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 import jdk.vm.ci.meta.TriState;
54
55 @NodeInfo(shortName = "<")
56 public final class IntegerLessThanNode extends IntegerLowerThanNode {
57 public static final NodeClass<IntegerLessThanNode> TYPE = NodeClass.create(IntegerLessThanNode.class);
58 private static final LessThanOp OP = new LessThanOp();
59
60 public IntegerLessThanNode(ValueNode x, ValueNode y) {
61 super(TYPE, x, y, OP);
62 assert !x.getStackKind().isNumericFloat() && x.getStackKind() != JavaKind.Object;
63 assert !y.getStackKind().isNumericFloat() && y.getStackKind() != JavaKind.Object;
64 }
65
66 public static LogicNode create(ValueNode x, ValueNode y, NodeView view) {
67 return OP.create(x, y, view);
68 }
69
70 public static LogicNode create(ConstantReflectionProvider constantReflection, MetaAccessProvider metaAccess, OptionValues options, Integer smallestCompareWidth,
71 ValueNode x, ValueNode y, NodeView view) {
72 LogicNode value = OP.canonical(constantReflection, metaAccess, options, smallestCompareWidth, OP.getCondition(), false, x, y, view);
73 if (value != null) {
74 return value;
75 }
76 return create(x, y, view);
77 }
78
79 @Override
80 public Node canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) {
81 NodeView view = NodeView.from(tool);
82 ValueNode value = OP.canonical(tool.getConstantReflection(), tool.getMetaAccess(), tool.getOptions(), tool.smallestCompareWidth(), OP.getCondition(), false, forX, forY, view);
83 if (value != null) {
84 return value;
85 }
86 return this;
87 }
88
89 public static boolean subtractMayUnderflow(long x, long y, long minValue) {
90 long r = x - y;
91 // HD 2-12 Overflow iff the arguments have different signs and
92 // the sign of the result is different than the sign of x
93 return (((x ^ y) & (x ^ r)) < 0) || r <= minValue;
94 }
95
96 public static boolean subtractMayOverflow(long x, long y, long maxValue) {
97 long r = x - y;
98 // HD 2-12 Overflow iff the arguments have different signs and
99 // the sign of the result is different than the sign of x
100 return (((x ^ y) & (x ^ r)) < 0) || r > maxValue;
101 }
102
103 public static class LessThanOp extends LowerOp {
104 @Override
105 protected CompareNode duplicateModified(ValueNode newX, ValueNode newY, boolean unorderedIsTrue, NodeView view) {
106 if (newX.stamp(view) instanceof FloatStamp && newY.stamp(view) instanceof FloatStamp) {
107 return new FloatLessThanNode(newX, newY, unorderedIsTrue); // TODO: Is the last arg
108 // supposed to be true?
109 } else if (newX.stamp(view) instanceof IntegerStamp && newY.stamp(view) instanceof IntegerStamp) {
110 return new IntegerLessThanNode(newX, newY);
111 }
112 throw GraalError.shouldNotReachHere();
113 }
114
115 @Override
116 protected LogicNode optimizeNormalizeCompare(ConstantReflectionProvider constantReflection, MetaAccessProvider metaAccess, OptionValues options, Integer smallestCompareWidth,
117 Constant constant, AbstractNormalizeCompareNode normalizeNode, boolean mirrored, NodeView view) {
118 PrimitiveConstant primitive = (PrimitiveConstant) constant;
119 /* @formatter:off
120 * a NC b < c (not mirrored)
121 * cases for c:
122 * 0 -> a < b
123 * [MIN, -1] -> false
124 * 1 -> a <= b
125 * [2, MAX] -> true
126 * unordered-is-less means unordered-is-true.
127 *
128 * c < a NC b (mirrored)
129 * cases for c:
130 * 0 -> a > b
131 * [1, MAX] -> false
132 * -1 -> a >= b
133 * [MIN, -2] -> true
134 * unordered-is-less means unordered-is-false.
135 *
136 * We can handle mirroring by swapping a & b and negating the constant.
137 * @formatter:on
138 */
139 long cst = mirrored ? -primitive.asLong() : primitive.asLong();
140
141 if (cst == 0) {
142 return normalizeNode.createLowerComparison(mirrored, constantReflection, metaAccess, options, smallestCompareWidth, view);
143 } else if (cst == 1) {
144 // a <= b <=> !(a > b)
145 // since we negate, we have to reverse the unordered result
146 LogicNode compare = normalizeNode.createLowerComparison(!mirrored, constantReflection, metaAccess, options, smallestCompareWidth, view);
147 return LogicNegationNode.create(compare);
148 } else if (cst <= -1) {
149 return LogicConstantNode.contradiction();
150 } else {
151 assert cst >= 2;
152 return LogicConstantNode.tautology();
153 }
154 }
155
156 @Override
157 protected LogicNode findSynonym(ValueNode forX, ValueNode forY, NodeView view) {
158 LogicNode result = super.findSynonym(forX, forY, view);
159 if (result != null) {
160 return result;
161 }
162 if (forX.stamp(view) instanceof IntegerStamp && forY.stamp(view) instanceof IntegerStamp) {
163 if (IntegerStamp.sameSign((IntegerStamp) forX.stamp(view), (IntegerStamp) forY.stamp(view))) {
164 return new IntegerBelowNode(forX, forY);
165 }
166 }
167
168 // Attempt to optimize the case where we can fold a constant from the left side (either
169 // from an add or sub) into the constant on the right side.
170 if (forY.isConstant()) {
171 if (forX instanceof SubNode) {
172 SubNode sub = (SubNode) forX;
173 ValueNode xx = null;
174 ValueNode yy = null;
175 boolean negate = false;
176 if (forY.asConstant().isDefaultForKind()) {
177 // (x - y) < 0 when x - y is known not to underflow <=> x < y
178 xx = sub.getX();
179 yy = sub.getY();
180 } else if (forY.isJavaConstant() && forY.asJavaConstant().asLong() == 1) {
181 // (x - y) < 1 when x - y is known not to underflow <=> !(y < x)
182 xx = sub.getY();
183 yy = sub.getX();
184 negate = true;
185 }
186 if (xx != null) {
187 assert yy != null;
188 IntegerStamp xStamp = (IntegerStamp) sub.getX().stamp(view);
189 IntegerStamp yStamp = (IntegerStamp) sub.getY().stamp(view);
190 long minValue = CodeUtil.minValue(xStamp.getBits());
191 long maxValue = CodeUtil.maxValue(xStamp.getBits());
192
193 if (!subtractMayUnderflow(xStamp.lowerBound(), yStamp.upperBound(), minValue) && !subtractMayOverflow(xStamp.upperBound(), yStamp.lowerBound(), maxValue)) {
194 LogicNode logic = new IntegerLessThanNode(xx, yy);
195 if (negate) {
196 logic = LogicNegationNode.create(logic);
197 }
198 return logic;
199 }
200 }
201 } else if (forX instanceof AddNode) {
202
203 // (x + xConstant) < forY => x < (forY - xConstant)
204 AddNode addNode = (AddNode) forX;
205 if (addNode.getY().isJavaConstant()) {
206 IntegerStamp xStamp = (IntegerStamp) addNode.getX().stamp(view);
207 if (!IntegerStamp.addCanOverflow(xStamp, (IntegerStamp) addNode.getY().stamp(view))) {
208 long minValue = CodeUtil.minValue(xStamp.getBits());
209 long maxValue = CodeUtil.maxValue(xStamp.getBits());
210 long yConstant = forY.asJavaConstant().asLong();
211 long xConstant = addNode.getY().asJavaConstant().asLong();
212 if (!subtractMayUnderflow(yConstant, xConstant, minValue) && !subtractMayOverflow(yConstant, xConstant, maxValue)) {
213 long newConstant = yConstant - xConstant;
214 return IntegerLessThanNode.create(addNode.getX(), ConstantNode.forIntegerStamp(xStamp, newConstant), view);
215 }
216 }
217 }
218 }
219 }
220
221 if (forX.stamp(view) instanceof IntegerStamp) {
222 assert forY.stamp(view) instanceof IntegerStamp;
223 int bits = ((IntegerStamp) forX.stamp(view)).getBits();
224 assert ((IntegerStamp) forY.stamp(view)).getBits() == bits;
225 LogicNode logic = canonicalizeRangeFlip(forX, forY, bits, true, view);
226 if (logic != null) {
227 return logic;
228 }
229 }
230 return null;
231 }
232
233 @Override
234 protected CanonicalCondition getCondition() {
235 return LT;
236 }
237
238 @Override
239 protected IntegerLowerThanNode createNode(ValueNode x, ValueNode y) {
240 return new IntegerLessThanNode(x, y);
241 }
242
243 @Override
244 protected long upperBound(IntegerStamp stamp) {
245 return stamp.upperBound();
246 }
247
248 @Override
249 protected long lowerBound(IntegerStamp stamp) {
250 return stamp.lowerBound();
251 }
252
253 @Override
254 protected int compare(long a, long b) {
255 return Long.compare(a, b);
256 }
257
258 @Override
259 protected long min(long a, long b) {
260 return Math.min(a, b);
261 }
262
263 @Override
264 protected long max(long a, long b) {
265 return Math.max(a, b);
266 }
267
268 @Override
269 protected long cast(long a, int bits) {
270 return CodeUtil.signExtend(a, bits);
271 }
272
273 @Override
274 protected long minValue(int bits) {
275 return NumUtil.minValue(bits);
276 }
277
278 @Override
279 protected long maxValue(int bits) {
280 return NumUtil.maxValue(bits);
281 }
282
283 @Override
284 protected IntegerStamp forInteger(int bits, long min, long max) {
285 return StampFactory.forInteger(bits, cast(min, bits), cast(max, bits));
286 }
287 }
288
289 @Override
290 public TriState implies(boolean thisNegated, LogicNode other) {
291 if (!thisNegated) {
292 if (other instanceof IntegerLessThanNode) {
293 ValueNode otherX = ((IntegerLessThanNode) other).getX();
294 ValueNode otherY = ((IntegerLessThanNode) other).getY();
295 // x < y => !y < x
296 if (getX() == otherY && getY() == otherX) {
297 return TriState.FALSE;
298 }
299 }
300
301 // x < y => !x == y
302 // x < y => !y == x
303 if (other instanceof IntegerEqualsNode) {
304 ValueNode otherX = ((IntegerEqualsNode) other).getX();
305 ValueNode otherY = ((IntegerEqualsNode) other).getY();
306 if ((getX() == otherX && getY() == otherY) || (getX() == otherY && getY() == otherX)) {
307 return TriState.FALSE;
308 }
309 }
310 }
311 return super.implies(thisNegated, other);
312 }
313 }