Hi Josef,
Thanks for your reply. I did run valgrind with
guest_chase_thresh = 0 and was able to do capture the calls.
But my doubt was that I can't see the jump statement(is it that
unconditional jumps are not displayed in IR)
Sorry I am new, but an unconditional branch we should just set the IP to the
called location?Am I right?
How it this being taken care of in the IR?
I also had another question :
Can we read the values written on stack. For example if I want to get the
arguments being passed to a certain function?
I have been able to intercept the calls to that particular function and get
the Stack Pointer. How do I read the stack values?
Regards,
pankaj
On Thu, Jul 7, 2011 at 5:07 PM, Josef Weidendorfer <
[email protected]> wrote:
> On Thursday 07 July 2011, pankaj pawan wrote:
> > Hi all,
> >
> > I had doubt regarding the flattened IR for a call instruction. When I try
> > and print the IR statements for call instructions, i can see the return
> > instruction being written on the stack but i am unable to see how the
> > branching is being done.
> > I can't capture it in Ist_Exit .
>
> A call is nothing more than an unconditional jump with putting a return
> address
> on the stack. As such, the call will disappear in the middle of a
> superblock.
> You could detect that there is a jump in the addresses of subsequent guest
> instructions, but AFAIK, there is no way to detect whether
> it just was a jump or a call (*).
>
> Instead, you can prohibit the building of superblocks by setting VEX
> attributes
>
> VG_(clo_vex_control).iropt_unroll_thresh = 0;
> VG_(clo_vex_control).guest_chase_thresh = 0;
>
> in your tool initialization (as callgrind does).
> Then, a call should end a BB, and IRSB attribute jumpkind should be
> Ijk_Call
> if the BB ends in a guest call instruction.
>
> Josef
>
> (*) It can make sense to add a VEX noop IR hint about that there was a
> given
> call/jump in the middle of a superblock translation. But only if a tool
> really
> would need it...
>
>
> >
> > Can someone explain me what am I missing.
> >
> > Thanks,
> > pankaj
> >
>
>
>
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