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SubjectRe: [PATCH] C undefined behavior fix
<<Ah... so (paraphrasing) -- if you have two byte size volatile objects,
and they happen to end up adjacent in memory, the compiler is
explicitly forbidden from turning an access to one of them into a
wider access -- because that would be an access to both of them, which
is a *different* side effect. (Certainly that exactly matches the
hardware-centric view of why "volatile" exists.) And the compiler
isn't allowed to change side effects, including causing them when the
source code didn't ask you to cause them.

Right, and as you see that is covered by the language on external effects
in the Ada standard (remember the intent in Ada was to exactly match the
C rules :-)

But one thing in the Ada world that we consider left open is whether a
compiler is free to combine two volatile loads into a single load. Probably
the answer should be no, but the language at least in the Ada standard does
not seem strong enough to say this.
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