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 | } |