https://bugs.kde.org/show_bug.cgi?id=477992
Bug ID: 477992
Summary: compiler generated overlapping memcpy diagnosed
Classification: Developer tools
Product: valgrind
Version: unspecified
Platform: unspecified
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
GCC (and apparently clang as well) specifically requires that memcpy() with an
exact overlap does not trigger undefined behaviour
(https://gcc.godbolt.org/z/E4rqz7bn6):
> Contrary to the standards covering memcpy GCC expects the case of an exact
> overlap of source and destination to work and not invoke undefined behavior.
(from https://gcc.gnu.org/onlinedocs/gcc.pdf)
However, it seems valgrind diagnoses these memcpy() calls as invalid, so it may
happen that perfectly valid code is diagnosed as invalid due to the compiler's
code generation.
See also:
https://gitlab.freedesktop.org/pipewire/pipewire/-/merge_requests/1799
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