*) Factors slice union computation out of LoopFusion into Analysis/Utils (where other iteration slice utilities exist).
*) Generalizes slice union computation to take the union of slices computed on all loads/stores pairs between source and destination loop nests.
*) Fixes a bug in FlatAffineConstraints::addSliceBounds where redundant constraints were added.
*) Takes care of a TODO to expose FlatAffineConstraints::mergeAndAlignIds as a public method.
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PiperOrigin-RevId: 250561529
*) Adds LoopFusionUtils which will expose a set of loop fusion utilities (e.g. dependence checks, fusion cost/storage reduction, loop fusion transformation) for use by loop fusion algorithms. Support for checking block-level fusion-preventing dependences is added in this CL (additional loop fusion utilities will be added in subsequent CLs).
*) Adds TestLoopFusion test pass for testing LoopFusionUtils at a fine granularity.
*) Adds unit test for testing dependence check for block-level fusion-preventing dependences.
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PiperOrigin-RevId: 249861071
