[cfe-commits] [PATCH] RegionStore

[Zhongxing Xu]

On Mon, Oct 20, 2008 at 2:38 PM, Ted Kremenek <kremenek at apple.com> wrote:

>
> On Oct 19, 2008, at 9:48 PM, Zhongxing Xu wrote:
>
>  When we visit (*p)[3] = 1, we evaluate (*p)'s rvalue. We will do a load on
>> p's rvalue, which is loc::MemRegionVal(region of a). We want (*p)'s rvalue
>> still be loc::MemRegionVal(region of a). So we should handle this in Store.
>>
>
> In this example, I don't see where GetSVal() gets used other than handling
> the dereference of p, which will return the loc::MemRegionVal(region of a).
>  It seems like it just works (no special handling of array types


This does not just work. We get loc::MemRegionVal(region of a) through
special handling in GRExprEngine originally when we eval a's rvalue. And for
the case of rvalue evaluation of *p, we will get UnknownVal in the original
code.

Now as this patch does, we will get UnknownVal.


> required); VisitArraySubscriptExpr (with asLValue=true) will then call the
> store's VisitLValueElement with loc::MemRegionVal and nonloc::ConcreteInt
> respectively, returning an lvalue for the entire expression.  Since
> BasicStore doesn't reason about array accesses, (*p)[3] will evaluate to
> UnknownVal().
>
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