Source Code Cross Referenced for ConstFold.java in  » 6.0-JDK-Modules-sun » javac-compiler » com » sun » tools » javac » comp » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » 6.0 JDK Modules sun » javac compiler » com.sun.tools.javac.comp 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.
003:         * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004:         *
005:         * This code is free software; you can redistribute it and/or modify it
006:         * under the terms of the GNU General Public License version 2 only, as
007:         * published by the Free Software Foundation.  Sun designates this
008:         * particular file as subject to the "Classpath" exception as provided
009:         * by Sun in the LICENSE file that accompanied this code.
010:         *
011:         * This code is distributed in the hope that it will be useful, but WITHOUT
012:         * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013:         * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
014:         * version 2 for more details (a copy is included in the LICENSE file that
015:         * accompanied this code).
016:         *
017:         * You should have received a copy of the GNU General Public License version
018:         * 2 along with this work; if not, write to the Free Software Foundation,
019:         * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020:         *
021:         * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022:         * CA 95054 USA or visit www.sun.com if you need additional information or
023:         * have any questions.
024:         */
025:
026:        package com.sun.tools.javac.comp;
027:
028:        import com.sun.tools.javac.code.*;
029:        import com.sun.tools.javac.jvm.*;
030:        import com.sun.tools.javac.util.*;
031:
032:        import com.sun.tools.javac.code.Type.*;
033:
034:        import static com.sun.tools.javac.code.TypeTags.*;
035:        import static com.sun.tools.javac.jvm.ByteCodes.*;
036:
037:        /** Helper class for constant folding, used by the attribution phase.
038:         *  This class is marked strictfp as mandated by JLS 15.4.
039:         *
040:         *  <p><b>This is NOT part of any API supported by Sun Microsystems.  If
041:         *  you write code that depends on this, you do so at your own risk.
042:         *  This code and its internal interfaces are subject to change or
043:         *  deletion without notice.</b>
044:         */
045:        @Version("@(#)ConstFold.java	1.35 07/05/05")
046:        strictfp class ConstFold {
047:            protected static final Context.Key<ConstFold> constFoldKey = new Context.Key<ConstFold>();
048:
049:            private Symtab syms;
050:
051:            public static ConstFold instance(Context context) {
052:                ConstFold instance = context.get(constFoldKey);
053:                if (instance == null)
054:                    instance = new ConstFold(context);
055:                return instance;
056:            }
057:
058:            private ConstFold(Context context) {
059:                context.put(constFoldKey, this );
060:
061:                syms = Symtab.instance(context);
062:            }
063:
064:            static Integer minusOne = -1;
065:            static Integer zero = 0;
066:            static Integer one = 1;
067:
068:            /** Convert boolean to integer (true = 1, false = 0).
069:             */
070:            private static Integer b2i(boolean b) {
071:                return b ? one : zero;
072:            }
073:
074:            private static int intValue(Object x) {
075:                return ((Number) x).intValue();
076:            }
077:
078:            private static long longValue(Object x) {
079:                return ((Number) x).longValue();
080:            }
081:
082:            private static float floatValue(Object x) {
083:                return ((Number) x).floatValue();
084:            }
085:
086:            private static double doubleValue(Object x) {
087:                return ((Number) x).doubleValue();
088:            }
089:
090:            /** Fold binary or unary operation, returning constant type reflecting the
091:             *  operations result. Return null if fold failed due to an
092:             *  arithmetic exception.
093:             *  @param opcode    The operation's opcode instruction (usually a byte code),
094:             *                   as entered by class Symtab.
095:             *  @param argtypes  The operation's argument types (a list of length 1 or 2).
096:             *                   Argument types are assumed to have non-null constValue's.
097:             */
098:            Type fold(int opcode, List<Type> argtypes) {
099:                int argCount = argtypes.length();
100:                if (argCount == 1)
101:                    return fold1(opcode, argtypes.head);
102:                else if (argCount == 2)
103:                    return fold2(opcode, argtypes.head, argtypes.tail.head);
104:                else
105:                    throw new AssertionError();
106:            }
107:
108:            /** Fold unary operation.
109:             *  @param opcode    The operation's opcode instruction (usually a byte code),
110:             *                   as entered by class Symtab.
111:             *                   opcode's ifeq to ifge are for postprocessing
112:             *                   xcmp; ifxx pairs of instructions.
113:             *  @param operand   The operation's operand type.
114:             *                   Argument types are assumed to have non-null constValue's.
115:             */
116:            Type fold1(int opcode, Type operand) {
117:                try {
118:                    Object od = operand.constValue();
119:                    switch (opcode) {
120:                    case nop:
121:                        return operand;
122:                    case ineg: // unary -
123:                        return syms.intType.constType(-intValue(od));
124:                    case ixor: // ~
125:                        return syms.intType.constType(~intValue(od));
126:                    case bool_not: // !
127:                        return syms.booleanType
128:                                .constType(b2i(intValue(od) == 0));
129:                    case ifeq:
130:                        return syms.booleanType
131:                                .constType(b2i(intValue(od) == 0));
132:                    case ifne:
133:                        return syms.booleanType
134:                                .constType(b2i(intValue(od) != 0));
135:                    case iflt:
136:                        return syms.booleanType
137:                                .constType(b2i(intValue(od) < 0));
138:                    case ifgt:
139:                        return syms.booleanType
140:                                .constType(b2i(intValue(od) > 0));
141:                    case ifle:
142:                        return syms.booleanType
143:                                .constType(b2i(intValue(od) <= 0));
144:                    case ifge:
145:                        return syms.booleanType
146:                                .constType(b2i(intValue(od) >= 0));
147:
148:                    case lneg: // unary -
149:                        return syms.longType
150:                                .constType(new Long(-longValue(od)));
151:                    case lxor: // ~
152:                        return syms.longType
153:                                .constType(new Long(~longValue(od)));
154:
155:                    case fneg: // unary -
156:                        return syms.floatType.constType(new Float(
157:                                -floatValue(od)));
158:
159:                    case dneg: // ~
160:                        return syms.doubleType.constType(new Double(
161:                                -doubleValue(od)));
162:
163:                    default:
164:                        return null;
165:                    }
166:                } catch (ArithmeticException e) {
167:                    return null;
168:                }
169:            }
170:
171:            /** Fold binary operation.
172:             *  @param opcode    The operation's opcode instruction (usually a byte code),
173:             *                   as entered by class Symtab.
174:             *                   opcode's ifeq to ifge are for postprocessing
175:             *                   xcmp; ifxx pairs of instructions.
176:             *  @param left      The type of the operation's left operand.
177:             *  @param right     The type of the operation's right operand.
178:             */
179:            Type fold2(int opcode, Type left, Type right) {
180:                try {
181:                    if (opcode > ByteCodes.preMask) {
182:                        // we are seeing a composite instruction of the form xcmp; ifxx.
183:                        // In this case fold both instructions separately.
184:                        Type t1 = fold2(opcode >> ByteCodes.preShift, left,
185:                                right);
186:                        return (t1.constValue() == null) ? t1 : fold1(opcode
187:                                & ByteCodes.preMask, t1);
188:                    } else {
189:                        Object l = left.constValue();
190:                        Object r = right.constValue();
191:                        switch (opcode) {
192:                        case iadd:
193:                            return syms.intType.constType(intValue(l)
194:                                    + intValue(r));
195:                        case isub:
196:                            return syms.intType.constType(intValue(l)
197:                                    - intValue(r));
198:                        case imul:
199:                            return syms.intType.constType(intValue(l)
200:                                    * intValue(r));
201:                        case idiv:
202:                            return syms.intType.constType(intValue(l)
203:                                    / intValue(r));
204:                        case imod:
205:                            return syms.intType.constType(intValue(l)
206:                                    % intValue(r));
207:                        case iand:
208:                            return (left.tag == BOOLEAN ? syms.booleanType
209:                                    : syms.intType).constType(intValue(l)
210:                                    & intValue(r));
211:                        case bool_and:
212:                            return syms.booleanType
213:                                    .constType(b2i((intValue(l) & intValue(r)) != 0));
214:                        case ior:
215:                            return (left.tag == BOOLEAN ? syms.booleanType
216:                                    : syms.intType).constType(intValue(l)
217:                                    | intValue(r));
218:                        case bool_or:
219:                            return syms.booleanType
220:                                    .constType(b2i((intValue(l) | intValue(r)) != 0));
221:                        case ixor:
222:                            return (left.tag == BOOLEAN ? syms.booleanType
223:                                    : syms.intType).constType(intValue(l)
224:                                    ^ intValue(r));
225:                        case ishl:
226:                        case ishll:
227:                            return syms.intType
228:                                    .constType(intValue(l) << intValue(r));
229:                        case ishr:
230:                        case ishrl:
231:                            return syms.intType
232:                                    .constType(intValue(l) >> intValue(r));
233:                        case iushr:
234:                        case iushrl:
235:                            return syms.intType
236:                                    .constType(intValue(l) >>> intValue(r));
237:                        case if_icmpeq:
238:                            return syms.booleanType
239:                                    .constType(b2i(intValue(l) == intValue(r)));
240:                        case if_icmpne:
241:                            return syms.booleanType
242:                                    .constType(b2i(intValue(l) != intValue(r)));
243:                        case if_icmplt:
244:                            return syms.booleanType
245:                                    .constType(b2i(intValue(l) < intValue(r)));
246:                        case if_icmpgt:
247:                            return syms.booleanType
248:                                    .constType(b2i(intValue(l) > intValue(r)));
249:                        case if_icmple:
250:                            return syms.booleanType
251:                                    .constType(b2i(intValue(l) <= intValue(r)));
252:                        case if_icmpge:
253:                            return syms.booleanType
254:                                    .constType(b2i(intValue(l) >= intValue(r)));
255:
256:                        case ladd:
257:                            return syms.longType.constType(new Long(
258:                                    longValue(l) + longValue(r)));
259:                        case lsub:
260:                            return syms.longType.constType(new Long(
261:                                    longValue(l) - longValue(r)));
262:                        case lmul:
263:                            return syms.longType.constType(new Long(
264:                                    longValue(l) * longValue(r)));
265:                        case ldiv:
266:                            return syms.longType.constType(new Long(
267:                                    longValue(l) / longValue(r)));
268:                        case lmod:
269:                            return syms.longType.constType(new Long(
270:                                    longValue(l) % longValue(r)));
271:                        case land:
272:                            return syms.longType.constType(new Long(
273:                                    longValue(l) & longValue(r)));
274:                        case lor:
275:                            return syms.longType.constType(new Long(
276:                                    longValue(l) | longValue(r)));
277:                        case lxor:
278:                            return syms.longType.constType(new Long(
279:                                    longValue(l) ^ longValue(r)));
280:                        case lshl:
281:                        case lshll:
282:                            return syms.longType.constType(new Long(
283:                                    longValue(l) << intValue(r)));
284:                        case lshr:
285:                        case lshrl:
286:                            return syms.longType.constType(new Long(
287:                                    longValue(l) >> intValue(r)));
288:                        case lushr:
289:                            return syms.longType.constType(new Long(
290:                                    longValue(l) >>> intValue(r)));
291:                        case lcmp:
292:                            if (longValue(l) < longValue(r))
293:                                return syms.intType.constType(minusOne);
294:                            else if (longValue(l) > longValue(r))
295:                                return syms.intType.constType(one);
296:                            else
297:                                return syms.intType.constType(zero);
298:                        case fadd:
299:                            return syms.floatType.constType(new Float(
300:                                    floatValue(l) + floatValue(r)));
301:                        case fsub:
302:                            return syms.floatType.constType(new Float(
303:                                    floatValue(l) - floatValue(r)));
304:                        case fmul:
305:                            return syms.floatType.constType(new Float(
306:                                    floatValue(l) * floatValue(r)));
307:                        case fdiv:
308:                            return syms.floatType.constType(new Float(
309:                                    floatValue(l) / floatValue(r)));
310:                        case fmod:
311:                            return syms.floatType.constType(new Float(
312:                                    floatValue(l) % floatValue(r)));
313:                        case fcmpg:
314:                        case fcmpl:
315:                            if (floatValue(l) < floatValue(r))
316:                                return syms.intType.constType(minusOne);
317:                            else if (floatValue(l) > floatValue(r))
318:                                return syms.intType.constType(one);
319:                            else if (floatValue(l) == floatValue(r))
320:                                return syms.intType.constType(zero);
321:                            else if (opcode == fcmpg)
322:                                return syms.intType.constType(one);
323:                            else
324:                                return syms.intType.constType(minusOne);
325:                        case dadd:
326:                            return syms.doubleType.constType(new Double(
327:                                    doubleValue(l) + doubleValue(r)));
328:                        case dsub:
329:                            return syms.doubleType.constType(new Double(
330:                                    doubleValue(l) - doubleValue(r)));
331:                        case dmul:
332:                            return syms.doubleType.constType(new Double(
333:                                    doubleValue(l) * doubleValue(r)));
334:                        case ddiv:
335:                            return syms.doubleType.constType(new Double(
336:                                    doubleValue(l) / doubleValue(r)));
337:                        case dmod:
338:                            return syms.doubleType.constType(new Double(
339:                                    doubleValue(l) % doubleValue(r)));
340:                        case dcmpg:
341:                        case dcmpl:
342:                            if (doubleValue(l) < doubleValue(r))
343:                                return syms.intType.constType(minusOne);
344:                            else if (doubleValue(l) > doubleValue(r))
345:                                return syms.intType.constType(one);
346:                            else if (doubleValue(l) == doubleValue(r))
347:                                return syms.intType.constType(zero);
348:                            else if (opcode == dcmpg)
349:                                return syms.intType.constType(one);
350:                            else
351:                                return syms.intType.constType(minusOne);
352:                        case if_acmpeq:
353:                            return syms.booleanType.constType(b2i(l.equals(r)));
354:                        case if_acmpne:
355:                            return syms.booleanType
356:                                    .constType(b2i(!l.equals(r)));
357:                        case string_add:
358:                            return syms.stringType.constType(left.stringValue()
359:                                    + right.stringValue());
360:                        default:
361:                            return null;
362:                        }
363:                    }
364:                } catch (ArithmeticException e) {
365:                    return null;
366:                }
367:            }
368:
369:            /** Coerce constant type to target type.
370:             *  @param etype      The source type of the coercion,
371:             *                    which is assumed to be a constant type compatble with
372:             *                    ttype.
373:             *  @param ttype      The target type of the coercion.
374:             */
375:            Type coerce(Type etype, Type ttype) {
376:                // WAS if (etype.baseType() == ttype.baseType())
377:                if (etype.tsym.type == ttype.tsym.type)
378:                    return etype;
379:                if (etype.tag <= DOUBLE) {
380:                    Object n = etype.constValue();
381:                    switch (ttype.tag) {
382:                    case BYTE:
383:                        return syms.byteType.constType(0 + (byte) intValue(n));
384:                    case CHAR:
385:                        return syms.charType.constType(0 + (char) intValue(n));
386:                    case SHORT:
387:                        return syms.shortType
388:                                .constType(0 + (short) intValue(n));
389:                    case INT:
390:                        return syms.intType.constType(intValue(n));
391:                    case LONG:
392:                        return syms.longType.constType(longValue(n));
393:                    case FLOAT:
394:                        return syms.floatType.constType(floatValue(n));
395:                    case DOUBLE:
396:                        return syms.doubleType.constType(doubleValue(n));
397:                    }
398:                }
399:                return ttype;
400:            }
401:        }
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