LoopFusion: insert the source loop nest slice at a depth in the destination...

LoopFusion: insert the source loop nest slice at a depth in the destination loop nest which preserves dependences (above any loop carried or other dependences). This is accomplished by updating the maximum destination loop depth based on dependence checks between source loop nest loads and stores which access the memref on which the source loop nest has a store op. In addition, prevent fusing in source loop nests which write to memrefs which escape or are live out.

PiperOrigin-RevId: 231684492