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1 /* |
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2 * Copyright 1999-2006 Sun Microsystems, Inc. All Rights Reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Sun designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Sun in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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22 * CA 95054 USA or visit www.sun.com if you need additional information or |
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23 * have any questions. |
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24 */ |
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25 |
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26 package com.sun.tools.javac.comp; |
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27 |
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28 import com.sun.tools.javac.code.*; |
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29 import com.sun.tools.javac.jvm.*; |
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30 import com.sun.tools.javac.util.*; |
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31 |
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32 import com.sun.tools.javac.code.Type.*; |
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33 |
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34 import static com.sun.tools.javac.code.TypeTags.*; |
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35 import static com.sun.tools.javac.jvm.ByteCodes.*; |
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36 |
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37 /** Helper class for constant folding, used by the attribution phase. |
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38 * This class is marked strictfp as mandated by JLS 15.4. |
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39 * |
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40 * <p><b>This is NOT part of any API supported by Sun Microsystems. If |
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41 * you write code that depends on this, you do so at your own risk. |
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42 * This code and its internal interfaces are subject to change or |
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43 * deletion without notice.</b> |
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44 */ |
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45 strictfp class ConstFold { |
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46 protected static final Context.Key<ConstFold> constFoldKey = |
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47 new Context.Key<ConstFold>(); |
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48 |
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49 private Symtab syms; |
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50 |
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51 public static ConstFold instance(Context context) { |
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52 ConstFold instance = context.get(constFoldKey); |
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53 if (instance == null) |
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54 instance = new ConstFold(context); |
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55 return instance; |
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56 } |
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57 |
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58 private ConstFold(Context context) { |
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59 context.put(constFoldKey, this); |
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60 |
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61 syms = Symtab.instance(context); |
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62 } |
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63 |
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64 static Integer minusOne = -1; |
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65 static Integer zero = 0; |
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66 static Integer one = 1; |
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67 |
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68 /** Convert boolean to integer (true = 1, false = 0). |
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69 */ |
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70 private static Integer b2i(boolean b) { |
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71 return b ? one : zero; |
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72 } |
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73 private static int intValue(Object x) { return ((Number)x).intValue(); } |
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74 private static long longValue(Object x) { return ((Number)x).longValue(); } |
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75 private static float floatValue(Object x) { return ((Number)x).floatValue(); } |
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76 private static double doubleValue(Object x) { return ((Number)x).doubleValue(); } |
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77 |
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78 /** Fold binary or unary operation, returning constant type reflecting the |
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79 * operations result. Return null if fold failed due to an |
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80 * arithmetic exception. |
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81 * @param opcode The operation's opcode instruction (usually a byte code), |
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82 * as entered by class Symtab. |
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83 * @param argtypes The operation's argument types (a list of length 1 or 2). |
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84 * Argument types are assumed to have non-null constValue's. |
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85 */ |
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86 Type fold(int opcode, List<Type> argtypes) { |
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87 int argCount = argtypes.length(); |
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88 if (argCount == 1) |
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89 return fold1(opcode, argtypes.head); |
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90 else if (argCount == 2) |
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91 return fold2(opcode, argtypes.head, argtypes.tail.head); |
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92 else |
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93 throw new AssertionError(); |
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94 } |
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95 |
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96 /** Fold unary operation. |
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97 * @param opcode The operation's opcode instruction (usually a byte code), |
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98 * as entered by class Symtab. |
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99 * opcode's ifeq to ifge are for postprocessing |
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100 * xcmp; ifxx pairs of instructions. |
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101 * @param operand The operation's operand type. |
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102 * Argument types are assumed to have non-null constValue's. |
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103 */ |
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104 Type fold1(int opcode, Type operand) { |
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105 try { |
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106 Object od = operand.constValue(); |
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107 switch (opcode) { |
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108 case nop: |
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109 return operand; |
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110 case ineg: // unary - |
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111 return syms.intType.constType(-intValue(od)); |
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112 case ixor: // ~ |
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113 return syms.intType.constType(~intValue(od)); |
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114 case bool_not: // ! |
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115 return syms.booleanType.constType(b2i(intValue(od) == 0)); |
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116 case ifeq: |
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117 return syms.booleanType.constType(b2i(intValue(od) == 0)); |
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118 case ifne: |
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119 return syms.booleanType.constType(b2i(intValue(od) != 0)); |
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120 case iflt: |
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121 return syms.booleanType.constType(b2i(intValue(od) < 0)); |
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122 case ifgt: |
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123 return syms.booleanType.constType(b2i(intValue(od) > 0)); |
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124 case ifle: |
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125 return syms.booleanType.constType(b2i(intValue(od) <= 0)); |
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126 case ifge: |
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127 return syms.booleanType.constType(b2i(intValue(od) >= 0)); |
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128 |
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129 case lneg: // unary - |
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130 return syms.longType.constType(new Long(-longValue(od))); |
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131 case lxor: // ~ |
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132 return syms.longType.constType(new Long(~longValue(od))); |
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133 |
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134 case fneg: // unary - |
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135 return syms.floatType.constType(new Float(-floatValue(od))); |
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136 |
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137 case dneg: // ~ |
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138 return syms.doubleType.constType(new Double(-doubleValue(od))); |
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139 |
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140 default: |
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141 return null; |
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142 } |
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143 } catch (ArithmeticException e) { |
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144 return null; |
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145 } |
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146 } |
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147 |
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148 /** Fold binary operation. |
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149 * @param opcode The operation's opcode instruction (usually a byte code), |
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150 * as entered by class Symtab. |
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151 * opcode's ifeq to ifge are for postprocessing |
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152 * xcmp; ifxx pairs of instructions. |
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153 * @param left The type of the operation's left operand. |
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154 * @param right The type of the operation's right operand. |
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155 */ |
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156 Type fold2(int opcode, Type left, Type right) { |
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157 try { |
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158 if (opcode > ByteCodes.preMask) { |
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159 // we are seeing a composite instruction of the form xcmp; ifxx. |
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160 // In this case fold both instructions separately. |
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161 Type t1 = fold2(opcode >> ByteCodes.preShift, left, right); |
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162 return (t1.constValue() == null) ? t1 |
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163 : fold1(opcode & ByteCodes.preMask, t1); |
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164 } else { |
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165 Object l = left.constValue(); |
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166 Object r = right.constValue(); |
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167 switch (opcode) { |
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168 case iadd: |
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169 return syms.intType.constType(intValue(l) + intValue(r)); |
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170 case isub: |
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171 return syms.intType.constType(intValue(l) - intValue(r)); |
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172 case imul: |
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173 return syms.intType.constType(intValue(l) * intValue(r)); |
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174 case idiv: |
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175 return syms.intType.constType(intValue(l) / intValue(r)); |
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176 case imod: |
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177 return syms.intType.constType(intValue(l) % intValue(r)); |
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178 case iand: |
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179 return (left.tag == BOOLEAN |
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180 ? syms.booleanType : syms.intType) |
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181 .constType(intValue(l) & intValue(r)); |
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182 case bool_and: |
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183 return syms.booleanType.constType(b2i((intValue(l) & intValue(r)) != 0)); |
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184 case ior: |
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185 return (left.tag == BOOLEAN |
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186 ? syms.booleanType : syms.intType) |
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187 .constType(intValue(l) | intValue(r)); |
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188 case bool_or: |
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189 return syms.booleanType.constType(b2i((intValue(l) | intValue(r)) != 0)); |
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190 case ixor: |
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191 return (left.tag == BOOLEAN |
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192 ? syms.booleanType : syms.intType) |
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193 .constType(intValue(l) ^ intValue(r)); |
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194 case ishl: case ishll: |
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195 return syms.intType.constType(intValue(l) << intValue(r)); |
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196 case ishr: case ishrl: |
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197 return syms.intType.constType(intValue(l) >> intValue(r)); |
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198 case iushr: case iushrl: |
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199 return syms.intType.constType(intValue(l) >>> intValue(r)); |
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200 case if_icmpeq: |
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201 return syms.booleanType.constType( |
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202 b2i(intValue(l) == intValue(r))); |
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203 case if_icmpne: |
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204 return syms.booleanType.constType( |
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205 b2i(intValue(l) != intValue(r))); |
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206 case if_icmplt: |
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207 return syms.booleanType.constType( |
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208 b2i(intValue(l) < intValue(r))); |
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209 case if_icmpgt: |
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210 return syms.booleanType.constType( |
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211 b2i(intValue(l) > intValue(r))); |
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212 case if_icmple: |
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213 return syms.booleanType.constType( |
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214 b2i(intValue(l) <= intValue(r))); |
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215 case if_icmpge: |
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216 return syms.booleanType.constType( |
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217 b2i(intValue(l) >= intValue(r))); |
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218 |
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219 case ladd: |
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220 return syms.longType.constType( |
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221 new Long(longValue(l) + longValue(r))); |
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222 case lsub: |
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223 return syms.longType.constType( |
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224 new Long(longValue(l) - longValue(r))); |
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225 case lmul: |
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226 return syms.longType.constType( |
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227 new Long(longValue(l) * longValue(r))); |
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228 case ldiv: |
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229 return syms.longType.constType( |
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230 new Long(longValue(l) / longValue(r))); |
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231 case lmod: |
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232 return syms.longType.constType( |
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233 new Long(longValue(l) % longValue(r))); |
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234 case land: |
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235 return syms.longType.constType( |
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236 new Long(longValue(l) & longValue(r))); |
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237 case lor: |
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238 return syms.longType.constType( |
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239 new Long(longValue(l) | longValue(r))); |
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240 case lxor: |
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241 return syms.longType.constType( |
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242 new Long(longValue(l) ^ longValue(r))); |
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243 case lshl: case lshll: |
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244 return syms.longType.constType( |
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245 new Long(longValue(l) << intValue(r))); |
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246 case lshr: case lshrl: |
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247 return syms.longType.constType( |
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248 new Long(longValue(l) >> intValue(r))); |
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249 case lushr: |
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250 return syms.longType.constType( |
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251 new Long(longValue(l) >>> intValue(r))); |
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252 case lcmp: |
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253 if (longValue(l) < longValue(r)) |
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254 return syms.intType.constType(minusOne); |
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255 else if (longValue(l) > longValue(r)) |
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256 return syms.intType.constType(one); |
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257 else |
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258 return syms.intType.constType(zero); |
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259 case fadd: |
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260 return syms.floatType.constType( |
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261 new Float(floatValue(l) + floatValue(r))); |
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262 case fsub: |
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263 return syms.floatType.constType( |
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264 new Float(floatValue(l) - floatValue(r))); |
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265 case fmul: |
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266 return syms.floatType.constType( |
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267 new Float(floatValue(l) * floatValue(r))); |
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268 case fdiv: |
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269 return syms.floatType.constType( |
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270 new Float(floatValue(l) / floatValue(r))); |
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271 case fmod: |
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272 return syms.floatType.constType( |
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273 new Float(floatValue(l) % floatValue(r))); |
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274 case fcmpg: case fcmpl: |
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275 if (floatValue(l) < floatValue(r)) |
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276 return syms.intType.constType(minusOne); |
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277 else if (floatValue(l) > floatValue(r)) |
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278 return syms.intType.constType(one); |
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279 else if (floatValue(l) == floatValue(r)) |
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280 return syms.intType.constType(zero); |
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281 else if (opcode == fcmpg) |
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282 return syms.intType.constType(one); |
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283 else |
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284 return syms.intType.constType(minusOne); |
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285 case dadd: |
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286 return syms.doubleType.constType( |
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287 new Double(doubleValue(l) + doubleValue(r))); |
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288 case dsub: |
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289 return syms.doubleType.constType( |
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290 new Double(doubleValue(l) - doubleValue(r))); |
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291 case dmul: |
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292 return syms.doubleType.constType( |
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293 new Double(doubleValue(l) * doubleValue(r))); |
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294 case ddiv: |
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295 return syms.doubleType.constType( |
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296 new Double(doubleValue(l) / doubleValue(r))); |
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297 case dmod: |
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298 return syms.doubleType.constType( |
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299 new Double(doubleValue(l) % doubleValue(r))); |
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300 case dcmpg: case dcmpl: |
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301 if (doubleValue(l) < doubleValue(r)) |
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302 return syms.intType.constType(minusOne); |
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303 else if (doubleValue(l) > doubleValue(r)) |
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304 return syms.intType.constType(one); |
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305 else if (doubleValue(l) == doubleValue(r)) |
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306 return syms.intType.constType(zero); |
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307 else if (opcode == dcmpg) |
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308 return syms.intType.constType(one); |
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309 else |
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310 return syms.intType.constType(minusOne); |
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311 case if_acmpeq: |
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312 return syms.booleanType.constType(b2i(l.equals(r))); |
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313 case if_acmpne: |
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314 return syms.booleanType.constType(b2i(!l.equals(r))); |
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315 case string_add: |
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316 return syms.stringType.constType( |
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317 left.stringValue() + right.stringValue()); |
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318 default: |
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319 return null; |
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320 } |
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321 } |
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322 } catch (ArithmeticException e) { |
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323 return null; |
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324 } |
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325 } |
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326 |
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327 /** Coerce constant type to target type. |
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328 * @param etype The source type of the coercion, |
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329 * which is assumed to be a constant type compatble with |
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330 * ttype. |
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331 * @param ttype The target type of the coercion. |
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332 */ |
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333 Type coerce(Type etype, Type ttype) { |
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334 // WAS if (etype.baseType() == ttype.baseType()) |
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335 if (etype.tsym.type == ttype.tsym.type) |
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336 return etype; |
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337 if (etype.tag <= DOUBLE) { |
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338 Object n = etype.constValue(); |
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339 switch (ttype.tag) { |
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340 case BYTE: |
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341 return syms.byteType.constType(0 + (byte)intValue(n)); |
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342 case CHAR: |
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343 return syms.charType.constType(0 + (char)intValue(n)); |
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344 case SHORT: |
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345 return syms.shortType.constType(0 + (short)intValue(n)); |
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346 case INT: |
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347 return syms.intType.constType(intValue(n)); |
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348 case LONG: |
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349 return syms.longType.constType(longValue(n)); |
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350 case FLOAT: |
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351 return syms.floatType.constType(floatValue(n)); |
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352 case DOUBLE: |
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353 return syms.doubleType.constType(doubleValue(n)); |
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354 } |
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355 } |
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356 return ttype; |
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357 } |
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358 } |