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The backend converts 64-bit ORs into subreg moves if the upper 32 bits of one operand and the low 32 bits of the other are known to be zero. It then tries to peel away redundant ANDs from the upper 32 bits. Since AND masks are canonicalized to exclude known-zero bits, the test ORs the mask and the known-zero bits together before checking for redundancy. The problem was that it was using the wrong node when checking for known-zero bits, so could drop ANDs that were still needed. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196267 91177308-0d34-0410-b5e6-96231b3b80d8
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