[PATCH] D126270: [InstCombine] Preserve !nosanitize for newly created instructions.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

It might make sense to take a step back, and look again at how ASan works here.

There's a comment in AddressSanitizer.cpp: "This is a rough heuristic; it may cause both false positives and false negatives. The proper implementation requires cooperation with the frontend."  Instead of trying to preserve metadata on random instructions, can we fix pointer subtraction/comparison under asan to use some dedicated intrinsic that reflects the necessary semantics?

(See also discussion on https://discourse.llvm.org/t/rfc-safe-optimizations-for-sanitizers/62729 .)


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D126270/new/

https://reviews.llvm.org/D126270