1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/classes/com/sun/tools/javac/comp/ConstFold.java Wed Apr 27 01:34:52 2016 +0800
1.3 @@ -0,0 +1,357 @@
1.4 +/*
1.5 + * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Oracle designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Oracle in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 + * or visit www.oracle.com if you need additional information or have any
1.26 + * questions.
1.27 + */
1.28 +
1.29 +package com.sun.tools.javac.comp;
1.30 +
1.31 +import com.sun.tools.javac.code.*;
1.32 +import com.sun.tools.javac.jvm.*;
1.33 +import com.sun.tools.javac.util.*;
1.34 +
1.35 +import static com.sun.tools.javac.code.TypeTag.BOOLEAN;
1.36 +
1.37 +import static com.sun.tools.javac.jvm.ByteCodes.*;
1.38 +
1.39 +/** Helper class for constant folding, used by the attribution phase.
1.40 + * This class is marked strictfp as mandated by JLS 15.4.
1.41 + *
1.42 + * <p><b>This is NOT part of any supported API.
1.43 + * If you write code that depends on this, you do so at your own risk.
1.44 + * This code and its internal interfaces are subject to change or
1.45 + * deletion without notice.</b>
1.46 + */
1.47 +strictfp class ConstFold {
1.48 + protected static final Context.Key<ConstFold> constFoldKey =
1.49 + new Context.Key<ConstFold>();
1.50 +
1.51 + private Symtab syms;
1.52 +
1.53 + public static ConstFold instance(Context context) {
1.54 + ConstFold instance = context.get(constFoldKey);
1.55 + if (instance == null)
1.56 + instance = new ConstFold(context);
1.57 + return instance;
1.58 + }
1.59 +
1.60 + private ConstFold(Context context) {
1.61 + context.put(constFoldKey, this);
1.62 +
1.63 + syms = Symtab.instance(context);
1.64 + }
1.65 +
1.66 + static final Integer minusOne = -1;
1.67 + static final Integer zero = 0;
1.68 + static final Integer one = 1;
1.69 +
1.70 + /** Convert boolean to integer (true = 1, false = 0).
1.71 + */
1.72 + private static Integer b2i(boolean b) {
1.73 + return b ? one : zero;
1.74 + }
1.75 + private static int intValue(Object x) { return ((Number)x).intValue(); }
1.76 + private static long longValue(Object x) { return ((Number)x).longValue(); }
1.77 + private static float floatValue(Object x) { return ((Number)x).floatValue(); }
1.78 + private static double doubleValue(Object x) { return ((Number)x).doubleValue(); }
1.79 +
1.80 + /** Fold binary or unary operation, returning constant type reflecting the
1.81 + * operations result. Return null if fold failed due to an
1.82 + * arithmetic exception.
1.83 + * @param opcode The operation's opcode instruction (usually a byte code),
1.84 + * as entered by class Symtab.
1.85 + * @param argtypes The operation's argument types (a list of length 1 or 2).
1.86 + * Argument types are assumed to have non-null constValue's.
1.87 + */
1.88 + Type fold(int opcode, List<Type> argtypes) {
1.89 + int argCount = argtypes.length();
1.90 + if (argCount == 1)
1.91 + return fold1(opcode, argtypes.head);
1.92 + else if (argCount == 2)
1.93 + return fold2(opcode, argtypes.head, argtypes.tail.head);
1.94 + else
1.95 + throw new AssertionError();
1.96 + }
1.97 +
1.98 + /** Fold unary operation.
1.99 + * @param opcode The operation's opcode instruction (usually a byte code),
1.100 + * as entered by class Symtab.
1.101 + * opcode's ifeq to ifge are for postprocessing
1.102 + * xcmp; ifxx pairs of instructions.
1.103 + * @param operand The operation's operand type.
1.104 + * Argument types are assumed to have non-null constValue's.
1.105 + */
1.106 + Type fold1(int opcode, Type operand) {
1.107 + try {
1.108 + Object od = operand.constValue();
1.109 + switch (opcode) {
1.110 + case nop:
1.111 + return operand;
1.112 + case ineg: // unary -
1.113 + return syms.intType.constType(-intValue(od));
1.114 + case ixor: // ~
1.115 + return syms.intType.constType(~intValue(od));
1.116 + case bool_not: // !
1.117 + return syms.booleanType.constType(b2i(intValue(od) == 0));
1.118 + case ifeq:
1.119 + return syms.booleanType.constType(b2i(intValue(od) == 0));
1.120 + case ifne:
1.121 + return syms.booleanType.constType(b2i(intValue(od) != 0));
1.122 + case iflt:
1.123 + return syms.booleanType.constType(b2i(intValue(od) < 0));
1.124 + case ifgt:
1.125 + return syms.booleanType.constType(b2i(intValue(od) > 0));
1.126 + case ifle:
1.127 + return syms.booleanType.constType(b2i(intValue(od) <= 0));
1.128 + case ifge:
1.129 + return syms.booleanType.constType(b2i(intValue(od) >= 0));
1.130 +
1.131 + case lneg: // unary -
1.132 + return syms.longType.constType(new Long(-longValue(od)));
1.133 + case lxor: // ~
1.134 + return syms.longType.constType(new Long(~longValue(od)));
1.135 +
1.136 + case fneg: // unary -
1.137 + return syms.floatType.constType(new Float(-floatValue(od)));
1.138 +
1.139 + case dneg: // ~
1.140 + return syms.doubleType.constType(new Double(-doubleValue(od)));
1.141 +
1.142 + default:
1.143 + return null;
1.144 + }
1.145 + } catch (ArithmeticException e) {
1.146 + return null;
1.147 + }
1.148 + }
1.149 +
1.150 + /** Fold binary operation.
1.151 + * @param opcode The operation's opcode instruction (usually a byte code),
1.152 + * as entered by class Symtab.
1.153 + * opcode's ifeq to ifge are for postprocessing
1.154 + * xcmp; ifxx pairs of instructions.
1.155 + * @param left The type of the operation's left operand.
1.156 + * @param right The type of the operation's right operand.
1.157 + */
1.158 + Type fold2(int opcode, Type left, Type right) {
1.159 + try {
1.160 + if (opcode > ByteCodes.preMask) {
1.161 + // we are seeing a composite instruction of the form xcmp; ifxx.
1.162 + // In this case fold both instructions separately.
1.163 + Type t1 = fold2(opcode >> ByteCodes.preShift, left, right);
1.164 + return (t1.constValue() == null) ? t1
1.165 + : fold1(opcode & ByteCodes.preMask, t1);
1.166 + } else {
1.167 + Object l = left.constValue();
1.168 + Object r = right.constValue();
1.169 + switch (opcode) {
1.170 + case iadd:
1.171 + return syms.intType.constType(intValue(l) + intValue(r));
1.172 + case isub:
1.173 + return syms.intType.constType(intValue(l) - intValue(r));
1.174 + case imul:
1.175 + return syms.intType.constType(intValue(l) * intValue(r));
1.176 + case idiv:
1.177 + return syms.intType.constType(intValue(l) / intValue(r));
1.178 + case imod:
1.179 + return syms.intType.constType(intValue(l) % intValue(r));
1.180 + case iand:
1.181 + return (left.hasTag(BOOLEAN)
1.182 + ? syms.booleanType : syms.intType)
1.183 + .constType(intValue(l) & intValue(r));
1.184 + case bool_and:
1.185 + return syms.booleanType.constType(b2i((intValue(l) & intValue(r)) != 0));
1.186 + case ior:
1.187 + return (left.hasTag(BOOLEAN)
1.188 + ? syms.booleanType : syms.intType)
1.189 + .constType(intValue(l) | intValue(r));
1.190 + case bool_or:
1.191 + return syms.booleanType.constType(b2i((intValue(l) | intValue(r)) != 0));
1.192 + case ixor:
1.193 + return (left.hasTag(BOOLEAN)
1.194 + ? syms.booleanType : syms.intType)
1.195 + .constType(intValue(l) ^ intValue(r));
1.196 + case ishl: case ishll:
1.197 + return syms.intType.constType(intValue(l) << intValue(r));
1.198 + case ishr: case ishrl:
1.199 + return syms.intType.constType(intValue(l) >> intValue(r));
1.200 + case iushr: case iushrl:
1.201 + return syms.intType.constType(intValue(l) >>> intValue(r));
1.202 + case if_icmpeq:
1.203 + return syms.booleanType.constType(
1.204 + b2i(intValue(l) == intValue(r)));
1.205 + case if_icmpne:
1.206 + return syms.booleanType.constType(
1.207 + b2i(intValue(l) != intValue(r)));
1.208 + case if_icmplt:
1.209 + return syms.booleanType.constType(
1.210 + b2i(intValue(l) < intValue(r)));
1.211 + case if_icmpgt:
1.212 + return syms.booleanType.constType(
1.213 + b2i(intValue(l) > intValue(r)));
1.214 + case if_icmple:
1.215 + return syms.booleanType.constType(
1.216 + b2i(intValue(l) <= intValue(r)));
1.217 + case if_icmpge:
1.218 + return syms.booleanType.constType(
1.219 + b2i(intValue(l) >= intValue(r)));
1.220 +
1.221 + case ladd:
1.222 + return syms.longType.constType(
1.223 + new Long(longValue(l) + longValue(r)));
1.224 + case lsub:
1.225 + return syms.longType.constType(
1.226 + new Long(longValue(l) - longValue(r)));
1.227 + case lmul:
1.228 + return syms.longType.constType(
1.229 + new Long(longValue(l) * longValue(r)));
1.230 + case ldiv:
1.231 + return syms.longType.constType(
1.232 + new Long(longValue(l) / longValue(r)));
1.233 + case lmod:
1.234 + return syms.longType.constType(
1.235 + new Long(longValue(l) % longValue(r)));
1.236 + case land:
1.237 + return syms.longType.constType(
1.238 + new Long(longValue(l) & longValue(r)));
1.239 + case lor:
1.240 + return syms.longType.constType(
1.241 + new Long(longValue(l) | longValue(r)));
1.242 + case lxor:
1.243 + return syms.longType.constType(
1.244 + new Long(longValue(l) ^ longValue(r)));
1.245 + case lshl: case lshll:
1.246 + return syms.longType.constType(
1.247 + new Long(longValue(l) << intValue(r)));
1.248 + case lshr: case lshrl:
1.249 + return syms.longType.constType(
1.250 + new Long(longValue(l) >> intValue(r)));
1.251 + case lushr:
1.252 + return syms.longType.constType(
1.253 + new Long(longValue(l) >>> intValue(r)));
1.254 + case lcmp:
1.255 + if (longValue(l) < longValue(r))
1.256 + return syms.intType.constType(minusOne);
1.257 + else if (longValue(l) > longValue(r))
1.258 + return syms.intType.constType(one);
1.259 + else
1.260 + return syms.intType.constType(zero);
1.261 + case fadd:
1.262 + return syms.floatType.constType(
1.263 + new Float(floatValue(l) + floatValue(r)));
1.264 + case fsub:
1.265 + return syms.floatType.constType(
1.266 + new Float(floatValue(l) - floatValue(r)));
1.267 + case fmul:
1.268 + return syms.floatType.constType(
1.269 + new Float(floatValue(l) * floatValue(r)));
1.270 + case fdiv:
1.271 + return syms.floatType.constType(
1.272 + new Float(floatValue(l) / floatValue(r)));
1.273 + case fmod:
1.274 + return syms.floatType.constType(
1.275 + new Float(floatValue(l) % floatValue(r)));
1.276 + case fcmpg: case fcmpl:
1.277 + if (floatValue(l) < floatValue(r))
1.278 + return syms.intType.constType(minusOne);
1.279 + else if (floatValue(l) > floatValue(r))
1.280 + return syms.intType.constType(one);
1.281 + else if (floatValue(l) == floatValue(r))
1.282 + return syms.intType.constType(zero);
1.283 + else if (opcode == fcmpg)
1.284 + return syms.intType.constType(one);
1.285 + else
1.286 + return syms.intType.constType(minusOne);
1.287 + case dadd:
1.288 + return syms.doubleType.constType(
1.289 + new Double(doubleValue(l) + doubleValue(r)));
1.290 + case dsub:
1.291 + return syms.doubleType.constType(
1.292 + new Double(doubleValue(l) - doubleValue(r)));
1.293 + case dmul:
1.294 + return syms.doubleType.constType(
1.295 + new Double(doubleValue(l) * doubleValue(r)));
1.296 + case ddiv:
1.297 + return syms.doubleType.constType(
1.298 + new Double(doubleValue(l) / doubleValue(r)));
1.299 + case dmod:
1.300 + return syms.doubleType.constType(
1.301 + new Double(doubleValue(l) % doubleValue(r)));
1.302 + case dcmpg: case dcmpl:
1.303 + if (doubleValue(l) < doubleValue(r))
1.304 + return syms.intType.constType(minusOne);
1.305 + else if (doubleValue(l) > doubleValue(r))
1.306 + return syms.intType.constType(one);
1.307 + else if (doubleValue(l) == doubleValue(r))
1.308 + return syms.intType.constType(zero);
1.309 + else if (opcode == dcmpg)
1.310 + return syms.intType.constType(one);
1.311 + else
1.312 + return syms.intType.constType(minusOne);
1.313 + case if_acmpeq:
1.314 + return syms.booleanType.constType(b2i(l.equals(r)));
1.315 + case if_acmpne:
1.316 + return syms.booleanType.constType(b2i(!l.equals(r)));
1.317 + case string_add:
1.318 + return syms.stringType.constType(
1.319 + left.stringValue() + right.stringValue());
1.320 + default:
1.321 + return null;
1.322 + }
1.323 + }
1.324 + } catch (ArithmeticException e) {
1.325 + return null;
1.326 + }
1.327 + }
1.328 +
1.329 + /** Coerce constant type to target type.
1.330 + * @param etype The source type of the coercion,
1.331 + * which is assumed to be a constant type compatible with
1.332 + * ttype.
1.333 + * @param ttype The target type of the coercion.
1.334 + */
1.335 + Type coerce(Type etype, Type ttype) {
1.336 + // WAS if (etype.baseType() == ttype.baseType())
1.337 + if (etype.tsym.type == ttype.tsym.type)
1.338 + return etype;
1.339 + if (etype.isNumeric()) {
1.340 + Object n = etype.constValue();
1.341 + switch (ttype.getTag()) {
1.342 + case BYTE:
1.343 + return syms.byteType.constType(0 + (byte)intValue(n));
1.344 + case CHAR:
1.345 + return syms.charType.constType(0 + (char)intValue(n));
1.346 + case SHORT:
1.347 + return syms.shortType.constType(0 + (short)intValue(n));
1.348 + case INT:
1.349 + return syms.intType.constType(intValue(n));
1.350 + case LONG:
1.351 + return syms.longType.constType(longValue(n));
1.352 + case FLOAT:
1.353 + return syms.floatType.constType(floatValue(n));
1.354 + case DOUBLE:
1.355 + return syms.doubleType.constType(doubleValue(n));
1.356 + }
1.357 + }
1.358 + return ttype;
1.359 + }
1.360 +}
