On 6/15/2024 10:38 AM, Thomas Wollenzin wrote:
Hi,
I'm not too familiar with valgrind yet so excuse a potentially dumb
question.
I'm trying to fix an issue in our code base that valgrind reported as
'Conditional jump or move depends on uninitialised value(s)'. In
particular I have a hard time understanding what the exact item is
that's being seen as uninitialised. I can't share code as it's very
complex and non-public.
What happens is that a rather large class is allocated via operator
new which comes with tons of subsequent data. Unfortunately, a lot of
that data isn't default initialized so it's rather impossible to go by
trial and error. Valgrind does report the place where the condition is
but it's a super busy loop that works on tons of templated data.
Is there a way to have Valgrind tell me what type exactly has the
uninitialised field or at best break at the time this exact incident
occurs?
Thanks,
Thomas
I have fixed so many bugs by initializing seemingly harmless variables
that I now initialize all variables and all data structure fields, even
if only to nullptr. Valgrind found one use of an uninitialized
variable; you probably have many more that didn't show up in this run.
My advice is to make some guesses and initialize the most likely
suspects until the problem goes away. You might call that "trial and
error", but initialization fixes bugs; it does not create new ones.
Then schedule a pass to go over all your code and initialize everything
else. You won't regret it.
--
David chapmandcchap...@acm.org
Chapman Consulting -- San Jose, CA
EDA Software Developer, Expert Witness
www.chapman-consulting-sj.com
2018-2019 Chair, IEEE Consultants' Network of Silicon Valley
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