[PATCH] Add support for annotated minimum dependence distance

[hfinkel at anl.gov]

In http://reviews.llvm.org/D5123#137651, @ArchDRobison wrote:

> I believe that support for forward lexical dependences was the item that required partial ordering support, but was orthogonal to this patch, which addresses minimum dependence distance.


I was not under the impression that it is orthogonal (or it is a prerequisite). Right now, we only have a way to specify that a loop is completely data parallel (no loop carried dependencies at all), so it does not really matter. It does matter, however, if we have a minimum dependency distance, because that distance can have a validity dependence on lexical dependencies (forward and backward) that are sensitive to potential reordering.

Also, as a separate matter, the unroller, when it does partial unrolling, needs to update this metadata (to divide the distances by the unrolling factor).


http://reviews.llvm.org/D5123

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