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