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/*
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* Copyright 1999-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package com.sun.tools.javac.comp;
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import com.sun.tools.javac.code.*;
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import com.sun.tools.javac.jvm.*;
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import com.sun.tools.javac.util.*;
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import com.sun.tools.javac.code.Type.*;
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import static com.sun.tools.javac.code.TypeTags.*;
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import static com.sun.tools.javac.jvm.ByteCodes.*;
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/** Helper class for constant folding, used by the attribution phase.
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* This class is marked strictfp as mandated by JLS 15.4.
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*
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* <p><b>This is NOT part of any API supported by Sun Microsystems. If
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* you write code that depends on this, you do so at your own risk.
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* This code and its internal interfaces are subject to change or
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* deletion without notice.</b>
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*/
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strictfp class ConstFold {
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protected static final Context.Key<ConstFold> constFoldKey =
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new Context.Key<ConstFold>();
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private Symtab syms;
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public static ConstFold instance(Context context) {
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ConstFold instance = context.get(constFoldKey);
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if (instance == null)
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instance = new ConstFold(context);
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return instance;
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}
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private ConstFold(Context context) {
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context.put(constFoldKey, this);
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syms = Symtab.instance(context);
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}
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static Integer minusOne = -1;
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static Integer zero = 0;
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static Integer one = 1;
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/** Convert boolean to integer (true = 1, false = 0).
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*/
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private static Integer b2i(boolean b) {
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return b ? one : zero;
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}
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private static int intValue(Object x) { return ((Number)x).intValue(); }
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private static long longValue(Object x) { return ((Number)x).longValue(); }
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private static float floatValue(Object x) { return ((Number)x).floatValue(); }
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private static double doubleValue(Object x) { return ((Number)x).doubleValue(); }
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/** Fold binary or unary operation, returning constant type reflecting the
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* operations result. Return null if fold failed due to an
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* arithmetic exception.
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* @param opcode The operation's opcode instruction (usually a byte code),
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* as entered by class Symtab.
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* @param argtypes The operation's argument types (a list of length 1 or 2).
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* Argument types are assumed to have non-null constValue's.
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*/
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Type fold(int opcode, List<Type> argtypes) {
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int argCount = argtypes.length();
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if (argCount == 1)
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return fold1(opcode, argtypes.head);
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else if (argCount == 2)
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return fold2(opcode, argtypes.head, argtypes.tail.head);
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else
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throw new AssertionError();
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}
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/** Fold unary operation.
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* @param opcode The operation's opcode instruction (usually a byte code),
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* as entered by class Symtab.
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* opcode's ifeq to ifge are for postprocessing
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* xcmp; ifxx pairs of instructions.
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* @param operand The operation's operand type.
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* Argument types are assumed to have non-null constValue's.
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*/
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Type fold1(int opcode, Type operand) {
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try {
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Object od = operand.constValue();
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switch (opcode) {
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case nop:
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return operand;
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case ineg: // unary -
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return syms.intType.constType(-intValue(od));
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case ixor: // ~
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return syms.intType.constType(~intValue(od));
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case bool_not: // !
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return syms.booleanType.constType(b2i(intValue(od) == 0));
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case ifeq:
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return syms.booleanType.constType(b2i(intValue(od) == 0));
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case ifne:
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return syms.booleanType.constType(b2i(intValue(od) != 0));
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case iflt:
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return syms.booleanType.constType(b2i(intValue(od) < 0));
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case ifgt:
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return syms.booleanType.constType(b2i(intValue(od) > 0));
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case ifle:
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return syms.booleanType.constType(b2i(intValue(od) <= 0));
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case ifge:
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return syms.booleanType.constType(b2i(intValue(od) >= 0));
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case lneg: // unary -
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return syms.longType.constType(new Long(-longValue(od)));
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case lxor: // ~
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return syms.longType.constType(new Long(~longValue(od)));
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case fneg: // unary -
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return syms.floatType.constType(new Float(-floatValue(od)));
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case dneg: // ~
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return syms.doubleType.constType(new Double(-doubleValue(od)));
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default:
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return null;
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}
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} catch (ArithmeticException e) {
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return null;
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}
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}
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/** Fold binary operation.
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* @param opcode The operation's opcode instruction (usually a byte code),
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* as entered by class Symtab.
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* opcode's ifeq to ifge are for postprocessing
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* xcmp; ifxx pairs of instructions.
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* @param left The type of the operation's left operand.
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* @param right The type of the operation's right operand.
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*/
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Type fold2(int opcode, Type left, Type right) {
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try {
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if (opcode > ByteCodes.preMask) {
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// we are seeing a composite instruction of the form xcmp; ifxx.
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// In this case fold both instructions separately.
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Type t1 = fold2(opcode >> ByteCodes.preShift, left, right);
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return (t1.constValue() == null) ? t1
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: fold1(opcode & ByteCodes.preMask, t1);
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} else {
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Object l = left.constValue();
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Object r = right.constValue();
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switch (opcode) {
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case iadd:
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return syms.intType.constType(intValue(l) + intValue(r));
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case isub:
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return syms.intType.constType(intValue(l) - intValue(r));
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case imul:
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return syms.intType.constType(intValue(l) * intValue(r));
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case idiv:
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return syms.intType.constType(intValue(l) / intValue(r));
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case imod:
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return syms.intType.constType(intValue(l) % intValue(r));
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case iand:
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return (left.tag == BOOLEAN
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? syms.booleanType : syms.intType)
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.constType(intValue(l) & intValue(r));
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case bool_and:
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return syms.booleanType.constType(b2i((intValue(l) & intValue(r)) != 0));
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case ior:
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return (left.tag == BOOLEAN
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? syms.booleanType : syms.intType)
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.constType(intValue(l) | intValue(r));
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case bool_or:
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return syms.booleanType.constType(b2i((intValue(l) | intValue(r)) != 0));
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case ixor:
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return (left.tag == BOOLEAN
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? syms.booleanType : syms.intType)
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.constType(intValue(l) ^ intValue(r));
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case ishl: case ishll:
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return syms.intType.constType(intValue(l) << intValue(r));
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case ishr: case ishrl:
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return syms.intType.constType(intValue(l) >> intValue(r));
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case iushr: case iushrl:
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return syms.intType.constType(intValue(l) >>> intValue(r));
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case if_icmpeq:
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return syms.booleanType.constType(
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b2i(intValue(l) == intValue(r)));
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case if_icmpne:
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return syms.booleanType.constType(
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b2i(intValue(l) != intValue(r)));
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case if_icmplt:
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return syms.booleanType.constType(
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b2i(intValue(l) < intValue(r)));
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case if_icmpgt:
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return syms.booleanType.constType(
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b2i(intValue(l) > intValue(r)));
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case if_icmple:
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return syms.booleanType.constType(
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b2i(intValue(l) <= intValue(r)));
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case if_icmpge:
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return syms.booleanType.constType(
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b2i(intValue(l) >= intValue(r)));
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case ladd:
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return syms.longType.constType(
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new Long(longValue(l) + longValue(r)));
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case lsub:
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return syms.longType.constType(
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new Long(longValue(l) - longValue(r)));
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case lmul:
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return syms.longType.constType(
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new Long(longValue(l) * longValue(r)));
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case ldiv:
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return syms.longType.constType(
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new Long(longValue(l) / longValue(r)));
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case lmod:
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return syms.longType.constType(
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new Long(longValue(l) % longValue(r)));
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case land:
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return syms.longType.constType(
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new Long(longValue(l) & longValue(r)));
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case lor:
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return syms.longType.constType(
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new Long(longValue(l) | longValue(r)));
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case lxor:
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return syms.longType.constType(
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new Long(longValue(l) ^ longValue(r)));
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case lshl: case lshll:
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return syms.longType.constType(
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new Long(longValue(l) << intValue(r)));
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case lshr: case lshrl:
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return syms.longType.constType(
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new Long(longValue(l) >> intValue(r)));
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case lushr:
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return syms.longType.constType(
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new Long(longValue(l) >>> intValue(r)));
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case lcmp:
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if (longValue(l) < longValue(r))
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return syms.intType.constType(minusOne);
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else if (longValue(l) > longValue(r))
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return syms.intType.constType(one);
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else
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return syms.intType.constType(zero);
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case fadd:
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return syms.floatType.constType(
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new Float(floatValue(l) + floatValue(r)));
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case fsub:
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return syms.floatType.constType(
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new Float(floatValue(l) - floatValue(r)));
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case fmul:
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return syms.floatType.constType(
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new Float(floatValue(l) * floatValue(r)));
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case fdiv:
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return syms.floatType.constType(
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new Float(floatValue(l) / floatValue(r)));
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case fmod:
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return syms.floatType.constType(
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new Float(floatValue(l) % floatValue(r)));
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case fcmpg: case fcmpl:
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if (floatValue(l) < floatValue(r))
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return syms.intType.constType(minusOne);
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else if (floatValue(l) > floatValue(r))
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return syms.intType.constType(one);
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else if (floatValue(l) == floatValue(r))
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return syms.intType.constType(zero);
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else if (opcode == fcmpg)
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return syms.intType.constType(one);
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else
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return syms.intType.constType(minusOne);
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case dadd:
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return syms.doubleType.constType(
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new Double(doubleValue(l) + doubleValue(r)));
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case dsub:
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return syms.doubleType.constType(
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new Double(doubleValue(l) - doubleValue(r)));
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case dmul:
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return syms.doubleType.constType(
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new Double(doubleValue(l) * doubleValue(r)));
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case ddiv:
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return syms.doubleType.constType(
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new Double(doubleValue(l) / doubleValue(r)));
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case dmod:
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return syms.doubleType.constType(
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new Double(doubleValue(l) % doubleValue(r)));
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case dcmpg: case dcmpl:
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if (doubleValue(l) < doubleValue(r))
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return syms.intType.constType(minusOne);
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else if (doubleValue(l) > doubleValue(r))
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return syms.intType.constType(one);
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else if (doubleValue(l) == doubleValue(r))
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return syms.intType.constType(zero);
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else if (opcode == dcmpg)
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return syms.intType.constType(one);
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else
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return syms.intType.constType(minusOne);
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case if_acmpeq:
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return syms.booleanType.constType(b2i(l.equals(r)));
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case if_acmpne:
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return syms.booleanType.constType(b2i(!l.equals(r)));
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case string_add:
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return syms.stringType.constType(
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left.stringValue() + right.stringValue());
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default:
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return null;
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}
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}
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} catch (ArithmeticException e) {
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return null;
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}
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}
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/** Coerce constant type to target type.
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* @param etype The source type of the coercion,
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* which is assumed to be a constant type compatble with
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* ttype.
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* @param ttype The target type of the coercion.
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*/
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Type coerce(Type etype, Type ttype) {
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// WAS if (etype.baseType() == ttype.baseType())
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if (etype.tsym.type == ttype.tsym.type)
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return etype;
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if (etype.tag <= DOUBLE) {
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Object n = etype.constValue();
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switch (ttype.tag) {
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case BYTE:
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return syms.byteType.constType(0 + (byte)intValue(n));
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case CHAR:
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return syms.charType.constType(0 + (char)intValue(n));
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case SHORT:
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return syms.shortType.constType(0 + (short)intValue(n));
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case INT:
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return syms.intType.constType(intValue(n));
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case LONG:
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return syms.longType.constType(longValue(n));
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case FLOAT:
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return syms.floatType.constType(floatValue(n));
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case DOUBLE:
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return syms.doubleType.constType(doubleValue(n));
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}
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}
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return ttype;
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}
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}
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