RE: [Valgrind-users] not understanding some valgrind errors against afs...

[Nicholas N. <nj...@ca...>]

On Thu, 17 Apr 2003, Jeremy Fitzhardinge wrote:

> > Would a client request be a good compromise?  Eg.  insert
> > VALGRIND_STACK_SWITCH just before the stack switch?  It's more
> > intrusive than a command line option, but it's more precise.  Similar
> > to the client request for handling self-modifying code.
> >
> > [I haven't thought through how the request would actually be
> > implemented, but it shouldn't be too hard, I think...]
>
> Yeah, it would.  It would need to mean something like "the next change to %esp is
> a stack switch", but what if changing the stack changes %esp multiple times?  How
> do you know if the compiler is going to generate some non-stack switch changes to
> %esp as part of its codegen?

Maybe have VALGRIND_START_STACK_SWITCH and VALGRIND_END_STACK_SWITCH, and
within that look for a "sizeable" %esp change (eg. anything bigger than
1KB or something) as a genuine switch?  Or maybe not, I don't know.


> I think the correct solution is to move stack switch detection into the skin
> themselves (memcheck, addrcheck and helgrind are the only ones I know of which
> care).  Memcheck and addrcheck can use their existing validity info to make the
> determination; helgrind is harder.

How does validity info help?

N