[PATCH] D65718: [LangRef] Document forward-progress requirement

[Sassa Nf via Phabricator via llvm-commits]

sassa.nf added a comment.

> What would be a main benefit for allowing out-of-order execution between instructions having no data dependency in a sequential program?

The same as elimination of dead code. The example that you give has `f(x)` in it, which is an important difference.

My original question was about whether "forward progress guarantee" is a necessary condition.

But actually the language I was thinking of defines program order as the total order, no partial order with data dependencies involved. So I can see now where the "forward progress guarantee" comes in into this optimization: without this guarantee, and without the partial order you can't ignore non-termination, even if you are not observing the loop's outcome (i.e. even if you do not have a data dependency).


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