[PATCH] D21165: Disable MSan-hostile loop unswitching.

[Evgeniy Stepanov via llvm-commits]

eugenis created this revision.
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Loop unswitching may cause MSan false positive when the unswitch
condition is not guaranteed to execute.

This is very similar to ASan and TSan special case in
llvm::isSafeToSpeculativelyExecute (they don't like speculative loads
and stores), but for branch instructions.

Fixes PR28054.

Repository:
  rL LLVM

http://reviews.llvm.org/D21165

Files:
  include/llvm/Transforms/Utils/LoopUtils.h
  lib/Transforms/Scalar/LICM.cpp
  lib/Transforms/Scalar/LoopUnswitch.cpp
  test/Transforms/LoopUnswitch/msan.ll

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