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> Furthermore, at every sequence point the value last stored in the object shall agree with that prescribed by the abstract machine, except as modified by the u

by shakna 5mo ago

> Furthermore, at every sequence point the value last stored in the object shall agree with that prescribed by the abstract machine, except as modified by the unknown factors mentioned previously. I quoted the C standard, first. Not compiler behaviour. I showed where it requires the compiler not to optimise this. How about, instead of one-line throwaway disagreements, you point out where they are permitted to do this, instead?

dwattttt 5mo ago
The compiler is required to not optimise out reads/writes through volatile. That's unrelated to code also having UB: you can't sprinkle volatile through arbitrary UB and suddenly have it be defined. > A compliant compiler is only free to optimise away, where it can determine there are no side-effects A compliant compiler is also allowed to assume UB cannot occur.