goblint / goblint/analyzer

ExpRelation analysis ignores overflows

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#776 2 comments 0 reactions 0 assignees View on GitHub

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cleanup unsound
Dominant language
OCaml
Stars
252
Forks
90
Avg merge
4d 1m
Merged PRs (30d)
19

Description

As pointed out in https://github.com/goblint/analyzer/pull/770#discussion_r912977915, the expRelation analysis makes some claims about expressions containing arithmetic which may overflow. Depending on the configuration, we might not want it to make definite claims about expressions that become unsound due to overflows. This doesn't concern just signed overflow (for which we have an option), but also unsigned overflow.

As I found out in #770, most of those seem completely untested beforehand, so instead of fixing maybe they could largely just be removed. Unless there are some non-regression test programs where these expRelations matter.

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Research direction

Start with the expRelation analysis and the discussion in PR 770, focusing on arithmetic expressions that can undergo signed or unsigned overflow. Check the configuration-dependent behavior and look for non-regression test programs; done means unsound claims are removed or corrected and retained behavior is covered by tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
c, ocaml
Domain
devtools, testing-qa
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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