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The Flow.java Java example source code
/*
* Copyright (c) 1999, 2013, 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.
*/
//todo: one might eliminate uninits.andSets when monotonic
package com.sun.tools.javac.comp;
import java.util.HashMap;
import com.sun.tools.javac.code.*;
import com.sun.tools.javac.tree.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.tree.JCTree.*;
import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.Flags.BLOCK;
import static com.sun.tools.javac.code.Kinds.*;
import static com.sun.tools.javac.code.TypeTag.BOOLEAN;
import static com.sun.tools.javac.code.TypeTag.VOID;
import static com.sun.tools.javac.tree.JCTree.Tag.*;
/** This pass implements dataflow analysis for Java programs though
* different AST visitor steps. Liveness analysis (see AliveAlanyzer) checks that
* every statement is reachable. Exception analysis (see FlowAnalyzer) ensures that
* every checked exception that is thrown is declared or caught. Definite assignment analysis
* (see AssignAnalyzer) ensures that each variable is assigned when used. Definite
* unassignment analysis (see AssignAnalyzer) in ensures that no final variable
* is assigned more than once. Finally, local variable capture analysis (see CaptureAnalyzer)
* determines that local variables accessed within the scope of an inner class/lambda
* are either final or effectively-final.
*
* <p>The JLS has a number of problems in the
* specification of these flow analysis problems. This implementation
* attempts to address those issues.
*
* <p>First, there is no accommodation for a finally clause that cannot
* complete normally. For liveness analysis, an intervening finally
* clause can cause a break, continue, or return not to reach its
* target. For exception analysis, an intervening finally clause can
* cause any exception to be "caught". For DA/DU analysis, the finally
* clause can prevent a transfer of control from propagating DA/DU
* state to the target. In addition, code in the finally clause can
* affect the DA/DU status of variables.
*
* <p>For try statements, we introduce the idea of a variable being
* definitely unassigned "everywhere" in a block. A variable V is
* "unassigned everywhere" in a block iff it is unassigned at the
* beginning of the block and there is no reachable assignment to V
* in the block. An assignment V=e is reachable iff V is not DA
* after e. Then we can say that V is DU at the beginning of the
* catch block iff V is DU everywhere in the try block. Similarly, V
* is DU at the beginning of the finally block iff V is DU everywhere
* in the try block and in every catch block. Specifically, the
* following bullet is added to 16.2.2
* <pre>
* V is <em>unassigned everywhere in a block if it is
* unassigned before the block and there is no reachable
* assignment to V within the block.
* </pre>
* <p>In 16.2.15, the third bullet (and all of its sub-bullets) for all
* try blocks is changed to
* <pre>
* V is definitely unassigned before a catch block iff V is
* definitely unassigned everywhere in the try block.
* </pre>
* <p>The last bullet (and all of its sub-bullets) for try blocks that
* have a finally block is changed to
* <pre>
* V is definitely unassigned before the finally block iff
* V is definitely unassigned everywhere in the try block
* and everywhere in each catch block of the try statement.
* </pre>
* <p>In addition,
* <pre>
* V is definitely assigned at the end of a constructor iff
* V is definitely assigned after the block that is the body
* of the constructor and V is definitely assigned at every
* return that can return from the constructor.
* </pre>
* <p>In addition, each continue statement with the loop as its target
* is treated as a jump to the end of the loop body, and "intervening"
* finally clauses are treated as follows: V is DA "due to the
* continue" iff V is DA before the continue statement or V is DA at
* the end of any intervening finally block. V is DU "due to the
* continue" iff any intervening finally cannot complete normally or V
* is DU at the end of every intervening finally block. This "due to
* the continue" concept is then used in the spec for the loops.
*
* <p>Similarly, break statements must consider intervening finally
* blocks. For liveness analysis, a break statement for which any
* intervening finally cannot complete normally is not considered to
* cause the target statement to be able to complete normally. Then
* we say V is DA "due to the break" iff V is DA before the break or
* V is DA at the end of any intervening finally block. V is DU "due
* to the break" iff any intervening finally cannot complete normally
* or V is DU at the break and at the end of every intervening
* finally block. (I suspect this latter condition can be
* simplified.) This "due to the break" is then used in the spec for
* all statements that can be "broken".
*
* <p>The return statement is treated similarly. V is DA "due to a
* return statement" iff V is DA before the return statement or V is
* DA at the end of any intervening finally block. Note that we
* don't have to worry about the return expression because this
* concept is only used for construcrors.
*
* <p>There is no spec in the JLS for when a variable is definitely
* assigned at the end of a constructor, which is needed for final
* fields (8.3.1.2). We implement the rule that V is DA at the end
* of the constructor iff it is DA and the end of the body of the
* constructor and V is DA "due to" every return of the constructor.
*
* <p>Intervening finally blocks similarly affect exception analysis. An
* intervening finally that cannot complete normally allows us to ignore
* an otherwise uncaught exception.
*
* <p>To implement the semantics of intervening finally clauses, all
* nonlocal transfers (break, continue, return, throw, method call that
* can throw a checked exception, and a constructor invocation that can
* thrown a checked exception) are recorded in a queue, and removed
* from the queue when we complete processing the target of the
* nonlocal transfer. This allows us to modify the queue in accordance
* with the above rules when we encounter a finally clause. The only
* exception to this [no pun intended] is that checked exceptions that
* are known to be caught or declared to be caught in the enclosing
* method are not recorded in the queue, but instead are recorded in a
* global variable "{@code Set<Type> thrown}" that records the type of all
* exceptions that can be thrown.
*
* <p>Other minor issues the treatment of members of other classes
* (always considered DA except that within an anonymous class
* constructor, where DA status from the enclosing scope is
* preserved), treatment of the case expression (V is DA before the
* case expression iff V is DA after the switch expression),
* treatment of variables declared in a switch block (the implied
* DA/DU status after the switch expression is DU and not DA for
* variables defined in a switch block), the treatment of boolean ?:
* expressions (The JLS rules only handle b and c non-boolean; the
* new rule is that if b and c are boolean valued, then V is
* (un)assigned after a?b:c when true/false iff V is (un)assigned
* after b when true/false and V is (un)assigned after c when
* true/false).
*
* <p>There is the remaining question of what syntactic forms constitute a
* reference to a variable. It is conventional to allow this.x on the
* left-hand-side to initialize a final instance field named x, yet
* this.x isn't considered a "use" when appearing on a right-hand-side
* in most implementations. Should parentheses affect what is
* considered a variable reference? The simplest rule would be to
* allow unqualified forms only, parentheses optional, and phase out
* support for assigning to a final field via this.x.
*
* <p>This is NOT part of any supported API.
* If you write code that depends on this, you do so at your own risk.
* This code and its internal interfaces are subject to change or
* deletion without notice.</b>
*/
public class Flow {
protected static final Context.Key<Flow> flowKey =
new Context.Key<Flow>();
private final Names names;
private final Log log;
private final Symtab syms;
private final Types types;
private final Check chk;
private TreeMaker make;
private final Resolve rs;
private final JCDiagnostic.Factory diags;
private Env<AttrContext> attrEnv;
private Lint lint;
private final boolean allowImprovedRethrowAnalysis;
private final boolean allowImprovedCatchAnalysis;
private final boolean allowEffectivelyFinalInInnerClasses;
public static Flow instance(Context context) {
Flow instance = context.get(flowKey);
if (instance == null)
instance = new Flow(context);
return instance;
}
public void analyzeTree(Env<AttrContext> env, TreeMaker make) {
new AliveAnalyzer().analyzeTree(env, make);
new AssignAnalyzer(log, syms, lint, names).analyzeTree(env);
new FlowAnalyzer().analyzeTree(env, make);
new CaptureAnalyzer().analyzeTree(env, make);
}
public void analyzeLambda(Env<AttrContext> env, JCLambda that, TreeMaker make, boolean speculative) {
Log.DiagnosticHandler diagHandler = null;
//we need to disable diagnostics temporarily; the problem is that if
//a lambda expression contains e.g. an unreachable statement, an error
//message will be reported and will cause compilation to skip the flow analyis
//step - if we suppress diagnostics, we won't stop at Attr for flow-analysis
//related errors, which will allow for more errors to be detected
if (!speculative) {
diagHandler = new Log.DiscardDiagnosticHandler(log);
}
try {
new AliveAnalyzer().analyzeTree(env, that, make);
} finally {
if (!speculative) {
log.popDiagnosticHandler(diagHandler);
}
}
}
public List<Type> analyzeLambdaThrownTypes(Env env, JCLambda that, TreeMaker make) {
//we need to disable diagnostics temporarily; the problem is that if
//a lambda expression contains e.g. an unreachable statement, an error
//message will be reported and will cause compilation to skip the flow analyis
//step - if we suppress diagnostics, we won't stop at Attr for flow-analysis
//related errors, which will allow for more errors to be detected
Log.DiagnosticHandler diagHandler = new Log.DiscardDiagnosticHandler(log);
try {
new AssignAnalyzer(log, syms, lint, names).analyzeTree(env);
LambdaFlowAnalyzer flowAnalyzer = new LambdaFlowAnalyzer();
flowAnalyzer.analyzeTree(env, that, make);
return flowAnalyzer.inferredThrownTypes;
} finally {
log.popDiagnosticHandler(diagHandler);
}
}
/**
* Definite assignment scan mode
*/
enum FlowKind {
/**
* This is the normal DA/DU analysis mode
*/
NORMAL("var.might.already.be.assigned", false),
/**
* This is the speculative DA/DU analysis mode used to speculatively
* derive assertions within loop bodies
*/
SPECULATIVE_LOOP("var.might.be.assigned.in.loop", true);
final String errKey;
final boolean isFinal;
FlowKind(String errKey, boolean isFinal) {
this.errKey = errKey;
this.isFinal = isFinal;
}
boolean isFinal() {
return isFinal;
}
}
protected Flow(Context context) {
context.put(flowKey, this);
names = Names.instance(context);
log = Log.instance(context);
syms = Symtab.instance(context);
types = Types.instance(context);
chk = Check.instance(context);
lint = Lint.instance(context);
rs = Resolve.instance(context);
diags = JCDiagnostic.Factory.instance(context);
Source source = Source.instance(context);
allowImprovedRethrowAnalysis = source.allowImprovedRethrowAnalysis();
allowImprovedCatchAnalysis = source.allowImprovedCatchAnalysis();
allowEffectivelyFinalInInnerClasses = source.allowEffectivelyFinalInInnerClasses();
}
/**
* Base visitor class for all visitors implementing dataflow analysis logic.
* This class define the shared logic for handling jumps (break/continue statements).
*/
static abstract class BaseAnalyzer<P extends BaseAnalyzer.PendingExit> extends TreeScanner {
enum JumpKind {
BREAK(JCTree.Tag.BREAK) {
@Override
JCTree getTarget(JCTree tree) {
return ((JCBreak)tree).target;
}
},
CONTINUE(JCTree.Tag.CONTINUE) {
@Override
JCTree getTarget(JCTree tree) {
return ((JCContinue)tree).target;
}
};
final JCTree.Tag treeTag;
private JumpKind(Tag treeTag) {
this.treeTag = treeTag;
}
abstract JCTree getTarget(JCTree tree);
}
/** The currently pending exits that go from current inner blocks
* to an enclosing block, in source order.
*/
ListBuffer<P> pendingExits;
/** A pending exit. These are the statements return, break, and
* continue. In addition, exception-throwing expressions or
* statements are put here when not known to be caught. This
* will typically result in an error unless it is within a
* try-finally whose finally block cannot complete normally.
*/
static class PendingExit {
JCTree tree;
PendingExit(JCTree tree) {
this.tree = tree;
}
void resolveJump(JCTree tree) {
//do nothing
}
}
abstract void markDead(JCTree tree);
/** Record an outward transfer of control. */
void recordExit(JCTree tree, P pe) {
pendingExits.append(pe);
markDead(tree);
}
/** Resolve all jumps of this statement. */
private boolean resolveJump(JCTree tree,
ListBuffer<P> oldPendingExits,
JumpKind jk) {
boolean resolved = false;
List<P> exits = pendingExits.toList();
pendingExits = oldPendingExits;
for (; exits.nonEmpty(); exits = exits.tail) {
P exit = exits.head;
if (exit.tree.hasTag(jk.treeTag) &&
jk.getTarget(exit.tree) == tree) {
exit.resolveJump(tree);
resolved = true;
} else {
pendingExits.append(exit);
}
}
return resolved;
}
/** Resolve all continues of this statement. */
boolean resolveContinues(JCTree tree) {
return resolveJump(tree, new ListBuffer<P>(), JumpKind.CONTINUE);
}
/** Resolve all breaks of this statement. */
boolean resolveBreaks(JCTree tree, ListBuffer<P> oldPendingExits) {
return resolveJump(tree, oldPendingExits, JumpKind.BREAK);
}
@Override
public void scan(JCTree tree) {
if (tree != null && (
tree.type == null ||
tree.type != Type.stuckType)) {
super.scan(tree);
}
}
}
/**
* This pass implements the first step of the dataflow analysis, namely
* the liveness analysis check. This checks that every statement is reachable.
* The output of this analysis pass are used by other analyzers. This analyzer
* sets the 'finallyCanCompleteNormally' field in the JCTry class.
*/
class AliveAnalyzer extends BaseAnalyzer<BaseAnalyzer.PendingExit> {
/** A flag that indicates whether the last statement could
* complete normally.
*/
private boolean alive;
@Override
void markDead(JCTree tree) {
alive = false;
}
/*************************************************************************
* Visitor methods for statements and definitions
*************************************************************************/
/** Analyze a definition.
*/
void scanDef(JCTree tree) {
scanStat(tree);
if (tree != null && tree.hasTag(JCTree.Tag.BLOCK) && !alive) {
log.error(tree.pos(),
"initializer.must.be.able.to.complete.normally");
}
}
/** Analyze a statement. Check that statement is reachable.
*/
void scanStat(JCTree tree) {
if (!alive && tree != null) {
log.error(tree.pos(), "unreachable.stmt");
if (!tree.hasTag(SKIP)) alive = true;
}
scan(tree);
}
/** Analyze list of statements.
*/
void scanStats(List<? extends JCStatement> trees) {
if (trees != null)
for (List<? extends JCStatement> l = trees; l.nonEmpty(); l = l.tail)
scanStat(l.head);
}
/* ------------ Visitor methods for various sorts of trees -------------*/
public void visitClassDef(JCClassDecl tree) {
if (tree.sym == null) return;
boolean alivePrev = alive;
ListBuffer<PendingExit> pendingExitsPrev = pendingExits;
Lint lintPrev = lint;
pendingExits = new ListBuffer<PendingExit>();
lint = lint.augment(tree.sym);
try {
// process all the static initializers
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) != 0) {
scanDef(l.head);
}
}
// process all the instance initializers
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) == 0) {
scanDef(l.head);
}
}
// process all the methods
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (l.head.hasTag(METHODDEF)) {
scan(l.head);
}
}
} finally {
pendingExits = pendingExitsPrev;
alive = alivePrev;
lint = lintPrev;
}
}
public void visitMethodDef(JCMethodDecl tree) {
if (tree.body == null) return;
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
Assert.check(pendingExits.isEmpty());
try {
alive = true;
scanStat(tree.body);
if (alive && !tree.sym.type.getReturnType().hasTag(VOID))
log.error(TreeInfo.diagEndPos(tree.body), "missing.ret.stmt");
List<PendingExit> exits = pendingExits.toList();
pendingExits = new ListBuffer<PendingExit>();
while (exits.nonEmpty()) {
PendingExit exit = exits.head;
exits = exits.tail;
Assert.check(exit.tree.hasTag(RETURN));
}
} finally {
lint = lintPrev;
}
}
public void visitVarDef(JCVariableDecl tree) {
if (tree.init != null) {
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
try{
scan(tree.init);
} finally {
lint = lintPrev;
}
}
}
public void visitBlock(JCBlock tree) {
scanStats(tree.stats);
}
public void visitDoLoop(JCDoWhileLoop tree) {
ListBuffer<PendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<PendingExit>();
scanStat(tree.body);
alive |= resolveContinues(tree);
scan(tree.cond);
alive = alive && !tree.cond.type.isTrue();
alive |= resolveBreaks(tree, prevPendingExits);
}
public void visitWhileLoop(JCWhileLoop tree) {
ListBuffer<PendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<PendingExit>();
scan(tree.cond);
alive = !tree.cond.type.isFalse();
scanStat(tree.body);
alive |= resolveContinues(tree);
alive = resolveBreaks(tree, prevPendingExits) ||
!tree.cond.type.isTrue();
}
public void visitForLoop(JCForLoop tree) {
ListBuffer<PendingExit> prevPendingExits = pendingExits;
scanStats(tree.init);
pendingExits = new ListBuffer<PendingExit>();
if (tree.cond != null) {
scan(tree.cond);
alive = !tree.cond.type.isFalse();
} else {
alive = true;
}
scanStat(tree.body);
alive |= resolveContinues(tree);
scan(tree.step);
alive = resolveBreaks(tree, prevPendingExits) ||
tree.cond != null && !tree.cond.type.isTrue();
}
public void visitForeachLoop(JCEnhancedForLoop tree) {
visitVarDef(tree.var);
ListBuffer<PendingExit> prevPendingExits = pendingExits;
scan(tree.expr);
pendingExits = new ListBuffer<PendingExit>();
scanStat(tree.body);
alive |= resolveContinues(tree);
resolveBreaks(tree, prevPendingExits);
alive = true;
}
public void visitLabelled(JCLabeledStatement tree) {
ListBuffer<PendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<PendingExit>();
scanStat(tree.body);
alive |= resolveBreaks(tree, prevPendingExits);
}
public void visitSwitch(JCSwitch tree) {
ListBuffer<PendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<PendingExit>();
scan(tree.selector);
boolean hasDefault = false;
for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) {
alive = true;
JCCase c = l.head;
if (c.pat == null)
hasDefault = true;
else
scan(c.pat);
scanStats(c.stats);
// Warn about fall-through if lint switch fallthrough enabled.
if (alive &&
lint.isEnabled(Lint.LintCategory.FALLTHROUGH) &&
c.stats.nonEmpty() && l.tail.nonEmpty())
log.warning(Lint.LintCategory.FALLTHROUGH,
l.tail.head.pos(),
"possible.fall-through.into.case");
}
if (!hasDefault) {
alive = true;
}
alive |= resolveBreaks(tree, prevPendingExits);
}
public void visitTry(JCTry tree) {
ListBuffer<PendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<PendingExit>();
for (JCTree resource : tree.resources) {
if (resource instanceof JCVariableDecl) {
JCVariableDecl vdecl = (JCVariableDecl) resource;
visitVarDef(vdecl);
} else if (resource instanceof JCExpression) {
scan((JCExpression) resource);
} else {
throw new AssertionError(tree); // parser error
}
}
scanStat(tree.body);
boolean aliveEnd = alive;
for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
alive = true;
JCVariableDecl param = l.head.param;
scan(param);
scanStat(l.head.body);
aliveEnd |= alive;
}
if (tree.finalizer != null) {
ListBuffer<PendingExit> exits = pendingExits;
pendingExits = prevPendingExits;
alive = true;
scanStat(tree.finalizer);
tree.finallyCanCompleteNormally = alive;
if (!alive) {
if (lint.isEnabled(Lint.LintCategory.FINALLY)) {
log.warning(Lint.LintCategory.FINALLY,
TreeInfo.diagEndPos(tree.finalizer),
"finally.cannot.complete");
}
} else {
while (exits.nonEmpty()) {
pendingExits.append(exits.next());
}
alive = aliveEnd;
}
} else {
alive = aliveEnd;
ListBuffer<PendingExit> exits = pendingExits;
pendingExits = prevPendingExits;
while (exits.nonEmpty()) pendingExits.append(exits.next());
}
}
@Override
public void visitIf(JCIf tree) {
scan(tree.cond);
scanStat(tree.thenpart);
if (tree.elsepart != null) {
boolean aliveAfterThen = alive;
alive = true;
scanStat(tree.elsepart);
alive = alive | aliveAfterThen;
} else {
alive = true;
}
}
public void visitBreak(JCBreak tree) {
recordExit(tree, new PendingExit(tree));
}
public void visitContinue(JCContinue tree) {
recordExit(tree, new PendingExit(tree));
}
public void visitReturn(JCReturn tree) {
scan(tree.expr);
recordExit(tree, new PendingExit(tree));
}
public void visitThrow(JCThrow tree) {
scan(tree.expr);
markDead(tree);
}
public void visitApply(JCMethodInvocation tree) {
scan(tree.meth);
scan(tree.args);
}
public void visitNewClass(JCNewClass tree) {
scan(tree.encl);
scan(tree.args);
if (tree.def != null) {
scan(tree.def);
}
}
@Override
public void visitLambda(JCLambda tree) {
if (tree.type != null &&
tree.type.isErroneous()) {
return;
}
ListBuffer<PendingExit> prevPending = pendingExits;
boolean prevAlive = alive;
try {
pendingExits = new ListBuffer<>();
alive = true;
scanStat(tree.body);
tree.canCompleteNormally = alive;
}
finally {
pendingExits = prevPending;
alive = prevAlive;
}
}
public void visitTopLevel(JCCompilationUnit tree) {
// Do nothing for TopLevel since each class is visited individually
}
/**************************************************************************
* main method
*************************************************************************/
/** Perform definite assignment/unassignment analysis on a tree.
*/
public void analyzeTree(Env<AttrContext> env, TreeMaker make) {
analyzeTree(env, env.tree, make);
}
public void analyzeTree(Env<AttrContext> env, JCTree tree, TreeMaker make) {
try {
attrEnv = env;
Flow.this.make = make;
pendingExits = new ListBuffer<PendingExit>();
alive = true;
scan(tree);
} finally {
pendingExits = null;
Flow.this.make = null;
}
}
}
/**
* This pass implements the second step of the dataflow analysis, namely
* the exception analysis. This is to ensure that every checked exception that is
* thrown is declared or caught. The analyzer uses some info that has been set by
* the liveliness analyzer.
*/
class FlowAnalyzer extends BaseAnalyzer<FlowAnalyzer.FlowPendingExit> {
/** A flag that indicates whether the last statement could
* complete normally.
*/
HashMap<Symbol, List preciseRethrowTypes;
/** The current class being defined.
*/
JCClassDecl classDef;
/** The list of possibly thrown declarable exceptions.
*/
List<Type> thrown;
/** The list of exceptions that are either caught or declared to be
* thrown.
*/
List<Type> caught;
class FlowPendingExit extends BaseAnalyzer.PendingExit {
Type thrown;
FlowPendingExit(JCTree tree, Type thrown) {
super(tree);
this.thrown = thrown;
}
}
@Override
void markDead(JCTree tree) {
//do nothing
}
/*-------------------- Exceptions ----------------------*/
/** Complain that pending exceptions are not caught.
*/
void errorUncaught() {
for (FlowPendingExit exit = pendingExits.next();
exit != null;
exit = pendingExits.next()) {
if (classDef != null &&
classDef.pos == exit.tree.pos) {
log.error(exit.tree.pos(),
"unreported.exception.default.constructor",
exit.thrown);
} else if (exit.tree.hasTag(VARDEF) &&
((JCVariableDecl)exit.tree).sym.isResourceVariable()) {
log.error(exit.tree.pos(),
"unreported.exception.implicit.close",
exit.thrown,
((JCVariableDecl)exit.tree).sym.name);
} else {
log.error(exit.tree.pos(),
"unreported.exception.need.to.catch.or.throw",
exit.thrown);
}
}
}
/** Record that exception is potentially thrown and check that it
* is caught.
*/
void markThrown(JCTree tree, Type exc) {
if (!chk.isUnchecked(tree.pos(), exc)) {
if (!chk.isHandled(exc, caught)) {
pendingExits.append(new FlowPendingExit(tree, exc));
}
thrown = chk.incl(exc, thrown);
}
}
/*************************************************************************
* Visitor methods for statements and definitions
*************************************************************************/
/* ------------ Visitor methods for various sorts of trees -------------*/
public void visitClassDef(JCClassDecl tree) {
if (tree.sym == null) return;
JCClassDecl classDefPrev = classDef;
List<Type> thrownPrev = thrown;
List<Type> caughtPrev = caught;
ListBuffer<FlowPendingExit> pendingExitsPrev = pendingExits;
Lint lintPrev = lint;
pendingExits = new ListBuffer<FlowPendingExit>();
if (tree.name != names.empty) {
caught = List.nil();
}
classDef = tree;
thrown = List.nil();
lint = lint.augment(tree.sym);
try {
// process all the static initializers
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) != 0) {
scan(l.head);
errorUncaught();
}
}
// add intersection of all thrown clauses of initial constructors
// to set of caught exceptions, unless class is anonymous.
if (tree.name != names.empty) {
boolean firstConstructor = true;
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (TreeInfo.isInitialConstructor(l.head)) {
List<Type> mthrown =
((JCMethodDecl) l.head).sym.type.getThrownTypes();
if (firstConstructor) {
caught = mthrown;
firstConstructor = false;
} else {
caught = chk.intersect(mthrown, caught);
}
}
}
}
// process all the instance initializers
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) == 0) {
scan(l.head);
errorUncaught();
}
}
// in an anonymous class, add the set of thrown exceptions to
// the throws clause of the synthetic constructor and propagate
// outwards.
// Changing the throws clause on the fly is okay here because
// the anonymous constructor can't be invoked anywhere else,
// and its type hasn't been cached.
if (tree.name == names.empty) {
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (TreeInfo.isInitialConstructor(l.head)) {
JCMethodDecl mdef = (JCMethodDecl)l.head;
mdef.thrown = make.Types(thrown);
mdef.sym.type = types.createMethodTypeWithThrown(mdef.sym.type, thrown);
}
}
thrownPrev = chk.union(thrown, thrownPrev);
}
// process all the methods
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (l.head.hasTag(METHODDEF)) {
scan(l.head);
errorUncaught();
}
}
thrown = thrownPrev;
} finally {
pendingExits = pendingExitsPrev;
caught = caughtPrev;
classDef = classDefPrev;
lint = lintPrev;
}
}
public void visitMethodDef(JCMethodDecl tree) {
if (tree.body == null) return;
List<Type> caughtPrev = caught;
List<Type> mthrown = tree.sym.type.getThrownTypes();
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
Assert.check(pendingExits.isEmpty());
try {
for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
JCVariableDecl def = l.head;
scan(def);
}
if (TreeInfo.isInitialConstructor(tree))
caught = chk.union(caught, mthrown);
else if ((tree.sym.flags() & (BLOCK | STATIC)) != BLOCK)
caught = mthrown;
// else we are in an instance initializer block;
// leave caught unchanged.
scan(tree.body);
List<FlowPendingExit> exits = pendingExits.toList();
pendingExits = new ListBuffer<FlowPendingExit>();
while (exits.nonEmpty()) {
FlowPendingExit exit = exits.head;
exits = exits.tail;
if (exit.thrown == null) {
Assert.check(exit.tree.hasTag(RETURN));
} else {
// uncaught throws will be reported later
pendingExits.append(exit);
}
}
} finally {
caught = caughtPrev;
lint = lintPrev;
}
}
public void visitVarDef(JCVariableDecl tree) {
if (tree.init != null) {
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
try{
scan(tree.init);
} finally {
lint = lintPrev;
}
}
}
public void visitBlock(JCBlock tree) {
scan(tree.stats);
}
public void visitDoLoop(JCDoWhileLoop tree) {
ListBuffer<FlowPendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<FlowPendingExit>();
scan(tree.body);
resolveContinues(tree);
scan(tree.cond);
resolveBreaks(tree, prevPendingExits);
}
public void visitWhileLoop(JCWhileLoop tree) {
ListBuffer<FlowPendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<FlowPendingExit>();
scan(tree.cond);
scan(tree.body);
resolveContinues(tree);
resolveBreaks(tree, prevPendingExits);
}
public void visitForLoop(JCForLoop tree) {
ListBuffer<FlowPendingExit> prevPendingExits = pendingExits;
scan(tree.init);
pendingExits = new ListBuffer<FlowPendingExit>();
if (tree.cond != null) {
scan(tree.cond);
}
scan(tree.body);
resolveContinues(tree);
scan(tree.step);
resolveBreaks(tree, prevPendingExits);
}
public void visitForeachLoop(JCEnhancedForLoop tree) {
visitVarDef(tree.var);
ListBuffer<FlowPendingExit> prevPendingExits = pendingExits;
scan(tree.expr);
pendingExits = new ListBuffer<FlowPendingExit>();
scan(tree.body);
resolveContinues(tree);
resolveBreaks(tree, prevPendingExits);
}
public void visitLabelled(JCLabeledStatement tree) {
ListBuffer<FlowPendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<FlowPendingExit>();
scan(tree.body);
resolveBreaks(tree, prevPendingExits);
}
public void visitSwitch(JCSwitch tree) {
ListBuffer<FlowPendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<FlowPendingExit>();
scan(tree.selector);
for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) {
JCCase c = l.head;
if (c.pat != null) {
scan(c.pat);
}
scan(c.stats);
}
resolveBreaks(tree, prevPendingExits);
}
public void visitTry(JCTry tree) {
List<Type> caughtPrev = caught;
List<Type> thrownPrev = thrown;
thrown = List.nil();
for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
List<JCExpression> subClauses = TreeInfo.isMultiCatch(l.head) ?
((JCTypeUnion)l.head.param.vartype).alternatives :
List.of(l.head.param.vartype);
for (JCExpression ct : subClauses) {
caught = chk.incl(ct.type, caught);
}
}
ListBuffer<FlowPendingExit> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<FlowPendingExit>();
for (JCTree resource : tree.resources) {
if (resource instanceof JCVariableDecl) {
JCVariableDecl vdecl = (JCVariableDecl) resource;
visitVarDef(vdecl);
} else if (resource instanceof JCExpression) {
scan((JCExpression) resource);
} else {
throw new AssertionError(tree); // parser error
}
}
for (JCTree resource : tree.resources) {
List<Type> closeableSupertypes = resource.type.isCompound() ?
types.interfaces(resource.type).prepend(types.supertype(resource.type)) :
List.of(resource.type);
for (Type sup : closeableSupertypes) {
if (types.asSuper(sup, syms.autoCloseableType.tsym) != null) {
Symbol closeMethod = rs.resolveQualifiedMethod(tree,
attrEnv,
sup,
names.close,
List.<Type>nil(),
List.<Type>nil());
Type mt = types.memberType(resource.type, closeMethod);
if (closeMethod.kind == MTH) {
for (Type t : mt.getThrownTypes()) {
markThrown(resource, t);
}
}
}
}
}
scan(tree.body);
List<Type> thrownInTry = allowImprovedCatchAnalysis ?
chk.union(thrown, List.of(syms.runtimeExceptionType, syms.errorType)) :
thrown;
thrown = thrownPrev;
caught = caughtPrev;
List<Type> caughtInTry = List.nil();
for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
JCVariableDecl param = l.head.param;
List<JCExpression> subClauses = TreeInfo.isMultiCatch(l.head) ?
((JCTypeUnion)l.head.param.vartype).alternatives :
List.of(l.head.param.vartype);
List<Type> ctypes = List.nil();
List<Type> rethrownTypes = chk.diff(thrownInTry, caughtInTry);
for (JCExpression ct : subClauses) {
Type exc = ct.type;
if (exc != syms.unknownType) {
ctypes = ctypes.append(exc);
if (types.isSameType(exc, syms.objectType))
continue;
checkCaughtType(l.head.pos(), exc, thrownInTry, caughtInTry);
caughtInTry = chk.incl(exc, caughtInTry);
}
}
scan(param);
preciseRethrowTypes.put(param.sym, chk.intersect(ctypes, rethrownTypes));
scan(l.head.body);
preciseRethrowTypes.remove(param.sym);
}
if (tree.finalizer != null) {
List<Type> savedThrown = thrown;
thrown = List.nil();
ListBuffer<FlowPendingExit> exits = pendingExits;
pendingExits = prevPendingExits;
scan(tree.finalizer);
if (!tree.finallyCanCompleteNormally) {
// discard exits and exceptions from try and finally
thrown = chk.union(thrown, thrownPrev);
} else {
thrown = chk.union(thrown, chk.diff(thrownInTry, caughtInTry));
thrown = chk.union(thrown, savedThrown);
// FIX: this doesn't preserve source order of exits in catch
// versus finally!
while (exits.nonEmpty()) {
pendingExits.append(exits.next());
}
}
} else {
thrown = chk.union(thrown, chk.diff(thrownInTry, caughtInTry));
ListBuffer<FlowPendingExit> exits = pendingExits;
pendingExits = prevPendingExits;
while (exits.nonEmpty()) pendingExits.append(exits.next());
}
}
@Override
public void visitIf(JCIf tree) {
scan(tree.cond);
scan(tree.thenpart);
if (tree.elsepart != null) {
scan(tree.elsepart);
}
}
void checkCaughtType(DiagnosticPosition pos, Type exc, List<Type> thrownInTry, List caughtInTry) {
if (chk.subset(exc, caughtInTry)) {
log.error(pos, "except.already.caught", exc);
} else if (!chk.isUnchecked(pos, exc) &&
!isExceptionOrThrowable(exc) &&
!chk.intersects(exc, thrownInTry)) {
log.error(pos, "except.never.thrown.in.try", exc);
} else if (allowImprovedCatchAnalysis) {
List<Type> catchableThrownTypes = chk.intersect(List.of(exc), thrownInTry);
// 'catchableThrownTypes' cannnot possibly be empty - if 'exc' was an
// unchecked exception, the result list would not be empty, as the augmented
// thrown set includes { RuntimeException, Error }; if 'exc' was a checked
// exception, that would have been covered in the branch above
if (chk.diff(catchableThrownTypes, caughtInTry).isEmpty() &&
!isExceptionOrThrowable(exc)) {
String key = catchableThrownTypes.length() == 1 ?
"unreachable.catch" :
"unreachable.catch.1";
log.warning(pos, key, catchableThrownTypes);
}
}
}
//where
private boolean isExceptionOrThrowable(Type exc) {
return exc.tsym == syms.throwableType.tsym ||
exc.tsym == syms.exceptionType.tsym;
}
public void visitBreak(JCBreak tree) {
recordExit(tree, new FlowPendingExit(tree, null));
}
public void visitContinue(JCContinue tree) {
recordExit(tree, new FlowPendingExit(tree, null));
}
public void visitReturn(JCReturn tree) {
scan(tree.expr);
recordExit(tree, new FlowPendingExit(tree, null));
}
public void visitThrow(JCThrow tree) {
scan(tree.expr);
Symbol sym = TreeInfo.symbol(tree.expr);
if (sym != null &&
sym.kind == VAR &&
(sym.flags() & (FINAL | EFFECTIVELY_FINAL)) != 0 &&
preciseRethrowTypes.get(sym) != null &&
allowImprovedRethrowAnalysis) {
for (Type t : preciseRethrowTypes.get(sym)) {
markThrown(tree, t);
}
}
else {
markThrown(tree, tree.expr.type);
}
markDead(tree);
}
public void visitApply(JCMethodInvocation tree) {
scan(tree.meth);
scan(tree.args);
for (List<Type> l = tree.meth.type.getThrownTypes(); l.nonEmpty(); l = l.tail)
markThrown(tree, l.head);
}
public void visitNewClass(JCNewClass tree) {
scan(tree.encl);
scan(tree.args);
// scan(tree.def);
for (List<Type> l = tree.constructorType.getThrownTypes();
l.nonEmpty();
l = l.tail) {
markThrown(tree, l.head);
}
List<Type> caughtPrev = caught;
try {
// If the new class expression defines an anonymous class,
// analysis of the anonymous constructor may encounter thrown
// types which are unsubstituted type variables.
// However, since the constructor's actual thrown types have
// already been marked as thrown, it is safe to simply include
// each of the constructor's formal thrown types in the set of
// 'caught/declared to be thrown' types, for the duration of
// the class def analysis.
if (tree.def != null)
for (List<Type> l = tree.constructor.type.getThrownTypes();
l.nonEmpty();
l = l.tail) {
caught = chk.incl(l.head, caught);
}
scan(tree.def);
}
finally {
caught = caughtPrev;
}
}
@Override
public void visitLambda(JCLambda tree) {
if (tree.type != null &&
tree.type.isErroneous()) {
return;
}
List<Type> prevCaught = caught;
List<Type> prevThrown = thrown;
ListBuffer<FlowPendingExit> prevPending = pendingExits;
try {
pendingExits = new ListBuffer<>();
caught = tree.getDescriptorType(types).getThrownTypes();
thrown = List.nil();
scan(tree.body);
List<FlowPendingExit> exits = pendingExits.toList();
pendingExits = new ListBuffer<FlowPendingExit>();
while (exits.nonEmpty()) {
FlowPendingExit exit = exits.head;
exits = exits.tail;
if (exit.thrown == null) {
Assert.check(exit.tree.hasTag(RETURN));
} else {
// uncaught throws will be reported later
pendingExits.append(exit);
}
}
errorUncaught();
} finally {
pendingExits = prevPending;
caught = prevCaught;
thrown = prevThrown;
}
}
public void visitTopLevel(JCCompilationUnit tree) {
// Do nothing for TopLevel since each class is visited individually
}
/**************************************************************************
* main method
*************************************************************************/
/** Perform definite assignment/unassignment analysis on a tree.
*/
public void analyzeTree(Env<AttrContext> env, TreeMaker make) {
analyzeTree(env, env.tree, make);
}
public void analyzeTree(Env<AttrContext> env, JCTree tree, TreeMaker make) {
try {
attrEnv = env;
Flow.this.make = make;
pendingExits = new ListBuffer<FlowPendingExit>();
preciseRethrowTypes = new HashMap<Symbol, List();
this.thrown = this.caught = null;
this.classDef = null;
scan(tree);
} finally {
pendingExits = null;
Flow.this.make = null;
this.thrown = this.caught = null;
this.classDef = null;
}
}
}
/**
* Specialized pass that performs inference of thrown types for lambdas.
*/
class LambdaFlowAnalyzer extends FlowAnalyzer {
List<Type> inferredThrownTypes;
boolean inLambda;
@Override
public void visitLambda(JCLambda tree) {
if ((tree.type != null &&
tree.type.isErroneous()) || inLambda) {
return;
}
List<Type> prevCaught = caught;
List<Type> prevThrown = thrown;
ListBuffer<FlowPendingExit> prevPending = pendingExits;
inLambda = true;
try {
pendingExits = new ListBuffer<>();
caught = List.of(syms.throwableType);
thrown = List.nil();
scan(tree.body);
inferredThrownTypes = thrown;
} finally {
pendingExits = prevPending;
caught = prevCaught;
thrown = prevThrown;
inLambda = false;
}
}
@Override
public void visitClassDef(JCClassDecl tree) {
//skip
}
}
/**
* This pass implements (i) definite assignment analysis, which ensures that
* each variable is assigned when used and (ii) definite unassignment analysis,
* which ensures that no final variable is assigned more than once. This visitor
* depends on the results of the liveliness analyzer. This pass is also used to mark
* effectively-final local variables/parameters.
*/
public abstract static class AbstractAssignAnalyzer<P extends AbstractAssignAnalyzer.AbstractAssignPendingExit>
extends BaseAnalyzer<P> {
/** The set of definitely assigned variables.
*/
protected final Bits inits;
/** The set of definitely unassigned variables.
*/
final Bits uninits;
/** The set of variables that are definitely unassigned everywhere
* in current try block. This variable is maintained lazily; it is
* updated only when something gets removed from uninits,
* typically by being assigned in reachable code. To obtain the
* correct set of variables which are definitely unassigned
* anywhere in current try block, intersect uninitsTry and
* uninits.
*/
final Bits uninitsTry;
/** When analyzing a condition, inits and uninits are null.
* Instead we have:
*/
final Bits initsWhenTrue;
final Bits initsWhenFalse;
final Bits uninitsWhenTrue;
final Bits uninitsWhenFalse;
/** A mapping from addresses to variable symbols.
*/
protected JCVariableDecl[] vardecls;
/** The current class being defined.
*/
JCClassDecl classDef;
/** The first variable sequence number in this class definition.
*/
int firstadr;
/** The next available variable sequence number.
*/
protected int nextadr;
/** The first variable sequence number in a block that can return.
*/
protected int returnadr;
/** The list of unreferenced automatic resources.
*/
Scope unrefdResources;
/** Set when processing a loop body the second time for DU analysis. */
FlowKind flowKind = FlowKind.NORMAL;
/** The starting position of the analysed tree */
int startPos;
final Symtab syms;
protected Names names;
public static class AbstractAssignPendingExit extends BaseAnalyzer.PendingExit {
final Bits inits;
final Bits uninits;
final Bits exit_inits = new Bits(true);
final Bits exit_uninits = new Bits(true);
public AbstractAssignPendingExit(JCTree tree, final Bits inits, final Bits uninits) {
super(tree);
this.inits = inits;
this.uninits = uninits;
this.exit_inits.assign(inits);
this.exit_uninits.assign(uninits);
}
@Override
public void resolveJump(JCTree tree) {
inits.andSet(exit_inits);
uninits.andSet(exit_uninits);
}
}
public AbstractAssignAnalyzer(Bits inits, Symtab syms, Names names) {
this.inits = inits;
uninits = new Bits();
uninitsTry = new Bits();
initsWhenTrue = new Bits(true);
initsWhenFalse = new Bits(true);
uninitsWhenTrue = new Bits(true);
uninitsWhenFalse = new Bits(true);
this.syms = syms;
this.names = names;
}
@Override
protected void markDead(JCTree tree) {
inits.inclRange(returnadr, nextadr);
uninits.inclRange(returnadr, nextadr);
}
/*-------------- Processing variables ----------------------*/
/** Do we need to track init/uninit state of this symbol?
* I.e. is symbol either a local or a blank final variable?
*/
protected boolean trackable(VarSymbol sym) {
return
sym.pos >= startPos &&
((sym.owner.kind == MTH ||
((sym.flags() & (FINAL | HASINIT | PARAMETER)) == FINAL &&
classDef.sym.isEnclosedBy((ClassSymbol)sym.owner))));
}
/** Initialize new trackable variable by setting its address field
* to the next available sequence number and entering it under that
* index into the vars array.
*/
void newVar(JCVariableDecl varDecl) {
VarSymbol sym = varDecl.sym;
vardecls = ArrayUtils.ensureCapacity(vardecls, nextadr);
if ((sym.flags() & FINAL) == 0) {
sym.flags_field |= EFFECTIVELY_FINAL;
}
sym.adr = nextadr;
vardecls[nextadr] = varDecl;
exclVarFromInits(varDecl, nextadr);
uninits.incl(nextadr);
nextadr++;
}
protected void exclVarFromInits(JCTree tree, int adr) {
inits.excl(adr);
}
protected void assignToInits(JCTree tree, Bits bits) {
inits.assign(bits);
}
protected void andSetInits(JCTree tree, Bits bits) {
inits.andSet(bits);
}
protected void orSetInits(JCTree tree, Bits bits) {
inits.orSet(bits);
}
/** Record an initialization of a trackable variable.
*/
void letInit(DiagnosticPosition pos, VarSymbol sym) {
if (sym.adr >= firstadr && trackable(sym)) {
if (uninits.isMember(sym.adr)) {
uninit(sym);
}
inits.incl(sym.adr);
}
}
//where
void uninit(VarSymbol sym) {
if (!inits.isMember(sym.adr)) {
// reachable assignment
uninits.excl(sym.adr);
uninitsTry.excl(sym.adr);
} else {
//log.rawWarning(pos, "unreachable assignment");//DEBUG
uninits.excl(sym.adr);
}
}
/** If tree is either a simple name or of the form this.name or
* C.this.name, and tree represents a trackable variable,
* record an initialization of the variable.
*/
void letInit(JCTree tree) {
tree = TreeInfo.skipParens(tree);
if (tree.hasTag(IDENT) || tree.hasTag(SELECT)) {
Symbol sym = TreeInfo.symbol(tree);
if (sym.kind == VAR) {
letInit(tree.pos(), (VarSymbol)sym);
}
}
}
/** Check that trackable variable is initialized.
*/
void checkInit(DiagnosticPosition pos, VarSymbol sym) {
checkInit(pos, sym, "var.might.not.have.been.initialized");
}
void checkInit(DiagnosticPosition pos, VarSymbol sym, String errkey) {}
/** Utility method to reset several Bits instances.
*/
private void resetBits(Bits... bits) {
for (Bits b : bits) {
b.reset();
}
}
/** Split (duplicate) inits/uninits into WhenTrue/WhenFalse sets
*/
void split(boolean setToNull) {
initsWhenFalse.assign(inits);
uninitsWhenFalse.assign(uninits);
initsWhenTrue.assign(inits);
uninitsWhenTrue.assign(uninits);
if (setToNull) {
resetBits(inits, uninits);
}
}
/** Merge (intersect) inits/uninits from WhenTrue/WhenFalse sets.
*/
protected void merge(JCTree tree) {
inits.assign(initsWhenFalse.andSet(initsWhenTrue));
uninits.assign(uninitsWhenFalse.andSet(uninitsWhenTrue));
}
/* ************************************************************************
* Visitor methods for statements and definitions
*************************************************************************/
/** Analyze an expression. Make sure to set (un)inits rather than
* (un)initsWhenTrue(WhenFalse) on exit.
*/
void scanExpr(JCTree tree) {
if (tree != null) {
scan(tree);
if (inits.isReset()) {
merge(tree);
}
}
}
/** Analyze a list of expressions.
*/
void scanExprs(List<? extends JCExpression> trees) {
if (trees != null)
for (List<? extends JCExpression> l = trees; l.nonEmpty(); l = l.tail)
scanExpr(l.head);
}
/** Analyze a condition. Make sure to set (un)initsWhenTrue(WhenFalse)
* rather than (un)inits on exit.
*/
void scanCond(JCTree tree) {
if (tree.type.isFalse()) {
if (inits.isReset()) merge(tree);
initsWhenTrue.assign(inits);
initsWhenTrue.inclRange(firstadr, nextadr);
uninitsWhenTrue.assign(uninits);
uninitsWhenTrue.inclRange(firstadr, nextadr);
initsWhenFalse.assign(inits);
uninitsWhenFalse.assign(uninits);
} else if (tree.type.isTrue()) {
if (inits.isReset()) merge(tree);
initsWhenFalse.assign(inits);
initsWhenFalse.inclRange(firstadr, nextadr);
uninitsWhenFalse.assign(uninits);
uninitsWhenFalse.inclRange(firstadr, nextadr);
initsWhenTrue.assign(inits);
uninitsWhenTrue.assign(uninits);
} else {
scan(tree);
if (!inits.isReset())
split(tree.type != syms.unknownType);
}
if (tree.type != syms.unknownType) {
resetBits(inits, uninits);
}
}
/* ------------ Visitor methods for various sorts of trees -------------*/
@Override
public void visitClassDef(JCClassDecl tree) {
if (tree.sym == null) {
return;
}
JCClassDecl classDefPrev = classDef;
int firstadrPrev = firstadr;
int nextadrPrev = nextadr;
ListBuffer<P> pendingExitsPrev = pendingExits;
pendingExits = new ListBuffer<P>();
if (tree.name != names.empty) {
firstadr = nextadr;
}
classDef = tree;
try {
// define all the static fields
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (l.head.hasTag(VARDEF)) {
JCVariableDecl def = (JCVariableDecl)l.head;
if ((def.mods.flags & STATIC) != 0) {
VarSymbol sym = def.sym;
if (trackable(sym)) {
newVar(def);
}
}
}
}
// process all the static initializers
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) != 0) {
scan(l.head);
}
}
// define all the instance fields
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (l.head.hasTag(VARDEF)) {
JCVariableDecl def = (JCVariableDecl)l.head;
if ((def.mods.flags & STATIC) == 0) {
VarSymbol sym = def.sym;
if (trackable(sym)) {
newVar(def);
}
}
}
}
// process all the instance initializers
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) == 0) {
scan(l.head);
}
}
// process all the methods
for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
if (l.head.hasTag(METHODDEF)) {
scan(l.head);
}
}
} finally {
pendingExits = pendingExitsPrev;
nextadr = nextadrPrev;
firstadr = firstadrPrev;
classDef = classDefPrev;
}
}
@Override
public void visitMethodDef(JCMethodDecl tree) {
if (tree.body == null) {
return;
}
/* Ignore synthetic methods, except for translated lambda methods.
*/
if ((tree.sym.flags() & (SYNTHETIC | LAMBDA_METHOD)) == SYNTHETIC) {
return;
}
final Bits initsPrev = new Bits(inits);
final Bits uninitsPrev = new Bits(uninits);
int nextadrPrev = nextadr;
int firstadrPrev = firstadr;
int returnadrPrev = returnadr;
Assert.check(pendingExits.isEmpty());
try {
boolean isInitialConstructor =
TreeInfo.isInitialConstructor(tree);
if (!isInitialConstructor) {
firstadr = nextadr;
}
for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
JCVariableDecl def = l.head;
scan(def);
Assert.check((def.sym.flags() & PARAMETER) != 0, "Method parameter without PARAMETER flag");
/* If we are executing the code from Gen, then there can be
* synthetic or mandated variables, ignore them.
*/
initParam(def);
}
// else we are in an instance initializer block;
// leave caught unchanged.
scan(tree.body);
if (isInitialConstructor) {
boolean isSynthesized = (tree.sym.flags() &
GENERATEDCONSTR) != 0;
for (int i = firstadr; i < nextadr; i++) {
JCVariableDecl vardecl = vardecls[i];
VarSymbol var = vardecl.sym;
if (var.owner == classDef.sym) {
// choose the diagnostic position based on whether
// the ctor is default(synthesized) or not
if (isSynthesized) {
checkInit(TreeInfo.diagnosticPositionFor(var, vardecl),
var, "var.not.initialized.in.default.constructor");
} else {
checkInit(TreeInfo.diagEndPos(tree.body), var);
}
}
}
}
List<P> exits = pendingExits.toList();
pendingExits = new ListBuffer<>();
while (exits.nonEmpty()) {
P exit = exits.head;
exits = exits.tail;
Assert.check(exit.tree.hasTag(RETURN), exit.tree);
if (isInitialConstructor) {
assignToInits(exit.tree, exit.exit_inits);
for (int i = firstadr; i < nextadr; i++) {
checkInit(exit.tree.pos(), vardecls[i].sym);
}
}
}
} finally {
assignToInits(tree, initsPrev);
uninits.assign(uninitsPrev);
nextadr = nextadrPrev;
firstadr = firstadrPrev;
returnadr = returnadrPrev;
}
}
protected void initParam(JCVariableDecl def) {
inits.incl(def.sym.adr);
uninits.excl(def.sym.adr);
}
public void visitVarDef(JCVariableDecl tree) {
boolean track = trackable(tree.sym);
if (track && tree.sym.owner.kind == MTH) {
newVar(tree);
}
if (tree.init != null) {
scanExpr(tree.init);
if (track) {
letInit(tree.pos(), tree.sym);
}
}
}
public void visitBlock(JCBlock tree) {
int nextadrPrev = nextadr;
scan(tree.stats);
nextadr = nextadrPrev;
}
int getLogNumberOfErrors() {
return 0;
}
public void visitDoLoop(JCDoWhileLoop tree) {
ListBuffer<P> prevPendingExits = pendingExits;
FlowKind prevFlowKind = flowKind;
flowKind = FlowKind.NORMAL;
final Bits initsSkip = new Bits(true);
final Bits uninitsSkip = new Bits(true);
pendingExits = new ListBuffer<P>();
int prevErrors = getLogNumberOfErrors();
do {
final Bits uninitsEntry = new Bits(uninits);
uninitsEntry.excludeFrom(nextadr);
scan(tree.body);
resolveContinues(tree);
scanCond(tree.cond);
if (!flowKind.isFinal()) {
initsSkip.assign(initsWhenFalse);
uninitsSkip.assign(uninitsWhenFalse);
}
if (getLogNumberOfErrors() != prevErrors ||
flowKind.isFinal() ||
new Bits(uninitsEntry).diffSet(uninitsWhenTrue).nextBit(firstadr)==-1)
break;
assignToInits(tree.cond, initsWhenTrue);
uninits.assign(uninitsEntry.andSet(uninitsWhenTrue));
flowKind = FlowKind.SPECULATIVE_LOOP;
} while (true);
flowKind = prevFlowKind;
assignToInits(tree, initsSkip);
uninits.assign(uninitsSkip);
resolveBreaks(tree, prevPendingExits);
}
public void visitWhileLoop(JCWhileLoop tree) {
ListBuffer<P> prevPendingExits = pendingExits;
FlowKind prevFlowKind = flowKind;
flowKind = FlowKind.NORMAL;
final Bits initsSkip = new Bits(true);
final Bits uninitsSkip = new Bits(true);
pendingExits = new ListBuffer<>();
int prevErrors = getLogNumberOfErrors();
final Bits uninitsEntry = new Bits(uninits);
uninitsEntry.excludeFrom(nextadr);
do {
scanCond(tree.cond);
if (!flowKind.isFinal()) {
initsSkip.assign(initsWhenFalse) ;
uninitsSkip.assign(uninitsWhenFalse);
}
assignToInits(tree, initsWhenTrue);
uninits.assign(uninitsWhenTrue);
scan(tree.body);
resolveContinues(tree);
if (getLogNumberOfErrors() != prevErrors ||
flowKind.isFinal() ||
new Bits(uninitsEntry).diffSet(uninits).nextBit(firstadr) == -1) {
break;
}
uninits.assign(uninitsEntry.andSet(uninits));
flowKind = FlowKind.SPECULATIVE_LOOP;
} while (true);
flowKind = prevFlowKind;
//a variable is DA/DU after the while statement, if it's DA/DU assuming the
//branch is not taken AND if it's DA/DU before any break statement
assignToInits(tree.body, initsSkip);
uninits.assign(uninitsSkip);
resolveBreaks(tree, prevPendingExits);
}
public void visitForLoop(JCForLoop tree) {
ListBuffer<P> prevPendingExits = pendingExits;
FlowKind prevFlowKind = flowKind;
flowKind = FlowKind.NORMAL;
int nextadrPrev = nextadr;
scan(tree.init);
final Bits initsSkip = new Bits(true);
final Bits uninitsSkip = new Bits(true);
pendingExits = new ListBuffer<P>();
int prevErrors = getLogNumberOfErrors();
do {
final Bits uninitsEntry = new Bits(uninits);
uninitsEntry.excludeFrom(nextadr);
if (tree.cond != null) {
scanCond(tree.cond);
if (!flowKind.isFinal()) {
initsSkip.assign(initsWhenFalse);
uninitsSkip.assign(uninitsWhenFalse);
}
assignToInits(tree.body, initsWhenTrue);
uninits.assign(uninitsWhenTrue);
} else if (!flowKind.isFinal()) {
initsSkip.assign(inits);
initsSkip.inclRange(firstadr, nextadr);
uninitsSkip.assign(uninits);
uninitsSkip.inclRange(firstadr, nextadr);
}
scan(tree.body);
resolveContinues(tree);
scan(tree.step);
if (getLogNumberOfErrors() != prevErrors ||
flowKind.isFinal() ||
new Bits(uninitsEntry).diffSet(uninits).nextBit(firstadr) == -1)
break;
uninits.assign(uninitsEntry.andSet(uninits));
flowKind = FlowKind.SPECULATIVE_LOOP;
} while (true);
flowKind = prevFlowKind;
//a variable is DA/DU after a for loop, if it's DA/DU assuming the
//branch is not taken AND if it's DA/DU before any break statement
assignToInits(tree.body, initsSkip);
uninits.assign(uninitsSkip);
resolveBreaks(tree, prevPendingExits);
nextadr = nextadrPrev;
}
public void visitForeachLoop(JCEnhancedForLoop tree) {
visitVarDef(tree.var);
ListBuffer<P> prevPendingExits = pendingExits;
FlowKind prevFlowKind = flowKind;
flowKind = FlowKind.NORMAL;
int nextadrPrev = nextadr;
scan(tree.expr);
final Bits initsStart = new Bits(inits);
final Bits uninitsStart = new Bits(uninits);
letInit(tree.pos(), tree.var.sym);
pendingExits = new ListBuffer<P>();
int prevErrors = getLogNumberOfErrors();
do {
final Bits uninitsEntry = new Bits(uninits);
uninitsEntry.excludeFrom(nextadr);
scan(tree.body);
resolveContinues(tree);
if (getLogNumberOfErrors() != prevErrors ||
flowKind.isFinal() ||
new Bits(uninitsEntry).diffSet(uninits).nextBit(firstadr) == -1)
break;
uninits.assign(uninitsEntry.andSet(uninits));
flowKind = FlowKind.SPECULATIVE_LOOP;
} while (true);
flowKind = prevFlowKind;
assignToInits(tree.body, initsStart);
uninits.assign(uninitsStart.andSet(uninits));
resolveBreaks(tree, prevPendingExits);
nextadr = nextadrPrev;
}
public void visitLabelled(JCLabeledStatement tree) {
ListBuffer<P> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<P>();
scan(tree.body);
resolveBreaks(tree, prevPendingExits);
}
public void visitSwitch(JCSwitch tree) {
ListBuffer<P> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
int nextadrPrev = nextadr;
scanExpr(tree.selector);
final Bits initsSwitch = new Bits(inits);
final Bits uninitsSwitch = new Bits(uninits);
boolean hasDefault = false;
for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) {
assignToInits(l.head, initsSwitch);
uninits.assign(uninits.andSet(uninitsSwitch));
JCCase c = l.head;
if (c.pat == null) {
hasDefault = true;
} else {
scanExpr(c.pat);
}
if (hasDefault) {
assignToInits(null, initsSwitch);
uninits.assign(uninits.andSet(uninitsSwitch));
}
scan(c.stats);
addVars(c.stats, initsSwitch, uninitsSwitch);
if (!hasDefault) {
assignToInits(l.head.stats.last(), initsSwitch);
uninits.assign(uninits.andSet(uninitsSwitch));
}
// Warn about fall-through if lint switch fallthrough enabled.
}
if (!hasDefault) {
andSetInits(null, initsSwitch);
}
resolveBreaks(tree, prevPendingExits);
nextadr = nextadrPrev;
}
// where
/** Add any variables defined in stats to inits and uninits. */
private void addVars(List<JCStatement> stats, final Bits inits,
final Bits uninits) {
for (;stats.nonEmpty(); stats = stats.tail) {
JCTree stat = stats.head;
if (stat.hasTag(VARDEF)) {
int adr = ((JCVariableDecl) stat).sym.adr;
inits.excl(adr);
uninits.incl(adr);
}
}
}
boolean isEnabled(Lint.LintCategory lc) {
return false;
}
void reportWarning(Lint.LintCategory lc, DiagnosticPosition pos, String key, Object ... args) {}
public void visitTry(JCTry tree) {
ListBuffer<JCVariableDecl> resourceVarDecls = new ListBuffer<>();
final Bits uninitsTryPrev = new Bits(uninitsTry);
ListBuffer<P> prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
final Bits initsTry = new Bits(inits);
uninitsTry.assign(uninits);
for (JCTree resource : tree.resources) {
if (resource instanceof JCVariableDecl) {
JCVariableDecl vdecl = (JCVariableDecl) resource;
visitVarDef(vdecl);
unrefdResources.enter(vdecl.sym);
resourceVarDecls.append(vdecl);
} else if (resource instanceof JCExpression) {
scanExpr((JCExpression) resource);
} else {
throw new AssertionError(tree); // parser error
}
}
scan(tree.body);
uninitsTry.andSet(uninits);
final Bits initsEnd = new Bits(inits);
final Bits uninitsEnd = new Bits(uninits);
int nextadrCatch = nextadr;
if (!resourceVarDecls.isEmpty() &&
isEnabled(Lint.LintCategory.TRY)) {
for (JCVariableDecl resVar : resourceVarDecls) {
if (unrefdResources.includes(resVar.sym)) {
reportWarning(Lint.LintCategory.TRY, resVar.pos(),
"try.resource.not.referenced", resVar.sym);
unrefdResources.remove(resVar.sym);
}
}
}
/* The analysis of each catch should be independent.
* Each one should have the same initial values of inits and
* uninits.
*/
final Bits initsCatchPrev = new Bits(initsTry);
final Bits uninitsCatchPrev = new Bits(uninitsTry);
for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
JCVariableDecl param = l.head.param;
assignToInits(tree.body, initsCatchPrev);
uninits.assign(uninitsCatchPrev);
scan(param);
/* If this is a TWR and we are executing the code from Gen,
* then there can be synthetic variables, ignore them.
*/
initParam(param);
scan(l.head.body);
initsEnd.andSet(inits);
uninitsEnd.andSet(uninits);
nextadr = nextadrCatch;
}
if (tree.finalizer != null) {
assignToInits(tree.finalizer, initsTry);
uninits.assign(uninitsTry);
ListBuffer<P> exits = pendingExits;
pendingExits = prevPendingExits;
scan(tree.finalizer);
if (!tree.finallyCanCompleteNormally) {
// discard exits and exceptions from try and finally
} else {
uninits.andSet(uninitsEnd);
// FIX: this doesn't preserve source order of exits in catch
// versus finally!
while (exits.nonEmpty()) {
P exit = exits.next();
if (exit.exit_inits != null) {
exit.exit_inits.orSet(inits);
exit.exit_uninits.andSet(uninits);
}
pendingExits.append(exit);
}
orSetInits(tree, initsEnd);
}
} else {
assignToInits(tree, initsEnd);
uninits.assign(uninitsEnd);
ListBuffer<P> exits = pendingExits;
pendingExits = prevPendingExits;
while (exits.nonEmpty()) pendingExits.append(exits.next());
}
uninitsTry.andSet(uninitsTryPrev).andSet(uninits);
}
public void visitConditional(JCConditional tree) {
scanCond(tree.cond);
final Bits initsBeforeElse = new Bits(initsWhenFalse);
final Bits uninitsBeforeElse = new Bits(uninitsWhenFalse);
assignToInits(tree.cond, initsWhenTrue);
uninits.assign(uninitsWhenTrue);
if (tree.truepart.type.hasTag(BOOLEAN) &&
tree.falsepart.type.hasTag(BOOLEAN)) {
// if b and c are boolean valued, then
// v is (un)assigned after a?b:c when true iff
// v is (un)assigned after b when true and
// v is (un)assigned after c when true
scanCond(tree.truepart);
final Bits initsAfterThenWhenTrue = new Bits(initsWhenTrue);
final Bits initsAfterThenWhenFalse = new Bits(initsWhenFalse);
final Bits uninitsAfterThenWhenTrue = new Bits(uninitsWhenTrue);
final Bits uninitsAfterThenWhenFalse = new Bits(uninitsWhenFalse);
assignToInits(tree.truepart, initsBeforeElse);
uninits.assign(uninitsBeforeElse);
scanCond(tree.falsepart);
initsWhenTrue.andSet(initsAfterThenWhenTrue);
initsWhenFalse.andSet(initsAfterThenWhenFalse);
uninitsWhenTrue.andSet(uninitsAfterThenWhenTrue);
uninitsWhenFalse.andSet(uninitsAfterThenWhenFalse);
} else {
scanExpr(tree.truepart);
final Bits initsAfterThen = new Bits(inits);
final Bits uninitsAfterThen = new Bits(uninits);
assignToInits(tree.truepart, initsBeforeElse);
uninits.assign(uninitsBeforeElse);
scanExpr(tree.falsepart);
andSetInits(tree.falsepart, initsAfterThen);
uninits.andSet(uninitsAfterThen);
}
}
public void visitIf(JCIf tree) {
scanCond(tree.cond);
final Bits initsBeforeElse = new Bits(initsWhenFalse);
final Bits uninitsBeforeElse = new Bits(uninitsWhenFalse);
assignToInits(tree.cond, initsWhenTrue);
uninits.assign(uninitsWhenTrue);
scan(tree.thenpart);
if (tree.elsepart != null) {
final Bits initsAfterThen = new Bits(inits);
final Bits uninitsAfterThen = new Bits(uninits);
assignToInits(tree.thenpart, initsBeforeElse);
uninits.assign(uninitsBeforeElse);
scan(tree.elsepart);
andSetInits(tree.elsepart, initsAfterThen);
uninits.andSet(uninitsAfterThen);
} else {
andSetInits(tree.thenpart, initsBeforeElse);
uninits.andSet(uninitsBeforeElse);
}
}
protected P createNewPendingExit(JCTree tree, Bits inits, Bits uninits) {
return null;
}
@Override
public void visitBreak(JCBreak tree) {
recordExit(tree, createNewPendingExit(tree, inits, uninits));
}
@Override
public void visitContinue(JCContinue tree) {
recordExit(tree, createNewPendingExit(tree, inits, uninits));
}
@Override
public void visitReturn(JCReturn tree) {
scanExpr(tree.expr);
recordExit(tree, createNewPendingExit(tree, inits, uninits));
}
public void visitThrow(JCThrow tree) {
scanExpr(tree.expr);
markDead(tree.expr);
}
public void visitApply(JCMethodInvocation tree) {
scanExpr(tree.meth);
scanExprs(tree.args);
}
public void visitNewClass(JCNewClass tree) {
scanExpr(tree.encl);
scanExprs(tree.args);
scan(tree.def);
}
@Override
public void visitLambda(JCLambda tree) {
final Bits prevUninits = new Bits(uninits);
final Bits prevInits = new Bits(inits);
int returnadrPrev = returnadr;
ListBuffer<P> prevPending = pendingExits;
try {
returnadr = nextadr;
pendingExits = new ListBuffer<P>();
for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
JCVariableDecl def = l.head;
scan(def);
inits.incl(def.sym.adr);
uninits.excl(def.sym.adr);
}
if (tree.getBodyKind() == JCLambda.BodyKind.EXPRESSION) {
scanExpr(tree.body);
} else {
scan(tree.body);
}
}
finally {
returnadr = returnadrPrev;
uninits.assign(prevUninits);
assignToInits(tree, prevInits);
pendingExits = prevPending;
}
}
public void visitNewArray(JCNewArray tree) {
scanExprs(tree.dims);
scanExprs(tree.elems);
}
public void visitAssert(JCAssert tree) {
final Bits initsExit = new Bits(inits);
final Bits uninitsExit = new Bits(uninits);
scanCond(tree.cond);
uninitsExit.andSet(uninitsWhenTrue);
if (tree.detail != null) {
assignToInits(tree, initsWhenFalse);
uninits.assign(uninitsWhenFalse);
scanExpr(tree.detail);
}
assignToInits(tree, initsExit);
uninits.assign(uninitsExit);
}
public void visitAssign(JCAssign tree) {
JCTree lhs = TreeInfo.skipParens(tree.lhs);
if (!(lhs instanceof JCIdent)) {
scanExpr(lhs);
}
scanExpr(tree.rhs);
letInit(lhs);
}
public void visitAssignop(JCAssignOp tree) {
scanExpr(tree.lhs);
scanExpr(tree.rhs);
letInit(tree.lhs);
}
public void visitUnary(JCUnary tree) {
switch (tree.getTag()) {
case NOT:
scanCond(tree.arg);
final Bits t = new Bits(initsWhenFalse);
initsWhenFalse.assign(initsWhenTrue);
initsWhenTrue.assign(t);
t.assign(uninitsWhenFalse);
uninitsWhenFalse.assign(uninitsWhenTrue);
uninitsWhenTrue.assign(t);
break;
case PREINC: case POSTINC:
case PREDEC: case POSTDEC:
scanExpr(tree.arg);
letInit(tree.arg);
break;
default:
scanExpr(tree.arg);
}
}
public void visitBinary(JCBinary tree) {
switch (tree.getTag()) {
case AND:
scanCond(tree.lhs);
final Bits initsWhenFalseLeft = new Bits(initsWhenFalse);
final Bits uninitsWhenFalseLeft = new Bits(uninitsWhenFalse);
assignToInits(tree.lhs, initsWhenTrue);
uninits.assign(uninitsWhenTrue);
scanCond(tree.rhs);
initsWhenFalse.andSet(initsWhenFalseLeft);
uninitsWhenFalse.andSet(uninitsWhenFalseLeft);
break;
case OR:
scanCond(tree.lhs);
final Bits initsWhenTrueLeft = new Bits(initsWhenTrue);
final Bits uninitsWhenTrueLeft = new Bits(uninitsWhenTrue);
assignToInits(tree.lhs, initsWhenFalse);
uninits.assign(uninitsWhenFalse);
scanCond(tree.rhs);
initsWhenTrue.andSet(initsWhenTrueLeft);
uninitsWhenTrue.andSet(uninitsWhenTrueLeft);
break;
default:
scanExpr(tree.lhs);
scanExpr(tree.rhs);
}
}
public void visitIdent(JCIdent tree) {
if (tree.sym.kind == VAR) {
checkInit(tree.pos(), (VarSymbol)tree.sym);
referenced(tree.sym);
}
}
void referenced(Symbol sym) {
unrefdResources.remove(sym);
}
public void visitAnnotatedType(JCAnnotatedType tree) {
// annotations don't get scanned
tree.underlyingType.accept(this);
}
public void visitTopLevel(JCCompilationUnit tree) {
// Do nothing for TopLevel since each class is visited individually
}
/**************************************************************************
* main method
*************************************************************************/
/** Perform definite assignment/unassignment analysis on a tree.
*/
public void analyzeTree(Env<?> env) {
analyzeTree(env, env.tree);
}
public void analyzeTree(Env<?> env, JCTree tree) {
try {
startPos = tree.pos().getStartPosition();
if (vardecls == null)
vardecls = new JCVariableDecl[32];
else
for (int i=0; i<vardecls.length; i++)
vardecls[i] = null;
firstadr = 0;
nextadr = 0;
pendingExits = new ListBuffer<>();
this.classDef = null;
unrefdResources = new Scope(env.enclClass.sym);
scan(tree);
} finally {
// note that recursive invocations of this method fail hard
startPos = -1;
resetBits(inits, uninits, uninitsTry, initsWhenTrue,
initsWhenFalse, uninitsWhenTrue, uninitsWhenFalse);
if (vardecls != null) {
for (int i=0; i<vardecls.length; i++)
vardecls[i] = null;
}
firstadr = 0;
nextadr = 0;
pendingExits = null;
this.classDef = null;
unrefdResources = null;
}
}
}
public static class AssignAnalyzer
extends AbstractAssignAnalyzer<AssignAnalyzer.AssignPendingExit> {
Log log;
Lint lint;
public static class AssignPendingExit
extends AbstractAssignAnalyzer.AbstractAssignPendingExit {
public AssignPendingExit(JCTree tree, final Bits inits, final Bits uninits) {
super(tree, inits, uninits);
}
}
public AssignAnalyzer(Log log, Symtab syms, Lint lint, Names names) {
super(new Bits(), syms, names);
this.log = log;
this.lint = lint;
}
@Override
protected AssignPendingExit createNewPendingExit(JCTree tree,
Bits inits, Bits uninits) {
return new AssignPendingExit(tree, inits, uninits);
}
/** Record an initialization of a trackable variable.
*/
@Override
void letInit(DiagnosticPosition pos, VarSymbol sym) {
if (sym.adr >= firstadr && trackable(sym)) {
if ((sym.flags() & EFFECTIVELY_FINAL) != 0) {
if (!uninits.isMember(sym.adr)) {
//assignment targeting an effectively final variable
//makes the variable lose its status of effectively final
//if the variable is _not_ definitively unassigned
sym.flags_field &= ~EFFECTIVELY_FINAL;
} else {
uninit(sym);
}
}
else if ((sym.flags() & FINAL) != 0) {
if ((sym.flags() & PARAMETER) != 0) {
if ((sym.flags() & UNION) != 0) { //multi-catch parameter
log.error(pos, "multicatch.parameter.may.not.be.assigned", sym);
}
else {
log.error(pos, "final.parameter.may.not.be.assigned",
sym);
}
} else if (!uninits.isMember(sym.adr)) {
log.error(pos, flowKind.errKey, sym);
} else {
uninit(sym);
}
}
inits.incl(sym.adr);
} else if ((sym.flags() & FINAL) != 0) {
log.error(pos, "var.might.already.be.assigned", sym);
}
}
@Override
void checkInit(DiagnosticPosition pos, VarSymbol sym, String errkey) {
if ((sym.adr >= firstadr || sym.owner.kind != TYP) &&
trackable(sym) &&
!inits.isMember(sym.adr)) {
log.error(pos, errkey, sym);
inits.incl(sym.adr);
}
}
@Override
void reportWarning(Lint.LintCategory lc, DiagnosticPosition pos,
String key, Object ... args) {
log.warning(lc, pos, key, args);
}
@Override
int getLogNumberOfErrors() {
return log.nerrors;
}
@Override
boolean isEnabled(Lint.LintCategory lc) {
return lint.isEnabled(lc);
}
@Override
public void visitClassDef(JCClassDecl tree) {
if (tree.sym == null) {
return;
}
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
try {
super.visitClassDef(tree);
} finally {
lint = lintPrev;
}
}
@Override
public void visitMethodDef(JCMethodDecl tree) {
if (tree.body == null) {
return;
}
/* MemberEnter can generate synthetic methods ignore them
*/
if ((tree.sym.flags() & SYNTHETIC) != 0) {
return;
}
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
try {
super.visitMethodDef(tree);
} finally {
lint = lintPrev;
}
}
@Override
public void visitVarDef(JCVariableDecl tree) {
if (tree.init == null) {
super.visitVarDef(tree);
} else {
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
try{
super.visitVarDef(tree);
} finally {
lint = lintPrev;
}
}
}
}
/**
* This pass implements the last step of the dataflow analysis, namely
* the effectively-final analysis check. This checks that every local variable
* reference from a lambda body/local inner class is either final or effectively final.
* As effectively final variables are marked as such during DA/DU, this pass must run after
* AssignAnalyzer.
*/
class CaptureAnalyzer extends BaseAnalyzer<BaseAnalyzer.PendingExit> {
JCTree currentTree; //local class or lambda
@Override
void markDead(JCTree tree) {
//do nothing
}
@SuppressWarnings("fallthrough")
void checkEffectivelyFinal(DiagnosticPosition pos, VarSymbol sym) {
if (currentTree != null &&
sym.owner.kind == MTH &&
sym.pos < currentTree.getStartPosition()) {
switch (currentTree.getTag()) {
case CLASSDEF:
if (!allowEffectivelyFinalInInnerClasses) {
if ((sym.flags() & FINAL) == 0) {
reportInnerClsNeedsFinalError(pos, sym);
}
break;
}
case LAMBDA:
if ((sym.flags() & (EFFECTIVELY_FINAL | FINAL)) == 0) {
reportEffectivelyFinalError(pos, sym);
}
}
}
}
@SuppressWarnings("fallthrough")
void letInit(JCTree tree) {
tree = TreeInfo.skipParens(tree);
if (tree.hasTag(IDENT) || tree.hasTag(SELECT)) {
Symbol sym = TreeInfo.symbol(tree);
if (currentTree != null &&
sym.kind == VAR &&
sym.owner.kind == MTH &&
((VarSymbol)sym).pos < currentTree.getStartPosition()) {
switch (currentTree.getTag()) {
case CLASSDEF:
if (!allowEffectivelyFinalInInnerClasses) {
reportInnerClsNeedsFinalError(tree, sym);
break;
}
case LAMBDA:
reportEffectivelyFinalError(tree, sym);
}
}
}
}
void reportEffectivelyFinalError(DiagnosticPosition pos, Symbol sym) {
String subKey = currentTree.hasTag(LAMBDA) ?
"lambda" : "inner.cls";
log.error(pos, "cant.ref.non.effectively.final.var", sym, diags.fragment(subKey));
}
void reportInnerClsNeedsFinalError(DiagnosticPosition pos, Symbol sym) {
log.error(pos,
"local.var.accessed.from.icls.needs.final",
sym);
}
/*************************************************************************
* Visitor methods for statements and definitions
*************************************************************************/
/* ------------ Visitor methods for various sorts of trees -------------*/
public void visitClassDef(JCClassDecl tree) {
JCTree prevTree = currentTree;
try {
currentTree = tree.sym.isLocal() ? tree : null;
super.visitClassDef(tree);
} finally {
currentTree = prevTree;
}
}
@Override
public void visitLambda(JCLambda tree) {
JCTree prevTree = currentTree;
try {
currentTree = tree;
super.visitLambda(tree);
} finally {
currentTree = prevTree;
}
}
@Override
public void visitIdent(JCIdent tree) {
if (tree.sym.kind == VAR) {
checkEffectivelyFinal(tree, (VarSymbol)tree.sym);
}
}
public void visitAssign(JCAssign tree) {
JCTree lhs = TreeInfo.skipParens(tree.lhs);
if (!(lhs instanceof JCIdent)) {
scan(lhs);
}
scan(tree.rhs);
letInit(lhs);
}
public void visitAssignop(JCAssignOp tree) {
scan(tree.lhs);
scan(tree.rhs);
letInit(tree.lhs);
}
public void visitUnary(JCUnary tree) {
switch (tree.getTag()) {
case PREINC: case POSTINC:
case PREDEC: case POSTDEC:
scan(tree.arg);
letInit(tree.arg);
break;
default:
scan(tree.arg);
}
}
public void visitTopLevel(JCCompilationUnit tree) {
// Do nothing for TopLevel since each class is visited individually
}
/**************************************************************************
* main method
*************************************************************************/
/** Perform definite assignment/unassignment analysis on a tree.
*/
public void analyzeTree(Env<AttrContext> env, TreeMaker make) {
analyzeTree(env, env.tree, make);
}
public void analyzeTree(Env<AttrContext> env, JCTree tree, TreeMaker make) {
try {
attrEnv = env;
Flow.this.make = make;
pendingExits = new ListBuffer<PendingExit>();
scan(tree);
} finally {
pendingExits = null;
Flow.this.make = null;
}
}
}
}
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