RE: [Valgrind-users] Uninitialised values

[Vincent Penquerc'h <Vin...@ar...>]

> This function does a lot of left shifts, right shifts and other
> bit-level stuff. Is it possible that my data accidentally contains the
> bit pattern used by valgrind to trace uninitialised data ?

AFAIK, Valgrind doesn't rely on any pattern in the actual data to
detect uninitialized data, especially as it can detect this at the
bit level (you'd have to choose either 0 or 1 to mean "uninitialized"
for a bit, which makes it hard to avoid the pattern :))

Valgrind maintains separate validity/addressability bits, but that
is outside your program, so you don't see it.
It's possible that Valgrind gets confused, if some insn wrongly
sets/checks validity flags. Or, maybe you are encoding more than
the actual data ? Or do you mean random data, as initialized via
a pseudo random number generator, or as whatever happened to lie
in memory at the time (in which case you will get undefinedness) ?

-- 
Vincent Penquerc'h