[llvm-dev] Adding asan poison to Recycler and ArrayRecycler

[Justin Bogner via llvm-dev]

Nicolai Hähnle via llvm-dev <llvm-dev at lists.llvm.org> writes:
> Hi all,
>
> I intend to add address sanitizer (un)poison calls to Recycler and
> ArrayRecycler since I spent a few hours tracking down a bug in the
> AMDGPU backend that turned out to be a use-after-free that would have
> been detected by asan if it weren't for the Recycler. See
> https://reviews.llvm.org/D25313.
>
> Naturally, such a change exposes a bunch of bugs or things that are
> dodgy and happen not to be problematic today, but might easily break
> in the future, across all backends. I have prepared patches to fix all
> the issues in the CodeGen/AMDGPU lit tests; all the non-AMDGPU fixes
> are rolled into the patch above (although it probably makes sense to
> commit them first as a separate change before switching asan on). But
> it's clearly not my job to fix the inevitable build bot regressions in
> other backends.
>
> How do you want to handle this?

Changes like this are kind of tricky to stage, as you've noticed ;)

You have a few options, ranging from least work to fastest:

1. File bugs for the other backends and attach the patch that adds the
   annotations.

2. Include the ASAN backtraces in those bugs (Presumably there are a lot
   of duplicates, so you can attach one backtrace per backend and
   possibly have to repeat, or spend some time trying to pick out the
   duplicates and file a bug each)

3. Fix everyone else's backends yourself

Unfortunately, both (1) and (2) tend to take a depressingly long time,
so it's kind of hard to actually do these things without resorting to
(3). A lot of the failures look like they're in X86 and ARM though, and
there are a lot of contributors to those, so (2) might not be too bad in
this case.