[hsn915]

> They perform optimizing transformations which are guaranteed to preserve the behavior of valid programs. Some programs are considered invalid (those which execute invalid operations like out-of-bounds array accesses at runtime), and those same optimizing transformations are simply not required to preserve the behavior of such programs.

I think this is the core of the problem and it's why people don't like these optimizations and turn them off.

Again I'm not the odin designer nor a core maintainer, so I can't speak on behalf of the language, but from what I understand, Odin's stance is that the compiler may not make assumptions about what kind of code is invalid and whose behavior therefore need not be preserved by the transformations it makes.