On Thursday 25 August 2011, Emilio Coppa wrote:
> > Hmm... strlen shouldn't need to call calloc, so your output seems to be
> > sane.
... 
> > Can you locate the relevant output of "valgrind --tool=callgrind
> > --ct-verbose=2 ..."?

Thanks! There are a lot of strlen called here, but all end with returning
from strlen. So that is sane. And that makes sense, as...

> Obtained with objdump -d /lib/i386-linux-gnu/ld-2.13.so--start-address=0x16c20
> Here: http://pastebin.com/ugf3HzRJ

... the disassembly also does not contain any calls.

So there must be something wrong with the --ct-verbose=1 output you got.
So, am I right that if you select strlen in kcachegrind, you do not see
any callees there, too?

There is a section where strlen returns to _dl_new_object, and according to
your log (--ct-verbose=2), it then calls 040007e4/P (from PLT section),
which also gets the symbol "_dl_new_object", and from there it is jumping
to calloc. I have no idea why the call into the PLT section gets the same
symbol.
Can you check if objdump sees some symbol at offset 74e in ld.so.13 ?

Thanks,
Josef

> 
> 
> > > > Valgrind does not know where we are: 0x40007E4
> >
> > When do you print out this?
> 
> 
> It's printed by the helper function (called at the beginning of a BB) when
> Valgrind doesn't give me debug info [VG_(get_fnname)],
> 
> 
> > Of course it does. But it could be that there is not debug info available,
> > and thus, Valgrind can not tell whether this is the beginning of a function
> > or not.
> 
> 
> Ok, thanks.
> 
> In the next days I modify my code based on your observations. We'll see what
> I get :)
> 
> Emilio.
> 


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