Package soot.dexpler

Class DexNumTransformer

java.lang.Object

soot.Transformer

soot.BodyTransformer

soot.dexpler.DexTransformer

soot.dexpler.DexNumTransformer

public class DexNumTransformer
extends DexTransformer

BodyTransformer to find and change initialization type of Jimple variables. Dalvik bytecode does not provide enough information regarding the type of initialized variables. For instance, using the dexdump disassembler on some Dalvik bytecode can produce the following (wrong) output: 006c : const -wide v6 , #double 0.000000 // #0014404410000000 0071: and-long /2 addr v6 , v4 At 0x6c, the initialized register is not of type double, but of type long because it is used in a long and operation at 0x71. Thus, one need to check how the register is used to deduce its type. By default, and since the dexdump disassembler does not perform such analysis, it supposes the register is of type double. Dalvik comes with the following instructions to initialize constants: 0x12 const/4 vx,lit4 0x13 const/16 vx,lit16 0x14 const vx, lit32 0x15 const/high16 v0, lit16 0x16 const-wide/16 vx, lit16 0x17 const-wide/32 vx, lit32 0x18 const-wide vx, lit64 0x19 const-wide/high16 vx,lit16 0x1A const-string vx,string id 0x1B const-string-jumbo vx,string 0x1C const-class vx,type id Instructions 0x12, 0x1A, 0x1B, 0x1C can not produce wrong initialized registers. The other instructions are converted to the following Jimple statement: JAssignStmt ( Local, rightValue ). Since at the time of the statement creation the no analysis can be performed, a default type is given to rightValue. This default type is "int" for registers whose size is less or equal to 32bits and "long" to registers whose size is 64bits. The problem is that 32bits registers could be either "int" or "float" and 64bits registers "long" or "double". If the analysis concludes that an "int" has to be changed to a "float", rightValue has to change from IntConstant.v(literal) to Float.intBitsToFloat((int) literal). If the analysis concludes that an "long" has to be changed to a "double, rightValue has to change from LongConstant.v(literal) to DoubleConstant.v(Double.longBitsToDouble(literal)).

Constructor Summary

Constructors

Constructor	Description
DexNumTransformer()

Method Summary

Modifier and Type	Method	Description
protected boolean	examineBinopExpr(Unit u)
protected void	internalTransform(Body body, String phaseName, Map<String,String> options)	This method is called to perform the transformation itself.
static DexNumTransformer	v()

Methods inherited from class soot.dexpler.DexTransformer

collectDefinitionsWithAliases, findArrayType

Methods inherited from class soot.BodyTransformer

transform, transform, transform

Methods inherited from class java.lang.Object

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

Constructor Detail

DexNumTransformer

public DexNumTransformer()

Method Detail

v

public static DexNumTransformer v()

internalTransform

protected void internalTransform(Body body,
                                 String phaseName,
                                 Map<String,String> options)

Description copied from class: BodyTransformer

This method is called to perform the transformation itself. It is declared abstract; subclasses must implement this method by making it the entry point to their actual Body transformation.

Specified by:

internalTransform in class BodyTransformer

Parameters:

body - the body on which to apply the transformation

phaseName - the phasename for this transform; not typically used by implementations.

options - the actual computed options; a combination of default options and Scene specified options.

examineBinopExpr

protected boolean examineBinopExpr(Unit u)