[mlir][tensor] Add a custom builder for pack op.

[hanchung]

Summary

The paddingValue and outerDimsPerm are optional to the op;
innerTiles can be variadic in terms of static sizes and dynamic sizes.
Add a custom builder for building pack op easier.

[hanchung]

remove unrelated changes

[chelini]

Thanks!

mlir/include/mlir/Dialect/Tensor/IR/TensorOps.td

let assemblyFormat = [{
     (`padding_value` `(` $padding_value^ `:` type($padding_value) `)`)?
     (`outer_dims_perm` `=` $outer_dims_perm^)?  
     `inner_dims_pos` `=` $inner_dims_pos
     `inner_tiles` `=`
     custom<DynamicIndexList>($inner_tiles, $static_inner_tiles)
     `into` $dest attr-dict `:` type($source) `->` type($dest)
   }];
 
+  let builders = [
+    OpBuilder<(ins "Value":$source, "Value":$dest,
+      "ArrayRef<int64_t>":$innerDimsPos,
+      "ArrayRef<OpFoldResult>":$innerTiles,
+      CArg<"Optional<Value>", "llvm::None">:$paddingValue,
+      CArg<"ArrayRef<int64_t>", "{}">:$outerDimsPerm)>
+  ];
+
   let extraClassDeclaration = commonExtraClassDeclaration # [{
     // Method to get the `ShapedType` of the result based on the inner tiles,
     // position of the inner tiles (innerDimsPos)  and interchange vector of  
     // outer loops (outerDimsPerm).
     static ShapedType inferPackedType(ShapedType sourceType,
         ArrayRef<int64_t> innerTileSizes, ArrayRef<int64_t> innerDimsPos,
         ArrayRef<int64_t> outerDimsPerm = {});
   }]; 

mlir/lib/Dialect/Tensor/IR/TensorOps.cpp

 //===----------------------------------------------------------------------===//
 // PackOp
 //===----------------------------------------------------------------------===//
 
 void PackOp::getAsmResultNames(function_ref<void(Value, StringRef)> setNameFn) {
   setNameFn(getResult(), "pack");
 }
 
+void PackOp::build(OpBuilder &builder, OperationState &state, Value source,
+                   Value dest, ArrayRef<int64_t> innerDimsPos,
+                   ArrayRef<OpFoldResult> innerTiles,
+                   Optional<Value> paddingValue,
+                   ArrayRef<int64_t> outerDimsPerm) {
+  assert(innerDimsPos.size() == innerTiles.size() &&
+         "number of tile sizes specified must match the specified number of "
+         "original dimensions to be tiled");
+  SmallVector<int64_t> staticTileSizes;
+  SmallVector<Value> dynamicTileSizes;
+  dispatchIndexOpFoldResults(innerTiles, dynamicTileSizes, staticTileSizes,
+                             ShapedType::kDynamic);
+  build(builder, state, dest.getType(), source, dest,
+        paddingValue ? paddingValue.value() : nullptr,
+        outerDimsPerm.empty() ? nullptr
+                              : builder.getDenseI64ArrayAttr(outerDimsPerm),
+        builder.getDenseI64ArrayAttr(innerDimsPos), dynamicTileSizes,
+        builder.getDenseI64ArrayAttr(staticTileSizes));
+}
+
 LogicalResult
 PackOp::reifyResultShapes(OpBuilder &builder,
                           ReifiedRankedShapedTypeDims &reifiedReturnShapes) {
   return reifyResultShapesImpl(*this, builder, reifiedReturnShapes);
 }
 
 DenseMap<int64_t, OpFoldResult> PackOp::getDimAndTileMapping() {
   return getDimAndTileMappingImpl(*this);