[PATCH] D83595: [Draft][MSAN] Optimize away poisoning allocas that are always written before load

[Gui Andrade via Phabricator via llvm-commits]

guiand updated this revision to Diff 277491.
guiand added a comment.
Herald added a project: Sanitizers.
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I've expanded this to be able to find chained uses like through a bitcast.

Mostly a proof-of-concept; this still needs a check to make sure the final store is over the whole size of the initial type. And, of course, the main issue is that this really slows down compilation. So I think using MemSSA might be necessary for performance reasons, unless there's some algorithm tweak I can make here that would reduce the complexity.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D83595/new/

https://reviews.llvm.org/D83595

Files:
  compiler-rt/test/msan/Linux/fopencookie.cpp
  compiler-rt/test/msan/getaddrinfo.cpp
  compiler-rt/test/msan/qsort.cpp
  compiler-rt/test/msan/vararg.cpp
  llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
  llvm/test/Instrumentation/MemorySanitizer/alloca-store.ll
  llvm/test/Instrumentation/MemorySanitizer/alloca.ll
  llvm/test/Instrumentation/MemorySanitizer/msan_x86_bts_asm.ll

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