1 /*
2 * Copyright (c) 2011, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23 package org.graalvm.compiler.nodes.memory;
24
25 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_2;
26 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;
27 import static org.graalvm.compiler.nodes.NamedLocationIdentity.ARRAY_LENGTH_LOCATION;
28
29 import org.graalvm.compiler.core.common.LIRKind;
30 import org.graalvm.compiler.core.common.LocationIdentity;
31 import org.graalvm.compiler.core.common.type.Stamp;
32 import org.graalvm.compiler.core.common.type.StampFactory;
33 import org.graalvm.compiler.debug.DebugCloseable;
34 import org.graalvm.compiler.debug.GraalError;
35 import org.graalvm.compiler.graph.Node;
36 import org.graalvm.compiler.graph.NodeClass;
37 import org.graalvm.compiler.graph.spi.Canonicalizable;
38 import org.graalvm.compiler.graph.spi.CanonicalizerTool;
39 import org.graalvm.compiler.nodeinfo.InputType;
40 import org.graalvm.compiler.nodeinfo.NodeInfo;
41 import org.graalvm.compiler.nodes.CanonicalizableLocation;
42 import org.graalvm.compiler.nodes.ConstantNode;
43 import org.graalvm.compiler.nodes.FixedNode;
44 import org.graalvm.compiler.nodes.FrameState;
45 import org.graalvm.compiler.nodes.PiNode;
46 import org.graalvm.compiler.nodes.ValueNode;
47 import org.graalvm.compiler.nodes.extended.GuardingNode;
48 import org.graalvm.compiler.nodes.extended.ValueAnchorNode;
49 import org.graalvm.compiler.nodes.memory.address.AddressNode;
50 import org.graalvm.compiler.nodes.memory.address.OffsetAddressNode;
51 import org.graalvm.compiler.nodes.spi.LIRLowerable;
52 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
53 import org.graalvm.compiler.nodes.spi.Virtualizable;
54 import org.graalvm.compiler.nodes.spi.VirtualizerTool;
55 import org.graalvm.compiler.nodes.util.GraphUtil;
56
57 import jdk.vm.ci.meta.Constant;
58 import jdk.vm.ci.meta.MetaAccessProvider;
59
60 /**
61 * Reads an {@linkplain FixedAccessNode accessed} value.
62 */
63 @NodeInfo(nameTemplate = "Read#{p#location/s}", cycles = CYCLES_2, size = SIZE_1)
64 public class ReadNode extends FloatableAccessNode implements LIRLowerable, Canonicalizable, Virtualizable, GuardingNode {
65
66 public static final NodeClass<ReadNode> TYPE = NodeClass.create(ReadNode.class);
67
68 public ReadNode(AddressNode address, LocationIdentity location, Stamp stamp, BarrierType barrierType) {
69 super(TYPE, address, location, stamp, null, barrierType);
70 }
71
72 public ReadNode(AddressNode address, LocationIdentity location, Stamp stamp, GuardingNode guard, BarrierType barrierType) {
73 super(TYPE, address, location, stamp, guard, barrierType);
74 }
75
76 public ReadNode(AddressNode address, LocationIdentity location, Stamp stamp, GuardingNode guard, BarrierType barrierType, boolean nullCheck, FrameState stateBefore) {
77 this(TYPE, address, location, stamp, guard, barrierType, nullCheck, stateBefore);
78 }
79
80 protected ReadNode(NodeClass<? extends ReadNode> c, AddressNode address, LocationIdentity location, Stamp stamp, GuardingNode guard, BarrierType barrierType, boolean nullCheck,
81 FrameState stateBefore) {
82 super(c, address, location, stamp, guard, barrierType, nullCheck, stateBefore);
83 }
84
85 public ReadNode(AddressNode address, LocationIdentity location, ValueNode guard, BarrierType barrierType) {
86 /*
87 * Used by node intrinsics. Really, you can trust me on that! Since the initial value for
88 * location is a parameter, i.e., a ParameterNode, the constructor cannot use the declared
89 * type LocationNode.
90 */
91 super(TYPE, address, location, StampFactory.forNodeIntrinsic(), (GuardingNode) guard, barrierType);
92 }
93
94 @Override
95 public void generate(NodeLIRBuilderTool gen) {
96 LIRKind readKind = gen.getLIRGeneratorTool().getLIRKind(stamp());
97 gen.setResult(this, gen.getLIRGeneratorTool().getArithmetic().emitLoad(readKind, gen.operand(address), gen.state(this)));
98 }
99
100 @Override
101 public Node canonical(CanonicalizerTool tool) {
102 if (tool.allUsagesAvailable() && hasNoUsages()) {
103 if (getGuard() != null && !(getGuard() instanceof FixedNode)) {
104 // The guard is necessary even if the read goes away.
105 return new ValueAnchorNode((ValueNode) getGuard());
106 } else {
107 // Read without usages or guard can be safely removed.
108 return null;
109 }
110 }
111 if (getAddress() instanceof OffsetAddressNode) {
112 OffsetAddressNode objAddress = (OffsetAddressNode) getAddress();
113 if (objAddress.getBase() instanceof PiNode && ((PiNode) objAddress.getBase()).getGuard() == getGuard()) {
114 OffsetAddressNode newAddress = new OffsetAddressNode(((PiNode) objAddress.getBase()).getOriginalNode(), objAddress.getOffset());
115 return new ReadNode(newAddress, getLocationIdentity(), stamp(), getGuard(), getBarrierType(), getNullCheck(), stateBefore());
116 }
117 }
118 if (!getNullCheck()) {
119 return canonicalizeRead(this, getAddress(), getLocationIdentity(), tool);
120 } else {
121 // if this read is a null check, then replacing it with the value is incorrect for
122 // guard-type usages
123 return this;
124 }
125 }
126
127 @SuppressWarnings("try")
128 @Override
129 public FloatingAccessNode asFloatingNode(MemoryNode lastLocationAccess) {
130 try (DebugCloseable position = withNodeSourcePosition()) {
131 return graph().unique(new FloatingReadNode(getAddress(), getLocationIdentity(), lastLocationAccess, stamp(), getGuard(), getBarrierType()));
132 }
133 }
134
135 @Override
136 public boolean isAllowedUsageType(InputType type) {
137 return (getNullCheck() && type == InputType.Guard) ? true : super.isAllowedUsageType(type);
138 }
139
140 public static ValueNode canonicalizeRead(ValueNode read, AddressNode address, LocationIdentity locationIdentity, CanonicalizerTool tool) {
141 MetaAccessProvider metaAccess = tool.getMetaAccess();
142 if (tool.canonicalizeReads() && address instanceof OffsetAddressNode) {
143 OffsetAddressNode objAddress = (OffsetAddressNode) address;
144 ValueNode object = objAddress.getBase();
145 if (metaAccess != null && object.isConstant() && !object.isNullConstant() && objAddress.getOffset().isConstant()) {
146 long displacement = objAddress.getOffset().asJavaConstant().asLong();
147 int stableDimension = ((ConstantNode) object).getStableDimension();
148 if (locationIdentity.isImmutable() || stableDimension > 0) {
149 Constant constant = read.stamp().readConstant(tool.getConstantReflection().getMemoryAccessProvider(), object.asConstant(), displacement);
150 boolean isDefaultStable = locationIdentity.isImmutable() || ((ConstantNode) object).isDefaultStable();
151 if (constant != null && (isDefaultStable || !constant.isDefaultForKind())) {
152 return ConstantNode.forConstant(read.stamp(), constant, Math.max(stableDimension - 1, 0), isDefaultStable, metaAccess);
153 }
154 }
155 }
156 if (locationIdentity.equals(ARRAY_LENGTH_LOCATION)) {
157 ValueNode length = GraphUtil.arrayLength(object);
158 if (length != null) {
159 // TODO Does this need a PiCastNode to the positive range?
160 return length;
161 }
162 }
163 if (locationIdentity instanceof CanonicalizableLocation) {
164 CanonicalizableLocation canonicalize = (CanonicalizableLocation) locationIdentity;
165 ValueNode result = canonicalize.canonicalizeRead(read, address, object, tool);
166 assert result != null && result.stamp().isCompatible(read.stamp());
167 return result;
168 }
169
170 }
171 return read;
172 }
173
174 @Override
175 public void virtualize(VirtualizerTool tool) {
176 throw GraalError.shouldNotReachHere("unexpected ReadNode before PEA");
177 }
178
179 @Override
180 public boolean canNullCheck() {
181 return true;
182 }
183 }