------------------dom_lca_for_get_late_ctrl_internal------------- +// Pair-wise LCA with tags. +// Tag each index with the node 'tag' currently being processed +// before advancing up the dominator chain using idom(). +// Later calls that find a match to 'tag' know that this path has already +// been considered in the current LCA (which is input 'n1' by convention). +// Since get_late_ctrl() is only called once for each node, the tag array +// does not need to be cleared between calls to get_late_ctrl(). +// Algorithm trades a larger constant factor for better asymptotic behavior +// +Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) { + uint d1 = dom_depth(n1); + uint d2 = dom_depth(n2); + + do { + if (d1 > d2) { + // current lca is deeper than n2 + _dom_lca_tags.map(n1->_idx, tag); + n1 = idom(n1); + d1 = dom_depth(n1); + } else if (d1 < d2) { + // n2 is deeper than current lca + Node *memo = _dom_lca_tags[n2->_idx]; + if( memo == tag ) { + return n1; // Return the current LCA + } + _dom_lca_tags.map(n2->_idx, tag); + n2 = idom(n2); + d2 = dom_depth(n2); + } else { + // Here d1 == d2. Due to edits of the dominator-tree, sections + // of the tree might have the same depth. These sections have + // to be searched more carefully. + + // Scan up all the n1's with equal depth, looking for n2. + _dom_lca_tags.map(n1->_idx, tag); + Node *t1 = idom(n1); + while (dom_depth(t1) == d1) { + if (t1 == n2) return n2; + _dom_lca_tags.map(t1->_idx, tag); + t1 = idom(t1); + } + // Scan up all the n2's with equal depth, looking for n1. + _dom_lca_tags.map(n2->_idx, tag); + Node *t2 = idom(n2); + while (dom_depth(t2) == d2) { + if (t2 == n1) return n1; + _dom_lca_tags.map(t2->_idx, tag); + t2 = idom(t2); + } + // Move up to a new dominator-depth value as well as up the dom-tree. + n1 = t1; + n2 = t2; + d1 = dom_depth(n1); + d2 = dom_depth(n2); + } + } while (n1 != n2); + return n1; +} + +//------------------------------init_dom_lca_tags------------------------------ +// Tag could be a node's integer index, 32bits instead of 64bits in some cases +// Intended use does not involve any growth for the array, so it could +// be of fixed size. +void PhaseIdealLoop::init_dom_lca_tags() { + uint limit = C->unique() + 1; + _dom_lca_tags.map( limit, NULL ); +#ifdef ASSERT + for( uint i = 0; i < limit; ++i ) { + assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer"); + } +#endif // ASSERT +} + +//------------------------------clear_dom_lca_tags------------------------------ +// Tag could be a node's integer index, 32bits instead of 64bits in some cases +// Intended use does not involve any growth for the array, so it could +// be of fixed size. +void PhaseIdealLoop::clear_dom_lca_tags() { + uint limit = C->unique() + 1; + _dom_lca_tags.map( limit, NULL ); + _dom_lca_tags.clear(); +#ifdef ASSERT + for( uint i = 0; i < limit; ++i ) { + assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer"); + } +#endif // ASSERT +} + +//------------------------------build_loop_late-------------------------------- +// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. +// Second pass finds latest legal placement, and ideal loop placement. +void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me ) { + while (worklist.size() != 0) { + Node *n = worklist.pop(); + // Only visit once + if (visited.test_set(n->_idx)) continue; + uint cnt = n->outcnt(); + uint i = 0; + while (true) { + assert( _nodes[n->_idx], "no dead nodes" ); + // Visit all children + if (i < cnt) { + Node* use = n->raw_out(i); + ++i; + // Check for dead uses. Aggressively prune such junk. It might be + // dead in the global sense, but still have local uses so I cannot + // easily call 'remove_dead_node'. + if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead? + // Due to cycles, we might not hit the same fixed point in the verify + // pass as we do in the regular pass. Instead, visit such phis as + // simple uses of the loop head. + if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) { + if( !visited.test(use->_idx) ) + worklist.push(use); + } else if( !visited.test_set(use->_idx) ) { + nstack.push(n, i); // Save parent and next use's index. + n = use; // Process all children of current use. + cnt = use->outcnt(); + i = 0; + } + } else { + // Do not visit around the backedge of loops via data edges. + // push dead code onto a worklist + _deadlist.push(use); + } + } else { + // All of n's children have been processed, complete post-processing. + build_loop_late_post(n, verify_me); + if (nstack.is_empty()) { + // Finished all nodes on stack. + // Process next node on the worklist. + break; + } + // Get saved parent node and next use's index. Visit the rest of uses. + n = nstack.node(); + cnt = n->outcnt(); + i = nstack.index(); + nstack.pop(); + } + } + } +} + +//------------------------------build_loop_late_post--------------------------- +// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. +// Second pass finds latest legal placement, and ideal loop placement. +void PhaseIdealLoop::build_loop_late_post( Node *n, const PhaseIdealLoop *verify_me ) { + + if (n->req() == 2 && n->Opcode() == Op_ConvI2L && !C->major_progress()) { + _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops. + } + + // CFG and pinned nodes already handled + if( n->in(0) ) { + if( n->in(0)->is_top() ) return; // Dead? + + // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads + // _must_ be pinned (they have to observe their control edge of course). + // Unlike Stores (which modify an unallocable resource, the memory + // state), Mods/Loads can float around. So free them up. + bool pinned = true; + switch( n->Opcode() ) { + case Op_DivI: + case Op_DivF: + case Op_DivD: + case Op_ModI: + case Op_ModF: + case Op_ModD: + case Op_LoadB: // Same with Loads; they can sink + case Op_LoadC: // during loop optimizations. + case Op_LoadD: + case Op_LoadF: + case Op_LoadI: + case Op_LoadKlass: + case Op_LoadL: + case Op_LoadS: + case Op_LoadP: + case Op_LoadRange: + case Op_LoadD_unaligned: + case Op_LoadL_unaligned: + case Op_StrComp: // Does a bunch of load-like effects + pinned = false; + } + if( pinned ) { + IdealLoopTree *choosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n)); + if( !choosen_loop->_child ) // Inner loop? + choosen_loop->_body.push(n); // Collect inner loops + return; + } + } else { // No slot zero + if( n->is_CFG() ) { // CFG with no slot 0 is dead + _nodes.map(n->_idx,0); // No block setting, it's globally dead + return; + } + assert(!n->is_CFG() || n->outcnt() == 0, ""); + } + + // Do I have a "safe range" I can select over? + Node *early = get_ctrl(n);// Early location already computed + + // Compute latest point this Node can go + Node *LCA = get_late_ctrl( n, early ); + // LCA is NULL due to uses being dead + if( LCA == NULL ) { +#ifdef ASSERT + for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) { + assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead"); + } +#endif + _nodes.map(n->_idx, 0); // This node is useless + _deadlist.push(n); + return; + } + assert(LCA != NULL && !LCA->is_top(), "no dead nodes"); + + Node *legal = LCA; // Walk 'legal' up the IDOM chain + Node *least = legal; // Best legal position so far + while( early != legal ) { // While not at earliest legal + // Find least loop nesting depth + legal = idom(legal); // Bump up the IDOM tree + // Check for lower nesting depth + if( get_loop(legal)->_nest < get_loop(least)->_nest ) + least = legal; + } + + // Try not to place code on a loop entry projection + // which can inhibit range check elimination. + if (least != early) { + Node* ctrl_out = least->unique_ctrl_out(); + if (ctrl_out && ctrl_out->is_CountedLoop() && + least == ctrl_out->in(LoopNode::EntryControl)) { + Node* least_dom = idom(least); + if (get_loop(least_dom)->is_member(get_loop(least))) { + least = least_dom; + } + } + } + +#ifdef ASSERT + // If verifying, verify that 'verify_me' has a legal location + // and choose it as our location. + if( verify_me ) { + Node *v_ctrl = verify_me->get_ctrl_no_update(n); + Node *legal = LCA; + while( early != legal ) { // While not at earliest legal + if( legal == v_ctrl ) break; // Check for prior good location + legal = idom(legal) ;// Bump up the IDOM tree + } + // Check for prior good location + if( legal == v_ctrl ) least = legal; // Keep prior if found + } +#endif + + // Assign discovered "here or above" point + least = find_non_split_ctrl(least); + set_ctrl(n, least); + + // Collect inner loop bodies + IdealLoopTree *choosen_loop = get_loop(least); + if( !choosen_loop->_child ) // Inner loop? + choosen_loop->_body.push(n);// Collect inner loops +} + +#ifndef PRODUCT +//------------------------------dump------------------------------------------- +void PhaseIdealLoop::dump( ) const { + ResourceMark rm; + Arena* arena = Thread::current()->resource_area(); + Node_Stack stack(arena, C->unique() >> 2); + Node_List rpo_list; + VectorSet visited(arena); + visited.set(C->top()->_idx); + rpo( C->root(), stack, visited, rpo_list ); + // Dump root loop indexed by last element in PO order + dump( _ltree_root, rpo_list.size(), rpo_list ); +} + +void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const { + + // Indent by loop nesting depth + for( uint x = 0; x < loop->_nest; x++ ) + tty->print(" "); + tty->print_cr("---- Loop N%d-N%d ----", loop->_head->_idx,loop->_tail->_idx); + + // Now scan for CFG nodes in the same loop + for( uint j=idx; j > 0; j-- ) { + Node *n = rpo_list[j-1]; + if( !_nodes[n->_idx] ) // Skip dead nodes + continue; + if( get_loop(n) != loop ) { // Wrong loop nest + if( get_loop(n)->_head == n && // Found nested loop? + get_loop(n)->_parent == loop ) + dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly + continue; + } + + // Dump controlling node + for( uint x = 0; x < loop->_nest; x++ ) + tty->print(" "); + tty->print("C"); + if( n == C->root() ) { + n->dump(); + } else { + Node* cached_idom = idom_no_update(n); + Node *computed_idom = n->in(0); + if( n->is_Region() ) { + computed_idom = compute_idom(n); + // computed_idom() will return n->in(0) when idom(n) is an IfNode (or + // any MultiBranch ctrl node), so apply a similar transform to + // the cached idom returned from idom_no_update. + cached_idom = find_non_split_ctrl(cached_idom); + } + tty->print(" ID:%d",computed_idom->_idx); + n->dump(); + if( cached_idom != computed_idom ) { + tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d", + computed_idom->_idx, cached_idom->_idx); + } + } + // Dump nodes it controls + for( uint k = 0; k < _nodes.Size(); k++ ) { + // (k < C->unique() && get_ctrl(find(k)) == n) + if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) { + Node *m = C->root()->find(k); + if( m && m->outcnt() > 0 ) { + if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) { + tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p", + _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL); + } + for( uint j = 0; j < loop->_nest; j++ ) + tty->print(" "); + tty->print(" "); + m->dump(); + } + } + } + } +} + +// Collect a R-P-O for the whole CFG. +// Result list is in post-order (scan backwards for RPO) +void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const { + stk.push(start, 0); + visited.set(start->_idx); + + while (stk.is_nonempty()) { + Node* m = stk.node(); + uint idx = stk.index(); + if (idx < m->outcnt()) { + stk.set_index(idx + 1); + Node* n = m->raw_out(idx); + if (n->is_CFG() && !visited.test_set(n->_idx)) { + stk.push(n, 0); + } + } else { + rpo_list.push(m); + stk.pop(); + } + } +} +#endif + + +//============================================================================= +//------------------------------LoopTreeIterator----------------------------------- + +// Advance to next loop tree using a preorder, left-to-right traversal. +void LoopTreeIterator::next() { + assert(!done(), "must not be done."); + if (_curnt->_child != NULL) { + _curnt = _curnt->_child; + } else if (_curnt->_next != NULL) { + _curnt = _curnt->_next; + } else { + while (_curnt != _root && _curnt->_next == NULL) { + _curnt = _curnt->_parent; + } + if (_curnt == _root) { + _curnt = NULL; + assert(done(), "must be done."); + } else { + assert(_curnt->_next != NULL, "must be more to do"); + _curnt = _curnt->_next; + } + } +}