alt Hacker News> prevents the compiler from deciding this itself.
Interesting. I understand why it does that, but it makes me realise that I usually think "the compiler will reuse the loaded value/perform CSE" without considering the cases where it won't. Are there tools that will detect and warn/indicate this situation? e.g. "warning: could not reuse previously loaded value of 'foo' due to aliasing hazard 'memcpy' at line 234."
Not that I know of; and such would necessarily have false-positives (...or, rather, entirely consist of potential false-positives) because you may actually want the re-read.