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[Bug tree-optimization/82103] spurious stringop-overflow warning
- From: "law at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 05 Dec 2017 19:11:08 +0000
- Subject: [Bug tree-optimization/82103] spurious stringop-overflow warning
- Auto-submitted: auto-generated
- References: <bug-82103-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82103
--- Comment #6 from Jeffrey A. Law <law at redhat dot com> ---
It should. It may not though because one the n != 0 test is removed, the
resulting range of N is probably VR_VARYING rather than ~[0,0] at the call to
memset.
The former signifies we know nothing about the length and given how often that
likely occurs in practice I suspect the warning code suppresses the warning in
that case.
The latter says we know the range is everything except 0. With that sliver of
information the warnings kick in.
It's a bit of speculation on my part, but it's informed speculation.