Refine the abstract domain of values #490
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Introduce a `Num p` abstract value that stands for any number (but no pointers), with provenance `p`. In non-strict mode, this makes the value analysis more precise than using `Ifptr p` for the same purpose, like we did before. Also: minor simplifications and cleanups in the management of provenance. In strict mode, instead of setting all provenances to `Pbot`, just propagate them but ignore them in `aptr_of_aval`. Simplify `vnormalize` and its proof consequently.
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NB. This will need to be run against AbsInt's test suite to check that it does not cause over-optimization. |
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Indeed, this allows, for instance, to establish that a stack variable and |
One possible case (Ptr, Num) and many impossible cases (e.g. I, F) were sent to Vtop and are now given more precise upper bounds.
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Testing shows no over-optimization. Merging. |
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Introduce a
Num pabstract value that stands for any number (but no pointers), with provenancep. In non-strict mode, this makes the value analysis more precise than usingIfptr pfor the same purpose, like we did before. (In particular, it should address the imprecision mentioned in #489, even though thevlubfunction remains non-monotonic.)Also: minor simplifications and cleanups in the management of provenance. In strict mode, instead of setting all provenances to
Pbot, just propagate them but ignore them inaptr_of_aval. Simplifyvnormalizeand its proof consequently.