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As of LLVM 9.0, certain calls to memcmp may be converted to bcmp, which I guess could save a single subtraction on some architectures. [1] bcmp is just like memcmp except instead of returning the difference between the two differing bytes, it returns non-zero instead. As such, memcmp is a valid implementation of bcmp. If we care about size, bcmp should just call memcmp. If we care about speed, we can change bcmp to look like this instead: ```rust pub unsafe extern "C" fn bcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 { let mut i = 0; while i < n { let a = *s1.offset(i as isize); let b = *s2.offset(i as isize); if a != b { return 1; } i += 1; } 0 } ``` In this PR I do not address any changes which may or may not be needed for arm aebi as I lack proper test hardware. [1]: https://releases.llvm.org/9.0.0/docs/ReleaseNotes.html#noteworthy-optimizations
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