Mercurial > hg > truffle
diff src/share/vm/opto/loopPredicate.cpp @ 2445:08eb13460b3a
7004535: Clone loop predicate during loop unswitch
Summary: Clone loop predicate for clonned loops
Reviewed-by: never
author | kvn |
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date | Sat, 02 Apr 2011 10:54:15 -0700 |
parents | |
children | 2e038ad0c1d0 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/opto/loopPredicate.cpp Sat Apr 02 10:54:15 2011 -0700 @@ -0,0 +1,960 @@ +/* + * Copyright (c) 2011, 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/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). +*/ + +//-------------------------------is_uncommon_trap_proj---------------------------- +// Return true if proj is the form of "proj->[region->..]call_uct" +bool PhaseIdealLoop::is_uncommon_trap_proj(ProjNode* proj, Deoptimization::DeoptReason reason) { + int path_limit = 10; + assert(proj, "invalid argument"); + Node* out = proj; + for (int ct = 0; ct < path_limit; ct++) { + out = out->unique_ctrl_out(); + if (out == NULL) + return false; + if (out->is_CallStaticJava()) { + int req = out->as_CallStaticJava()->uncommon_trap_request(); + if (req != 0) { + Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req); + if (trap_reason == reason || reason == Deoptimization::Reason_none) { + return true; + } + } + return false; // don't do further after call + } + if (out->Opcode() != Op_Region) + return false; + } + return false; +} + +//-------------------------------is_uncommon_trap_if_pattern------------------------- +// Return true for "if(test)-> proj -> ... +// | +// V +// other_proj->[region->..]call_uct" +// +// "must_reason_predicate" means the uct reason must be Reason_predicate +bool PhaseIdealLoop::is_uncommon_trap_if_pattern(ProjNode *proj, Deoptimization::DeoptReason reason) { + Node *in0 = proj->in(0); + if (!in0->is_If()) return false; + // Variation of a dead If node. + if (in0->outcnt() < 2) return false; + IfNode* iff = in0->as_If(); + + // we need "If(Conv2B(Opaque1(...)))" pattern for reason_predicate + if (reason != Deoptimization::Reason_none) { + if (iff->in(1)->Opcode() != Op_Conv2B || + iff->in(1)->in(1)->Opcode() != Op_Opaque1) { + return false; + } + } + + ProjNode* other_proj = iff->proj_out(1-proj->_con)->as_Proj(); + if (is_uncommon_trap_proj(other_proj, reason)) { + assert(reason == Deoptimization::Reason_none || + Compile::current()->is_predicate_opaq(iff->in(1)->in(1)), "should be on the list"); + return true; + } + return false; +} + +//-------------------------------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(is_uncommon_trap_if_pattern(cont_proj, 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, 1) 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, 1) IfTrueNode(new_iff); + Node *if_uct = new (C, 1) 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.hash_delete(use); + use->add_req(use->in(proj_index)); + _igvn._worklist.push(use); + 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(PhaseIdealLoop::is_uncommon_trap_if_pattern(cont_proj, 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, 1) 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, 1) IfTrueNode(new_iff); + Node *if_uct = new (C, 1) 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) { + hash_delete(use); + use->add_req(use->in(proj_index)); + _worklist.push(use); + 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, 2) Opaque1Node(igvn->C, predicate_proj->in(0)->in(1)->in(1)->in(1)); + igvn->C->add_predicate_opaq(opq); + + Node* bol = new (igvn->C, 2) 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; +} + +//--------------------------move_predicate----------------------- +// Cut predicate from old place and move it to new. +ProjNode* PhaseIdealLoop::move_predicate(ProjNode* predicate_proj, Node* new_entry, + Deoptimization::DeoptReason reason, + PhaseIdealLoop* loop_phase, + PhaseIterGVN* igvn) { + assert(new_entry != NULL, "must be"); + assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); + IfNode* iff = predicate_proj->in(0)->as_If(); + Node* old_entry = iff->in(0); + + // Cut predicate from old place. + Node* old = predicate_proj; + igvn->_worklist.push(old); + for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) { + Node* use = old->last_out(i); // for each use... + igvn->hash_delete(use); + igvn->_worklist.push(use); + // Update use-def info + uint uses_found = 0; + for (uint j = 0; j < use->req(); j++) { + if (use->in(j) == old) { + use->set_req(j, old_entry); + uses_found++; + if (loop_phase != NULL) { + if (use->is_CFG()) { + // When called from beautify_loops() idom is not constructed yet. + if (loop_phase->_idom != NULL) + loop_phase->set_idom(use, old_entry, loop_phase->dom_depth(use)); + } else { + loop_phase->set_ctrl(use, old_entry); + } + } + } + } + i -= uses_found; // we deleted 1 or more copies of this edge + } + + // Move predicate. + igvn->hash_delete(iff); + iff->set_req(0, new_entry); + igvn->_worklist.push(iff); + + if (loop_phase != NULL) { + // Fix up idom and ctrl. + loop_phase->set_ctrl(iff->in(1), new_entry); + loop_phase->set_ctrl(iff->in(1)->in(1), new_entry); + // When called from beautify_loops() idom is not constructed yet. + if (loop_phase->_idom != NULL) + loop_phase->set_idom(iff, new_entry, loop_phase->dom_depth(iff)); + } + + return predicate_proj; +} + +//--------------------------clone_loop_predicates----------------------- +// Interface from IGVN +Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry) { + return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, false, NULL, this); +} +Node* PhaseIterGVN::move_loop_predicates(Node* old_entry, Node* new_entry) { + return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, true, NULL, this); +} + +// Interface from PhaseIdealLoop +Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry) { + return clone_loop_predicates(old_entry, new_entry, false, this, &this->_igvn); +} +Node* PhaseIdealLoop::move_loop_predicates(Node* old_entry, Node* new_entry) { + return clone_loop_predicates(old_entry, new_entry, true, 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 move_predicates, + 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; + 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 + assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); + if (move_predicates) { + new_entry = move_predicate(predicate_proj, new_entry, + Deoptimization::Reason_predicate, + loop_phase, igvn); + assert(new_entry == predicate_proj, "old predicate fall through projection"); + } else { + // 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_cr("Loop Predicate %s: ", move_predicates ? "moved" : "cloned"); + debug_only( new_entry->in(0)->dump(); ) + } + } + } + return new_entry; +} + +//--------------------------eliminate_loop_predicates----------------------- +void PhaseIdealLoop::eliminate_loop_predicates(Node* entry) { + 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 + Node* n = entry->in(0)->in(1)->in(1); + assert(n->Opcode()==Op_Opaque1, "must be"); + // Remove Opaque1 node from predicates list. + // IGVN will remove this predicate check. + _igvn.replace_node(n, n->in(1)); + } + } +} + +//--------------------------skip_loop_predicates------------------------------ +// Skip related predicates. +Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) { + Node* predicate = NULL; + if (UseLoopPredicate) { + predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); + if (predicate != NULL) { // right pattern that can be used by loop predication + assert(entry->is_Proj() && entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); + 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 (is_uncommon_trap_if_pattern(start_c->as_Proj(), reason)) { + return start_c->as_Proj(); + } + return NULL; +} + +//--------------------------find_predicate------------------------------------ +// Find a predicate +Node* PhaseIdealLoop::find_predicate(Node* entry) { + Node* predicate = NULL; + if (UseLoopPredicate) { + predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); + if (predicate != NULL) { // right pattern that can be used by loop predication + assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); + 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) { + _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) + {} + + // 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 (!OptimizeFill || 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(Node* ctrl, + int scale, Node* offset, + Node* init, Node* limit, Node* stride, + Node* range, bool upper) { + DEBUG_ONLY(ttyLocker ttyl); + if (TraceLoopPredicate) tty->print("rc_predicate "); + + Node* max_idx_expr = init; + int stride_con = stride->get_int(); + if ((stride_con > 0) == (scale > 0) == upper) { + max_idx_expr = new (C, 3) SubINode(limit, stride); + register_new_node(max_idx_expr, ctrl); + if (TraceLoopPredicate) tty->print("(limit - stride) "); + } else { + if (TraceLoopPredicate) tty->print("init "); + } + + if (scale != 1) { + ConNode* con_scale = _igvn.intcon(scale); + max_idx_expr = new (C, 3) MulINode(max_idx_expr, con_scale); + register_new_node(max_idx_expr, ctrl); + if (TraceLoopPredicate) tty->print("* %d ", scale); + } + + if (offset && (!offset->is_Con() || offset->get_int() != 0)){ + max_idx_expr = new (C, 3) AddINode(max_idx_expr, offset); + register_new_node(max_idx_expr, ctrl); + if (TraceLoopPredicate) + if (offset->is_Con()) tty->print("+ %d ", offset->get_int()); + else tty->print("+ offset "); + } + + CmpUNode* cmp = new (C, 3) CmpUNode(max_idx_expr, range); + register_new_node(cmp, ctrl); + BoolNode* bol = new (C, 2) BoolNode(cmp, BoolTest::lt); + register_new_node(bol, ctrl); + + if (TraceLoopPredicate) tty->print_cr("<u range"); + 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; + } + + if (loop->_head->unique_ctrl_out()->Opcode() == Op_NeverBranch) { + // do nothing for infinite loops + return false; + } + + CountedLoopNode *cl = NULL; + if (loop->_head->is_CountedLoop()) { + cl = loop->_head->as_CountedLoop(); + // do nothing for iteration-splitted loops + if (!cl->is_normal_loop()) return false; + } + + LoopNode *lpn = loop->_head->as_Loop(); + Node* entry = lpn->in(LoopNode::EntryControl); + + ProjNode *predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); + if (!predicate_proj) { +#ifndef PRODUCT + if (TraceLoopPredicate) { + tty->print("missing predicate:"); + loop->dump_head(); + lpn->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); + LoopNode *head = loop->_head->as_Loop(); + 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 (!is_uncommon_trap_if_pattern(proj, 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, 2) 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 && loop->is_range_check_if(iff, this, invar)) { + assert(proj->_con == predicate_proj->_con, "must match"); + + // 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"); + assert(cmp->in(2)->Opcode() == Op_LoadRange || OptimizeFill, "must be"); + Node* rng = cmp->in(2); + 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(); + Node* limit = cl->limit(); + Node* stride = cl->stride(); + + // 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); + } + + // Test the lower bound + Node* lower_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, false); + 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(ctrl, scale, offset, init, limit, stride, rng, true); + 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; +} +