[cfe-dev] Consumed analysis resets its state in between CFG blocks

[Manuel Klimek]

Btw, I see a similar problem with the ReachableCode analysis:
lib/Analysis/ReachableCode.cpp:61 static bool isDeadReturn(...)
seems to rely on the invariant:
"A new block may only be started if there is control flow"
Is the analyzer actually trying to enforce this invariant?

Thanks!
/Manuel




On Sat, May 3, 2014 at 5:38 PM, Manuel Klimek <klimek at google.com> wrote:

> Heya,
>
> I am currently playing around with how the CFG looks in the face of
> temporary destructors; one interesting tidbit is that temporary destructors
> insert CFG blocks in places where one might not have expected them - for
> example, before the call to an arbitrary destructor at the end of a full
> expression.
>
> Now the consumed analysis kills it state unconditionally at the end of
> each block:
>
> http://reviews.llvm.org/diffusion/L/browse/cfe/trunk/lib/Analysis/Consumed.cpp;207914$1400
> This leads to missed warnings when we leave a CFG block in the middle of
> an expression, and in general feels very brittle regarding future changes
> to the CFG's layout.
>
> I was wondering whether there are already mechanisms in the CFG to deal
> with issues like this (I'd have expected a consumed analysis to work on the
> scope of a variable instead of arbitrary block boundaries - for example,
> could we use REGISTER_MAP_WITH_PROGRAMSTATE?).
>
> Thoughts?
> /Manuel
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20140505/02766517/attachment.html>