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

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.

Reviewed By: mravishankar

Differential Revision: https://reviews.llvm.org/D138860

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

@@ -1761,6 +1761,14 @@ def Tensor_PackOp : Tensor_RelayoutOp<"pack", [
     `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  

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

@@ -3238,6 +3238,26 @@ 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) {