Summary:
Summaries are modified before saving from disk, for example the attributes of the postcondition can change.
I have observed flaky reports of the internal error NULL_TEST_AFTER_DEREFERENCE. Some attributes (e.g. assigned) are changed before saving, but the spec table in memory is not changed.
So in case:
1) the procedure is analyzed on-demand, then subsequent uses in the same process use the summary in memory with the unchanged attribute, and the issue is not reported.
2) the procedure is already on disk and loaded, then the loaded summary has the changed attributes, and the issue is reported.
Flakiness happens as because of parallelism, whether a procedure is analyzed already or whether it is analyzed on-demand, can change.
The normalization function can change the instrumentation of a symbolic heap because it uses the existing comparison functions, which ignore instrumentations.
So normalization can replace part of a symbolic heap with an identical one but where the instrumentation is different — this is what I have observed.
The diff uses a different comparison function where instrumentations are taken into account.
Reviewed By: jberdine
Differential Revision: D4140031
fbshipit-source-id: f4f119a
Summary:
Move the Sil.attribute type and associated types and operations to a new
PredSymb module.
Reviewed By: cristianoc
Differential Revision: D3683834
fbshipit-source-id: d3606a8
Cristiano Calcagno
Josh Berdine