Bit-wise reasoning for atomic accesses

language design Unsafe Code Guidelines
7

A hypothetical example? Yes, compilers are allowed to turn

x = 0;

into

x = 1;
x = 0;

Now, a realistic example… that will be harder. One could imagine a compiler moving an assignment out of a conditional if it knows that it will be overwritten later anyway:

if foo {
  x = 0;
} else {
  x = 1;
  bar();
}

could be turned into

x = 1;
if foo {
  x = 0;
} else {
  bar();
}

Still seems somewhat dump, but compilers do move assignments out of conditionals (and that is the reason for some of the quirks in relaxed accesses).

I will ask some people if they can come up with more realistic examples.

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