[msan] Add handlers for AVX masked load/store intrinsics (#123857)

This patch adds explicit support for AVX masked load/store intrinsics,
largely by applying the intrinsics to the shadows (but subtly different
to handleIntrinsicByApplyingToShadow()).

We do not reuse the handleMaskedLoad/Store functions. The key challenge
is that the LLVM masked intrinsics require a vector of booleans, while
AVX masked intrinsics use the MSBs of a vector of integers.
X86InstCombineIntrinsic.cpp::simplifyX86MaskedLoad mentions that the x86
backend does not know how to efficiently convert from a vector of
booleans back into the AVX mask format; therefore, they (and we) do not
reduce AVX masked intrinsics into LLVM masked intrinsics.

0 files changed, 0 insertions, 0 deletions