[cfe-dev] How can I get a FieldRegion in a CompoundAssignOperator in Static Analyzer?

[Arthur Yoo]

Hi Jordan,

When evaluating a BinaryAssignOperator(*obj.a = 1;*), if I use
*state->getSVal(LHS,
C.getLocationContext())*, I will get the SVal of LHS, which actually is a
MemRegionVal. So I can get LHS's MemRegion via MemRegionVal. However, for
my test code snippet above, I've tried to use *state->getSVal(LHS,
C.getLocationContext())* to get the SVal of LHS when evaluating '*obj.a +=
sizeof(long);*' in *void checkPostStmt(const BinaryOperator *Op,
CheckerContext &C) const, *the Analyzer gave me '0 S32b'. I know that '0
S32b' does be the value for obj.a. But I want to get the FieldRegion of obj.a,
not its SVal. However, I don't know how to get its FieldRegion when
evaluating a CompoundAssignOperator.


2014/1/22 Jordan Rose <jordan_rose at apple.com>

>
> On Jan 21, 2014, at 5:19 , Arthur Yoo <phjy007 at gmail.com> wrote:
>
> Hi all,
>
>
> I want to get a FieldRegion when evaluating a CompoundAssignOperator. The
> code snippet for my test is like below:
>
>
> typedef struct {
>
>            int a;
>
>            int *p;
>
> } Obj;
>
> Obj obj;
>
> obj.a = 0;
>
> obj.a += sizeof(long);
>
>
> When evaluating the statement ‘*obj.a += sizeof(long);*’ in the method *void
> checkPostStmt(const BinaryOperator *Op, CheckerContext &C) const*, I want
> to get the FieldRegion of *obj.a*. But I don’t know how to get it. Is
> there anyone can provide me a way to get *obj.a*’s FieldRegion? Thanks a
> lot.
>
>
> Hi, Arthur. The value of the BinaryOperator's LHS should be an SVal
> representing the FieldRegion. Are you not seeing that?
>
> Jordan
>



-- 
Best regards,
Arthur Yoo
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