[cfe-dev] Disabling label-unioning in dataflow sanitizer?

[Christian Convey]

Hi guys,

Does anyone know if clang's dataflow sanitizer supports the following
option, or if there are plans to?

Right now (clang 3.6), it seems that when two or more inputs of a given
operation carry different labels, the resulting value is tagged with the
*union* of those labels.  But I'm interested in a different kind of
analysis, where I track the pristine flow of a value.  So in my analysis,
when an operation does anything other than cleanly propagate an input value
to its output, I want the output to be unlabeled.

For example, if we have:
   int c = a + b;
Then I want 'c' to be have a dfas label if and only if 'a' and 'b' both
have the same label.

Thanks,
Christian
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