Writing down binary data... with padding bytes

[atagunov]

@comex

LLVM could still theoretically assume that the memory will not change, e.g. by changing one load into two redundant loads and optimizing based on the assumption that both loads will return the same value

Back to zero-overhead: could Rust say these are not UB for padding bytes?

• libc::memcpy
• libc::write

Ways to get confidence:

• examine compiled libc
• re-implement manually in asm