Handle the rewrite of multiple identical loads in Loop Carry.
Handle the rewrite of multiple identical loads in Loop Carry.

Suppose we have more than one identical load in a for loop that
are identical, then we should group them together so that if we
ecide to replace them with a load from a scratch buffer, we'll be
able to replace all of these identical loads.

jiawen/Halide,jiawen/Halide,ronen/Halide,ronen/Halide,ronen/Halide,kgnk/Halide,kgnk/Halide,jiawen/Halide,kgnk/Halide,ronen/Halide,jiawen/Halide,psuriana/Halide,ronen/Halide,psuriana/Halide,psuriana/Halide,jiawen/Halide,kgnk/Halide,psuriana/Halide,kgnk/Halide,kgnk/Halide,jiawen/Halide,ronen/Halide,ronen/Halide,kgnk/Halide,jiawen/Halide,psuriana/Halide,ronen/Halide,psuriana/Halide,psuriana/Halide,kgnk/Halide