--- /dev/null 2016-05-31 09:42:47.975716356 -0700
+++ new/src/jdk.vm.compiler/share/classes/org.graalvm.compiler.phases.common/src/org/graalvm/compiler/phases/common/GuardLoweringPhase.java 2016-12-09 00:56:14.181159446 -0800
@@ -0,0 +1,291 @@
+/*
+ * Copyright (c) 2013, 2015, 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.
+ */
+package org.graalvm.compiler.phases.common;
+
+import static org.graalvm.compiler.core.common.GraalOptions.OptImplicitNullChecks;
+
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.graalvm.compiler.core.common.cfg.Loop;
+import org.graalvm.compiler.debug.Debug;
+import org.graalvm.compiler.debug.DebugCloseable;
+import org.graalvm.compiler.debug.DebugCounter;
+import org.graalvm.compiler.graph.Node;
+import org.graalvm.compiler.nodes.AbstractBeginNode;
+import org.graalvm.compiler.nodes.BeginNode;
+import org.graalvm.compiler.nodes.DeoptimizeNode;
+import org.graalvm.compiler.nodes.FixedWithNextNode;
+import org.graalvm.compiler.nodes.GuardNode;
+import org.graalvm.compiler.nodes.IfNode;
+import org.graalvm.compiler.nodes.LogicNode;
+import org.graalvm.compiler.nodes.LoopBeginNode;
+import org.graalvm.compiler.nodes.LoopExitNode;
+import org.graalvm.compiler.nodes.PiNode;
+import org.graalvm.compiler.nodes.StateSplit;
+import org.graalvm.compiler.nodes.StructuredGraph;
+import org.graalvm.compiler.nodes.StructuredGraph.GuardsStage;
+import org.graalvm.compiler.nodes.StructuredGraph.ScheduleResult;
+import org.graalvm.compiler.nodes.ValueNode;
+import org.graalvm.compiler.nodes.calc.IsNullNode;
+import org.graalvm.compiler.nodes.cfg.Block;
+import org.graalvm.compiler.nodes.memory.Access;
+import org.graalvm.compiler.nodes.memory.FixedAccessNode;
+import org.graalvm.compiler.nodes.memory.FloatingAccessNode;
+import org.graalvm.compiler.nodes.memory.MemoryNode;
+import org.graalvm.compiler.nodes.memory.address.OffsetAddressNode;
+import org.graalvm.compiler.nodes.util.GraphUtil;
+import org.graalvm.compiler.phases.BasePhase;
+import org.graalvm.compiler.phases.graph.ScheduledNodeIterator;
+import org.graalvm.compiler.phases.schedule.SchedulePhase;
+import org.graalvm.compiler.phases.schedule.SchedulePhase.SchedulingStrategy;
+import org.graalvm.compiler.phases.tiers.MidTierContext;
+
+import jdk.vm.ci.meta.JavaConstant;
+
+/**
+ * This phase lowers {@link GuardNode GuardNodes} into corresponding control-flow structure and
+ * {@link DeoptimizeNode DeoptimizeNodes}.
+ *
+ * This allow to enter the {@link GuardsStage#FIXED_DEOPTS FIXED_DEOPTS} stage of the graph where
+ * all node that may cause deoptimization are fixed.
+ *
+ * It first makes a schedule in order to know where the control flow should be placed. Then, for
+ * each block, it applies two passes. The first one tries to replace null-check guards with implicit
+ * null checks performed by access to the objects that need to be null checked. The second phase
+ * does the actual control-flow expansion of the remaining {@link GuardNode GuardNodes}.
+ */
+public class GuardLoweringPhase extends BasePhase {
+
+ private static final DebugCounter counterImplicitNullCheck = Debug.counter("ImplicitNullCheck");
+
+ private static class UseImplicitNullChecks extends ScheduledNodeIterator {
+
+ private final Map nullGuarded = Node.newIdentityMap();
+ private final int implicitNullCheckLimit;
+
+ UseImplicitNullChecks(int implicitNullCheckLimit) {
+ this.implicitNullCheckLimit = implicitNullCheckLimit;
+ }
+
+ @Override
+ protected void processNode(Node node) {
+ if (node instanceof GuardNode) {
+ processGuard(node);
+ } else if (node instanceof Access) {
+ processAccess((Access) node);
+ } else if (node instanceof PiNode) {
+ processPi((PiNode) node);
+ }
+ if (node instanceof StateSplit && ((StateSplit) node).stateAfter() != null) {
+ nullGuarded.clear();
+ } else {
+ /*
+ * The OffsetAddressNode itself never forces materialization of a null check, even
+ * if its input is a PiNode. The null check will be folded into the first usage of
+ * the OffsetAddressNode, so we need to keep it in the nullGuarded map.
+ */
+ if (!(node instanceof OffsetAddressNode)) {
+ Iterator> it = nullGuarded.entrySet().iterator();
+ while (it.hasNext()) {
+ Entry entry = it.next();
+ ValueNode guard = entry.getValue();
+ if (guard.usages().contains(node)) {
+ it.remove();
+ } else if (guard instanceof PiNode && guard != node) {
+ PiNode piNode = (PiNode) guard;
+ if (piNode.getGuard().asNode().usages().contains(node)) {
+ it.remove();
+ }
+ }
+ }
+ }
+ }
+ }
+
+ private boolean processPi(PiNode node) {
+ ValueNode guardNode = nullGuarded.get(node.object());
+ if (guardNode != null && node.getGuard() == guardNode) {
+ nullGuarded.put(node, node);
+ return true;
+ }
+ return false;
+ }
+
+ private void processAccess(Access access) {
+ if (access.canNullCheck() && access.getAddress() instanceof OffsetAddressNode) {
+ OffsetAddressNode address = (OffsetAddressNode) access.getAddress();
+ check(access, address);
+ }
+ }
+
+ private void check(Access access, OffsetAddressNode address) {
+ ValueNode base = address.getBase();
+ ValueNode guard = nullGuarded.get(base);
+ if (guard != null && isImplicitNullCheck(address.getOffset())) {
+ if (guard instanceof PiNode) {
+ PiNode piNode = (PiNode) guard;
+ assert guard == address.getBase();
+ assert piNode.getGuard() instanceof GuardNode : piNode;
+ address.setBase(piNode.getOriginalNode());
+ } else {
+ assert guard instanceof GuardNode;
+ }
+ counterImplicitNullCheck.increment();
+ access.setGuard(null);
+ FixedAccessNode fixedAccess;
+ if (access instanceof FloatingAccessNode) {
+ FloatingAccessNode floatingAccessNode = (FloatingAccessNode) access;
+ MemoryNode lastLocationAccess = floatingAccessNode.getLastLocationAccess();
+ fixedAccess = floatingAccessNode.asFixedNode();
+ replaceCurrent(fixedAccess);
+ if (lastLocationAccess != null) {
+ // fixed accesses are not currently part of the memory graph
+ GraphUtil.tryKillUnused(lastLocationAccess.asNode());
+ }
+ } else {
+ fixedAccess = (FixedAccessNode) access;
+ }
+ fixedAccess.setNullCheck(true);
+ GuardNode guardNode = null;
+ if (guard instanceof GuardNode) {
+ guardNode = (GuardNode) guard;
+ } else {
+ PiNode piNode = (PiNode) guard;
+ guardNode = (GuardNode) piNode.getGuard();
+ }
+ LogicNode condition = guardNode.getCondition();
+ guardNode.replaceAndDelete(fixedAccess);
+ if (condition.hasNoUsages()) {
+ GraphUtil.killWithUnusedFloatingInputs(condition);
+ }
+ nullGuarded.remove(base);
+ }
+ }
+
+ private void processGuard(Node node) {
+ GuardNode guard = (GuardNode) node;
+ if (guard.isNegated() && guard.getCondition() instanceof IsNullNode && (guard.getSpeculation() == null || guard.getSpeculation().equals(JavaConstant.NULL_POINTER))) {
+ ValueNode obj = ((IsNullNode) guard.getCondition()).getValue();
+ nullGuarded.put(obj, guard);
+ }
+ }
+
+ private boolean isImplicitNullCheck(ValueNode offset) {
+ JavaConstant c = offset.asJavaConstant();
+ if (c != null) {
+ return c.asLong() < implicitNullCheckLimit;
+ } else {
+ return false;
+ }
+ }
+ }
+
+ private static class LowerGuards extends ScheduledNodeIterator {
+
+ private final Block block;
+ private boolean useGuardIdAsDebugId;
+
+ LowerGuards(Block block, boolean useGuardIdAsDebugId) {
+ this.block = block;
+ this.useGuardIdAsDebugId = useGuardIdAsDebugId;
+ }
+
+ @Override
+ protected void processNode(Node node) {
+ if (node instanceof GuardNode) {
+ GuardNode guard = (GuardNode) node;
+ FixedWithNextNode lowered = guard.lowerGuard();
+ if (lowered != null) {
+ replaceCurrent(lowered);
+ } else {
+ lowerToIf(guard);
+ }
+ }
+ }
+
+ @SuppressWarnings("try")
+ private void lowerToIf(GuardNode guard) {
+ try (DebugCloseable position = guard.withNodeSourcePosition()) {
+ StructuredGraph graph = guard.graph();
+ AbstractBeginNode fastPath = graph.add(new BeginNode());
+ @SuppressWarnings("deprecation")
+ int debugId = useGuardIdAsDebugId ? guard.getId() : DeoptimizeNode.DEFAULT_DEBUG_ID;
+ DeoptimizeNode deopt = graph.add(new DeoptimizeNode(guard.getAction(), guard.getReason(), debugId, guard.getSpeculation(), null));
+ AbstractBeginNode deoptBranch = BeginNode.begin(deopt);
+ AbstractBeginNode trueSuccessor;
+ AbstractBeginNode falseSuccessor;
+ insertLoopExits(deopt);
+ if (guard.isNegated()) {
+ trueSuccessor = deoptBranch;
+ falseSuccessor = fastPath;
+ } else {
+ trueSuccessor = fastPath;
+ falseSuccessor = deoptBranch;
+ }
+ IfNode ifNode = graph.add(new IfNode(guard.getCondition(), trueSuccessor, falseSuccessor, trueSuccessor == fastPath ? 1 : 0));
+ guard.replaceAndDelete(fastPath);
+ insert(ifNode, fastPath);
+ }
+ }
+
+ private void insertLoopExits(DeoptimizeNode deopt) {
+ Loop loop = block.getLoop();
+ StructuredGraph graph = deopt.graph();
+ while (loop != null) {
+ LoopExitNode exit = graph.add(new LoopExitNode((LoopBeginNode) loop.getHeader().getBeginNode()));
+ graph.addBeforeFixed(deopt, exit);
+ loop = loop.getParent();
+ }
+ }
+ }
+
+ @Override
+ protected void run(StructuredGraph graph, MidTierContext context) {
+ if (graph.getGuardsStage().allowsFloatingGuards()) {
+ SchedulePhase schedulePhase = new SchedulePhase(SchedulingStrategy.EARLIEST);
+ schedulePhase.apply(graph);
+ ScheduleResult schedule = graph.getLastSchedule();
+
+ for (Block block : schedule.getCFG().getBlocks()) {
+ processBlock(block, schedule, context != null ? context.getTarget().implicitNullCheckLimit : 0);
+ }
+ graph.setGuardsStage(GuardsStage.FIXED_DEOPTS);
+ }
+
+ assert assertNoGuardsLeft(graph);
+ }
+
+ private static boolean assertNoGuardsLeft(StructuredGraph graph) {
+ assert graph.getNodes().filter(GuardNode.class).isEmpty();
+ return true;
+ }
+
+ private static void processBlock(Block block, ScheduleResult schedule, int implicitNullCheckLimit) {
+ if (OptImplicitNullChecks.getValue() && implicitNullCheckLimit > 0) {
+ new UseImplicitNullChecks(implicitNullCheckLimit).processNodes(block, schedule);
+ }
+ new LowerGuards(block, Debug.isDumpEnabledForMethod() || Debug.isLogEnabledForMethod()).processNodes(block, schedule);
+ }
+}