1/*
2 * Copyright (c) 2012, 2014, 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 */
23package org.graalvm.compiler.replacements;
24
25import static org.graalvm.compiler.nodes.calc.CompareNode.createCompareNode;
26
27import java.util.List;
28
29import org.graalvm.compiler.api.replacements.SnippetReflectionProvider;
30import org.graalvm.compiler.core.common.calc.Condition;
31import org.graalvm.compiler.graph.Node;
32import org.graalvm.compiler.nodes.ConditionAnchorNode;
33import org.graalvm.compiler.nodes.ConstantNode;
34import org.graalvm.compiler.nodes.FixedGuardNode;
35import org.graalvm.compiler.nodes.IfNode;
36import org.graalvm.compiler.nodes.LogicConstantNode;
37import org.graalvm.compiler.nodes.LogicNode;
38import org.graalvm.compiler.nodes.PhiNode;
39import org.graalvm.compiler.nodes.ShortCircuitOrNode;
40import org.graalvm.compiler.nodes.StructuredGraph;
41import org.graalvm.compiler.nodes.ValueNode;
42import org.graalvm.compiler.nodes.calc.CompareNode;
43import org.graalvm.compiler.nodes.calc.ConditionalNode;
44import org.graalvm.compiler.nodes.calc.FloatingNode;
45import org.graalvm.compiler.nodes.java.ClassIsAssignableFromNode;
46import org.graalvm.compiler.nodes.java.InstanceOfDynamicNode;
47import org.graalvm.compiler.nodes.java.InstanceOfNode;
48import org.graalvm.compiler.nodes.spi.LoweringTool;
49import org.graalvm.compiler.nodes.util.GraphUtil;
50import org.graalvm.compiler.phases.util.Providers;
51import org.graalvm.compiler.replacements.SnippetTemplate.AbstractTemplates;
52import org.graalvm.compiler.replacements.SnippetTemplate.Arguments;
53import org.graalvm.compiler.replacements.SnippetTemplate.UsageReplacer;
54
55import jdk.vm.ci.code.TargetDescription;
56
57/**
58 * Helper class for lowering {@link InstanceOfNode}s with snippets. The majority of the complexity
59 * in such a lowering derives from the fact that {@link InstanceOfNode} is a floating node. A
60 * snippet used to lower an {@link InstanceOfNode} will almost always incorporate control flow and
61 * replacing a floating node with control flow is not trivial.
62 * <p>
63 * The mechanism implemented in this class ensures that the graph for an instanceof snippet is
64 * instantiated once per {@link InstanceOfNode} being lowered. The result produced is then re-used
65 * by all usages of the node. Additionally, if there is a single usage that is an {@link IfNode},
66 * the control flow in the snippet is connected directly to the true and false successors of the
67 * {@link IfNode}. This avoids materializing the instanceof test as a boolean which is then retested
68 * by the {@link IfNode}.
69 */
70public abstract class InstanceOfSnippetsTemplates extends AbstractTemplates {
71
72    public InstanceOfSnippetsTemplates(Providers providers, SnippetReflectionProvider snippetReflection, TargetDescription target) {
73        super(providers, snippetReflection, target);
74    }
75
76    /**
77     * Gets the arguments used to retrieve and instantiate an instanceof snippet template.
78     */
79    protected abstract Arguments makeArguments(InstanceOfUsageReplacer replacer, LoweringTool tool);
80
81    public void lower(FloatingNode instanceOf, LoweringTool tool) {
82        assert instanceOf instanceof InstanceOfNode || instanceOf instanceof InstanceOfDynamicNode || instanceOf instanceof ClassIsAssignableFromNode;
83        List<Node> usages = instanceOf.usages().snapshot();
84
85        Instantiation instantiation = new Instantiation();
86        for (Node usage : usages) {
87            final StructuredGraph graph = (StructuredGraph) usage.graph();
88
89            InstanceOfUsageReplacer replacer = createReplacer(instanceOf, instantiation, usage, graph);
90
91            if (instantiation.isInitialized()) {
92                // No need to re-instantiate the snippet - just re-use its result
93                replacer.replaceUsingInstantiation();
94            } else {
95                Arguments args = makeArguments(replacer, tool);
96                template(args).instantiate(providers.getMetaAccess(), instanceOf, replacer, tool, args);
97            }
98        }
99
100        assert instanceOf.hasNoUsages();
101        if (!instanceOf.isDeleted()) {
102            GraphUtil.killWithUnusedFloatingInputs(instanceOf);
103        }
104    }
105
106    /**
107     * Gets the specific replacer object used to replace the usage of an instanceof node with the
108     * result of an instantiated instanceof snippet.
109     */
110    protected InstanceOfUsageReplacer createReplacer(FloatingNode instanceOf, Instantiation instantiation, Node usage, final StructuredGraph graph) {
111        InstanceOfUsageReplacer replacer;
112        if (!canMaterialize(usage)) {
113            ValueNode trueValue = ConstantNode.forInt(1, graph);
114            ValueNode falseValue = ConstantNode.forInt(0, graph);
115            if (instantiation.isInitialized() && (trueValue != instantiation.trueValue || falseValue != instantiation.falseValue)) {
116                /*
117                 * This code doesn't really care what values are used so adopt the values from the
118                 * previous instantiation.
119                 */
120                trueValue = instantiation.trueValue;
121                falseValue = instantiation.falseValue;
122            }
123            replacer = new NonMaterializationUsageReplacer(instantiation, trueValue, falseValue, instanceOf, usage);
124        } else {
125            assert usage instanceof ConditionalNode : "unexpected usage of " + instanceOf + ": " + usage;
126            ConditionalNode c = (ConditionalNode) usage;
127            replacer = new MaterializationUsageReplacer(instantiation, c.trueValue(), c.falseValue(), instanceOf, c);
128        }
129        return replacer;
130    }
131
132    /**
133     * Determines if an {@code instanceof} usage can be materialized.
134     */
135    protected boolean canMaterialize(Node usage) {
136        if (usage instanceof ConditionalNode) {
137            ConditionalNode cn = (ConditionalNode) usage;
138            return cn.trueValue().isConstant() && cn.falseValue().isConstant();
139        }
140        if (usage instanceof IfNode || usage instanceof FixedGuardNode || usage instanceof ShortCircuitOrNode || usage instanceof ConditionAnchorNode) {
141            return false;
142        }
143        return true;
144    }
145
146    /**
147     * The result of instantiating an instanceof snippet. This enables a snippet instantiation to be
148     * re-used which reduces compile time and produces better code.
149     */
150    public static final class Instantiation {
151
152        private ValueNode result;
153        private LogicNode condition;
154        private ValueNode trueValue;
155        private ValueNode falseValue;
156
157        /**
158         * Determines if the instantiation has occurred.
159         */
160        boolean isInitialized() {
161            return result != null;
162        }
163
164        void initialize(ValueNode r, ValueNode t, ValueNode f) {
165            assert !isInitialized();
166            this.result = r;
167            this.trueValue = t;
168            this.falseValue = f;
169        }
170
171        /**
172         * Gets the result of this instantiation as a condition.
173         *
174         * @param testValue the returned condition is true if the result is equal to this value
175         */
176        LogicNode asCondition(ValueNode testValue) {
177            assert isInitialized();
178            if (result.isConstant()) {
179                assert testValue.isConstant();
180                return LogicConstantNode.forBoolean(result.asConstant().equals(testValue.asConstant()), result.graph());
181            }
182            if (condition == null || (!(condition instanceof CompareNode)) || ((CompareNode) condition).getY() != testValue) {
183                // Re-use previously generated condition if the trueValue for the test is the same
184                condition = createCompareNode(result.graph(), Condition.EQ, result, testValue, null);
185            }
186            return condition;
187        }
188
189        /**
190         * Gets the result of the instantiation as a materialized value.
191         *
192         * @param t the true value for the materialization
193         * @param f the false value for the materialization
194         */
195        ValueNode asMaterialization(StructuredGraph graph, ValueNode t, ValueNode f) {
196            assert isInitialized();
197            if (t == this.trueValue && f == this.falseValue) {
198                // Can simply use the phi result if the same materialized values are expected.
199                return result;
200            } else {
201                return graph.unique(new ConditionalNode(asCondition(trueValue), t, f));
202            }
203        }
204    }
205
206    /**
207     * Replaces a usage of an {@link InstanceOfNode} or {@link InstanceOfDynamicNode}.
208     */
209    public abstract static class InstanceOfUsageReplacer implements UsageReplacer {
210
211        public final Instantiation instantiation;
212        public final FloatingNode instanceOf;
213        public final ValueNode trueValue;
214        public final ValueNode falseValue;
215
216        public InstanceOfUsageReplacer(Instantiation instantiation, FloatingNode instanceOf, ValueNode trueValue, ValueNode falseValue) {
217            assert instanceOf instanceof InstanceOfNode || instanceOf instanceof InstanceOfDynamicNode || instanceOf instanceof ClassIsAssignableFromNode;
218            this.instantiation = instantiation;
219            this.instanceOf = instanceOf;
220            this.trueValue = trueValue;
221            this.falseValue = falseValue;
222        }
223
224        /**
225         * Does the replacement based on a previously snippet instantiation.
226         */
227        public abstract void replaceUsingInstantiation();
228    }
229
230    /**
231     * Replaces the usage of an {@link InstanceOfNode} or {@link InstanceOfDynamicNode} that does
232     * not materialize the result of the type test.
233     */
234    public static class NonMaterializationUsageReplacer extends InstanceOfUsageReplacer {
235
236        private final Node usage;
237
238        public NonMaterializationUsageReplacer(Instantiation instantiation, ValueNode trueValue, ValueNode falseValue, FloatingNode instanceOf, Node usage) {
239            super(instantiation, instanceOf, trueValue, falseValue);
240            this.usage = usage;
241        }
242
243        @Override
244        public void replaceUsingInstantiation() {
245            usage.replaceFirstInput(instanceOf, instantiation.asCondition(trueValue));
246        }
247
248        @Override
249        public void replace(ValueNode oldNode, ValueNode newNode) {
250            assert newNode instanceof PhiNode;
251            assert oldNode == instanceOf;
252            newNode.inferStamp();
253            instantiation.initialize(newNode, trueValue, falseValue);
254            usage.replaceFirstInput(oldNode, instantiation.asCondition(trueValue));
255        }
256    }
257
258    /**
259     * Replaces the usage of an {@link InstanceOfNode} or {@link InstanceOfDynamicNode} that does
260     * materializes the result of the type test.
261     */
262    public static class MaterializationUsageReplacer extends InstanceOfUsageReplacer {
263
264        public final ConditionalNode usage;
265
266        public MaterializationUsageReplacer(Instantiation instantiation, ValueNode trueValue, ValueNode falseValue, FloatingNode instanceOf, ConditionalNode usage) {
267            super(instantiation, instanceOf, trueValue, falseValue);
268            this.usage = usage;
269        }
270
271        @Override
272        public void replaceUsingInstantiation() {
273            ValueNode newValue = instantiation.asMaterialization(usage.graph(), trueValue, falseValue);
274            usage.replaceAtUsages(newValue);
275            assert usage.hasNoUsages();
276            GraphUtil.killWithUnusedFloatingInputs(usage);
277        }
278
279        @Override
280        public void replace(ValueNode oldNode, ValueNode newNode) {
281            assert newNode instanceof PhiNode;
282            assert oldNode == instanceOf;
283            newNode.inferStamp();
284            instantiation.initialize(newNode, trueValue, falseValue);
285            usage.replaceAtUsages(newNode);
286            assert usage.hasNoUsages();
287            GraphUtil.killWithUnusedFloatingInputs(usage);
288        }
289    }
290}
291