[cfe-dev] [StaticAnalyzer] getting back (original) (raw)

Daniel Marjamäki via cfe-dev cfe-dev at lists.llvm.org
Wed Dec 2 14:16:36 PST 2020

Hello!

I have started looking at clang static analyzer in some spare time. And I feel like a newbie.

I am currently looking into improving the checking for signed integer overflow.

If I want to get some early feedback .. would it be preferable to send a patch to this email list or can I post some kind of "Draft" pull request in the reviews.llvm.org..

Here is a simple test case, I want to diagnose the addition:

int f(int x) { return 0x7ffffff0 < x && x + 32 < 0x7fffffff; }

In short. Right now my solution is to modify SimpleSValBuilder so it will return UndefinedVal() for a signed integer addition that overflows.

With that change in SimpleSValBuilder, I see this diagnostic:

/home/danielm/cppcheck/1.c:1:43: warning: The result of the '+'

expression is undefined [core.UndefinedBinaryOperatorResult] int f(int x) { return 0x7ffffff0 < x && x + 32 < 0x7fffffff; } ~~^~~~

Well if my approach sounds good a patch will come on reviews.llvm.org soonish. Otherwise I'll rewrite it..

I do not feel that the diagnostic is very clear. It would be nice to write something about "Signed integer overflow". Would it feel like a good approach to put some logic in UndefinedBinaryOperatorResult to make the message more clear..

Best regards, Daniel Marjamäki

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