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src/share/classes/com/sun/tools/javac/comp/ConstFold.java@959103a6100f (annotated)

src/share/classes/com/sun/tools/javac/comp/ConstFold.java

Wed, 27 Apr 2016 01:34:52 +0800

author

aoqi

date

Wed, 27 Apr 2016 01:34:52 +0800

changeset 0

959103a6100f

child 2525

2eb010b6cb22

permissions

-rw-r--r--

Initial load
http://hg.openjdk.java.net/jdk8u/jdk8u/langtools/
changeset: 2573:53ca196be1ae
tag: jdk8u25-b17

aoqi@0	1	/*
aoqi@0	2	* Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0	4	*
aoqi@0	5	* This code is free software; you can redistribute it and/or modify it
aoqi@0	6	* under the terms of the GNU General Public License version 2 only, as
aoqi@0	7	* published by the Free Software Foundation. Oracle designates this
aoqi@0	8	* particular file as subject to the "Classpath" exception as provided
aoqi@0	9	* by Oracle in the LICENSE file that accompanied this code.
aoqi@0	10	*
aoqi@0	11	* This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0	12	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0	13	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
aoqi@0	14	* version 2 for more details (a copy is included in the LICENSE file that
aoqi@0	15	* accompanied this code).
aoqi@0	16	*
aoqi@0	17	* You should have received a copy of the GNU General Public License version
aoqi@0	18	* 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0	19	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0	20	*
aoqi@0	21	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0	22	* or visit www.oracle.com if you need additional information or have any
aoqi@0	23	* questions.
aoqi@0	24	*/
aoqi@0	25
aoqi@0	26	package com.sun.tools.javac.comp;
aoqi@0	27
aoqi@0	28	import com.sun.tools.javac.code.*;
aoqi@0	29	import com.sun.tools.javac.jvm.*;
aoqi@0	30	import com.sun.tools.javac.util.*;
aoqi@0	31
aoqi@0	32	import static com.sun.tools.javac.code.TypeTag.BOOLEAN;
aoqi@0	33
aoqi@0	34	import static com.sun.tools.javac.jvm.ByteCodes.*;
aoqi@0	35
aoqi@0	36	/** Helper class for constant folding, used by the attribution phase.
aoqi@0	37	* This class is marked strictfp as mandated by JLS 15.4.
aoqi@0	38	*
aoqi@0	39	* <p><b>This is NOT part of any supported API.
aoqi@0	40	* If you write code that depends on this, you do so at your own risk.
aoqi@0	41	* This code and its internal interfaces are subject to change or
aoqi@0	42	* deletion without notice.</b>
aoqi@0	43	*/
aoqi@0	44	strictfp class ConstFold {
aoqi@0	45	protected static final Context.Key<ConstFold> constFoldKey =
aoqi@0	46	new Context.Key<ConstFold>();
aoqi@0	47
aoqi@0	48	private Symtab syms;
aoqi@0	49
aoqi@0	50	public static ConstFold instance(Context context) {
aoqi@0	51	ConstFold instance = context.get(constFoldKey);
aoqi@0	52	if (instance == null)
aoqi@0	53	instance = new ConstFold(context);
aoqi@0	54	return instance;
aoqi@0	55	}
aoqi@0	56
aoqi@0	57	private ConstFold(Context context) {
aoqi@0	58	context.put(constFoldKey, this);
aoqi@0	59
aoqi@0	60	syms = Symtab.instance(context);
aoqi@0	61	}
aoqi@0	62
aoqi@0	63	static final Integer minusOne = -1;
aoqi@0	64	static final Integer zero = 0;
aoqi@0	65	static final Integer one = 1;
aoqi@0	66
aoqi@0	67	/** Convert boolean to integer (true = 1, false = 0).
aoqi@0	68	*/
aoqi@0	69	private static Integer b2i(boolean b) {
aoqi@0	70	return b ? one : zero;
aoqi@0	71	}
aoqi@0	72	private static int intValue(Object x) { return ((Number)x).intValue(); }
aoqi@0	73	private static long longValue(Object x) { return ((Number)x).longValue(); }
aoqi@0	74	private static float floatValue(Object x) { return ((Number)x).floatValue(); }
aoqi@0	75	private static double doubleValue(Object x) { return ((Number)x).doubleValue(); }
aoqi@0	76
aoqi@0	77	/** Fold binary or unary operation, returning constant type reflecting the
aoqi@0	78	* operations result. Return null if fold failed due to an
aoqi@0	79	* arithmetic exception.
aoqi@0	80	* @param opcode The operation's opcode instruction (usually a byte code),
aoqi@0	81	* as entered by class Symtab.
aoqi@0	82	* @param argtypes The operation's argument types (a list of length 1 or 2).
aoqi@0	83	* Argument types are assumed to have non-null constValue's.
aoqi@0	84	*/
aoqi@0	85	Type fold(int opcode, List<Type> argtypes) {
aoqi@0	86	int argCount = argtypes.length();
aoqi@0	87	if (argCount == 1)
aoqi@0	88	return fold1(opcode, argtypes.head);
aoqi@0	89	else if (argCount == 2)
aoqi@0	90	return fold2(opcode, argtypes.head, argtypes.tail.head);
aoqi@0	91	else
aoqi@0	92	throw new AssertionError();
aoqi@0	93	}
aoqi@0	94
aoqi@0	95	/** Fold unary operation.
aoqi@0	96	* @param opcode The operation's opcode instruction (usually a byte code),
aoqi@0	97	* as entered by class Symtab.
aoqi@0	98	* opcode's ifeq to ifge are for postprocessing
aoqi@0	99	* xcmp; ifxx pairs of instructions.
aoqi@0	100	* @param operand The operation's operand type.
aoqi@0	101	* Argument types are assumed to have non-null constValue's.
aoqi@0	102	*/
aoqi@0	103	Type fold1(int opcode, Type operand) {
aoqi@0	104	try {
aoqi@0	105	Object od = operand.constValue();
aoqi@0	106	switch (opcode) {
aoqi@0	107	case nop:
aoqi@0	108	return operand;
aoqi@0	109	case ineg: // unary -
aoqi@0	110	return syms.intType.constType(-intValue(od));
aoqi@0	111	case ixor: // ~
aoqi@0	112	return syms.intType.constType(~intValue(od));
aoqi@0	113	case bool_not: // !
aoqi@0	114	return syms.booleanType.constType(b2i(intValue(od) == 0));
aoqi@0	115	case ifeq:
aoqi@0	116	return syms.booleanType.constType(b2i(intValue(od) == 0));
aoqi@0	117	case ifne:
aoqi@0	118	return syms.booleanType.constType(b2i(intValue(od) != 0));
aoqi@0	119	case iflt:
aoqi@0	120	return syms.booleanType.constType(b2i(intValue(od) < 0));
aoqi@0	121	case ifgt:
aoqi@0	122	return syms.booleanType.constType(b2i(intValue(od) > 0));
aoqi@0	123	case ifle:
aoqi@0	124	return syms.booleanType.constType(b2i(intValue(od) <= 0));
aoqi@0	125	case ifge:
aoqi@0	126	return syms.booleanType.constType(b2i(intValue(od) >= 0));
aoqi@0	127
aoqi@0	128	case lneg: // unary -
aoqi@0	129	return syms.longType.constType(new Long(-longValue(od)));
aoqi@0	130	case lxor: // ~
aoqi@0	131	return syms.longType.constType(new Long(~longValue(od)));
aoqi@0	132
aoqi@0	133	case fneg: // unary -
aoqi@0	134	return syms.floatType.constType(new Float(-floatValue(od)));
aoqi@0	135
aoqi@0	136	case dneg: // ~
aoqi@0	137	return syms.doubleType.constType(new Double(-doubleValue(od)));
aoqi@0	138
aoqi@0	139	default:
aoqi@0	140	return null;
aoqi@0	141	}
aoqi@0	142	} catch (ArithmeticException e) {
aoqi@0	143	return null;
aoqi@0	144	}
aoqi@0	145	}
aoqi@0	146
aoqi@0	147	/** Fold binary operation.
aoqi@0	148	* @param opcode The operation's opcode instruction (usually a byte code),
aoqi@0	149	* as entered by class Symtab.
aoqi@0	150	* opcode's ifeq to ifge are for postprocessing
aoqi@0	151	* xcmp; ifxx pairs of instructions.
aoqi@0	152	* @param left The type of the operation's left operand.
aoqi@0	153	* @param right The type of the operation's right operand.
aoqi@0	154	*/
aoqi@0	155	Type fold2(int opcode, Type left, Type right) {
aoqi@0	156	try {
aoqi@0	157	if (opcode > ByteCodes.preMask) {
aoqi@0	158	// we are seeing a composite instruction of the form xcmp; ifxx.
aoqi@0	159	// In this case fold both instructions separately.
aoqi@0	160	Type t1 = fold2(opcode >> ByteCodes.preShift, left, right);
aoqi@0	161	return (t1.constValue() == null) ? t1
aoqi@0	162	: fold1(opcode & ByteCodes.preMask, t1);
aoqi@0	163	} else {
aoqi@0	164	Object l = left.constValue();
aoqi@0	165	Object r = right.constValue();
aoqi@0	166	switch (opcode) {
aoqi@0	167	case iadd:
aoqi@0	168	return syms.intType.constType(intValue(l) + intValue(r));
aoqi@0	169	case isub:
aoqi@0	170	return syms.intType.constType(intValue(l) - intValue(r));
aoqi@0	171	case imul:
aoqi@0	172	return syms.intType.constType(intValue(l) * intValue(r));
aoqi@0	173	case idiv:
aoqi@0	174	return syms.intType.constType(intValue(l) / intValue(r));
aoqi@0	175	case imod:
aoqi@0	176	return syms.intType.constType(intValue(l) % intValue(r));
aoqi@0	177	case iand:
aoqi@0	178	return (left.hasTag(BOOLEAN)
aoqi@0	179	? syms.booleanType : syms.intType)
aoqi@0	180	.constType(intValue(l) & intValue(r));
aoqi@0	181	case bool_and:
aoqi@0	182	return syms.booleanType.constType(b2i((intValue(l) & intValue(r)) != 0));
aoqi@0	183	case ior:
aoqi@0	184	return (left.hasTag(BOOLEAN)
aoqi@0	185	? syms.booleanType : syms.intType)
aoqi@0	186	.constType(intValue(l) | intValue(r));
aoqi@0	187	case bool_or:
aoqi@0	188	return syms.booleanType.constType(b2i((intValue(l) | intValue(r)) != 0));
aoqi@0	189	case ixor:
aoqi@0	190	return (left.hasTag(BOOLEAN)
aoqi@0	191	? syms.booleanType : syms.intType)
aoqi@0	192	.constType(intValue(l) ^ intValue(r));
aoqi@0	193	case ishl: case ishll:
aoqi@0	194	return syms.intType.constType(intValue(l) << intValue(r));
aoqi@0	195	case ishr: case ishrl:
aoqi@0	196	return syms.intType.constType(intValue(l) >> intValue(r));
aoqi@0	197	case iushr: case iushrl:
aoqi@0	198	return syms.intType.constType(intValue(l) >>> intValue(r));
aoqi@0	199	case if_icmpeq:
aoqi@0	200	return syms.booleanType.constType(
aoqi@0	201	b2i(intValue(l) == intValue(r)));
aoqi@0	202	case if_icmpne:
aoqi@0	203	return syms.booleanType.constType(
aoqi@0	204	b2i(intValue(l) != intValue(r)));
aoqi@0	205	case if_icmplt:
aoqi@0	206	return syms.booleanType.constType(
aoqi@0	207	b2i(intValue(l) < intValue(r)));
aoqi@0	208	case if_icmpgt:
aoqi@0	209	return syms.booleanType.constType(
aoqi@0	210	b2i(intValue(l) > intValue(r)));
aoqi@0	211	case if_icmple:
aoqi@0	212	return syms.booleanType.constType(
aoqi@0	213	b2i(intValue(l) <= intValue(r)));
aoqi@0	214	case if_icmpge:
aoqi@0	215	return syms.booleanType.constType(
aoqi@0	216	b2i(intValue(l) >= intValue(r)));
aoqi@0	217
aoqi@0	218	case ladd:
aoqi@0	219	return syms.longType.constType(
aoqi@0	220	new Long(longValue(l) + longValue(r)));
aoqi@0	221	case lsub:
aoqi@0	222	return syms.longType.constType(
aoqi@0	223	new Long(longValue(l) - longValue(r)));
aoqi@0	224	case lmul:
aoqi@0	225	return syms.longType.constType(
aoqi@0	226	new Long(longValue(l) * longValue(r)));
aoqi@0	227	case ldiv:
aoqi@0	228	return syms.longType.constType(
aoqi@0	229	new Long(longValue(l) / longValue(r)));
aoqi@0	230	case lmod:
aoqi@0	231	return syms.longType.constType(
aoqi@0	232	new Long(longValue(l) % longValue(r)));
aoqi@0	233	case land:
aoqi@0	234	return syms.longType.constType(
aoqi@0	235	new Long(longValue(l) & longValue(r)));
aoqi@0	236	case lor:
aoqi@0	237	return syms.longType.constType(
aoqi@0	238	new Long(longValue(l) | longValue(r)));
aoqi@0	239	case lxor:
aoqi@0	240	return syms.longType.constType(
aoqi@0	241	new Long(longValue(l) ^ longValue(r)));
aoqi@0	242	case lshl: case lshll:
aoqi@0	243	return syms.longType.constType(
aoqi@0	244	new Long(longValue(l) << intValue(r)));
aoqi@0	245	case lshr: case lshrl:
aoqi@0	246	return syms.longType.constType(
aoqi@0	247	new Long(longValue(l) >> intValue(r)));
aoqi@0	248	case lushr:
aoqi@0	249	return syms.longType.constType(
aoqi@0	250	new Long(longValue(l) >>> intValue(r)));
aoqi@0	251	case lcmp:
aoqi@0	252	if (longValue(l) < longValue(r))
aoqi@0	253	return syms.intType.constType(minusOne);
aoqi@0	254	else if (longValue(l) > longValue(r))
aoqi@0	255	return syms.intType.constType(one);
aoqi@0	256	else
aoqi@0	257	return syms.intType.constType(zero);
aoqi@0	258	case fadd:
aoqi@0	259	return syms.floatType.constType(
aoqi@0	260	new Float(floatValue(l) + floatValue(r)));
aoqi@0	261	case fsub:
aoqi@0	262	return syms.floatType.constType(
aoqi@0	263	new Float(floatValue(l) - floatValue(r)));
aoqi@0	264	case fmul:
aoqi@0	265	return syms.floatType.constType(
aoqi@0	266	new Float(floatValue(l) * floatValue(r)));
aoqi@0	267	case fdiv:
aoqi@0	268	return syms.floatType.constType(
aoqi@0	269	new Float(floatValue(l) / floatValue(r)));
aoqi@0	270	case fmod:
aoqi@0	271	return syms.floatType.constType(
aoqi@0	272	new Float(floatValue(l) % floatValue(r)));
aoqi@0	273	case fcmpg: case fcmpl:
aoqi@0	274	if (floatValue(l) < floatValue(r))
aoqi@0	275	return syms.intType.constType(minusOne);
aoqi@0	276	else if (floatValue(l) > floatValue(r))
aoqi@0	277	return syms.intType.constType(one);
aoqi@0	278	else if (floatValue(l) == floatValue(r))
aoqi@0	279	return syms.intType.constType(zero);
aoqi@0	280	else if (opcode == fcmpg)
aoqi@0	281	return syms.intType.constType(one);
aoqi@0	282	else
aoqi@0	283	return syms.intType.constType(minusOne);
aoqi@0	284	case dadd:
aoqi@0	285	return syms.doubleType.constType(
aoqi@0	286	new Double(doubleValue(l) + doubleValue(r)));
aoqi@0	287	case dsub:
aoqi@0	288	return syms.doubleType.constType(
aoqi@0	289	new Double(doubleValue(l) - doubleValue(r)));
aoqi@0	290	case dmul:
aoqi@0	291	return syms.doubleType.constType(
aoqi@0	292	new Double(doubleValue(l) * doubleValue(r)));
aoqi@0	293	case ddiv:
aoqi@0	294	return syms.doubleType.constType(
aoqi@0	295	new Double(doubleValue(l) / doubleValue(r)));
aoqi@0	296	case dmod:
aoqi@0	297	return syms.doubleType.constType(
aoqi@0	298	new Double(doubleValue(l) % doubleValue(r)));
aoqi@0	299	case dcmpg: case dcmpl:
aoqi@0	300	if (doubleValue(l) < doubleValue(r))
aoqi@0	301	return syms.intType.constType(minusOne);
aoqi@0	302	else if (doubleValue(l) > doubleValue(r))
aoqi@0	303	return syms.intType.constType(one);
aoqi@0	304	else if (doubleValue(l) == doubleValue(r))
aoqi@0	305	return syms.intType.constType(zero);
aoqi@0	306	else if (opcode == dcmpg)
aoqi@0	307	return syms.intType.constType(one);
aoqi@0	308	else
aoqi@0	309	return syms.intType.constType(minusOne);
aoqi@0	310	case if_acmpeq:
aoqi@0	311	return syms.booleanType.constType(b2i(l.equals(r)));
aoqi@0	312	case if_acmpne:
aoqi@0	313	return syms.booleanType.constType(b2i(!l.equals(r)));
aoqi@0	314	case string_add:
aoqi@0	315	return syms.stringType.constType(
aoqi@0	316	left.stringValue() + right.stringValue());
aoqi@0	317	default:
aoqi@0	318	return null;
aoqi@0	319	}
aoqi@0	320	}
aoqi@0	321	} catch (ArithmeticException e) {
aoqi@0	322	return null;
aoqi@0	323	}
aoqi@0	324	}
aoqi@0	325
aoqi@0	326	/** Coerce constant type to target type.
aoqi@0	327	* @param etype The source type of the coercion,
aoqi@0	328	* which is assumed to be a constant type compatible with
aoqi@0	329	* ttype.
aoqi@0	330	* @param ttype The target type of the coercion.
aoqi@0	331	*/
aoqi@0	332	Type coerce(Type etype, Type ttype) {
aoqi@0	333	// WAS if (etype.baseType() == ttype.baseType())
aoqi@0	334	if (etype.tsym.type == ttype.tsym.type)
aoqi@0	335	return etype;
aoqi@0	336	if (etype.isNumeric()) {
aoqi@0	337	Object n = etype.constValue();
aoqi@0	338	switch (ttype.getTag()) {
aoqi@0	339	case BYTE:
aoqi@0	340	return syms.byteType.constType(0 + (byte)intValue(n));
aoqi@0	341	case CHAR:
aoqi@0	342	return syms.charType.constType(0 + (char)intValue(n));
aoqi@0	343	case SHORT:
aoqi@0	344	return syms.shortType.constType(0 + (short)intValue(n));
aoqi@0	345	case INT:
aoqi@0	346	return syms.intType.constType(intValue(n));
aoqi@0	347	case LONG:
aoqi@0	348	return syms.longType.constType(longValue(n));
aoqi@0	349	case FLOAT:
aoqi@0	350	return syms.floatType.constType(floatValue(n));
aoqi@0	351	case DOUBLE:
aoqi@0	352	return syms.doubleType.constType(doubleValue(n));
aoqi@0	353	}
aoqi@0	354	}
aoqi@0	355	return ttype;
aoqi@0	356	}
aoqi@0	357	}