I've mentioned elsewhere the standards, and compilers as well, disagreeing with you here.

But feel free to run against the various compilers through godbolt. [0] They won't optimise the branch away. Access to a volatile, must be preserved, in the order that they exist. No optimisation, UB or otherwise, is allowed to impede that. Because an access is a side-effect.

[0] https://godbolt.org/z/85cGhq3Ta

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saagarjha an hour ago | parent [-]

That they won’t is as most a courtesy to you but they are not required to do this.

	▲	shakna an hour ago \| parent [-]
		> 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?