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/*
* Copyright (c) 1999, 2021, 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
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*/
//todo: one might eliminate uninits.andSets when monotonic
package com.sun.tools.javac.comp;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.StreamSupport;
import com.sun.source.tree.LambdaExpressionTree.BodyKind;
import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Scope.WriteableScope;
import com.sun.tools.javac.code.Source.Feature;
import com.sun.tools.javac.resources.CompilerProperties.Errors;
import com.sun.tools.javac.resources.CompilerProperties.Warnings;
import com.sun.tools.javac.tree.*;
import com.sun.tools.javac.tree.TreeInfo.PatternPrimaryType;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.util.JCDiagnostic.Error;
import com.sun.tools.javac.util.JCDiagnostic.Warning;
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.Kind.*;
import com.sun.tools.javac.code.Type.TypeVar;
import static com.sun.tools.javac.code.TypeTag.BOOLEAN;
import static com.sun.tools.javac.code.TypeTag.VOID;
import com.sun.tools.javac.resources.CompilerProperties.Fragments;
import static com.sun.tools.javac.tree.JCTree.Tag.*;
import com.sun.tools.javac.util.JCDiagnostic.Fragment;
/** This pass implements dataflow analysis for Java programs though
* different AST visitor steps. Liveness analysis (see AliveAnalyzer) 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.
*
* The JLS has a number of problems in the
* specification of these flow analysis problems. This implementation
* attempts to address those issues.
*
*
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.
*
*
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
*
* V is unassigned everywhere in a block if it is
* unassigned before the block and there is no reachable
* assignment to V within the block.
*
* In 16.2.15, the third bullet (and all of its sub-bullets) for all
* try blocks is changed to
*
* V is definitely unassigned before a catch block iff V is
* definitely unassigned everywhere in the try block.
*
* The last bullet (and all of its sub-bullets) for try blocks that
* have a finally block is changed to
*
* 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.
*
* In addition,
*
* 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.
*
* 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.
*
*
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".
*
*
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 constructors.
*
*
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.
*
*
Intervening finally blocks similarly affect exception analysis. An
* intervening finally that cannot complete normally allows us to ignore
* an otherwise uncaught exception.
*
*
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 thrown}" that records the type of all
* exceptions that can be thrown.
*
* 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).
*
*
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.
*
*
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.
*/
public class Flow {
protected static final Context.Key flowKey = new Context.Key<>();
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 final Enter enter;
private JCClassDecl reanalyzedClass;
private Env attrEnv;
private Lint lint;
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 env, TreeMaker make) {
new AliveAnalyzer().analyzeTree(env, make);
new AssignAnalyzer().analyzeTree(env, make);
new FlowAnalyzer().analyzeTree(env, make);
new CaptureAnalyzer().analyzeTree(env, make);
}
public void analyzeLambda(Env 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 analysis
//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 LambdaAliveAnalyzer().analyzeTree(env, that, make);
} finally {
if (!speculative) {
log.popDiagnosticHandler(diagHandler);
}
}
}
public List analyzeLambdaThrownTypes(final 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 analysis
//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 LambdaAssignAnalyzer(env).analyzeTree(env, that, make);
LambdaFlowAnalyzer flowAnalyzer = new LambdaFlowAnalyzer();
flowAnalyzer.analyzeTree(env, that, make);
return flowAnalyzer.inferredThrownTypes;
} finally {
log.popDiagnosticHandler(diagHandler);
}
}
public void reanalyzeMethod (final TreeMaker make, final JCClassDecl classDef) {
JCClassDecl oldReanalyzedClass = reanalyzedClass;
try {
reanalyzedClass = classDef;
Env env = enter.getEnv(classDef.sym);
new AliveAnalyzer().analyzeTree(env, classDef, make);
new AssignAnalyzer().analyzeTree(env, classDef, make);
new FlowAnalyzer().analyzeTree(env, classDef, make);
new CaptureAnalyzer().analyzeTree(env, classDef, make);
} finally {
reanalyzedClass = oldReanalyzedClass;
}
}
public boolean aliveAfter(Env env, JCTree that, TreeMaker make) {
//we need to disable diagnostics temporarily; the problem is that if
//"that" contains e.g. an unreachable statement, an error
//message will be reported and will cause compilation to skip the flow analysis
//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 {
SnippetAliveAnalyzer analyzer = new SnippetAliveAnalyzer();
analyzer.analyzeTree(env, that, make);
return analyzer.isAlive();
} finally {
log.popDiagnosticHandler(diagHandler);
}
}
public boolean breaksOutOf(Env env, JCTree loop, JCTree body, TreeMaker make) {
//we need to disable diagnostics temporarily; the problem is that if
//"that" contains e.g. an unreachable statement, an error
//message will be reported and will cause compilation to skip the flow analysis
//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 {
SnippetBreakAnalyzer analyzer = new SnippetBreakAnalyzer();
analyzer.analyzeTree(env, body, make);
return analyzer.breaksOut();
} 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);
enter = Enter.instance(context);
Source source = Source.instance(context);
allowEffectivelyFinalInInnerClasses = Feature.EFFECTIVELY_FINAL_IN_INNER_CLASSES.allowedInSource(source);
}
/**
* 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 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;
}
},
YIELD(JCTree.Tag.YIELD) {
@Override
JCTree getTarget(JCTree tree) {
return ((JCYield)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 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() {
//do nothing
}
}
abstract void markDead();
/** Record an outward transfer of control. */
void recordExit(PendingExit pe) {
pendingExits.append(pe);
markDead();
}
/** Resolve all jumps of this statement. */
private Liveness resolveJump(JCTree tree,
ListBuffer oldPendingExits,
JumpKind jk) {
boolean resolved = false;
List exits = pendingExits.toList();
pendingExits = oldPendingExits;
for (; exits.nonEmpty(); exits = exits.tail) {
PendingExit exit = exits.head;
if (exit.tree.hasTag(jk.treeTag) &&
jk.getTarget(exit.tree) == tree) {
exit.resolveJump();
resolved = true;
} else {
pendingExits.append(exit);
}
}
return Liveness.from(resolved);
}
/** Resolve all continues of this statement. */
Liveness resolveContinues(JCTree tree) {
return resolveJump(tree, new ListBuffer(), JumpKind.CONTINUE);
}
/** Resolve all breaks of this statement. */
Liveness resolveBreaks(JCTree tree, ListBuffer oldPendingExits) {
return resolveJump(tree, oldPendingExits, JumpKind.BREAK);
}
/** Resolve all yields of this statement. */
Liveness resolveYields(JCTree tree, ListBuffer oldPendingExits) {
return resolveJump(tree, oldPendingExits, JumpKind.YIELD);
}
@Override
public void scan(JCTree tree) {
if (tree != null && (
tree.type == null ||
tree.type != Type.stuckType)) {
super.scan(tree);
}
}
public void visitPackageDef(JCPackageDecl tree) {
// Do nothing for PackageDecl
}
protected void scanSyntheticBreak(TreeMaker make, JCTree swtch) {
if (swtch.hasTag(SWITCH_EXPRESSION)) {
JCYield brk = make.at(Position.NOPOS).Yield(null);
brk.target = swtch;
scan(brk);
} else {
JCBreak brk = make.at(Position.NOPOS).Break(null);
brk.target = swtch;
scan(brk);
}
}
}
/**
* 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 {
/** A flag that indicates whether the last statement could
* complete normally.
*/
private Liveness alive;
@Override
void markDead() {
alive = Liveness.DEAD;
}
/*************************************************************************
* Visitor methods for statements and definitions
*************************************************************************/
/** Analyze a definition.
*/
void scanDef(JCTree tree) {
scanStat(tree);
if (tree != null && tree.hasTag(JCTree.Tag.BLOCK) && alive == Liveness.DEAD) {
log.error(tree.pos(),
Errors.InitializerMustBeAbleToCompleteNormally);
}
}
/** Analyze a statement. Check that statement is reachable.
*/
void scanStat(JCTree tree) {
if (alive == Liveness.DEAD && tree != null) {
log.error(tree.pos(), Errors.UnreachableStmt);
if (!tree.hasTag(SKIP)) alive = Liveness.RECOVERY;
}
scan(tree);
}
/** Analyze list of statements.
*/
void scanStats(List trees) {
if (trees != null)
for (List 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;
Liveness alivePrev = alive;
ListBuffer pendingExitsPrev = pendingExits;
Lint lintPrev = lint;
pendingExits = new ListBuffer<>();
lint = lint.augment(tree.sym);
try {
// process all the static initializers
for (List l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) != 0) {
scanDef(l.head);
clearPendingExits(false);
}
}
// process all the instance initializers
for (List l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) == 0) {
scanDef(l.head);
clearPendingExits(false);
}
}
// process all the methods
for (List 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 || tree.sym == null) return;
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
Assert.check(pendingExits.isEmpty());
try {
alive = Liveness.ALIVE;
scanStat(tree.body);
tree.completesNormally = alive != Liveness.DEAD;
if (alive == Liveness.ALIVE && tree.sym.type.getReturnType() != null && !tree.sym.type.getReturnType().hasTag(VOID))
log.error(TreeInfo.diagEndPos(tree.body), Errors.MissingRetStmt);
clearPendingExits(true);
} finally {
lint = lintPrev;
}
}
private void clearPendingExits(boolean inMethod) {
List exits = pendingExits.toList();
pendingExits = new ListBuffer<>();
while (exits.nonEmpty()) {
PendingExit exit = exits.head;
exits = exits.tail;
Assert.check((inMethod && exit.tree.hasTag(RETURN)) ||
log.hasErrorOn(exit.tree.pos()));
}
}
public void visitVarDef(JCVariableDecl tree) {
if (tree.init != null && tree.sym != 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 prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scanStat(tree.body);
alive = alive.or(resolveContinues(tree));
scan(tree.cond);
alive = alive.and(tree.cond.type != null && !tree.cond.type.isTrue());
alive = alive.or(resolveBreaks(tree, prevPendingExits));
}
public void visitWhileLoop(JCWhileLoop tree) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scan(tree.cond);
alive = Liveness.from(tree.cond.type != null && !tree.cond.type.isFalse());
scanStat(tree.body);
alive = alive.or(resolveContinues(tree));
alive = resolveBreaks(tree, prevPendingExits).or(
tree.cond.type != null && !tree.cond.type.isTrue());
}
public void visitForLoop(JCForLoop tree) {
ListBuffer prevPendingExits = pendingExits;
scanStats(tree.init);
pendingExits = new ListBuffer<>();
if (tree.cond != null && tree.cond.type != null) {
scan(tree.cond);
alive = Liveness.from(!tree.cond.type.isFalse());
} else {
alive = Liveness.ALIVE;
}
scanStat(tree.body);
alive = alive.or(resolveContinues(tree));
scan(tree.step);
alive = resolveBreaks(tree, prevPendingExits).or(
tree.cond != null && tree.cond.type != null && !tree.cond.type.isTrue());
}
public void visitForeachLoop(JCEnhancedForLoop tree) {
visitVarDef(tree.var);
ListBuffer prevPendingExits = pendingExits;
scan(tree.expr);
pendingExits = new ListBuffer<>();
scanStat(tree.body);
alive = alive.or(resolveContinues(tree));
resolveBreaks(tree, prevPendingExits);
alive = Liveness.ALIVE;
}
public void visitLabelled(JCLabeledStatement tree) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scanStat(tree.body);
alive = alive.or(resolveBreaks(tree, prevPendingExits));
}
public void visitSwitch(JCSwitch tree) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scan(tree.selector);
boolean exhaustiveSwitch = tree.patternSwitch ||
tree.cases.stream()
.flatMap(c -> c.labels.stream())
.anyMatch(l -> TreeInfo.isNull(l));
Set constants = exhaustiveSwitch ? new HashSet<>() : null;
for (List l = tree.cases; l.nonEmpty(); l = l.tail) {
alive = Liveness.ALIVE;
JCCase c = l.head;
for (JCCaseLabel pat : c.labels) {
scan(pat);
handleConstantCaseLabel(constants, pat);
}
scanStats(c.stats);
if (alive != Liveness.DEAD && c.caseKind == JCCase.RULE) {
scanSyntheticBreak(make, tree);
alive = Liveness.DEAD;
}
// Warn about fall-through if lint switch fallthrough enabled.
if (alive == Liveness.ALIVE &&
lint.isEnabled(Lint.LintCategory.FALLTHROUGH) &&
c.stats.nonEmpty() && l.tail.nonEmpty())
log.warning(Lint.LintCategory.FALLTHROUGH,
l.tail.head.pos(),
Warnings.PossibleFallThroughIntoCase);
}
if (!tree.hasTotalPattern && exhaustiveSwitch &&
!TreeInfo.isErrorEnumSwitch(tree.selector, tree.cases) &&
(constants == null || !isExhaustive(tree.selector.type, constants))) {
log.error(tree, Errors.NotExhaustiveStatement);
}
if (!tree.hasTotalPattern) {
alive = Liveness.ALIVE;
}
alive = alive.or(resolveBreaks(tree, prevPendingExits));
}
@Override
public void visitSwitchExpression(JCSwitchExpression tree) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scan(tree.selector);
Set constants = new HashSet<>();
Liveness prevAlive = alive;
for (List l = tree.cases; l.nonEmpty(); l = l.tail) {
alive = Liveness.ALIVE;
JCCase c = l.head;
for (JCCaseLabel pat : c.labels) {
scan(pat);
handleConstantCaseLabel(constants, pat);
}
scanStats(c.stats);
if (alive == Liveness.ALIVE) {
if (c.caseKind == JCCase.RULE) {
log.error(TreeInfo.diagEndPos(c.body),
Errors.RuleCompletesNormally);
} else if (l.tail.isEmpty()) {
log.error(TreeInfo.diagEndPos(tree),
Errors.SwitchExpressionCompletesNormally);
}
}
}
if (!tree.hasTotalPattern && !TreeInfo.isErrorEnumSwitch(tree.selector, tree.cases) &&
!isExhaustive(tree.selector.type, constants)) {
log.error(tree, Errors.NotExhaustive);
}
alive = prevAlive;
alive = alive.or(resolveYields(tree, prevPendingExits));
}
private void handleConstantCaseLabel(Set constants, JCCaseLabel pat) {
if (constants != null) {
if (pat.isExpression()) {
JCExpression expr = (JCExpression) pat;
if (expr.hasTag(IDENT) && ((JCIdent) expr).sym.isEnum())
constants.add(((JCIdent) expr).sym);
} else if (pat.isPattern()) {
PatternPrimaryType patternType = TreeInfo.primaryPatternType((JCPattern) pat);
if (patternType.unconditional()) {
constants.add(patternType.type().tsym);
}
}
}
}
private void transitiveCovers(Set covered) {
List todo = List.from(covered);
while (todo.nonEmpty()) {
Symbol sym = todo.head;
todo = todo.tail;
switch (sym.kind) {
case VAR: {
Iterable constants = sym.owner
.members()
.getSymbols(s -> s.isEnum() &&
s.kind == VAR);
boolean hasAll = StreamSupport.stream(constants.spliterator(), false)
.allMatch(covered::contains);
if (hasAll && covered.add(sym.owner)) {
todo = todo.prepend(sym.owner);
}
}
break;
case TYP: {
for (Type sup : types.directSupertypes(sym.type)) {
if (sup.tsym.kind == TYP && sup.tsym.isAbstract() && sup.tsym.isSealed()) {
boolean hasAll = ((ClassSymbol) sup.tsym).permitted
.stream()
.allMatch(covered::contains);
if (hasAll && covered.add(sup.tsym)) {
todo = todo.prepend(sup.tsym);
}
}
}
}
break;
}
}
}
private boolean isExhaustive(Type seltype, Set covered) {
transitiveCovers(covered);
boolean isExhaustive = false;
switch (seltype.getTag()) {
case CLASS: {
if (seltype.isCompound()) {
if (seltype.isIntersection()) {
isExhaustive = ((Type.IntersectionClassType) seltype).getComponents().stream().anyMatch(t -> isExhaustive(t, covered));
}
isExhaustive = false;
}
isExhaustive = covered.contains(seltype.tsym);
}
break;
case TYPEVAR:
isExhaustive = isExhaustive(((TypeVar) seltype).getUpperBound(), covered);
break;
default:
isExhaustive = false;
}
return isExhaustive;
}
public void visitTry(JCTry tree) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
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);
Liveness aliveEnd = alive;
for (List l = tree.catchers; l.nonEmpty(); l = l.tail) {
alive = Liveness.ALIVE;
JCVariableDecl param = l.head.param;
scan(param);
scanStat(l.head.body);
aliveEnd = aliveEnd.or(alive);
}
if (tree.finalizer != null) {
ListBuffer exits = pendingExits;
pendingExits = prevPendingExits;
alive = Liveness.ALIVE;
scanStat(tree.finalizer);
tree.finallyCanCompleteNormally = alive != Liveness.DEAD;
if (alive == Liveness.DEAD) {
if (lint.isEnabled(Lint.LintCategory.FINALLY)) {
log.warning(Lint.LintCategory.FINALLY,
TreeInfo.diagEndPos(tree.finalizer),
Warnings.FinallyCannotComplete);
}
} else {
while (exits.nonEmpty()) {
pendingExits.append(exits.next());
}
alive = aliveEnd;
}
} else {
alive = aliveEnd;
ListBuffer 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) {
Liveness aliveAfterThen = alive;
alive = Liveness.ALIVE;
scanStat(tree.elsepart);
alive = alive.or(aliveAfterThen);
} else {
alive = Liveness.ALIVE;
}
}
public void visitBreak(JCBreak tree) {
recordExit(new PendingExit(tree));
}
@Override
public void visitYield(JCYield tree) {
scan(tree.value);
recordExit(new PendingExit(tree));
}
public void visitContinue(JCContinue tree) {
recordExit(new PendingExit(tree));
}
public void visitReturn(JCReturn tree) {
scan(tree.expr);
recordExit(new PendingExit(tree));
}
public void visitThrow(JCThrow tree) {
scan(tree.expr);
markDead();
}
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 prevPending = pendingExits;
Liveness prevAlive = alive;
try {
pendingExits = new ListBuffer<>();
alive = Liveness.ALIVE;
scanStat(tree.body);
tree.canCompleteNormally = alive != Liveness.DEAD;
}
finally {
pendingExits = prevPending;
alive = prevAlive;
}
}
public void visitModuleDef(JCModuleDecl tree) {
// Do nothing for modules
}
/**************************************************************************
* main method
*************************************************************************/
/** Perform definite assignment/unassignment analysis on a tree.
*/
public void analyzeTree(Env env, TreeMaker make) {
analyzeTree(env, env.tree, make);
}
public void analyzeTree(Env env, JCTree tree, TreeMaker make) {
try {
attrEnv = env;
Flow.this.make = make;
pendingExits = new ListBuffer<>();
alive = Liveness.ALIVE;
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 {
/** A flag that indicates whether the last statement could
* complete normally.
*/
HashMap> preciseRethrowTypes;
/** The current class being defined.
*/
JCClassDecl classDef;
/** The list of possibly thrown declarable exceptions.
*/
List thrown;
/** The list of exceptions that are either caught or declared to be
* thrown.
*/
List caught;
class ThrownPendingExit extends BaseAnalyzer.PendingExit {
Type thrown;
ThrownPendingExit(JCTree tree, Type thrown) {
super(tree);
this.thrown = thrown;
}
}
@Override
void markDead() {
//do nothing
}
/*-------------------- Exceptions ----------------------*/
/** Complain that pending exceptions are not caught.
*/
void errorUncaught() {
for (PendingExit exit = pendingExits.next();
exit != null;
exit = pendingExits.next()) {
if (exit instanceof ThrownPendingExit) {
ThrownPendingExit thrownExit = (ThrownPendingExit) exit;
if (classDef != null &&
classDef.pos == exit.tree.pos) {
log.error(exit.tree.pos(),
Errors.UnreportedExceptionDefaultConstructor(thrownExit.thrown));
} else if (exit.tree.hasTag(VARDEF) &&
((JCVariableDecl)exit.tree).sym.isResourceVariable()) {
log.error(exit.tree.pos(),
Errors.UnreportedExceptionImplicitClose(thrownExit.thrown,
((JCVariableDecl)exit.tree).sym.name));
} else {
log.error(exit.tree.pos(),
Errors.UnreportedExceptionNeedToCatchOrThrow(thrownExit.thrown));
}
} else {
Assert.check(log.hasErrorOn(exit.tree.pos()));
}
}
}
/** Record that exception is potentially thrown and check that it
* is caught.
*/
void markThrown(JCTree tree, Type exc) {
if (exc != syms.unknownType) {
if (!chk.isUnchecked(tree.pos(), exc)) {
if (!chk.isHandled(exc, caught)) {
pendingExits.append(new ThrownPendingExit(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 thrownPrev = thrown;
List caughtPrev = caught;
ListBuffer pendingExitsPrev = pendingExits;
Lint lintPrev = lint;
boolean anonymousClass = tree.name == names.empty;
pendingExits = new ListBuffer<>();
if (!anonymousClass) {
caught = List.nil();
}
classDef = tree;
thrown = List.nil();
if (tree.sym != null)
lint = lint.augment(tree.sym);
try {
// process all the static initializers
for (List 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 (!anonymousClass) {
boolean firstConstructor = true;
for (List l = tree.defs; l.nonEmpty(); l = l.tail) {
if (TreeInfo.isInitialConstructor(l.head)) {
MethodSymbol sym = ((JCMethodDecl) l.head).sym;
List mthrown = sym != null
? sym.type.getThrownTypes() : List.nil();
if (firstConstructor) {
caught = mthrown;
firstConstructor = false;
} else {
caught = chk.intersect(mthrown, caught);
}
}
}
}
// process all the instance initializers
for (List 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 (anonymousClass && thrownPrev != null) {
for (List l = tree.defs; l.nonEmpty(); l = l.tail) {
if (TreeInfo.isConstructor(l.head)) {
JCMethodDecl mdef = (JCMethodDecl)l.head;
scan(mdef);
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 l = tree.defs; l.nonEmpty(); l = l.tail) {
if (anonymousClass && TreeInfo.isConstructor(l.head))
continue; // there can never be an uncaught exception.
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 || tree.sym == null) return;
List caughtPrev = caught;
List mthrown = tree.sym.type.getThrownTypes();
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
Assert.check(pendingExits.isEmpty());
try {
for (List 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 exits = pendingExits.toList();
pendingExits = new ListBuffer<>();
while (exits.nonEmpty()) {
PendingExit exit = exits.head;
exits = exits.tail;
if (!(exit instanceof ThrownPendingExit)) {
Assert.check(exit.tree.hasTag(RETURN) ||
log.hasErrorOn(exit.tree.pos()));
} else {
// uncaught throws will be reported later
pendingExits.append(exit);
}
}
} finally {
caught = caughtPrev;
lint = lintPrev;
}
}
public void visitVarDef(JCVariableDecl tree) {
if (tree.sym == null) return;
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 prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scan(tree.body);
resolveContinues(tree);
scan(tree.cond);
resolveBreaks(tree, prevPendingExits);
}
public void visitWhileLoop(JCWhileLoop tree) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scan(tree.cond);
scan(tree.body);
resolveContinues(tree);
resolveBreaks(tree, prevPendingExits);
}
public void visitForLoop(JCForLoop tree) {
ListBuffer prevPendingExits = pendingExits;
scan(tree.init);
pendingExits = new ListBuffer<>();
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 prevPendingExits = pendingExits;
scan(tree.expr);
pendingExits = new ListBuffer<>();
scan(tree.body);
resolveContinues(tree);
resolveBreaks(tree, prevPendingExits);
}
public void visitLabelled(JCLabeledStatement tree) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scan(tree.body);
resolveBreaks(tree, prevPendingExits);
}
public void visitSwitch(JCSwitch tree) {
handleSwitch(tree, tree.selector, tree.cases);
}
@Override
public void visitSwitchExpression(JCSwitchExpression tree) {
handleSwitch(tree, tree.selector, tree.cases);
}
private void handleSwitch(JCTree tree, JCExpression selector, List cases) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scan(selector);
for (List l = cases; l.nonEmpty(); l = l.tail) {
JCCase c = l.head;
scan(c.labels);
scan(c.stats);
}
if (tree.hasTag(SWITCH_EXPRESSION)) {
resolveYields(tree, prevPendingExits);
} else {
resolveBreaks(tree, prevPendingExits);
}
}
public void visitTry(JCTry tree) {
List caughtPrev = caught;
List thrownPrev = thrown;
thrown = List.nil();
for (List l = tree.catchers; l.nonEmpty(); l = l.tail) {
List 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 prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
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 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,
types.skipTypeVars(sup, false),
names.close,
List.nil(),
List.nil());
Type mt = types.memberType(resource.type, closeMethod);
if (closeMethod.kind == MTH) {
for (Type t : mt.getThrownTypes()) {
markThrown(resource, t);
}
}
}
}
}
scan(tree.body);
List thrownInTry = chk.union(thrown, List.of(syms.runtimeExceptionType, syms.errorType));
thrown = thrownPrev;
caught = caughtPrev;
List caughtInTry = List.nil();
for (List l = tree.catchers; l.nonEmpty(); l = l.tail) {
JCVariableDecl param = l.head.param;
List subClauses = TreeInfo.isMultiCatch(l.head) ?
((JCTypeUnion)l.head.param.vartype).alternatives :
List.of(l.head.param.vartype);
List ctypes = List.nil();
List rethrownTypes = chk.diff(thrownInTry, caughtInTry);
for (JCExpression ct : subClauses) {
Type exc = ct.type;
if (exc != null && exc != syms.unknownType) {
ctypes = ctypes.append(exc);
if (types.isSameType(exc, syms.objectType))
continue;
DiagnosticPosition pos = subClauses.size() > 1 ? ct.pos() : l.head.pos();
checkCaughtType(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 savedThrown = thrown;
thrown = List.nil();
ListBuffer 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 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 thrownInTry, List caughtInTry) {
if (chk.subset(exc, caughtInTry)) {
log.error(pos, Errors.ExceptAlreadyCaught(exc));
} else if (!chk.isUnchecked(pos, exc) &&
!isExceptionOrThrowable(exc) &&
!chk.intersects(exc, thrownInTry)) {
log.error(pos, Errors.ExceptNeverThrownInTry(exc));
} else {
List catchableThrownTypes = chk.intersect(List.of(exc), thrownInTry);
// 'catchableThrownTypes' cannot 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)) {
Warning key = catchableThrownTypes.length() == 1 ?
Warnings.UnreachableCatch(catchableThrownTypes) :
Warnings.UnreachableCatch1(catchableThrownTypes);
log.warning(pos, key);
}
}
}
//where
private boolean isExceptionOrThrowable(Type exc) {
return exc.tsym == syms.throwableType.tsym ||
exc.tsym == syms.exceptionType.tsym;
}
public void visitBreak(JCBreak tree) {
recordExit(new PendingExit(tree));
}
public void visitYield(JCYield tree) {
scan(tree.value);
recordExit(new PendingExit(tree));
}
public void visitContinue(JCContinue tree) {
recordExit(new PendingExit(tree));
}
public void visitReturn(JCReturn tree) {
scan(tree.expr);
recordExit(new PendingExit(tree));
}
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) {
for (Type t : preciseRethrowTypes.get(sym)) {
markThrown(tree, t);
}
}
else {
markThrown(tree, tree.expr.type);
}
markDead();
}
public void visitApply(JCMethodInvocation tree) {
scan(tree.meth);
scan(tree.args);
if (tree.meth.type != null) {
for (List 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);
if (tree.constructorType != null) {
for (List l = tree.constructorType.getThrownTypes();
l.nonEmpty();
l = l.tail) {
markThrown(tree, l.head);
}
}
List 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 && tree.constructor != null && tree.constructor.type != null)
for (List 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 prevCaught = caught;
List prevThrown = thrown;
ListBuffer prevPending = pendingExits;
try {
pendingExits = new ListBuffer<>();
caught = tree.getDescriptorType(types).getThrownTypes();
thrown = List.nil();
scan(tree.body);
List exits = pendingExits.toList();
pendingExits = new ListBuffer<>();
while (exits.nonEmpty()) {
PendingExit exit = exits.head;
exits = exits.tail;
if (!(exit instanceof ThrownPendingExit)) {
Assert.check(exit.tree.hasTag(RETURN) ||
log.hasErrorOn(exit.tree.pos()));
} else {
// uncaught throws will be reported later
pendingExits.append(exit);
}
}
errorUncaught();
} finally {
pendingExits = prevPending;
caught = prevCaught;
thrown = prevThrown;
}
}
public void visitModuleDef(JCModuleDecl tree) {
// Do nothing for modules
}
/**************************************************************************
* main method
*************************************************************************/
/** Perform definite assignment/unassignment analysis on a tree.
*/
public void analyzeTree(Env env, TreeMaker make) {
analyzeTree(env, env.tree, make);
}
public void analyzeTree(Env env, JCTree tree, TreeMaker make) {
try {
attrEnv = env;
Flow.this.make = make;
pendingExits = new ListBuffer<>();
preciseRethrowTypes = new HashMap<>();
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 reachability analysis on a lambda
*/
class LambdaAliveAnalyzer extends AliveAnalyzer {
boolean inLambda;
@Override
public void visitReturn(JCReturn tree) {
//ignore lambda return expression (which might not even be attributed)
recordExit(new PendingExit(tree));
}
@Override
public void visitLambda(JCLambda tree) {
if (inLambda || tree.getBodyKind() == BodyKind.EXPRESSION) {
return;
}
inLambda = true;
try {
super.visitLambda(tree);
} finally {
inLambda = false;
}
}
@Override
public void visitClassDef(JCClassDecl tree) {
//skip
}
}
/**
* Determine if alive after the given tree.
*/
class SnippetAliveAnalyzer extends AliveAnalyzer {
@Override
public void visitClassDef(JCClassDecl tree) {
//skip
}
@Override
public void visitLambda(JCLambda tree) {
//skip
}
public boolean isAlive() {
return super.alive != Liveness.DEAD;
}
}
class SnippetBreakAnalyzer extends AliveAnalyzer {
private final Set seenTrees = new HashSet<>();
private boolean breaksOut;
public SnippetBreakAnalyzer() {
}
@Override
public void visitLabelled(JCTree.JCLabeledStatement tree) {
seenTrees.add(tree);
super.visitLabelled(tree);
}
@Override
public void visitWhileLoop(JCTree.JCWhileLoop tree) {
seenTrees.add(tree);
super.visitWhileLoop(tree);
}
@Override
public void visitForLoop(JCTree.JCForLoop tree) {
seenTrees.add(tree);
super.visitForLoop(tree);
}
@Override
public void visitForeachLoop(JCTree.JCEnhancedForLoop tree) {
seenTrees.add(tree);
super.visitForeachLoop(tree);
}
@Override
public void visitDoLoop(JCTree.JCDoWhileLoop tree) {
seenTrees.add(tree);
super.visitDoLoop(tree);
}
@Override
public void visitBreak(JCBreak tree) {
breaksOut |= (super.alive == Liveness.ALIVE &&
!seenTrees.contains(tree.target));
super.visitBreak(tree);
}
public boolean breaksOut() {
return breaksOut;
}
}
/**
* Specialized pass that performs DA/DU on a lambda
*/
class LambdaAssignAnalyzer extends AssignAnalyzer {
WriteableScope enclosedSymbols;
boolean inLambda;
LambdaAssignAnalyzer(Env env) {
enclosedSymbols = WriteableScope.create(env.enclClass.sym);
}
@Override
public void visitLambda(JCLambda tree) {
if (inLambda) {
return;
}
inLambda = true;
try {
super.visitLambda(tree);
} finally {
inLambda = false;
}
}
@Override
public void visitVarDef(JCVariableDecl tree) {
enclosedSymbols.enter(tree.sym);
super.visitVarDef(tree);
}
@Override
protected boolean trackable(VarSymbol sym) {
return enclosedSymbols.includes(sym) &&
sym.owner.kind == MTH;
}
@Override
public void visitClassDef(JCClassDecl tree) {
//skip
}
}
/**
* Specialized pass that performs inference of thrown types for lambdas.
*/
class LambdaFlowAnalyzer extends FlowAnalyzer {
List inferredThrownTypes;
boolean inLambda;
@Override
public void visitLambda(JCLambda tree) {
if ((tree.type != null &&
tree.type.isErroneous()) || inLambda) {
return;
}
List prevCaught = caught;
List prevThrown = thrown;
ListBuffer 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 class AssignAnalyzer extends BaseAnalyzer {
/** The set of definitely assigned variables.
*/
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.
*/
WriteableScope unrefdResources;
/** Modified when processing a loop body the second time for DU analysis. */
FlowKind flowKind = FlowKind.NORMAL;
/** The starting position of the analyzed tree */
int startPos;
public class AssignPendingExit extends BaseAnalyzer.PendingExit {
final Bits inits;
final Bits uninits;
final Bits exit_inits = new Bits(true);
final Bits exit_uninits = new Bits(true);
public AssignPendingExit(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() {
inits.andSet(exit_inits);
uninits.andSet(exit_uninits);
}
}
public AssignAnalyzer() {
this.inits = new Bits();
uninits = new Bits();
uninitsTry = new Bits();
initsWhenTrue = new Bits(true);
initsWhenFalse = new Bits(true);
uninitsWhenTrue = new Bits(true);
uninitsWhenFalse = new Bits(true);
}
private boolean isInitialConstructor = false;
@Override
protected void markDead() {
if (!isInitialConstructor) {
inits.inclRange(returnadr, nextadr);
} else {
for (int address = returnadr; address < nextadr; address++) {
if (!(isFinalUninitializedStaticField(vardecls[address].sym))) {
inits.incl(address);
}
}
}
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 != null && sym.owner != null &&
sym.pos >= startPos &&
((sym.owner.kind == MTH || sym.owner.kind == VAR ||
isFinalUninitializedField(sym)));
}
boolean isFinalUninitializedField(VarSymbol sym) {
return sym.owner.kind == TYP &&
((sym.flags() & (FINAL | HASINIT | PARAMETER)) == FINAL &&
classDef.sym.isEnclosedBy((ClassSymbol)sym.owner));
}
boolean isFinalUninitializedStaticField(VarSymbol sym) {
return isFinalUninitializedField(sym) && sym.isStatic();
}
/** 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;
inits.excl(nextadr);
uninits.incl(nextadr);
nextadr++;
}
/** Record an initialization of a trackable variable.
*/
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, Errors.MulticatchParameterMayNotBeAssigned(sym));
}
else {
log.error(pos,
Errors.FinalParameterMayNotBeAssigned(sym));
}
} else if (!uninits.isMember(sym.adr)) {
log.error(pos, diags.errorKey(flowKind.errKey, sym));
} else {
uninit(sym);
}
}
inits.incl(sym.adr);
} else if ((sym.flags() & FINAL) != 0) {
log.error(pos, Errors.VarMightAlreadyBeAssigned(sym));
}
}
//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 != null && sym.kind == VAR) {
letInit(tree.pos(), (VarSymbol)sym);
}
}
}
/** Check that trackable variable is initialized.
*/
void checkInit(DiagnosticPosition pos, VarSymbol sym) {
checkInit(pos, sym, Errors.VarMightNotHaveBeenInitialized(sym));
}
void checkInit(DiagnosticPosition pos, VarSymbol sym, Error errkey) {
if ((sym.adr >= firstadr || sym.owner.kind != TYP) &&
trackable(sym) &&
!inits.isMember(sym.adr) &&
(sym.flags_field & CLASH) == 0) {
log.error(pos, errkey);
inits.incl(sym.adr);
}
}
/** 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() {
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();
}
}
}
/** Analyze a list of expressions.
*/
void scanExprs(List trees) {
if (trees != null)
for (List 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 != null && tree.type.isFalse()) {
if (inits.isReset()) merge();
initsWhenTrue.assign(inits);
initsWhenTrue.inclRange(firstadr, nextadr);
uninitsWhenTrue.assign(uninits);
uninitsWhenTrue.inclRange(firstadr, nextadr);
initsWhenFalse.assign(inits);
uninitsWhenFalse.assign(uninits);
} else if (tree.type != null && tree.type.isTrue()) {
if (inits.isReset()) merge();
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 -------------*/
public void visitClassDef(JCClassDecl tree) {
if (tree.sym == null) {
return;
}
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
try {
if (tree.sym == null) {
return;
}
JCClassDecl classDefPrev = classDef;
int firstadrPrev = firstadr;
int nextadrPrev = nextadr;
ListBuffer pendingExitsPrev = pendingExits;
pendingExits = new ListBuffer<>();
if (tree.name != names.empty) {
firstadr = nextadr;
}
classDef = tree;
try {
// define all the static fields
for (List 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 l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) != 0) {
scan(l.head);
clearPendingExits(false);
}
}
// define all the instance fields
for (List 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 l = tree.defs; l.nonEmpty(); l = l.tail) {
if (!l.head.hasTag(METHODDEF) &&
(TreeInfo.flags(l.head) & STATIC) == 0) {
scan(l.head);
clearPendingExits(false);
}
}
// process all the methods
for (List 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;
}
} finally {
lint = lintPrev;
}
}
public void visitMethodDef(JCMethodDecl tree) {
if (tree.body == null || tree.sym == 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 {
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());
boolean lastInitialConstructor = isInitialConstructor;
try {
isInitialConstructor = TreeInfo.isInitialConstructor(tree);
if (!isInitialConstructor) {
firstadr = nextadr;
}
for (List 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);
boolean isCompactConstructor = (tree.sym.flags() & Flags.COMPACT_RECORD_CONSTRUCTOR) != 0;
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 && !isCompactConstructor) {
checkInit(TreeInfo.diagnosticPositionFor(var, vardecl),
var, Errors.VarNotInitializedInDefaultConstructor(var));
} else if (isCompactConstructor) {
boolean isInstanceRecordField = var.enclClass().isRecord() &&
(var.flags_field & (Flags.PRIVATE | Flags.FINAL | Flags.GENERATED_MEMBER | Flags.RECORD)) != 0 &&
!var.isStatic() &&
var.owner.kind == TYP;
if (isInstanceRecordField) {
boolean notInitialized = !inits.isMember(var.adr);
if (notInitialized && uninits.isMember(var.adr) && tree.completesNormally) {
/* this way we indicate Lower that it should generate an initialization for this field
* in the compact constructor
*/
var.flags_field |= UNINITIALIZED_FIELD;
} else {
checkInit(TreeInfo.diagEndPos(tree.body), var);
}
} else {
checkInit(TreeInfo.diagnosticPositionFor(var, vardecl), var);
}
} else {
checkInit(TreeInfo.diagEndPos(tree.body), var);
}
}
}
}
clearPendingExits(true);
} finally {
inits.assign(initsPrev);
uninits.assign(uninitsPrev);
nextadr = nextadrPrev;
firstadr = firstadrPrev;
returnadr = returnadrPrev;
isInitialConstructor = lastInitialConstructor;
}
} finally {
lint = lintPrev;
}
}
private void clearPendingExits(boolean inMethod) {
List exits = pendingExits.toList();
pendingExits = new ListBuffer<>();
while (exits.nonEmpty()) {
PendingExit exit = exits.head;
exits = exits.tail;
Assert.check((inMethod && exit.tree.hasTag(RETURN)) ||
log.hasErrorOn(exit.tree.pos()),
exit.tree);
if (inMethod && isInitialConstructor) {
Assert.check(exit instanceof AssignPendingExit);
inits.assign(((AssignPendingExit) exit).exit_inits);
for (int i = firstadr; i < nextadr; i++) {
checkInit(exit.tree.pos(), vardecls[i].sym);
}
}
}
}
protected void initParam(JCVariableDecl def) {
inits.incl(def.sym.adr);
uninits.excl(def.sym.adr);
}
public void visitVarDef(JCVariableDecl tree) {
if (tree.sym == null) return;
Lint lintPrev = lint;
lint = lint.augment(tree.sym);
try{
boolean track = trackable(tree.sym);
if (track && (tree.sym.owner.kind == MTH || tree.sym.owner.kind == VAR)) {
newVar(tree);
}
if (tree.init != null) {
scanExpr(tree.init);
if (track) {
letInit(tree.pos(), tree.sym);
}
}
} finally {
lint = lintPrev;
}
}
public void visitBlock(JCBlock tree) {
int nextadrPrev = nextadr;
scan(tree.stats);
nextadr = nextadrPrev;
}
public void visitDoLoop(JCDoWhileLoop tree) {
ListBuffer 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 = log.nerrors;
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 (log.nerrors != prevErrors ||
flowKind.isFinal() ||
new Bits(uninitsEntry).diffSet(uninitsWhenTrue).nextBit(firstadr)==-1)
break;
inits.assign(initsWhenTrue);
uninits.assign(uninitsEntry.andSet(uninitsWhenTrue));
flowKind = FlowKind.SPECULATIVE_LOOP;
} while (true);
flowKind = prevFlowKind;
inits.assign(initsSkip);
uninits.assign(uninitsSkip);
resolveBreaks(tree, prevPendingExits);
}
public void visitWhileLoop(JCWhileLoop tree) {
ListBuffer 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 = log.nerrors;
final Bits uninitsEntry = new Bits(uninits);
uninitsEntry.excludeFrom(nextadr);
do {
scanCond(tree.cond);
if (!flowKind.isFinal()) {
initsSkip.assign(initsWhenFalse) ;
uninitsSkip.assign(uninitsWhenFalse);
}
inits.assign(initsWhenTrue);
uninits.assign(uninitsWhenTrue);
scan(tree.body);
resolveContinues(tree);
if (log.nerrors != 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
inits.assign(initsSkip);
uninits.assign(uninitsSkip);
resolveBreaks(tree, prevPendingExits);
}
public void visitForLoop(JCForLoop tree) {
ListBuffer 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<>();
int prevErrors = log.nerrors;
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);
}
inits.assign(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 (log.nerrors != 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
inits.assign(initsSkip);
uninits.assign(uninitsSkip);
resolveBreaks(tree, prevPendingExits);
nextadr = nextadrPrev;
}
public void visitForeachLoop(JCEnhancedForLoop tree) {
visitVarDef(tree.var);
ListBuffer 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);
if (tree.var.sym != null)
letInit(tree.pos(), tree.var.sym);
pendingExits = new ListBuffer<>();
int prevErrors = log.nerrors;
do {
final Bits uninitsEntry = new Bits(uninits);
uninitsEntry.excludeFrom(nextadr);
scan(tree.body);
resolveContinues(tree);
if (log.nerrors != 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;
inits.assign(initsStart);
uninits.assign(uninitsStart.andSet(uninits));
resolveBreaks(tree, prevPendingExits);
nextadr = nextadrPrev;
}
public void visitLabelled(JCLabeledStatement tree) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
scan(tree.body);
resolveBreaks(tree, prevPendingExits);
}
public void visitSwitch(JCSwitch tree) {
handleSwitch(tree, tree.selector, tree.cases, tree.hasTotalPattern);
}
public void visitSwitchExpression(JCSwitchExpression tree) {
handleSwitch(tree, tree.selector, tree.cases, tree.hasTotalPattern);
}
private void handleSwitch(JCTree tree, JCExpression selector,
List cases, boolean hasTotalPattern) {
ListBuffer prevPendingExits = pendingExits;
pendingExits = new ListBuffer<>();
int nextadrPrev = nextadr;
scanExpr(selector);
final Bits initsSwitch = new Bits(inits);
final Bits uninitsSwitch = new Bits(uninits);
for (List l = cases; l.nonEmpty(); l = l.tail) {
inits.assign(initsSwitch);
uninits.assign(uninits.andSet(uninitsSwitch));
JCCase c = l.head;
for (JCCaseLabel pat : c.labels) {
scan(pat);
if (inits.isReset()) {
inits.assign(initsWhenTrue);
uninits.assign(uninitsWhenTrue);
}
}
if (l.head.stats.isEmpty() &&
l.tail.nonEmpty() &&
l.tail.head.labels.size() == 1 &&
l.tail.head.labels.head.isExpression() &&
TreeInfo.isNull(l.tail.head.labels.head)) {
//handling:
//case Integer i:
//case null:
//joining these two cases together - processing Integer i pattern,
//but statements from case null:
l = l.tail;
c = l.head;
}
scan(c.stats);
if (c.completesNormally && c.caseKind == JCCase.RULE) {
scanSyntheticBreak(make, tree);
}
addVars(c.stats, initsSwitch, uninitsSwitch);
// Warn about fall-through if lint switch fallthrough enabled.
}
if (!hasTotalPattern) {
if (tree.hasTag(SWITCH_EXPRESSION)) {
markDead();
} else {
inits.assign(initsSwitch);
uninits.assign(uninits.andSet(uninitsSwitch));
}
}
if (tree.hasTag(SWITCH_EXPRESSION)) {
resolveYields(tree, prevPendingExits);
} else {
resolveBreaks(tree, prevPendingExits);
}
nextadr = nextadrPrev;
}
// where
/** Add any variables defined in stats to inits and uninits. */
private void addVars(List 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);
}
}
}
public void visitTry(JCTry tree) {
ListBuffer resourceVarDecls = new ListBuffer<>();
final Bits uninitsTryPrev = new Bits(uninitsTry);
ListBuffer 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() &&
lint.isEnabled(Lint.LintCategory.TRY)) {
for (JCVariableDecl resVar : resourceVarDecls) {
if (unrefdResources.includes(resVar.sym)) {
log.warning(Lint.LintCategory.TRY, resVar.pos(),
Warnings.TryResourceNotReferenced(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 l = tree.catchers; l.nonEmpty(); l = l.tail) {
JCVariableDecl param = l.head.param;
inits.assign(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.
*/
if (param.sym != null) {
initParam(param);
}
scan(l.head.body);
initsEnd.andSet(inits);
uninitsEnd.andSet(uninits);
nextadr = nextadrCatch;
}
if (tree.finalizer != null) {
inits.assign(initsTry);
uninits.assign(uninitsTry);
ListBuffer 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()) {
PendingExit exit = exits.next();
if (exit instanceof AssignPendingExit) {
((AssignPendingExit) exit).exit_inits.orSet(inits);
((AssignPendingExit) exit).exit_uninits.andSet(uninits);
}
pendingExits.append(exit);
}
inits.orSet(initsEnd);
}
} else {
inits.assign(initsEnd);
uninits.assign(uninitsEnd);
ListBuffer 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);
inits.assign(initsWhenTrue);
uninits.assign(uninitsWhenTrue);
if (tree.truepart.type != null && tree.truepart.type.hasTag(BOOLEAN) &&
tree.falsepart.type != null && 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);
inits.assign(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);
inits.assign(initsBeforeElse);
uninits.assign(uninitsBeforeElse);
scanExpr(tree.falsepart);
inits.andSet(initsAfterThen);
uninits.andSet(uninitsAfterThen);
}
}
public void visitIf(JCIf tree) {
scanCond(tree.cond);
final Bits initsBeforeElse = new Bits(initsWhenFalse);
final Bits uninitsBeforeElse = new Bits(uninitsWhenFalse);
inits.assign(initsWhenTrue);
uninits.assign(uninitsWhenTrue);
scan(tree.thenpart);
if (tree.elsepart != null) {
final Bits initsAfterThen = new Bits(inits);
final Bits uninitsAfterThen = new Bits(uninits);
inits.assign(initsBeforeElse);
uninits.assign(uninitsBeforeElse);
scan(tree.elsepart);
inits.andSet(initsAfterThen);
uninits.andSet(uninitsAfterThen);
} else {
inits.andSet(initsBeforeElse);
uninits.andSet(uninitsBeforeElse);
}
}
@Override
public void visitBreak(JCBreak tree) {
recordExit(new AssignPendingExit(tree, inits, uninits));
}
@Override
public void visitYield(JCYield tree) {
JCSwitchExpression expr = (JCSwitchExpression) tree.target;
if (expr != null && expr.type.hasTag(BOOLEAN)) {
scanCond(tree.value);
Bits initsAfterBreakWhenTrue = new Bits(initsWhenTrue);
Bits initsAfterBreakWhenFalse = new Bits(initsWhenFalse);
Bits uninitsAfterBreakWhenTrue = new Bits(uninitsWhenTrue);
Bits uninitsAfterBreakWhenFalse = new Bits(uninitsWhenFalse);
PendingExit exit = new PendingExit(tree) {
@Override
void resolveJump() {
if (!inits.isReset()) {
split(true);
}
initsWhenTrue.andSet(initsAfterBreakWhenTrue);
initsWhenFalse.andSet(initsAfterBreakWhenFalse);
uninitsWhenTrue.andSet(uninitsAfterBreakWhenTrue);
uninitsWhenFalse.andSet(uninitsAfterBreakWhenFalse);
}
};
merge();
recordExit(exit);
return ;
} else {
scanExpr(tree.value);
recordExit(new AssignPendingExit(tree, inits, uninits));
}
}
@Override
public void visitContinue(JCContinue tree) {
recordExit(new AssignPendingExit(tree, inits, uninits));
}
@Override
public void visitReturn(JCReturn tree) {
scanExpr(tree.expr);
recordExit(new AssignPendingExit(tree, inits, uninits));
}
public void visitThrow(JCThrow tree) {
scanExpr(tree.expr);
markDead();
}
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;
int nextadrPrev = nextadr;
ListBuffer prevPending = pendingExits;
try {
returnadr = nextadr;
pendingExits = new ListBuffer<>();
for (List 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);
inits.assign(prevInits);
pendingExits = prevPending;
nextadr = nextadrPrev;
}
}
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) {
inits.assign(initsWhenFalse);
uninits.assign(uninitsWhenFalse);
scanExpr(tree.detail);
}
inits.assign(initsExit);
uninits.assign(uninitsExit);
}
public void visitAssign(JCAssign tree) {
if (!TreeInfo.isIdentOrThisDotIdent(tree.lhs))
scanExpr(tree.lhs);
scanExpr(tree.rhs);
letInit(tree.lhs);
}
// check fields accessed through this. are definitely
// assigned before reading their value
public void visitSelect(JCFieldAccess tree) {
super.visitSelect(tree);
if (TreeInfo.isThisQualifier(tree.selected) &&
tree.sym.kind == VAR) {
checkInit(tree.pos(), (VarSymbol)tree.sym);
}
}
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);
inits.assign(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);
inits.assign(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 != null && tree.sym.kind == VAR) {
checkInit(tree.pos(), (VarSymbol)tree.sym);
referenced(tree.sym);
}
}
@Override
public void visitBindingPattern(JCBindingPattern tree) {
super.visitBindingPattern(tree);
initParam(tree.var);
}
void referenced(Symbol sym) {
unrefdResources.remove(sym);
}
public void visitAnnotatedType(JCAnnotatedType tree) {
// annotations don't get scanned
tree.underlyingType.accept(this);
}
public void visitModuleDef(JCModuleDecl tree) {
// Do nothing for modules
}
/**************************************************************************
* main method
*************************************************************************/
/** Perform definite assignment/unassignment analysis on a tree.
*/
public void analyzeTree(Env env, TreeMaker make) {
analyzeTree(env, env.tree, make);
}
public void analyzeTree(Env env, JCTree tree, TreeMaker make) {
try {
startPos = tree.pos().getStartPosition();
if (vardecls == null)
vardecls = new JCVariableDecl[32];
else
for (int i=0; i();
this.classDef = null;
unrefdResources = WriteableScope.create(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 env, TreeMaker make) {
analyzeTree(env, env.tree, make);
}
public void analyzeTree(Env env, JCTree tree, TreeMaker make) {
try {
attrEnv = env;
Flow.this.make = make;
pendingExits = new ListBuffer<>();
scan(tree);
} finally {
pendingExits = null;
Flow.this.make = null;
}
}
}
enum Liveness {
ALIVE {
@Override
public Liveness or(Liveness other) {
return this;
}
@Override
public Liveness and(Liveness other) {
return other;
}
},
DEAD {
@Override
public Liveness or(Liveness other) {
return other;
}
@Override
public Liveness and(Liveness other) {
return this;
}
},
RECOVERY {
@Override
public Liveness or(Liveness other) {
if (other == ALIVE) {
return ALIVE;
} else {
return this;
}
}
@Override
public Liveness and(Liveness other) {
if (other == DEAD) {
return DEAD;
} else {
return this;
}
}
};
public abstract Liveness or(Liveness other);
public abstract Liveness and(Liveness other);
public Liveness or(boolean value) {
return or(from(value));
}
public Liveness and(boolean value) {
return and(from(value));
}
public static Liveness from(boolean value) {
return value ? ALIVE : DEAD;
}
}
}