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/*
* Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.tools.tree;
import sun.tools.java.*;
import sun.tools.asm.Assembler;
import sun.tools.asm.Label;
import java.util.Hashtable;
/**
* WARNING: The contents of this source file are not part of any
* supported API. Code that depends on them does so at its own risk:
* they are subject to change or removal without notice.
*/
public
class NotExpression extends UnaryExpression {
/**
* Constructor
*/
public NotExpression(long where, Expression right) {
super(NOT, where, Type.tBoolean, right);
}
/**
* Select the type of the expression
*/
void selectType(Environment env, Context ctx, int tm) {
right = convert(env, ctx, Type.tBoolean, right);
}
/*
* Check a "not" expression.
*
* cvars is modified so that
* cvar.vsTrue indicates variables with a known value if
* the expression is true.
* cvars.vsFalse indicates variables with a known value if
* the expression is false
*
* For "not" expressions, we look at the inside expression, and then
* swap true and false.
*/
public void checkCondition(Environment env, Context ctx, Vset vset,
Hashtable<Object, Object> exp, ConditionVars cvars) {
right.checkCondition(env, ctx, vset, exp, cvars);
right = convert(env, ctx, Type.tBoolean, right);
// swap true and false
Vset temp = cvars.vsFalse;
cvars.vsFalse = cvars.vsTrue;
cvars.vsTrue = temp;
}
/**
* Evaluate
*/
Expression eval(boolean a) {
return new BooleanExpression(where, !a);
}
/**
* Simplify
*/
Expression simplify() {
// Check if the expression can be optimized
switch (right.op) {
case NOT:
return ((NotExpression)right).right;
case EQ:
case NE:
case LT:
case LE:
case GT:
case GE:
break;
default:
return this;
}
// Can't negate real comparisons
BinaryExpression bin = (BinaryExpression)right;
if (bin.left.type.inMask(TM_REAL)) {
return this;
}
// Negate comparison
switch (right.op) {
case EQ:
return new NotEqualExpression(where, bin.left, bin.right);
case NE:
return new EqualExpression(where, bin.left, bin.right);
case LT:
return new GreaterOrEqualExpression(where, bin.left, bin.right);
case LE:
return new GreaterExpression(where, bin.left, bin.right);
case GT:
return new LessOrEqualExpression(where, bin.left, bin.right);
case GE:
return new LessExpression(where, bin.left, bin.right);
}
return this;
}
/**
* Code
*/
void codeBranch(Environment env, Context ctx, Assembler asm, Label lbl, boolean whenTrue) {
right.codeBranch(env, ctx, asm, lbl, !whenTrue);
}
/**
* Instead of relying on the default code generation which uses
* conditional branching, generate a simpler stream using XOR.
*/
public void codeValue(Environment env, Context ctx, Assembler asm) {
right.codeValue(env, ctx, asm);
asm.add(where, opc_ldc, 1);
asm.add(where, opc_ixor);
}
}
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