1 /* 2 * Copyright (c) 2019, 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.phases.common; 26 27 import jdk.internal.vm.compiler.collections.Pair; 28 import org.graalvm.compiler.core.common.type.IntegerStamp; 29 import org.graalvm.compiler.nodes.ConstantNode; 30 import org.graalvm.compiler.nodes.FixedNode; 31 import org.graalvm.compiler.nodes.NodeView; 32 import org.graalvm.compiler.nodes.StructuredGraph; 33 import org.graalvm.compiler.nodes.ValueNode; 34 import org.graalvm.compiler.nodes.calc.BinaryArithmeticNode; 35 import org.graalvm.compiler.nodes.calc.IntegerDivRemNode; 36 import org.graalvm.compiler.nodes.calc.IntegerMulHighNode; 37 import org.graalvm.compiler.nodes.calc.MulNode; 38 import org.graalvm.compiler.nodes.calc.NarrowNode; 39 import org.graalvm.compiler.nodes.calc.RightShiftNode; 40 import org.graalvm.compiler.nodes.calc.SignExtendNode; 41 import org.graalvm.compiler.nodes.calc.SignedDivNode; 42 import org.graalvm.compiler.nodes.calc.SignedRemNode; 43 import org.graalvm.compiler.nodes.calc.UnsignedRightShiftNode; 44 import org.graalvm.compiler.phases.Phase; 45 46 import jdk.vm.ci.code.CodeUtil; 47 48 public class OptimizeDivPhase extends Phase { 49 50 @Override 51 protected void run(StructuredGraph graph) { 52 for (IntegerDivRemNode rem : graph.getNodes(IntegerDivRemNode.TYPE)) { 53 if (rem instanceof SignedRemNode && divByNonZeroConstant(rem)) { 54 optimizeRem(rem); 55 } 56 } 57 for (IntegerDivRemNode div : graph.getNodes(IntegerDivRemNode.TYPE)) { 58 if (div instanceof SignedDivNode && divByNonZeroConstant(div)) { 59 optimizeSignedDiv((SignedDivNode) div); 60 } 61 } 62 } 63 64 @Override 65 public float codeSizeIncrease() { 66 return 5.0f; 67 } 68 69 protected static boolean divByNonZeroConstant(IntegerDivRemNode divRemNode) { 70 return divRemNode.getY().isConstant() && divRemNode.getY().asJavaConstant().asLong() != 0; 71 } 72 73 protected final void optimizeRem(IntegerDivRemNode rem) { 74 assert rem.getOp() == IntegerDivRemNode.Op.REM; 75 // Java spec 15.17.3.: (a/b)*b+(a%b) == a 76 // so a%b == a-(a/b)*b 77 StructuredGraph graph = rem.graph(); 78 ValueNode div = findDivForRem(rem); 79 ValueNode mul = BinaryArithmeticNode.mul(graph, div, rem.getY(), NodeView.DEFAULT); 80 ValueNode result = BinaryArithmeticNode.sub(graph, rem.getX(), mul, NodeView.DEFAULT); 81 graph.replaceFixedWithFloating(rem, result); 82 } 83 84 private ValueNode findDivForRem(IntegerDivRemNode rem) { 85 if (rem.next() instanceof IntegerDivRemNode) { 86 IntegerDivRemNode div = (IntegerDivRemNode) rem.next(); 87 if (div.getOp() == IntegerDivRemNode.Op.DIV && div.getType() == rem.getType() && div.getX() == rem.getX() && div.getY() == rem.getY()) { 88 return div; 89 } 90 } 91 if (rem.predecessor() instanceof IntegerDivRemNode) { 92 IntegerDivRemNode div = (IntegerDivRemNode) rem.predecessor(); 93 if (div.getOp() == IntegerDivRemNode.Op.DIV && div.getType() == rem.getType() && div.getX() == rem.getX() && div.getY() == rem.getY()) { 94 return div; 95 } 96 } 97 98 // not found, create a new one (will be optimized away later) 99 ValueNode div = rem.graph().addOrUniqueWithInputs(createDiv(rem)); 100 if (div instanceof FixedNode) { 101 rem.graph().addAfterFixed(rem, (FixedNode) div); 102 } 103 return div; 104 } 105 106 protected ValueNode createDiv(IntegerDivRemNode rem) { 107 assert rem instanceof SignedRemNode; 108 return SignedDivNode.create(rem.getX(), rem.getY(), rem.getZeroCheck(), NodeView.DEFAULT); 109 } 110 111 protected static void optimizeSignedDiv(SignedDivNode div) { 112 ValueNode forX = div.getX(); 113 long c = div.getY().asJavaConstant().asLong(); 114 assert c != 1 && c != -1 && c != 0; 115 116 IntegerStamp dividendStamp = (IntegerStamp) forX.stamp(NodeView.DEFAULT); 117 int bitSize = dividendStamp.getBits(); 118 Pair<Long, Integer> nums = magicDivideConstants(c, bitSize); 119 long magicNum = nums.getLeft().longValue(); 120 int shiftNum = nums.getRight().intValue(); 121 assert shiftNum >= 0; 122 ConstantNode m = ConstantNode.forLong(magicNum); 123 124 ValueNode value; 125 if (bitSize == 32) { 126 value = new MulNode(new SignExtendNode(forX, 64), m); 127 if ((c > 0 && magicNum < 0) || (c < 0 && magicNum > 0)) { 128 // Get upper 32-bits of the result 129 value = NarrowNode.create(new RightShiftNode(value, ConstantNode.forInt(32)), 32, NodeView.DEFAULT); 130 if (c > 0) { 131 value = BinaryArithmeticNode.add(value, forX, NodeView.DEFAULT); 132 } else { 133 value = BinaryArithmeticNode.sub(value, forX, NodeView.DEFAULT); 134 } 135 if (shiftNum > 0) { 136 value = new RightShiftNode(value, ConstantNode.forInt(shiftNum)); 137 } 138 } else { 139 value = new RightShiftNode(value, ConstantNode.forInt(32 + shiftNum)); 140 value = new NarrowNode(value, Integer.SIZE); 141 } 142 } else { 143 assert bitSize == 64; 144 value = new IntegerMulHighNode(forX, m); 145 if (c > 0 && magicNum < 0) { 146 value = BinaryArithmeticNode.add(value, forX, NodeView.DEFAULT); 147 } else if (c < 0 && magicNum > 0) { 148 value = BinaryArithmeticNode.sub(value, forX, NodeView.DEFAULT); 149 } 150 if (shiftNum > 0) { 151 value = new RightShiftNode(value, ConstantNode.forInt(shiftNum)); 152 } 153 } 154 155 if (c < 0) { 156 ConstantNode s = ConstantNode.forInt(bitSize - 1); 157 ValueNode sign = UnsignedRightShiftNode.create(value, s, NodeView.DEFAULT); 158 value = BinaryArithmeticNode.add(value, sign, NodeView.DEFAULT); 159 } else if (dividendStamp.canBeNegative()) { 160 ConstantNode s = ConstantNode.forInt(bitSize - 1); 161 ValueNode sign = UnsignedRightShiftNode.create(forX, s, NodeView.DEFAULT); 162 value = BinaryArithmeticNode.add(value, sign, NodeView.DEFAULT); 163 } 164 165 StructuredGraph graph = div.graph(); 166 graph.replaceFixed(div, graph.addOrUniqueWithInputs(value)); 167 } 168 169 /** 170 * Borrowed from Hacker's Delight by Henry S. Warren, Jr. Figure 10-1. 171 */ 172 private static Pair<Long, Integer> magicDivideConstants(long divisor, int size) { 173 final long twoW = 1L << (size - 1); // 2 ^ (size - 1). 174 long t = twoW + (divisor >>> 63); 175 long ad = Math.abs(divisor); 176 long anc = t - 1 - Long.remainderUnsigned(t, ad); // Absolute value of nc. 177 long q1 = Long.divideUnsigned(twoW, anc); // Init. q1 = 2**p/|nc|. 178 long r1 = Long.remainderUnsigned(twoW, anc); // Init. r1 = rem(2**p, |nc|). 179 long q2 = Long.divideUnsigned(twoW, ad); // Init. q2 = 2**p/|d|. 180 long r2 = Long.remainderUnsigned(twoW, ad); // Init. r2 = rem(2**p, |d|). 181 long delta; 182 183 int p = size - 1; // Init. p. 184 do { 185 p = p + 1; 186 q1 = 2 * q1; // Update q1 = 2**p/|nc|. 187 r1 = 2 * r1; // Update r1 = rem(2**p, |nc|). 188 if (Long.compareUnsigned(r1, anc) >= 0) { // Must be an unsigned comparison. 189 q1 = q1 + 1; 190 r1 = r1 - anc; 191 } 192 q2 = 2 * q2; // Update q2 = 2**p/|d|. 193 r2 = 2 * r2; // Update r2 = rem(2**p, |d|). 194 if (Long.compareUnsigned(r2, ad) >= 0) { // Must be an unsigned comparison. 195 q2 = q2 + 1; 196 r2 = r2 - ad; 197 } 198 delta = ad - r2; 199 } while (Long.compareUnsigned(q1, delta) < 0 || (q1 == delta && r1 == 0)); 200 201 long magic = CodeUtil.signExtend(q2 + 1, size); 202 if (divisor < 0) { 203 magic = -magic; 204 } 205 return Pair.create(magic, p - size); 206 } 207 208 }