[Soot-list] ifStmt transformation

[Bernhard Berger]

Hi,

a Chain is "simple" list of statements and the insertBefore operation inserts a object X before a object Y. I'm not expecting the chain to take care of gotos and so forth (if you have label0: stmt_1 in your Jimple code it will not insert a statement between the label and the statement). 
Regarding your transformation I see no problem.

Regards,
Bernahrd

Am 20.05.2013 um 09:22 schrieb Zeinab Lashkaripour <lashkaripour at yahoo.com>:

> Hi Bernhard,
> 
> Again I should thank you for the nice explanation.
> If I want to add my ifStmt before the specific Stmt and I use insertBefore is the result as I want?
> if (condition)
>     statement
> 
> I mean that is the Stmt not repeated again in the chain due to using insertBefore or does Soot take care of it?
> 
> Another question that I have and I would be grateful if you guided me is also related to transformation:
> I process UD chains, then iterate through the CFGs of the methods I have and look for specific statements.
> After finding them, I perform some processing on the UDs and depending on the results I need to transform my code.
> The question I have is that depending on the result I might need to transform a statement that I have iterated through before my specific statement.
> Am I able to perform my transformations?
> 
> Regards,
> Zeinab
> From: Bernhard Berger <berber at tzi.de>
> To: Zeinab Lashkaripour <lashkaripour at yahoo.com> 
> Cc: "soot-list at sable.mcgill.ca" <soot-list at sable.mcgill.ca> 
> Sent: Monday, May 20, 2013 11:20 AM
> Subject: Re: [Soot-list] ifStmt transformation
> 
> Hi Zeinab,
> 
> generating Jimple is not easy. You have to remember that every "line" in a Jimple file corresponds to a statement [1]. There you can see all possible subtypes of Stmt (such as an IfStmt). Inside of statements you can place Values [2]. In your case the second line in your Jimple code is a IfStmt containing an EqExpr. The EqExpr contains a Local ($z0) and an IntConstant. Theoretical you can add a InvokeExpr instead of the Local but I'm always carful because there is lots of code that expects the Jimple code to be the way it's generated by the frontend.
> Labels do not exist in the memory version of Jimple. They are resolved to references to statements. Take the following pseudo Jimple code:
> 
> Stmt_1;
> Stmt_2;
> if x == 0 goto label0;
> Stmt_3;
> Label0:
> Stmt_4;
> 
> After loading this code into memory the target of the IfStmt will point to Stmt4.
> 
> That's all Folks,
> Bernhard
> 
> [1] http://www.sable.mcgill.ca/soot/doc/index.html?soot/jimple/Stmt.html
> [2] http://www.sable.mcgill.ca/soot/doc/index.html?soot/Value.html
> 
> Am 19.05.2013 um 21:45 schrieb Zeinab Lashkaripour <lashkaripour at yahoo.com>:
> 
>> Hi everyone,
>> 
>> I would be grateful if some one guided me.
>> I need to add a function call in an ifStmt before a specific statement in the chain (As below).
>> (params stands for the parameters of the "fn")
>>     if ( fn(params) )     
>>     {
>>         statement in chain.
>>     }
>> I tried to work the other way round, I know that the equivalent Jimple is like below:
>>     $z0 = staticinvoke <class: boolean fn(param types)>(params);        
>>     if $z0 == 0 goto label2;
>>         statement in chain
>> 
>> I tried some code but got no result, I only know how to generate the green part. 
>> Do I need a ConditionExprBox?
>> Can I not use the "fn" call directly in ifStmt?
>> What about the label? How do I get the value of label?
>> 
>> If there is anything else that I need to take care of, I would be happy to know.
>> Thanks in advance.
>> 
>> Regards,
>> Zenab
>> _______________________________________________
>> Soot-list mailing list
>> Soot-list at sable.mcgill.ca
>> http://mailman.cs.mcgill.ca/mailman/listinfo/soot-list
> 
> 
> 

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