[PATCH] D64215: Add a transform pass to make the executable semantics of poison explicit in the IR

[Sanjoy Das via Phabricator via llvm-commits]

sanjoy added a comment.

I think this is an excellent idea!!

I personally won't have time to carefully review this & following patches anytime soon (I'm happy to have high level discussions though), but I'm hoping the other reviewers you and I added will have time.



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Comment at: lib/Transforms/Instrumentation/PoisonChecking.cpp:1
+//===- PoisonChecking.cpp - -----------------------------------------------===//
+//
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Maybe just call this PoisonSanitizer?


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Comment at: lib/Transforms/Instrumentation/PoisonChecking.cpp:41
+//   are well defined on the specific input used.
+// - Finding/confirming poison specific miscompiles by checking the poison
+//   status of an input/IR pair is the same before and after an optimization
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This will have false positives as long as `undef` is a thing right?  Unless the instrumentation added by this pass will produce poison if *any* value of `undef` produces poison (naively it seems this would require calling into a SAT solver at runtime)?


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D64215/new/

https://reviews.llvm.org/D64215