[LLVMdev] Tracing values in llvm IR

[Shining]

So you want to store all the variable value to a map, I think I can tell
you some details.
First, you must create a function which can store the variable value which
get from the params of the function to the map.
Second, you must write a pass, In this pass, you must insert the calling to
the function (which created in the first step) to the place which the
variable get the value.
Third, you can create a function with the "__attribute__((destructor))", it
will run after the function finished. You can use the function to output
your date which store in the map.

You must compile the functions(first and third step) to a lib. After you
run your pass (which create in the second step) on your code, get the
output IR, and run it with the lib. You can get what you want.

I hope I can help you.
Thanks.


2014/1/3 Sahoo, Swarup Kumar <ssahoo2 at illinois.edu>

>  You will have to insert callinst to tracing functions immediately after
> the value is produced, not at the entry points. Giri code has many such
> examples of how to do this.
>
> Thanks,
> Swarup.
>
>  ------------------------------
> *From:* llvmdev-bounces at cs.uiuc.edu [llvmdev-bounces at cs.uiuc.edu] on
> behalf of Jin Huang [54jin.huang at gmail.com]
> *Sent:* Thursday, January 02, 2014 9:47 PM
> *To:* llvmdev at cs.uiuc.edu; micah.villmow at smachines.com
>
> *Subject:* Re: [LLVMdev] Tracing values in llvm IR
>
>   Thank you,Micah.
>
>  This way sounds good, Do you mean writing a function to trace the value
> and insert a callinst to call this function in the entry of the program ?
> How can I insert a function writing by myself? Is there any code examples?
>
>  -Jin Huang
>
>
> 2014/1/3 Jin Huang <54jin.huang at gmail.com>
>
>>  Thank you , James.
>>
>>  But this way needs to determine whether the instruction is a LOAD/STORE
>> ,and if I want to preserve the operations on these variables for further
>> dynamic symbolic execution usage(just like KLEE ,but it's a static analysis
>> ,not dynamic),I had to backtrace instructions ,this may be not very
>> efficient if the operation is very complex!
>>
>>  -Jin Huang
>>
>>
>> 2014/1/3 Jin Huang <54jin.huang at gmail.com>
>>
>>>  Thank You ! John and Swarup. I have already downloaded the code!
>>>
>>>
>>>
>>>
>>> 2014/1/3 Sahoo, Swarup Kumar <ssahoo2 at illinois.edu>
>>>
>>>  Hi Jin Huang,
>>>>
>>>> The updated Giri code is available at https://github.com/liuml07/giri<https://github.com/liuml07/giri.>.
>>>> This will give you an idea of how to instrument the program to trace
>>>> different values. You can modify the code to achieve your goals.
>>>>
>>>> -Swarup.
>>>>
>>>>  ------------------------------
>>>> *From:* Criswell, John T
>>>> *Sent:* Thursday, January 02, 2014 2:12 PM
>>>> *To:* Jin Huang; llvmdev at cs.uiuc.edu; Sahoo, Swarup Kumar
>>>> *Subject:* Re: [LLVMdev] Tracing values in llvm IR
>>>>
>>>>    On 1/1/14 11:39 PM, Jin Huang wrote:
>>>>
>>>>  Hi, everyone.
>>>>
>>>>  I want to writing a Pass to get the variable value while the program
>>>> is running ,the basic idea is to insert an STL map in the program ,and get
>>>> every value and address a program use ,but whether it's possible to do this
>>>> by transforming the llvm IR?
>>>>
>>>>  I didn't find any useful functions to get a variable's address in
>>>> LLVM IR .It seems that the IR is an SSA form and we can not get a value's
>>>> address in compiling time.Is that right? But how can I dynamically get the
>>>> variable's value in run time by writing a Pass ?
>>>>
>>>>
>>>> The giri project does dynamic tracing of values stored to and loaded
>>>> from memory.  It stores the trace of memory accesses on disk because they
>>>> get very large very quickly.  You can either reuse the Giri code or modify
>>>> it to suit your purposes.
>>>>
>>>> Swarup, is there a place where people can download the updated Giri
>>>> code that your Google Summer of Code student worked on?
>>>>
>>>> -- John T.
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing listLLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.eduhttp://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
>>>>
>>>>
>>>
>>
>
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>


-- 
Shining(史宁)
Changchun, Jilin, China
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