[fpc-devel] volatile variables
DrDiettrich1 at aol.com
Tue Jun 28 18:11:29 CEST 2011
Andrew Brunner schrieb:
> On Tue, Jun 28, 2011 at 9:23 AM, Jonas Maebe <jonas.maebe at elis.ugent.be> wrote:
> On topic, Jonas can you take a few moments to describe how developers
> can force code execution in order w/o using a third party library? Is
> there a compiler directive we can use?
I think that you should give at least an example, where instruction
reordering makes a difference. Neither a compiler nor a processor is
allowed to reorder instructions in a way, that breaks the def/use
(produce/consume...) chain (see SSA - Single Static Assignment).
No library will prevent you from implementing undetectable side-effects,
or to use alias.
When in this code snippet
i := list.Count;
the statements cannot be executed out-of-sequence, or in parallel, then
I assume that every subroutine call will disallow to move instructions
from after the call to before it. Everything else would be insane.
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