[MLIR] Add memref dialect dependency for affine fusion pass

[vinayaka-polymage]

Summary

For AffineLoopFusion pass, add memref dialect as a dependent
dialect. Since the fusion pass can create memref::AllocOps, the
dialect must be registered in its dependent dialects.

The missing dependency was not discovered until now because the above
said op creation happes only when the input already has
memref::AllocOps in it, and all dialects in the input are
automatically added to the context.

[vinayaka-polymage]

Better commit summary and message

[vinayaka-polymage]

Adding why the issue was not discovered till now

[bondhugula]

Thanks! Interesting that this wasn't discovered this long! All test cases that required generation of an AllocOp in the fusion pass had to be those that were locally defined - so they already had an alloc op.

mlir/include/mlir/Transforms/Passes.td

Option<"fastMemorySpace", "fusion-fast-mem-space", "unsigned",
            /*default=*/"0",
            "Faster memory space number to promote fusion buffers to">,
     Option<"localBufSizeThreshold", "fusion-local-buf-threshold", "uint64_t",
            /*default=*/"0", "Threshold size (KiB) for promoting local buffers "
                             "to fast memory space">,
     Option<"maximalFusion", "fusion-maximal", "bool", /*default=*/"false",
            "Enables maximal loop fusion">,
   ];
+  let dependentDialects = ["memref::MemRefDialect"];
 }
 
 def AffinePipelineDataTransfer
     : FunctionPass<"affine-pipeline-data-transfer"> {
   let summary = "Pipeline non-blocking data transfers between explicitly "
                 "managed levels of the memory hierarchy";
   let description = [{
     This pass performs a transformation to overlap non-blocking DMA operations