1 /*
2 * Copyright (c) 2011, 2018, 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
24
25 package org.graalvm.compiler.nodes.calc;
26
27 import static org.graalvm.compiler.core.common.calc.CanonicalCondition.LT;
28
29 import org.graalvm.compiler.core.common.NumUtil;
30 import org.graalvm.compiler.core.common.calc.CanonicalCondition;
31 import org.graalvm.compiler.core.common.type.FloatStamp;
32 import org.graalvm.compiler.core.common.type.IntegerStamp;
33 import org.graalvm.compiler.core.common.type.StampFactory;
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.CanonicalizerTool;
38 import org.graalvm.compiler.nodeinfo.NodeInfo;
39 import org.graalvm.compiler.nodes.ConstantNode;
40 import org.graalvm.compiler.nodes.LogicConstantNode;
41 import org.graalvm.compiler.nodes.LogicNegationNode;
42 import org.graalvm.compiler.nodes.LogicNode;
43 import org.graalvm.compiler.nodes.NodeView;
44 import org.graalvm.compiler.nodes.ValueNode;
45 import org.graalvm.compiler.options.OptionValues;
46
47 import jdk.vm.ci.code.CodeUtil;
48 import jdk.vm.ci.meta.Constant;
49 import jdk.vm.ci.meta.ConstantReflectionProvider;
50 import jdk.vm.ci.meta.JavaKind;
51 import jdk.vm.ci.meta.MetaAccessProvider;
52 import jdk.vm.ci.meta.PrimitiveConstant;
53
54 @NodeInfo(shortName = "<")
55 public final class IntegerLessThanNode extends IntegerLowerThanNode {
56 public static final NodeClass<IntegerLessThanNode> TYPE = NodeClass.create(IntegerLessThanNode.class);
57 private static final LessThanOp OP = new LessThanOp();
58
59 public IntegerLessThanNode(ValueNode x, ValueNode y) {
60 super(TYPE, x, y, OP);
61 assert !x.getStackKind().isNumericFloat() && x.getStackKind() != JavaKind.Object;
62 assert !y.getStackKind().isNumericFloat() && y.getStackKind() != JavaKind.Object;
63 }
64
65 public static LogicNode create(ValueNode x, ValueNode y, NodeView view) {
66 return OP.create(x, y, view);
67 }
68
69 public static LogicNode create(ConstantReflectionProvider constantReflection, MetaAccessProvider metaAccess, OptionValues options, Integer smallestCompareWidth,
70 ValueNode x, ValueNode y, NodeView view) {
71 LogicNode value = OP.canonical(constantReflection, metaAccess, options, smallestCompareWidth, OP.getCondition(), false, x, y, view);
72 if (value != null) {
73 return value;
74 }
75 return create(x, y, view);
76 }
77
78 @Override
79 public Node canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) {
80 NodeView view = NodeView.from(tool);
81 ValueNode value = OP.canonical(tool.getConstantReflection(), tool.getMetaAccess(), tool.getOptions(), tool.smallestCompareWidth(), OP.getCondition(), false, forX, forY, view);
82 if (value != null) {
83 return value;
84 }
85 return this;
86 }
87
88 public static boolean subtractMayUnderflow(long x, long y, long minValue) {
89 long r = x - y;
90 // HD 2-12 Overflow iff the arguments have different signs and
91 // the sign of the result is different than the sign of x
92 return (((x ^ y) & (x ^ r)) < 0) || r <= minValue;
93 }
94
95 public static boolean subtractMayOverflow(long x, long y, long maxValue) {
96 long r = x - y;
97 // HD 2-12 Overflow iff the arguments have different signs and
98 // the sign of the result is different than the sign of x
99 return (((x ^ y) & (x ^ r)) < 0) || r > maxValue;
100 }
101
102 public static class LessThanOp extends LowerOp {
103 @Override
104 protected CompareNode duplicateModified(ValueNode newX, ValueNode newY, boolean unorderedIsTrue, NodeView view) {
105 if (newX.stamp(view) instanceof FloatStamp && newY.stamp(view) instanceof FloatStamp) {
106 return new FloatLessThanNode(newX, newY, unorderedIsTrue); // TODO: Is the last arg
107 // supposed to be true?
108 } else if (newX.stamp(view) instanceof IntegerStamp && newY.stamp(view) instanceof IntegerStamp) {
109 return new IntegerLessThanNode(newX, newY);
110 }
111 throw GraalError.shouldNotReachHere();
112 }
113
114 @Override
115 protected LogicNode optimizeNormalizeCompare(ConstantReflectionProvider constantReflection, MetaAccessProvider metaAccess, OptionValues options, Integer smallestCompareWidth,
116 Constant constant, NormalizeCompareNode normalizeNode, boolean mirrored, NodeView view) {
117 PrimitiveConstant primitive = (PrimitiveConstant) constant;
118 /* @formatter:off
119 * a NC b < c (not mirrored)
120 * cases for c:
121 * 0 -> a < b
122 * [MIN, -1] -> false
123 * 1 -> a <= b
124 * [2, MAX] -> true
125 * unordered-is-less means unordered-is-true.
126 *
127 * c < a NC b (mirrored)
128 * cases for c:
129 * 0 -> a > b
130 * [1, MAX] -> false
131 * -1 -> a >= b
132 * [MIN, -2] -> true
133 * unordered-is-less means unordered-is-false.
134 *
135 * We can handle mirroring by swapping a & b and negating the constant.
136 * @formatter:on
137 */
138 ValueNode a = mirrored ? normalizeNode.getY() : normalizeNode.getX();
139 ValueNode b = mirrored ? normalizeNode.getX() : normalizeNode.getY();
140 long cst = mirrored ? -primitive.asLong() : primitive.asLong();
141
142 if (cst == 0) {
143 if (normalizeNode.getX().getStackKind() == JavaKind.Double || normalizeNode.getX().getStackKind() == JavaKind.Float) {
144 return FloatLessThanNode.create(constantReflection, metaAccess, options, smallestCompareWidth, a, b, mirrored ^ normalizeNode.isUnorderedLess, view);
145 } else {
146 return IntegerLessThanNode.create(constantReflection, metaAccess, options, smallestCompareWidth, a, b, view);
147 }
148 } else if (cst == 1) {
149 // a <= b <=> !(a > b)
150 LogicNode compare;
151 if (normalizeNode.getX().getStackKind() == JavaKind.Double || normalizeNode.getX().getStackKind() == JavaKind.Float) {
152 // since we negate, we have to reverse the unordered result
153 compare = FloatLessThanNode.create(constantReflection, metaAccess, options, smallestCompareWidth, b, a, mirrored == normalizeNode.isUnorderedLess, view);
154 } else {
155 compare = IntegerLessThanNode.create(constantReflection, metaAccess, options, smallestCompareWidth, b, a, view);
156 }
157 return LogicNegationNode.create(compare);
158 } else if (cst <= -1) {
159 return LogicConstantNode.contradiction();
160 } else {
161 assert cst >= 2;
162 return LogicConstantNode.tautology();
163 }
164 }
165
166 @Override
167 protected LogicNode findSynonym(ValueNode forX, ValueNode forY, NodeView view) {
168 LogicNode result = super.findSynonym(forX, forY, view);
169 if (result != null) {
170 return result;
171 }
172 if (forX.stamp(view) instanceof IntegerStamp && forY.stamp(view) instanceof IntegerStamp) {
173 if (IntegerStamp.sameSign((IntegerStamp) forX.stamp(view), (IntegerStamp) forY.stamp(view))) {
174 return new IntegerBelowNode(forX, forY);
175 }
176 }
177
178 // Attempt to optimize the case where we can fold a constant from the left side (either
179 // from an add or sub) into the constant on the right side.
180 if (forY.isConstant()) {
181 if (forX instanceof SubNode) {
182 SubNode sub = (SubNode) forX;
183 ValueNode xx = null;
184 ValueNode yy = null;
185 boolean negate = false;
186 if (forY.asConstant().isDefaultForKind()) {
187 // (x - y) < 0 when x - y is known not to underflow <=> x < y
188 xx = sub.getX();
189 yy = sub.getY();
190 } else if (forY.isJavaConstant() && forY.asJavaConstant().asLong() == 1) {
191 // (x - y) < 1 when x - y is known not to underflow <=> !(y < x)
192 xx = sub.getY();
193 yy = sub.getX();
194 negate = true;
195 }
196 if (xx != null) {
197 assert yy != null;
198 IntegerStamp xStamp = (IntegerStamp) sub.getX().stamp(view);
199 IntegerStamp yStamp = (IntegerStamp) sub.getY().stamp(view);
200 long minValue = CodeUtil.minValue(xStamp.getBits());
201 long maxValue = CodeUtil.maxValue(xStamp.getBits());
202
203 if (!subtractMayUnderflow(xStamp.lowerBound(), yStamp.upperBound(), minValue) && !subtractMayOverflow(xStamp.upperBound(), yStamp.lowerBound(), maxValue)) {
204 LogicNode logic = new IntegerLessThanNode(xx, yy);
205 if (negate) {
206 logic = LogicNegationNode.create(logic);
207 }
208 return logic;
209 }
210 }
211 } else if (forX instanceof AddNode) {
212
213 // (x + xConstant) < forY => x < (forY - xConstant)
214 AddNode addNode = (AddNode) forX;
215 if (addNode.getY().isJavaConstant()) {
216 IntegerStamp xStamp = (IntegerStamp) addNode.getX().stamp(view);
217 if (!IntegerStamp.addCanOverflow(xStamp, (IntegerStamp) addNode.getY().stamp(view))) {
218 long minValue = CodeUtil.minValue(xStamp.getBits());
219 long maxValue = CodeUtil.maxValue(xStamp.getBits());
220 long yConstant = forY.asJavaConstant().asLong();
221 long xConstant = addNode.getY().asJavaConstant().asLong();
222 if (!subtractMayUnderflow(yConstant, xConstant, minValue) && !subtractMayOverflow(yConstant, xConstant, maxValue)) {
223 long newConstant = yConstant - xConstant;
224 return IntegerLessThanNode.create(addNode.getX(), ConstantNode.forIntegerStamp(xStamp, newConstant), view);
225 }
226 }
227 }
228
229 }
230 }
231
232 if (forX.stamp(view) instanceof IntegerStamp) {
233 assert forY.stamp(view) instanceof IntegerStamp;
234 int bits = ((IntegerStamp) forX.stamp(view)).getBits();
235 assert ((IntegerStamp) forY.stamp(view)).getBits() == bits;
236 LogicNode logic = canonicalizeRangeFlip(forX, forY, bits, true, view);
237 if (logic != null) {
238 return logic;
239 }
240 }
241 return null;
242 }
243
244 @Override
245 protected CanonicalCondition getCondition() {
246 return LT;
247 }
248
249 @Override
250 protected IntegerLowerThanNode createNode(ValueNode x, ValueNode y) {
251 return new IntegerLessThanNode(x, y);
252 }
253
254 @Override
255 protected long upperBound(IntegerStamp stamp) {
256 return stamp.upperBound();
257 }
258
259 @Override
260 protected long lowerBound(IntegerStamp stamp) {
261 return stamp.lowerBound();
262 }
263
264 @Override
265 protected int compare(long a, long b) {
266 return Long.compare(a, b);
267 }
268
269 @Override
270 protected long min(long a, long b) {
271 return Math.min(a, b);
272 }
273
274 @Override
275 protected long max(long a, long b) {
276 return Math.max(a, b);
277 }
278
279 @Override
280 protected long cast(long a, int bits) {
281 return CodeUtil.signExtend(a, bits);
282 }
283
284 @Override
285 protected long minValue(int bits) {
286 return NumUtil.minValue(bits);
287 }
288
289 @Override
290 protected long maxValue(int bits) {
291 return NumUtil.maxValue(bits);
292 }
293
294 @Override
295 protected IntegerStamp forInteger(int bits, long min, long max) {
296 return StampFactory.forInteger(bits, cast(min, bits), cast(max, bits));
297 }
298 }
299 }