Re: [Valgrind-users] move depends on [WHICH?] uninitialised value(s)

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

On Mon, 1 Dec 2008, Michael Rosellini wrote:

> When Valgrind says "Conditional jump or move depends on uninitialised 
> value(s)," it does not give an address or a size, so if I'm looking at a 
> line like
>
> 1264            if (inet_addr_equal(ip, ae->ip_addr, addrlen) && (ifc == ae->ifc)) {
>
> I really have very little idea what's going on.
>
> Before I go try to patch Valgrind so that it will print out some 
> information about where the undefinedness is, I thought I'd ask: Is there 
> some technical reason why Valgrind doesn't already do this?

http://www.valgrind.org/docs/origin-tracking2007.pdf has more detail on this 
than you ever wanted to know.  In short, it's difficult.

Nonetheless, it's been implemented (albeit in a simpler, less efficient but 
more robust way than that described in the paper).  Check out the current 
SVN trunk (see http://www.valgrind.org/downloads/repository.html for how) 
and try the --track-origins=yes option.

Nick