Mercurial > hg > graal-compiler
view graal/com.oracle.graal.phases.common/src/com/oracle/graal/phases/common/GuardLoweringPhase.java @ 12639:50aca0c0dff4
Merge.
author | Christian Humer <christian.humer@gmail.com> |
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date | Wed, 30 Oct 2013 11:08:00 +0100 |
parents | 0b1f0763bb18 |
children | 38b84d5a66fd |
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/* * Copyright (c) 2013, 2013, 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 com.oracle.graal.phases.common; import static com.oracle.graal.phases.GraalOptions.*; import java.util.*; import java.util.Map.Entry; import com.oracle.graal.graph.*; import com.oracle.graal.nodes.*; import com.oracle.graal.nodes.StructuredGraph.GuardsStage; import com.oracle.graal.nodes.calc.*; import com.oracle.graal.nodes.cfg.*; import com.oracle.graal.nodes.extended.*; import com.oracle.graal.nodes.util.*; import com.oracle.graal.phases.*; import com.oracle.graal.phases.graph.*; import com.oracle.graal.phases.schedule.*; import com.oracle.graal.phases.schedule.SchedulePhase.SchedulingStrategy; import com.oracle.graal.phases.tiers.*; /** * 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. * <p> * 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<MidTierContext> { private static class UseImplicitNullChecks extends ScheduledNodeIterator { private final IdentityHashMap<ValueNode, GuardNode> nullGuarded = new IdentityHashMap<>(); 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); } if (node instanceof StateSplit && ((StateSplit) node).stateAfter() != null) { nullGuarded.clear(); } else { Iterator<Entry<ValueNode, GuardNode>> it = nullGuarded.entrySet().iterator(); while (it.hasNext()) { Entry<ValueNode, GuardNode> entry = it.next(); GuardNode guard = entry.getValue(); if (guard.usages().contains(node)) { it.remove(); } } } } private void processAccess(Access access) { GuardNode guard = nullGuarded.get(access.object()); if (guard != null && isImplicitNullCheck(access.nullCheckLocation())) { access.setGuard(guard.getGuard()); Access fixedAccess = access; if (access instanceof FloatingAccessNode) { fixedAccess = ((FloatingAccessNode) access).asFixedNode(); replaceCurrent((FixedWithNextNode) fixedAccess.asNode()); } assert fixedAccess instanceof FixedNode; fixedAccess.setNullCheck(true); LogicNode condition = guard.condition(); guard.replaceAndDelete(fixedAccess.asNode()); if (condition.usages().isEmpty()) { GraphUtil.killWithUnusedFloatingInputs(condition); } nullGuarded.remove(fixedAccess.object()); } } private void processGuard(Node node) { GuardNode guard = (GuardNode) node; if (guard.negated() && guard.condition() instanceof IsNullNode) { ValueNode obj = ((IsNullNode) guard.condition()).object(); nullGuarded.put(obj, guard); } } private boolean isImplicitNullCheck(LocationNode location) { if (location instanceof ConstantLocationNode) { return ((ConstantLocationNode) location).getDisplacement() < implicitNullCheckLimit; } else { return false; } } } private static class LowerGuards extends ScheduledNodeIterator { private final Block block; public LowerGuards(Block block) { this.block = block; } @Override protected void processNode(Node node) { if (node instanceof GuardNode) { GuardNode guard = (GuardNode) node; if (guard.negated() && guard.condition() instanceof IsNullNode) { lowerToNullCheck(guard); } else { lowerToIf(guard); } } } private void lowerToIf(GuardNode guard) { StructuredGraph graph = guard.graph(); AbstractBeginNode fastPath = graph.add(new BeginNode()); DeoptimizeNode deopt = graph.add(new DeoptimizeNode(guard.action(), guard.reason())); AbstractBeginNode deoptBranch = AbstractBeginNode.begin(deopt); AbstractBeginNode trueSuccessor; AbstractBeginNode falseSuccessor; insertLoopExits(deopt); if (guard.negated()) { trueSuccessor = deoptBranch; falseSuccessor = fastPath; } else { trueSuccessor = fastPath; falseSuccessor = deoptBranch; } IfNode ifNode = graph.add(new IfNode(guard.condition(), trueSuccessor, falseSuccessor, trueSuccessor == fastPath ? 1 : 0)); guard.replaceAndDelete(fastPath); insert(ifNode, fastPath); } private void lowerToNullCheck(GuardNode guard) { IsNullNode isNull = (IsNullNode) guard.condition(); NullCheckNode nullCheck = guard.graph().add(new NullCheckNode(isNull.object())); replaceCurrent(nullCheck); if (isNull.usages().isEmpty()) { isNull.safeDelete(); } } private void insertLoopExits(DeoptimizeNode deopt) { Loop loop = block.getLoop(); StructuredGraph graph = deopt.graph(); while (loop != null) { LoopExitNode exit = graph.add(new LoopExitNode(loop.loopBegin())); graph.addBeforeFixed(deopt, exit); loop = loop.parent; } } } @Override protected void run(StructuredGraph graph, MidTierContext context) { SchedulePhase schedule = new SchedulePhase(SchedulingStrategy.EARLIEST); schedule.apply(graph); for (Block block : schedule.getCFG().getBlocks()) { processBlock(block, schedule, context.getTarget().implicitNullCheckLimit); } graph.setGuardsStage(GuardsStage.FIXED_DEOPTS); } private static void processBlock(Block block, SchedulePhase schedule, int implicitNullCheckLimit) { if (OptImplicitNullChecks.getValue() && implicitNullCheckLimit > 0) { new UseImplicitNullChecks(implicitNullCheckLimit).processNodes(block, schedule); } new LowerGuards(block).processNodes(block, schedule); } }