At 08:41 AM 14/11/2003, Evan Ireland wrote:
>Jeremy,
>
>Suppose we have two statements executed by a thread:
>
> (1) x.f = a; (f is non-volatile, x is known not to be null)
> (2) y.v = b; (v is volatile field, y is known not to be null)
>
>If statement (1) is executed before statement (2), then (1) hb (2),
>and thereby any thread subsequently reading y.v should be certain of
>seeing the modified value of x.f. I agree that this is implied by the
>happens-before rules.
>
>However, if statement (2) is executed before statement (1), due to
>reordering, then visibility of the modified value of x.f seems not
>to be assured by the happens-before rules.
The happens before rules are determined by the order in which the
statements appear in the program. They are not affected by any reordering
performed by the compiler or harware.
Sylvia.
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