--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/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;
+}
+