[PATCH] D84371: [DFSan] Add efficient fast16labels instrumentation mode.

[Matt Morehouse via Phabricator via cfe-commits]

morehouse added inline comments.


================
Comment at: compiler-rt/lib/dfsan/dfsan.cpp:180
 dfsan_label __dfsan_union(dfsan_label l1, dfsan_label l2) {
-  if (flags().fast16labels)
+  if (fast16labels)
     return l1 | l2;
----------------
morehouse wrote:
> vitalybuka wrote:
> > morehouse wrote:
> > > vitalybuka wrote:
> > > > isn't better just create new set of callbacks?
> > > > e.g __dfsan_fast16_union
> > > > and then we don't need any flags or preinit array initialization
> > > Should work for `__dfsan_union` and `__dfsan_union_load`, but what about all the other API functions the user can call directly?  We wouldn't be able to warn in those cases.
> > > Should work for `__dfsan_union` and `__dfsan_union_load`, but what about all the other API functions the user can call directly?  We wouldn't be able to warn in those cases.
> > 
> > Those calls are no-op, it would be nice, but it's not worth it.
> > You can avoid state variable fast16labels, and avoid preinit_array which time to time conflicts with other libs. Which looks more useful then warning.
> > 
> > 
> > 
> Thanks.  Turns out we only need `__dfsan_union_load_fast16labels`, which makes things simpler.
Turns out we might need a fast16 flag and preinit_array after all, since many of the custom wrappers call `dfsan_union`...

@vitalybuka Any ideas to avoid this?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D84371/new/

https://reviews.llvm.org/D84371