Re: [Valgrind-developers] Incorrect source line numbers

[Julian S. <js...@ac...>]

> So, a possible cause for the difference might be in the code generated
> byValgrind (e.g. for the client request and the maintenance of the
> simulated program counter) : if the code emitted for the client request
> does not store back the exact program counter to the VEX state before
> doing the client request, then both Valgrind and gdb unwinder will wrongly
> show another program counter.
> E.g. I do not know how the Valgrind optimiser is informed that a client
> request can e.g. read various registers and so that the state of these
> must be properly put back to the VEX state before doing the call ?

This was my first guess too.  But the thing is, AFAIR vex makes all
guest registers be up to date before doing a client request, because a
client request terminates a superblock, and all guest registers are
up to date at the end of a superblock -- at least in this case, when
the dispatch-ppc64-linux.S dispatcher returns to m_scheduler in order
to carry out the client request.  So I am not sure what's going on here.

J