[mlir][sparse] cleanup of CMake files

[aartbik]

Summary

Alphabetical order, less whitespace
removed some verbose comments for readability
(which are preserved in the history if ever needed)

mlir/include/mlir/Dialect/SparseTensor/CMakeLists.txt

 add_subdirectory(IR)
-add_subdirectory(Transforms)
 add_subdirectory(TransformOps)
+add_subdirectory(Transforms)

mlir/include/mlir/Dialect/SparseTensor/Transforms/CMakeLists.txt

 set(LLVM_TARGET_DEFINITIONS Passes.td)
 mlir_tablegen(Passes.h.inc -gen-pass-decls -name SparseTensor)
 mlir_tablegen(Passes.capi.h.inc -gen-pass-capi-header --prefix SparseTensor)
 mlir_tablegen(Passes.capi.cpp.inc -gen-pass-capi-impl --prefix SparseTensor)
 add_public_tablegen_target(MLIRSparseTensorPassIncGen)
-
 add_mlir_doc(Passes SparseTensorPasses ./ -gen-pass-doc)

mlir/lib/Dialect/SparseTensor/CMakeLists.txt

 add_subdirectory(IR)
-add_subdirectory(Transforms)
-add_subdirectory(TransformOps)
 add_subdirectory(Pipelines)
+add_subdirectory(TransformOps)
+add_subdirectory(Transforms)
 add_subdirectory(Utils)

mlir/lib/Dialect/SparseTensor/IR/CMakeLists.txt

 # This library is shared by both MLIRSparseTensorDialect and
 # MLIRSparseTensorRuntime, so it must not depend on any of the MLIR/LLVM
 # internals or else mlir_c_runner_utils will inherit that dependency.
 #
 # Because this is a header-only (`INTERFACE`) library, we cannot use
 # the `add_mlir_library` function.  So we do our best to replicate the
 # relevant portions below.  If doing so becomes too complicated, then
 # we should adjust the `add_mlir_library` function to also work for
 # `INTERFACE` libraries.
 set(MLIRSparseTensorEnums_hdrs
     mlir/Dialect/SparseTensor/IR/Enums.h)
-# This conditional is copypasta from `add_mlir_library`.
 if(MSVC_IDE OR XCODE)
   foreach(hdr ${MLIRSparseTensorEnums_hdrs})
     set_source_files_properties(${MLIR_MAIN_INCLUDE_DIR}/${hdr}
       PROPERTIES HEADER_FILE_ONLY ON)
   endforeach()
 endif()
-# Older versions of cmake (< 3.19) require INTERFACE libraries to separate
-# the `add_library` and `target_sources` calls.
 add_library(MLIRSparseTensorEnums INTERFACE)
-# If we call target_sources naively, then the library won't be
-# installed properly (i.e., so that it can be used by projects outside
-# the llvm-project repo).  To correct this, we must use BUILD_INTERFACE /
-# INSTALL_INTERFACE generator expressions to avoid paths being interpreted
-# as absolute; for more details, see <https://stackoverflow.com/a/62465051>.
-# Unfortunately BUILD_INTERFACE and INSTALL_INTERFACE require their file
-# paths to be relative to different things, hence why we use a foreach loop
-# to iterate over the sources (in case we ever need to have more than one).
 foreach(hdr ${MLIRSparseTensorEnums_hdrs})
   target_sources(MLIRSparseTensorEnums INTERFACE
     $<BUILD_INTERFACE:${MLIR_MAIN_INCLUDE_DIR}/${hdr}>
     $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/${hdr}>)
 endforeach()
-# The `add_mlir_library_install` is required for other libraries to
-# depend on this one, but the conditional itself and the phony target
-# are copypasta from `add_mlir_library`.  Afaict (wrengr), the version
-# in `add_mlir_library` is to prevent `add_mlir_library_install` from
-# raising additional errors whenever the underlying call to `add_llvm_library`
-# fails.  However, since we are using `add_library` directly, I'm not
-# sure if the conditional is helpful/required here or not.
 if(TARGET MLIRSparseTensorEnums)
   add_mlir_library_install(MLIRSparseTensorEnums)
 else()
-  # Add empty "phony" target
-  add_custom_target(MLIRSparseTensorEnums)
+  add_custom_target(MLIRSparseTensorEnums) # empty "phony" target
 endif()
-# Older versions of cmake (i.e., 3.18.0 but not 3.24.2) disallow setting
-# the CXX_STANDARD property for INTERFACE libraries.  However, this library
-# must adhere to the same CXX_STANDARD restriction as mlir_c_runner_utils.
-
 
 add_mlir_dialect_library(MLIRSparseTensorDialect
   SparseTensorDialect.cpp
   Detail/Var.cpp
   Detail/DimLvlMap.cpp
   Detail/LvlTypeParser.cpp
   Detail/DimLvlMapParser.cpp
 

mlir/lib/Dialect/SparseTensor/Pipelines/CMakeLists.txt

add_mlir_dialect_library(MLIRSparseTensorPipelines
   MLIRSparseTensorDialect
   MLIRSparseTensorTransforms
   MLIRTensorTransforms
   MLIRVectorToLLVM
   MLIRVectorTransforms
 )
 
 if(MLIR_ENABLE_CUDA_RUNNER)
-   # Enable gpu-to-cubin pass.
   target_compile_definitions(obj.MLIRSparseTensorPipelines
     PRIVATE
     MLIR_GPU_TO_CUBIN_PASS_ENABLE=1
   )
 endif()