That’s the point. C allows this function to be optimized to always return 1. A “pointers are addresses, just emit reads and writes and stop trying to be so clever” version of C would require x to be spilled to the stack, then the write, then reload x and return whatever it contained.
Then use the register keyword or just reword the standard to assume the register behavior if a variables address hasn't been taken.
The majority of useful optimizations can be kept in a "Sane C" with either code style changes (cache stuff in local vars to avoid aliasing for example) or with minor tweaks to the standard.
Register behavior is what you want essentially all of the time. So we’d just have to write `register` all over the place for no gain.
“Don’t optimize this, read and write it even if you think it’s not necessary” is a very rare case so it shouldn’t be the default. If you want it, use the volatile keyword.
There’s no need to reword the standard to assume the register behavior if the variable’s address hasn’t been taken. That’s already how it works. In this example, if you escape the value of `&x`, it’s not legal to optimize this function to always return 1.
Sure different compilers might allow inlining assembly or some other ways to access x on previous stack perhaps but then it is not really "C"