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We can invert a compare constant and preserve the logic as shown in this sampling: https://alive2.llvm.org/ce/z/YAXbfs (In theory, we could deal with non-all-ones/zero as well, but it doesn't seem worthwhile.) I noticed this as a part of the x86 codegen difference in https://llvm.org/PR51259 - it ends up using "test" instead of "not + cmp" in that example. This pattern also shows up in https://llvm.org/PR41312 and https://llvm.org/PR50798 . Differential Revision: https://reviews.llvm.org/D107170