[cfe-dev] [analyzer] What's up with c++-allocator-inlining?
Kristóf Umann via cfe-dev
cfe-dev at lists.llvm.org
Thu Feb 27 07:04:07 PST 2020
Ah, I see. Though, in the specific case of MallocChecker, I wonder whether
there's any point of using it once we touch postCall anyways.
On Thu, 27 Feb 2020 at 15:53, Artem Dergachev <noqnoqneo at gmail.com> wrote:
> On 2/26/20 6:45 PM, Artem Dergachev wrote:
> > Yes, we should remove the old code for c++-allocator-inlining=false.
> > The worry we've had back then was that in the new mode we've disabled
> > aggressive behavior of MallocChecker in which it reacted to some
> > overloaded operator new invocations but i think this was the right
> > thing to do and also nobody complained; also nothing prevents us from
> > bringing back the old behavior in a much less confusing way.
> > Using a CXXAllocatorCall sounds wonderful as well. I'm afraid it might
> > be technically difficult to do so because our Environment is screwed
> > due to CXXNewExpr serving two different purposes, so there's a wrong
> > SVal attached to it and CallEvent might be unable to retrieve the
> > right SVal, so we're passing it separately. If this issue is solved,
> > we might as well provide these callbacks as part of
> > checkPreCall/checkPostCall and then abandon the check::NewAllocator
> > callback entirely. More discussion on this in
> > http://lists.llvm.org/pipermail/cfe-dev/2017-December/056314.html
> > I think at this point we might actually do a good job sorting out this
> > check::NewAllocator issue because we have a "separate" "Environment"
> > to hold the other SVal, which is "objects under construction"! - so we
> > should probably simply teach CXXAllocatorCall to extract the value
> > from the objects-under-construction trait of the program state and
> > we're good.
> Nvm, i'm wrong. CXXAllocatorCall should have the value before the cast
> but "objects under construction" and check::NewAllocator should have the
> value after the cast. So there's still no easy way to fix CXXAllocatorCall.
> > On 2/26/20 5:02 PM, Kristóf Umann via cfe-dev wrote:
> >> Hey!
> >> This is short and sweet. MallocChecker uses both check::newAllocator
> >> and check::postStmt<CXXNewExpr> to model aspects of operator new.
> >> Mind that these two are redundant not only with each other, but with
> >> the already used check::postCall. The reason I can see is handling
> >> all values of the analyzer config c++-allocator-inlining.
> >> So, this flag has been true by default for a long-long time, and I
> >> personally never changed had the need to change it. Is there a need
> >> to keep tiptoeing around it? Here is a patch that tackles the issue,
> >> but it quite dated and I'm not too sure about the current state of
> >> things.
> >> [analyzer] Add a new checker callback, check::NewAllocator.
> >> https://reviews.llvm.org/D41406
> >> Also, shouldn't we make check::NewAllocator provide a
> >> CXXAllocatorCall rather then a CXXNewExpr and a related
> >> under-construction SVal?
> >> Cheers,
> >> Husi
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