soot.asm

Class AsmMethodSource

java.lang.Object

soot.asm.AsmMethodSource

All Implemented Interfaces:

MethodSource

public class AsmMethodSource
extends Object
implements MethodSource

Generates Jimple bodies from bytecode.

Author:

Aaloan Miftah

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<Integer,Local>	locals
protected int	nextLocal

Constructor Summary

Constructors

Constructor and Description
AsmMethodSource(int maxLocals, org.objectweb.asm.tree.InsnList insns, List<org.objectweb.asm.tree.LocalVariableNode> localVars, List<org.objectweb.asm.tree.TryCatchBlockNode> tryCatchBlocks, String module)

Method Summary

Modifier and Type	Method and Description
Body	getBody(SootMethod m, String phaseName) Returns a filled-out body for the given SootMethod.
protected String	getLocalName(int idx)
protected Local	newStackLocal()
protected void	tryCorrectingLocalNames(Jimple jimp, JimpleBody jb) When preserving original names, try to use the local variable table for guidance.

Methods inherited from class java.lang.Object

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

Field Detail

nextLocal

protected int nextLocal

locals

protected Map<Integer,Local> locals

Constructor Detail

AsmMethodSource

public AsmMethodSource(int maxLocals,
                       org.objectweb.asm.tree.InsnList insns,
                       List<org.objectweb.asm.tree.LocalVariableNode> localVars,
                       List<org.objectweb.asm.tree.TryCatchBlockNode> tryCatchBlocks,
                       String module)

Method Detail

getLocalName

protected String getLocalName(int idx)

newStackLocal

protected Local newStackLocal()

getBody

public Body getBody(SootMethod m,
                    String phaseName)

Description copied from interface: MethodSource

Returns a filled-out body for the given SootMethod.

Specified by:

getBody in interface MethodSource

tryCorrectingLocalNames

protected void tryCorrectingLocalNames(Jimple jimp,
                                       JimpleBody jb)

When preserving original names, try to use the local variable table for guidance. The LocalVariableTable from the input bytecode may contain two weird cases which can cause the loss of original local names, or worse, the appearance of the '#' character in local names in the output LocalVariableTable (some JVM implementations will give an error when trying to execute a method whose LocalVariableTable contains names with the '#' character).

1. When the LocalVariableTable associates different names with the same local variable index at different points in the method body, the "locals" Map would end up preserving only one of those names as the designated local name for that index. This leaves it up to the SharedInitializationLocalSplitter and LocalSplitter to then split that single Local back into distinct Locals, but at that time, information about the other original name(s) has been ignored (and the LocalVariableTable which contains that information is no longer available) so the best it can do is append "#x" (where x is a unique integer) to the end of the current name. In the end, those locals may be combined back into a single Local by the LocalPacker using whichever name was originally chosen by the "locals" Map here. In the worst case however, the LocalPacker cannot combine them back into a single Local (see the "Icky fix" in LocalPacker) and ends up keeping the '#' character in the Local name which leads to a problem if the "write-local-annotations" Soot option is also because the names containing a '#' character will end up in the output bytecode.
2. When the LocalVariableTable associates different indices with the same name at the same code location, we end up again with a case where the LocalPacker cannot remove the '#' character from local names.

Thus, this method checks for these ambiguous cases while the LocalVariableTable is still available, and assigns a unique name to each local that is based on the original name from the LocalVariableTable and does not use the '#' character.