1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
/*******************************************************************************
* Copyright (c) 2000, 2004 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.wst.jsdt.internal.compiler.ast;
import org.eclipse.wst.jsdt.internal.compiler.ASTVisitor;
import org.eclipse.wst.jsdt.internal.compiler.impl.*;
import org.eclipse.wst.jsdt.internal.compiler.codegen.*;
import org.eclipse.wst.jsdt.internal.compiler.flow.*;
import org.eclipse.wst.jsdt.internal.compiler.lookup.*;
public class DoStatement extends Statement {
public Expression condition;
public Statement action;
private Label breakLabel, continueLabel;
// for local variables table attributes
int mergedInitStateIndex = -1;
public DoStatement(Expression condition, Statement action, int s, int e) {
this.sourceStart = s;
this.sourceEnd = e;
this.condition = condition;
this.action = action;
// remember useful empty statement
if (action instanceof EmptyStatement) action.bits |= IsUsefulEmptyStatementMASK;
}
public FlowInfo analyseCode(
BlockScope currentScope,
FlowContext flowContext,
FlowInfo flowInfo) {
breakLabel = new Label();
continueLabel = new Label();
LoopingFlowContext loopingContext =
new LoopingFlowContext(
flowContext,
this,
breakLabel,
continueLabel,
currentScope);
Constant cst = condition.constant;
boolean isConditionTrue = cst != NotAConstant && cst.booleanValue() == true;
cst = condition.optimizedBooleanConstant();
boolean isConditionOptimizedTrue = cst != NotAConstant && cst.booleanValue() == true;
boolean isConditionOptimizedFalse = cst != NotAConstant && cst.booleanValue() == false;
int previousMode = flowInfo.reachMode();
if ((action != null) && !action.isEmptyBlock()) {
flowInfo = action.analyseCode(currentScope, loopingContext, flowInfo);
// code generation can be optimized when no need to continue in the loop
if (!flowInfo.isReachable() && !loopingContext.initsOnContinue.isReachable()) {
continueLabel = null;
}
}
/* Reset reach mode, to address following scenario.
* final blank;
* do { if (true) break; else blank = 0; } while(false);
* blank = 1; // may be initialized already
*/
flowInfo.setReachMode(previousMode);
flowInfo =
condition.analyseCode(
currentScope,
loopingContext,
(action == null
? flowInfo
: (flowInfo.mergedWith(loopingContext.initsOnContinue))));
if (!isConditionOptimizedFalse && continueLabel != null) {
loopingContext.complainOnFinalAssignmentsInLoop(currentScope, flowInfo);
}
// end of loop
FlowInfo mergedInfo = FlowInfo.mergedOptimizedBranches(
loopingContext.initsOnBreak,
isConditionOptimizedTrue,
flowInfo.initsWhenFalse(),
false, // never consider opt false case for DO loop, since break can always occur (47776)
!isConditionTrue /*do{}while(true); unreachable(); */);
mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(mergedInfo);
return mergedInfo;
}
/**
* Do statement code generation
*
*/
public void generateCode(BlockScope currentScope, CodeStream codeStream) {
if ((bits & IsReachableMASK) == 0) {
return;
}
int pc = codeStream.position;
// labels management
Label actionLabel = new Label(codeStream);
actionLabel.place();
breakLabel.initialize(codeStream);
if (continueLabel != null) {
continueLabel.initialize(codeStream);
}
// generate action
if (action != null) {
action.generateCode(currentScope, codeStream);
}
// generate condition
if (continueLabel != null) {
continueLabel.place();
condition.generateOptimizedBoolean(
currentScope,
codeStream,
actionLabel,
null,
true);
}
breakLabel.place();
// May loose some local variable initializations : affecting the local variable attributes
if (mergedInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, mergedInitStateIndex);
codeStream.addDefinitelyAssignedVariables(currentScope, mergedInitStateIndex);
}
codeStream.recordPositionsFrom(pc, this.sourceStart);
}
public StringBuffer printStatement(int indent, StringBuffer output) {
printIndent(indent, output).append("do"); //$NON-NLS-1$
if (action == null)
output.append(" ;\n"); //$NON-NLS-1$
else {
output.append('\n');
action.printStatement(indent + 1, output).append('\n');
}
output.append("while ("); //$NON-NLS-1$
return condition.printExpression(0, output).append(");"); //$NON-NLS-1$
}
public void resolve(BlockScope scope) {
TypeBinding type = condition.resolveTypeExpecting(scope, BooleanBinding);
condition.computeConversion(scope, type, type);
if (action != null)
action.resolve(scope);
}
public void traverse(ASTVisitor visitor, BlockScope scope) {
if (visitor.visit(this, scope)) {
if (action != null) {
action.traverse(visitor, scope);
}
condition.traverse(visitor, scope);
}
visitor.endVisit(this, scope);
}
}
|
