(please don't top-post - it is harder to follow the conversation)
On 6/17/2020 10:20 AM, Kunal Chauhan wrote:
On 17 Jun 2020 13:50, "Paul FLOYD" <pjfl...@wanadoo.fr
<mailto:pjfl...@wanadoo.fr>> wrote:
> Hi Team,
> Q.As for a valgrind usage , is valgrind only checks the memory
leakage of code which hits only?
> Q As for a can valgrind checks the all the code of binary
without hitting rhe scenerio. In code?
Kunal
Broadly speaking, there are two categories of software analysis tools.
1. Static analysis tools. For instance, clang analyzer. See
https://en.wikipedia.org/wiki/List_of_tools_for_static_code_analysis
<https://en.wikipedia.org/wiki/List_of_tools_for_static_code_analysis>
These tools parse all the code to produce some sort of model and
then do lots of 'what-if' analysis on all code paths.
Advantages: does not depend on your test coverage, can check for
very many kinds of errors.
Disadvantages: tools have to make tradeoffs between runtime and
really checking all possibilities. Also the models
are usually limited in scope which can cause false positives.
2. Dynamic analysis tools like Valgrind. Again wikipedia has a
page listing tools
https://en.wikipedia.org/wiki/Dynamic_program_analysis
<https://en.wikipedia.org/wiki/Dynamic_program_analysis>
These tools test running code.
Advantages: lower rate of false positives.
Disadvantage. Only as good as your tests - you should be measuring
your code coverage! Performance - usually there is a large memory
and/or runtime overhead, which can make running
dynamic tools on large applications/data imprectical.
A+
Paul
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Hi Team,
1. Is valgrind use particular format, to show memory leaks like double
free in c code.
2. If we have multiple pointers and some sig abort happens in code, is
valgrind works for that part also.?
Thnks
Kunal
1. The memcheck tool within valgrind will report repeated calls to
free(): https://www.valgrind.org/info/tools.html
2. valgrind/memcheck will report the state of memory when the program
exits, whatever the reason. If the error handler in your code does not
clean up all memory before the program exits, valgrind will generate a
very long report of the memory still in use. Because abort() calls can
occur anywhere in the code, many developers do not attempt to clean up
everything - the code to do so can be very complex.
Item 2 sounds very limiting, but if your program is crashing because of
one or more invalid memory accesses, valgrind will report where that
occurred. You can fix the access error(s), ignore the report of memory
still in use, then rerun valgrind. This is a very powerful debugging
method.
--
David Chapman dcchap...@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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