Package edu.umd.cs.findbugs.detect

Class FindDeadLocalStores

java.lang.Object

edu.umd.cs.findbugs.detect.FindDeadLocalStores

All Implemented Interfaces:

Detector, Priorities

public class FindDeadLocalStores
extends java.lang.Object
implements Detector

Find dead stores to local variables.

Field Summary

Fields

Modifier and Type	Field	Description
private BugReporter	bugReporter
private static boolean	DEBUG
private static java.util.BitSet	defensiveConstantValueOpcodes	Opcodes of instructions that load constant values that often indicate defensive programming.
private static java.util.Set<java.lang.String>	EXCLUDED_LOCALS
private static java.lang.String	FINDBUGS_EXCLUDED_LOCALS_PROP_NAME
private static boolean	SUPPRESS_IF_AT_LEAST_ONE_LIVE_STORE_ON_LINE	System property to enable a feature that suppresses warnings if there is at least one live store on the line where the warning would be reported.

Fields inherited from interface edu.umd.cs.findbugs.Priorities

EXP_PRIORITY, HIGH_PRIORITY, IGNORE_PRIORITY, LOW_PRIORITY, NORMAL_PRIORITY

Constructor Summary

Constructors

Constructor	Description
FindDeadLocalStores(BugReporter bugReporter)

Method Summary

Modifier and Type	Method	Description
private void	analyzeMethod(ClassContext classContext, org.apache.bcel.classfile.Method method)
private void	countLocalStoresLoadsAndIncrements(int[] localStoreCount, int[] localLoadCount, int[] localIncrementCount, CFG cfg)	Count stores, loads, and increments of local variables in method whose CFG is given.
private boolean	isLoad(Location location)	Is instruction at given location a load?
private boolean	isStore(Location location)	Is instruction at given location a store?
private boolean	prescreen(ClassContext classContext, org.apache.bcel.classfile.Method method)
void	report()	This method is called after all classes to be visited.
private void	suppressWarningsIfOneLiveStoreOnLine(BugAccumulator accumulator, java.util.BitSet liveStoreSourceLineSet)	If feature is enabled, suppress warnings where there is at least one live store on the line where the warning would be reported.
void	visitClassContext(ClassContext classContext)	Visit the ClassContext for a class which should be analyzed for instances of bug patterns.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEBUG

private static final boolean DEBUG

FINDBUGS_EXCLUDED_LOCALS_PROP_NAME

private static final java.lang.String FINDBUGS_EXCLUDED_LOCALS_PROP_NAME

See Also:

Constant Field Values

EXCLUDED_LOCALS

@StaticConstant
private static final java.util.Set<java.lang.String> EXCLUDED_LOCALS

SUPPRESS_IF_AT_LEAST_ONE_LIVE_STORE_ON_LINE

private static final boolean SUPPRESS_IF_AT_LEAST_ONE_LIVE_STORE_ON_LINE

System property to enable a feature that suppresses warnings if there is at least one live store on the line where the warning would be reported. Eliminates some FPs due to inlining/duplication of finally blocks. But, kills some legitimate warnings where there are truly multiple stores on the same line.

defensiveConstantValueOpcodes

private static final java.util.BitSet defensiveConstantValueOpcodes

Opcodes of instructions that load constant values that often indicate defensive programming.

bugReporter

private final BugReporter bugReporter

Constructor Detail

FindDeadLocalStores

public FindDeadLocalStores(BugReporter bugReporter)

Method Detail

prescreen

private boolean prescreen(ClassContext classContext,
                          org.apache.bcel.classfile.Method method)

visitClassContext

public void visitClassContext(ClassContext classContext)

Description copied from interface: Detector

Visit the ClassContext for a class which should be analyzed for instances of bug patterns.

Specified by:

visitClassContext in interface Detector

Parameters:

classContext - the ClassContext

analyzeMethod

private void analyzeMethod(ClassContext classContext,
                           org.apache.bcel.classfile.Method method)
                    throws DataflowAnalysisException,
                           CFGBuilderException

Throws:

DataflowAnalysisException

CFGBuilderException

suppressWarningsIfOneLiveStoreOnLine

private void suppressWarningsIfOneLiveStoreOnLine(BugAccumulator accumulator,
                                                  java.util.BitSet liveStoreSourceLineSet)

If feature is enabled, suppress warnings where there is at least one live store on the line where the warning would be reported.

Parameters:

accumulator - BugAccumulator containing warnings for method

liveStoreSourceLineSet - bitset of lines where at least one live store was seen

countLocalStoresLoadsAndIncrements

private void countLocalStoresLoadsAndIncrements(int[] localStoreCount,
                                                int[] localLoadCount,
                                                int[] localIncrementCount,
                                                CFG cfg)

Count stores, loads, and increments of local variables in method whose CFG is given.

Parameters:

localStoreCount - counts of local stores (indexed by local)

localLoadCount - counts of local loads (indexed by local)

localIncrementCount - counts of local increments (indexed by local)

cfg - control flow graph (CFG) of method

isStore

private boolean isStore(Location location)

Is instruction at given location a store?

Parameters:

location - the location

Returns:

true if instruction at given location is a store, false if not

isLoad

private boolean isLoad(Location location)

Is instruction at given location a load?

Parameters:

location - the location

Returns:

true if instruction at given location is a load, false if not

report

public void report()

Description copied from interface: Detector

This method is called after all classes to be visited. It should be used by any detectors which accumulate information over all visited classes to generate results.

Specified by:

report in interface Detector