/* * Copyright (c) 2011, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "opto/loopnode.hpp" #include "opto/addnode.hpp" #include "opto/callnode.hpp" #include "opto/connode.hpp" #include "opto/loopnode.hpp" #include "opto/matcher.hpp" #include "opto/mulnode.hpp" #include "opto/rootnode.hpp" #include "opto/subnode.hpp" /* * The general idea of Loop Predication is to insert a predicate on the entry * path to a loop, and raise a uncommon trap if the check of the condition fails. * The condition checks are promoted from inside the loop body, and thus * the checks inside the loop could be eliminated. Currently, loop predication * optimization has been applied to remove array range check and loop invariant * checks (such as null checks). */ //-------------------------------register_control------------------------- void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) { assert(n->is_CFG(), "must be control node"); _igvn.register_new_node_with_optimizer(n); loop->_body.push(n); set_loop(n, loop); // When called from beautify_loops() idom is not constructed yet. if (_idom != NULL) { set_idom(n, pred, dom_depth(pred)); } } //------------------------------create_new_if_for_predicate------------------------ // create a new if above the uct_if_pattern for the predicate to be promoted. // // before after // ---------- ---------- // ctrl ctrl // | | // | | // v v // iff new_iff // / \ / \ // / \ / \ // v v v v // uncommon_proj cont_proj if_uct if_cont // \ | | | | // \ | | | | // v v v | v // rgn loop | iff // | | / \ // | | / \ // v | v v // uncommon_trap | uncommon_proj cont_proj // \ \ | | // \ \ | | // v v v v // rgn loop // | // | // v // uncommon_trap // // // We will create a region to guard the uct call if there is no one there. // The true projecttion (if_cont) of the new_iff is returned. // This code is also used to clone predicates to clonned loops. ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, Deoptimization::DeoptReason reason) { assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!"); IfNode* iff = cont_proj->in(0)->as_If(); ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con); Node *rgn = uncommon_proj->unique_ctrl_out(); assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); uint proj_index = 1; // region's edge corresponding to uncommon_proj if (!rgn->is_Region()) { // create a region to guard the call assert(rgn->is_Call(), "must be call uct"); CallNode* call = rgn->as_Call(); IdealLoopTree* loop = get_loop(call); rgn = new (C) RegionNode(1); rgn->add_req(uncommon_proj); register_control(rgn, loop, uncommon_proj); _igvn.hash_delete(call); call->set_req(0, rgn); // When called from beautify_loops() idom is not constructed yet. if (_idom != NULL) { set_idom(call, rgn, dom_depth(rgn)); } } else { // Find region's edge corresponding to uncommon_proj for (; proj_index < rgn->req(); proj_index++) if (rgn->in(proj_index) == uncommon_proj) break; assert(proj_index < rgn->req(), "sanity"); } Node* entry = iff->in(0); if (new_entry != NULL) { // Clonning the predicate to new location. entry = new_entry; } // Create new_iff IdealLoopTree* lp = get_loop(entry); IfNode *new_iff = iff->clone()->as_If(); new_iff->set_req(0, entry); register_control(new_iff, lp, entry); Node *if_cont = new (C) IfTrueNode(new_iff); Node *if_uct = new (C) IfFalseNode(new_iff); if (cont_proj->is_IfFalse()) { // Swap Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp; } register_control(if_cont, lp, new_iff); register_control(if_uct, get_loop(rgn), new_iff); // if_uct to rgn _igvn.hash_delete(rgn); rgn->add_req(if_uct); // When called from beautify_loops() idom is not constructed yet. if (_idom != NULL) { Node* ridom = idom(rgn); Node* nrdom = dom_lca(ridom, new_iff); set_idom(rgn, nrdom, dom_depth(rgn)); } // If rgn has phis add new edges which has the same // value as on original uncommon_proj pass. assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last"); bool has_phi = false; for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) { Node* use = rgn->fast_out(i); if (use->is_Phi() && use->outcnt() > 0) { assert(use->in(0) == rgn, ""); _igvn.rehash_node_delayed(use); use->add_req(use->in(proj_index)); has_phi = true; } } assert(!has_phi || rgn->req() > 3, "no phis when region is created"); if (new_entry == NULL) { // Attach if_cont to iff _igvn.hash_delete(iff); iff->set_req(0, if_cont); if (_idom != NULL) { set_idom(iff, if_cont, dom_depth(iff)); } } return if_cont->as_Proj(); } //------------------------------create_new_if_for_predicate------------------------ // Create a new if below new_entry for the predicate to be cloned (IGVN optimization) ProjNode* PhaseIterGVN::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, Deoptimization::DeoptReason reason) { assert(new_entry != 0, "only used for clone predicate"); assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!"); IfNode* iff = cont_proj->in(0)->as_If(); ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con); Node *rgn = uncommon_proj->unique_ctrl_out(); assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); uint proj_index = 1; // region's edge corresponding to uncommon_proj if (!rgn->is_Region()) { // create a region to guard the call assert(rgn->is_Call(), "must be call uct"); CallNode* call = rgn->as_Call(); rgn = new (C) RegionNode(1); register_new_node_with_optimizer(rgn); rgn->add_req(uncommon_proj); hash_delete(call); call->set_req(0, rgn); } else { // Find region's edge corresponding to uncommon_proj for (; proj_index < rgn->req(); proj_index++) if (rgn->in(proj_index) == uncommon_proj) break; assert(proj_index < rgn->req(), "sanity"); } // Create new_iff in new location. IfNode *new_iff = iff->clone()->as_If(); new_iff->set_req(0, new_entry); register_new_node_with_optimizer(new_iff); Node *if_cont = new (C) IfTrueNode(new_iff); Node *if_uct = new (C) IfFalseNode(new_iff); if (cont_proj->is_IfFalse()) { // Swap Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp; } register_new_node_with_optimizer(if_cont); register_new_node_with_optimizer(if_uct); // if_uct to rgn hash_delete(rgn); rgn->add_req(if_uct); // If rgn has phis add corresponding new edges which has the same // value as on original uncommon_proj pass. assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last"); bool has_phi = false; for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) { Node* use = rgn->fast_out(i); if (use->is_Phi() && use->outcnt() > 0) { rehash_node_delayed(use); use->add_req(use->in(proj_index)); has_phi = true; } } assert(!has_phi || rgn->req() > 3, "no phis when region is created"); return if_cont->as_Proj(); } //--------------------------clone_predicate----------------------- ProjNode* PhaseIdealLoop::clone_predicate(ProjNode* predicate_proj, Node* new_entry, Deoptimization::DeoptReason reason, PhaseIdealLoop* loop_phase, PhaseIterGVN* igvn) { ProjNode* new_predicate_proj; if (loop_phase != NULL) { new_predicate_proj = loop_phase->create_new_if_for_predicate(predicate_proj, new_entry, reason); } else { new_predicate_proj = igvn->create_new_if_for_predicate(predicate_proj, new_entry, reason); } IfNode* iff = new_predicate_proj->in(0)->as_If(); Node* ctrl = iff->in(0); // Match original condition since predicate's projections could be swapped. assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); Node* opq = new (igvn->C) Opaque1Node(igvn->C, predicate_proj->in(0)->in(1)->in(1)->in(1)); igvn->C->add_predicate_opaq(opq); Node* bol = new (igvn->C) Conv2BNode(opq); if (loop_phase != NULL) { loop_phase->register_new_node(opq, ctrl); loop_phase->register_new_node(bol, ctrl); } else { igvn->register_new_node_with_optimizer(opq); igvn->register_new_node_with_optimizer(bol); } igvn->hash_delete(iff); iff->set_req(1, bol); return new_predicate_proj; } //--------------------------clone_loop_predicates----------------------- // Interface from IGVN Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, clone_limit_check, NULL, this); } // Interface from PhaseIdealLoop Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { return clone_loop_predicates(old_entry, new_entry, clone_limit_check, this, &this->_igvn); } // Clone loop predicates to cloned loops (peeled, unswitched, split_if). Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check, PhaseIdealLoop* loop_phase, PhaseIterGVN* igvn) { #ifdef ASSERT if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) { if (new_entry != NULL) new_entry->dump(); assert(false, "not IfTrue, IfFalse, Region or SafePoint"); } #endif // Search original predicates Node* entry = old_entry; ProjNode* limit_check_proj = NULL; if (LoopLimitCheck) { limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); if (limit_check_proj != NULL) { entry = entry->in(0)->in(0); } } if (UseLoopPredicate) { ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (predicate_proj != NULL) { // right pattern that can be used by loop predication // clone predicate new_entry = clone_predicate(predicate_proj, new_entry, Deoptimization::Reason_predicate, loop_phase, igvn); assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate"); if (TraceLoopPredicate) { tty->print("Loop Predicate cloned: "); debug_only( new_entry->in(0)->dump(); ) } } } if (limit_check_proj != NULL && clone_limit_check) { // Clone loop limit check last to insert it before loop. // Don't clone a limit check which was already finalized // for this counted loop (only one limit check is needed). new_entry = clone_predicate(limit_check_proj, new_entry, Deoptimization::Reason_loop_limit_check, loop_phase, igvn); assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check"); if (TraceLoopLimitCheck) { tty->print("Loop Limit Check cloned: "); debug_only( new_entry->in(0)->dump(); ) } } return new_entry; } //--------------------------skip_loop_predicates------------------------------ // Skip related predicates. Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) { Node* predicate = NULL; if (LoopLimitCheck) { predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); if (predicate != NULL) { entry = entry->in(0)->in(0); } } if (UseLoopPredicate) { predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (predicate != NULL) { // right pattern that can be used by loop predication IfNode* iff = entry->in(0)->as_If(); ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con); Node* rgn = uncommon_proj->unique_ctrl_out(); assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); entry = entry->in(0)->in(0); while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) { uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con); if (uncommon_proj->unique_ctrl_out() != rgn) break; entry = entry->in(0)->in(0); } } } return entry; } //--------------------------find_predicate_insertion_point------------------- // Find a good location to insert a predicate ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) { if (start_c == NULL || !start_c->is_Proj()) return NULL; if (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) { return start_c->as_Proj(); } return NULL; } //--------------------------find_predicate------------------------------------ // Find a predicate Node* PhaseIdealLoop::find_predicate(Node* entry) { Node* predicate = NULL; if (LoopLimitCheck) { predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); if (predicate != NULL) { // right pattern that can be used by loop predication return entry; } } if (UseLoopPredicate) { predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (predicate != NULL) { // right pattern that can be used by loop predication return entry; } } return NULL; } //------------------------------Invariance----------------------------------- // Helper class for loop_predication_impl to compute invariance on the fly and // clone invariants. class Invariance : public StackObj { VectorSet _visited, _invariant; Node_Stack _stack; VectorSet _clone_visited; Node_List _old_new; // map of old to new (clone) IdealLoopTree* _lpt; PhaseIdealLoop* _phase; // Helper function to set up the invariance for invariance computation // If n is a known invariant, set up directly. Otherwise, look up the // the possibility to push n onto the stack for further processing. void visit(Node* use, Node* n) { if (_lpt->is_invariant(n)) { // known invariant _invariant.set(n->_idx); } else if (!n->is_CFG()) { Node *n_ctrl = _phase->ctrl_or_self(n); Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG if (_phase->is_dominator(n_ctrl, u_ctrl)) { _stack.push(n, n->in(0) == NULL ? 1 : 0); } } } // Compute invariance for "the_node" and (possibly) all its inputs recursively // on the fly void compute_invariance(Node* n) { assert(_visited.test(n->_idx), "must be"); visit(n, n); while (_stack.is_nonempty()) { Node* n = _stack.node(); uint idx = _stack.index(); if (idx == n->req()) { // all inputs are processed _stack.pop(); // n is invariant if it's inputs are all invariant bool all_inputs_invariant = true; for (uint i = 0; i < n->req(); i++) { Node* in = n->in(i); if (in == NULL) continue; assert(_visited.test(in->_idx), "must have visited input"); if (!_invariant.test(in->_idx)) { // bad guy all_inputs_invariant = false; break; } } if (all_inputs_invariant) { // If n's control is a predicate that was moved out of the // loop, it was marked invariant but n is only invariant if // it depends only on that test. Otherwise, unless that test // is out of the loop, it's not invariant. if (n->is_CFG() || n->depends_only_on_test() || n->in(0) == NULL || !_phase->is_member(_lpt, n->in(0))) { _invariant.set(n->_idx); // I am a invariant too } } } else { // process next input _stack.set_index(idx + 1); Node* m = n->in(idx); if (m != NULL && !_visited.test_set(m->_idx)) { visit(n, m); } } } } // Helper function to set up _old_new map for clone_nodes. // If n is a known invariant, set up directly ("clone" of n == n). // Otherwise, push n onto the stack for real cloning. void clone_visit(Node* n) { assert(_invariant.test(n->_idx), "must be invariant"); if (_lpt->is_invariant(n)) { // known invariant _old_new.map(n->_idx, n); } else { // to be cloned assert(!n->is_CFG(), "should not see CFG here"); _stack.push(n, n->in(0) == NULL ? 1 : 0); } } // Clone "n" and (possibly) all its inputs recursively void clone_nodes(Node* n, Node* ctrl) { clone_visit(n); while (_stack.is_nonempty()) { Node* n = _stack.node(); uint idx = _stack.index(); if (idx == n->req()) { // all inputs processed, clone n! _stack.pop(); // clone invariant node Node* n_cl = n->clone(); _old_new.map(n->_idx, n_cl); _phase->register_new_node(n_cl, ctrl); for (uint i = 0; i < n->req(); i++) { Node* in = n_cl->in(i); if (in == NULL) continue; n_cl->set_req(i, _old_new[in->_idx]); } } else { // process next input _stack.set_index(idx + 1); Node* m = n->in(idx); if (m != NULL && !_clone_visited.test_set(m->_idx)) { clone_visit(m); // visit the input } } } } public: Invariance(Arena* area, IdealLoopTree* lpt) : _lpt(lpt), _phase(lpt->_phase), _visited(area), _invariant(area), _stack(area, 10 /* guess */), _clone_visited(area), _old_new(area) { Node* head = _lpt->_head; Node* entry = head->in(LoopNode::EntryControl); if (entry->outcnt() != 1) { // If a node is pinned between the predicates and the loop // entry, we won't be able to move any node in the loop that // depends on it above it in a predicate. Mark all those nodes // as non loop invariatnt. Unique_Node_List wq; wq.push(entry); for (uint next = 0; next < wq.size(); ++next) { Node *n = wq.at(next); for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { Node* u = n->fast_out(i); if (!u->is_CFG()) { Node* c = _phase->get_ctrl(u); if (_lpt->is_member(_phase->get_loop(c)) || _phase->is_dominator(c, head)) { _visited.set(u->_idx); wq.push(u); } } } } } } // Map old to n for invariance computation and clone void map_ctrl(Node* old, Node* n) { assert(old->is_CFG() && n->is_CFG(), "must be"); _old_new.map(old->_idx, n); // "clone" of old is n _invariant.set(old->_idx); // old is invariant _clone_visited.set(old->_idx); } // Driver function to compute invariance bool is_invariant(Node* n) { if (!_visited.test_set(n->_idx)) compute_invariance(n); return (_invariant.test(n->_idx) != 0); } // Driver function to clone invariant Node* clone(Node* n, Node* ctrl) { assert(ctrl->is_CFG(), "must be"); assert(_invariant.test(n->_idx), "must be an invariant"); if (!_clone_visited.test(n->_idx)) clone_nodes(n, ctrl); return _old_new[n->_idx]; } }; //------------------------------is_range_check_if ----------------------------------- // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format // Note: this function is particularly designed for loop predication. We require load_range // and offset to be loop invariant computed on the fly by "invar" bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const { if (!is_loop_exit(iff)) { return false; } if (!iff->in(1)->is_Bool()) { return false; } const BoolNode *bol = iff->in(1)->as_Bool(); if (bol->_test._test != BoolTest::lt) { return false; } if (!bol->in(1)->is_Cmp()) { return false; } const CmpNode *cmp = bol->in(1)->as_Cmp(); if (cmp->Opcode() != Op_CmpU) { return false; } Node* range = cmp->in(2); if (range->Opcode() != Op_LoadRange) { const TypeInt* tint = phase->_igvn.type(range)->isa_int(); if (tint == NULL || tint->empty() || tint->_lo < 0) { // Allow predication on positive values that aren't LoadRanges. // This allows optimization of loops where the length of the // array is a known value and doesn't need to be loaded back // from the array. return false; } } if (!invar.is_invariant(range)) { return false; } Node *iv = _head->as_CountedLoop()->phi(); int scale = 0; Node *offset = NULL; if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) { return false; } if (offset && !invar.is_invariant(offset)) { // offset must be invariant return false; } return true; } //------------------------------rc_predicate----------------------------------- // Create a range check predicate // // for (i = init; i < limit; i += stride) { // a[scale*i+offset] // } // // Compute max(scale*i + offset) for init <= i < limit and build the predicate // as "max(scale*i + offset) u< a.length". // // There are two cases for max(scale*i + offset): // (1) stride*scale > 0 // max(scale*i + offset) = scale*(limit-stride) + offset // (2) stride*scale < 0 // max(scale*i + offset) = scale*init + offset BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl, int scale, Node* offset, Node* init, Node* limit, jint stride, Node* range, bool upper, bool &overflow) { jint con_limit = limit->is_Con() ? limit->get_int() : 0; jint con_init = init->is_Con() ? init->get_int() : 0; jint con_offset = offset->is_Con() ? offset->get_int() : 0; stringStream* predString = NULL; if (TraceLoopPredicate) { predString = new stringStream(); predString->print("rc_predicate "); } overflow = false; Node* max_idx_expr = NULL; const TypeInt* idx_type = TypeInt::INT; if ((stride > 0) == (scale > 0) == upper) { if (TraceLoopPredicate) { if (limit->is_Con()) { predString->print("(%d ", con_limit); } else { predString->print("(limit "); } predString->print("- %d) ", stride); } // Check if (limit - stride) may overflow const TypeInt* limit_type = _igvn.type(limit)->isa_int(); jint limit_lo = limit_type->_lo; jint limit_hi = limit_type->_hi; jint res_lo = limit_lo - stride; jint res_hi = limit_hi - stride; if ((stride > 0 && (res_lo < limit_lo)) || (stride < 0 && (res_hi > limit_hi))) { // No overflow possible ConINode* con_stride = _igvn.intcon(stride); set_ctrl(con_stride, C->root()); max_idx_expr = new (C) SubINode(limit, con_stride); idx_type = TypeInt::make(limit_lo - stride, limit_hi - stride, limit_type->_widen); } else { // May overflow overflow = true; limit = new (C) ConvI2LNode(limit); register_new_node(limit, ctrl); ConLNode* con_stride = _igvn.longcon(stride); set_ctrl(con_stride, C->root()); max_idx_expr = new (C) SubLNode(limit, con_stride); } register_new_node(max_idx_expr, ctrl); } else { if (TraceLoopPredicate) { if (init->is_Con()) { predString->print("%d ", con_init); } else { predString->print("init "); } } idx_type = _igvn.type(init)->isa_int(); max_idx_expr = init; } if (scale != 1) { ConNode* con_scale = _igvn.intcon(scale); set_ctrl(con_scale, C->root()); if (TraceLoopPredicate) { predString->print("* %d ", scale); } // Check if (scale * max_idx_expr) may overflow const TypeInt* scale_type = TypeInt::make(scale); MulINode* mul = new (C) MulINode(max_idx_expr, con_scale); idx_type = (TypeInt*)mul->mul_ring(idx_type, scale_type); if (overflow || TypeInt::INT->higher_equal(idx_type)) { // May overflow mul->destruct(); if (!overflow) { max_idx_expr = new (C) ConvI2LNode(max_idx_expr); register_new_node(max_idx_expr, ctrl); } overflow = true; con_scale = _igvn.longcon(scale); set_ctrl(con_scale, C->root()); max_idx_expr = new (C) MulLNode(max_idx_expr, con_scale); } else { // No overflow possible max_idx_expr = mul; } register_new_node(max_idx_expr, ctrl); } if (offset && (!offset->is_Con() || con_offset != 0)){ if (TraceLoopPredicate) { if (offset->is_Con()) { predString->print("+ %d ", con_offset); } else { predString->print("+ offset"); } } // Check if (max_idx_expr + offset) may overflow const TypeInt* offset_type = _igvn.type(offset)->isa_int(); jint lo = idx_type->_lo + offset_type->_lo; jint hi = idx_type->_hi + offset_type->_hi; if (overflow || (lo > hi) || ((idx_type->_lo & offset_type->_lo) < 0 && lo >= 0) || ((~(idx_type->_hi | offset_type->_hi)) < 0 && hi < 0)) { // May overflow if (!overflow) { max_idx_expr = new (C) ConvI2LNode(max_idx_expr); register_new_node(max_idx_expr, ctrl); } overflow = true; offset = new (C) ConvI2LNode(offset); register_new_node(offset, ctrl); max_idx_expr = new (C) AddLNode(max_idx_expr, offset); } else { // No overflow possible max_idx_expr = new (C) AddINode(max_idx_expr, offset); } register_new_node(max_idx_expr, ctrl); } CmpNode* cmp = NULL; if (overflow) { // Integer expressions may overflow, do long comparison range = new (C) ConvI2LNode(range); register_new_node(range, ctrl); if (!Matcher::has_match_rule(Op_CmpUL)) { // We don't support unsigned long comparisons. Set 'max_idx_expr' // to max_julong if < 0 to make the signed comparison fail. ConINode* sign_pos = _igvn.intcon(BitsPerLong - 1); set_ctrl(sign_pos, C->root()); Node* sign_bit_mask = new (C) RShiftLNode(max_idx_expr, sign_pos); register_new_node(sign_bit_mask, ctrl); // OR with sign bit to set all bits to 1 if negative (otherwise no change) max_idx_expr = new (C) OrLNode(max_idx_expr, sign_bit_mask); register_new_node(max_idx_expr, ctrl); // AND with 0x7ff... to unset the sign bit ConLNode* remove_sign_mask = _igvn.longcon(max_jlong); set_ctrl(remove_sign_mask, C->root()); max_idx_expr = new (C) AndLNode(max_idx_expr, remove_sign_mask); register_new_node(max_idx_expr, ctrl); cmp = new (C) CmpLNode(max_idx_expr, range); } else { cmp = new (C) CmpULNode(max_idx_expr, range); } } else { cmp = new (C) CmpUNode(max_idx_expr, range); } register_new_node(cmp, ctrl); BoolNode* bol = new (C) BoolNode(cmp, BoolTest::lt); register_new_node(bol, ctrl); if (TraceLoopPredicate) { predString->print_cr("print("%s", predString->as_string()); } return bol; } //------------------------------ loop_predication_impl-------------------------- // Insert loop predicates for null checks and range checks bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) { if (!UseLoopPredicate) return false; if (!loop->_head->is_Loop()) { // Could be a simple region when irreducible loops are present. return false; } LoopNode* head = loop->_head->as_Loop(); if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) { // do nothing for infinite loops return false; } CountedLoopNode *cl = NULL; if (head->is_valid_counted_loop()) { cl = head->as_CountedLoop(); // do nothing for iteration-splitted loops if (!cl->is_normal_loop()) return false; // Avoid RCE if Counted loop's test is '!='. BoolTest::mask bt = cl->loopexit()->test_trip(); if (bt != BoolTest::lt && bt != BoolTest::gt) cl = NULL; } Node* entry = head->in(LoopNode::EntryControl); ProjNode *predicate_proj = NULL; // Loop limit check predicate should be near the loop. if (LoopLimitCheck) { predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); if (predicate_proj != NULL) entry = predicate_proj->in(0)->in(0); } predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (!predicate_proj) { #ifndef PRODUCT if (TraceLoopPredicate) { tty->print("missing predicate:"); loop->dump_head(); head->dump(1); } #endif return false; } ConNode* zero = _igvn.intcon(0); set_ctrl(zero, C->root()); ResourceArea *area = Thread::current()->resource_area(); Invariance invar(area, loop); // Create list of if-projs such that a newer proj dominates all older // projs in the list, and they all dominate loop->tail() Node_List if_proj_list(area); Node *current_proj = loop->tail(); //start from tail while (current_proj != head) { if (loop == get_loop(current_proj) && // still in the loop ? current_proj->is_Proj() && // is a projection ? current_proj->in(0)->Opcode() == Op_If) { // is a if projection ? if_proj_list.push(current_proj); } current_proj = idom(current_proj); } bool hoisted = false; // true if at least one proj is promoted while (if_proj_list.size() > 0) { // Following are changed to nonnull when a predicate can be hoisted ProjNode* new_predicate_proj = NULL; ProjNode* proj = if_proj_list.pop()->as_Proj(); IfNode* iff = proj->in(0)->as_If(); if (!proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) { if (loop->is_loop_exit(iff)) { // stop processing the remaining projs in the list because the execution of them // depends on the condition of "iff" (iff->in(1)). break; } else { // Both arms are inside the loop. There are two cases: // (1) there is one backward branch. In this case, any remaining proj // in the if_proj list post-dominates "iff". So, the condition of "iff" // does not determine the execution the remining projs directly, and we // can safely continue. // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj" // does not dominate loop->tail(), so it can not be in the if_proj list. continue; } } Node* test = iff->in(1); if (!test->is_Bool()){ //Conv2B, ... continue; } BoolNode* bol = test->as_Bool(); if (invar.is_invariant(bol)) { // Invariant test new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0); BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool(); // Negate test if necessary bool negated = false; if (proj->_con != predicate_proj->_con) { new_predicate_bol = new (C) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate()); register_new_node(new_predicate_bol, ctrl); negated = true; } IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If(); _igvn.hash_delete(new_predicate_iff); new_predicate_iff->set_req(1, new_predicate_bol); #ifndef PRODUCT if (TraceLoopPredicate) { tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx); loop->dump_head(); } else if (TraceLoopOpts) { tty->print("Predicate IC "); loop->dump_head(); } #endif } else if ((cl != NULL) && (proj->_con == predicate_proj->_con) && loop->is_range_check_if(iff, this, invar)) { // Range check for counted loops const Node* cmp = bol->in(1)->as_Cmp(); Node* idx = cmp->in(1); assert(!invar.is_invariant(idx), "index is variant"); Node* rng = cmp->in(2); assert(rng->Opcode() == Op_LoadRange || _igvn.type(rng)->is_int()->_lo >= 0, "must be"); assert(invar.is_invariant(rng), "range must be invariant"); int scale = 1; Node* offset = zero; bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset); assert(ok, "must be index expression"); Node* init = cl->init_trip(); // Limit is not exact. // Calculate exact limit here. // Note, counted loop's test is '<' or '>'. Node* limit = exact_limit(loop); int stride = cl->stride()->get_int(); // Build if's for the upper and lower bound tests. The // lower_bound test will dominate the upper bound test and all // cloned or created nodes will use the lower bound test as // their declared control. ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate"); Node *ctrl = lower_bound_proj->in(0)->as_If()->in(0); // Perform cloning to keep Invariance state correct since the // late schedule will place invariant things in the loop. rng = invar.clone(rng, ctrl); if (offset && offset != zero) { assert(invar.is_invariant(offset), "offset must be loop invariant"); offset = invar.clone(offset, ctrl); } // If predicate expressions may overflow in the integer range, longs are used. bool overflow = false; // Test the lower bound Node* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false, overflow); IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If(); _igvn.hash_delete(lower_bound_iff); lower_bound_iff->set_req(1, lower_bound_bol); if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx); // Test the upper bound Node* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true, overflow); IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If(); _igvn.hash_delete(upper_bound_iff); upper_bound_iff->set_req(1, upper_bound_bol); if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx); // Fall through into rest of the clean up code which will move // any dependent nodes onto the upper bound test. new_predicate_proj = upper_bound_proj; #ifndef PRODUCT if (TraceLoopOpts && !TraceLoopPredicate) { tty->print("Predicate RC "); loop->dump_head(); } #endif } else { // Loop variant check (for example, range check in non-counted loop) // with uncommon trap. continue; } assert(new_predicate_proj != NULL, "sanity"); // Success - attach condition (new_predicate_bol) to predicate if invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate // Eliminate the old If in the loop body dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con ); hoisted = true; C->set_major_progress(); } // end while #ifndef PRODUCT // report that the loop predication has been actually performed // for this loop if (TraceLoopPredicate && hoisted) { tty->print("Loop Predication Performed:"); loop->dump_head(); } #endif return hoisted; } //------------------------------loop_predication-------------------------------- // driver routine for loop predication optimization bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) { bool hoisted = false; // Recursively promote predicates if (_child) { hoisted = _child->loop_predication( phase); } // self if (!_irreducible && !tail()->is_top()) { hoisted |= phase->loop_predication_impl(this); } if (_next) { //sibling hoisted |= _next->loop_predication( phase); } return hoisted; }