llvm-project

b9d6cbd4 - [MLIR] Folding unpack and pack sequence in data layout propagation from padded domain (#138332)

[MLIR] Folding unpack and pack sequence in data layout propagation from padded domain (#138332) In `DataLayoutPropagation` patterns, it can populate sequence of unpack op followed by pack op. Such sequence tend to disrupt tiling and can be optimized. This is especially true for pack and unpack in padded values. The idea of this patch is to optimize the propagation by never creating the unpack + pack in cases where the padding value does not matter for the op that is being propagated through. We can optimize the unpack/pack pair away from in particular `PushDownUnPackOpThroughGenericOp` pattern. If the operand of the generic op happen to come from an unpack, there's no need to create new packs of the generic operand. We can fold the unpack -> pack sequence and use the operand from the original source of the unpack op.