Re: [Valgrind-developers] Valgrind updates (fwd)

[Johannes S. <Joh...@gm...>]

Hi,

On Sun, 1 Feb 2009, Julian Seward wrote:

> Going round in circles here.
> 
> > Your hint with VALGRIND_CHECK_MEM_IS_DEFINED() showed indeed that valgrind
> > thinks that the single byte at offset 51 (in a buffer of 58) is undefined.
> 
> I just spent some time chasing this.  I cannot reproduce the byte-51-is-
> undefined problem.  It only shows that 58 and later are undefined, which
> is as expected.  This is with various combinations of 32-bit and 64-bit
> builds, all optimisation levels, and with the system installed zlib and a
> from-source zlib.  This is on x86_64, openSUSE 11.0, gcc (SUSE Linux) 4.3.1
> 20080507.

Sorry, I get it only when configuring with '-O3 -DUNALIGNED_OK' (I thought 
I mentioned that already...)

> Can you tell me what exactly I need to do to get the byte-51 undef 
> error, including details of what distro you're using?

Ubuntu Gutsy and Intrepid, both x86_64, zlib-1.2.3.3-ubuntu5, although I 
can reproduce even with zlib-1.2.3.  The key is to use both -O3 and 
-DUNALIGNED_OK.

Ciao,
Dscho