Modifying the values of Gimple Instruction Operands
Mon Sep 23 18:09:00 GMT 2013

Can you guys please help me for variables and pointers ?

Any ideas or pointers will be fine!

Thank you very much in advance.

> Thank you very much Richard,
> Very good starter for me but I am actually having the hardest time with
> variables, pointers etc...
> I know this may be a lot to ask but,
> If you could help me with this I will very much appreciate it.
> Thanks again very much!
> I will be sure to include your name in my paper :)
>> On Tue, Sep 3, 2013 at 7:59 PM,  <> wrote:
>>> Sorry forgot to mention, my name is Tuncer.
>>> Again any help would be much appreciated.
>>> I know these maybe simple for some of you if you could lend me a hand,
>>> you
>>> will be doing a great deal of help.
>>> Changed the subject for better understanding,
>>> Thanks again guys :)
>> Something like
>>    oldop = gimple_assign_rhs1 (stmt);
>>    gsi = gsi_for_stmt (stmt);
>>    newop = force_gimple_operand_gsi (&gsi, fold_build2 (BIT_IOR_EXPR,
>> TREE_TYPE (oldop), oldop, build_int_cst (TREE_TYPE (oldop), 1<<3)),
>>    gimple_assign_set_rhs1 (stmt, newop);
>>    update_stmt (stmt);
>>>> Hi,
>>>> I am a student at Bilkent Uni. in Turkey and using GCC as a tool for
> my
>>>> M.S. Thesis which is about Software Fault Tolerance.
>>>> I am stuck, in terms of implementing bit flips in the operands of a
> gimple
>>>> statement.
>>>> I need to inject bit flips to all kinds of operands, constant
> integers,
>>>> floats, variables, pointers etc...
>>>> It is simpler for constants, but I am having a hard time to get the
>>>> value
>>>> of pointers and other variables.
>>>> My objective is to simply change the value of a tree operand, by
> injecting
>>>> a new instruction that changes the value or directly change the
> operand
>>>> to
>>>> a bit flipped value.
>>>> For constant integers I did something like this:
>>>> int valueBefore = TREE_INT_CST_LOW(operands[i]);
>>>> int valueAfter = (valueBefore ^ (1u << 2));
>>>>       tree number =
>>>> build_int_cst (integer_type_node, valueAfter);
>>>> I would love it if you can help me and
>>>> may even implement a tool for GCC for error injection purposes. Any
> help would be much appreciated!
>>>> Thank you very much!

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