[CMake][MLIR][Linalg] Adding variable to specify tablegen file dependencies.

[gysit]

Summary

Synchronizing multiple custom targets requires not only target but also
file dependencies. Building Linalg involves running yaml-gen followed by
tablegen. Currently, these custom targets are only synchronized using a
target dependency resulting in issues in specific incremental build
setups (https://llvm.discourse.group/t/missing-build-cmake-tblgen-dependency/3727/10).

This patch introduces a novel LLVM_TARGET_DEPENDS variable to the
TableGen.cmake file to provide a way to specify file dependencies.
Additionally, it adapts the Linalg CMakeLists.txt to introduce the
necessary file dependency between yaml-gen and tablegen.

[stellaraccident]

mlir/include/mlir/Dialect/Linalg/IR/CMakeLists.txt

28

Can you add a Todo that when this function is rewritten and the old tc parser is retired, to eliminate the parent scope manipulation and do the tablegen generation here in this scope?

I really don't like this action at a distance manipulation of something like a dependency. But since it is all in the same file, in an intermediate state, and I know you are getting ready to delete the old so this can be reworked, I'll favor submitting in this way to fix the incremental build issue.

67

Add a Todo here to factor this so that resetting the var like this is not required.

[gysit]

Address comments by adding comments.

[mehdi_amini]

LGTM with the TODO

[Meinersbur]

Thank you

llvm/cmake/modules/TableGen.cmake

-# LLVM_TARGET_DEFINITIONS must contain the name of the .td file to process.
+# LLVM_TARGET_DEFINITIONS must contain the name of the .td file to process,
+# while LLVM_TARGET_DEPENDS may contain additional file dependencies.
 # Extra parameters for `tblgen' may come after `ofn' parameter.
 # Adds the name of the generated file to TABLEGEN_OUTPUT.
 
 function(tablegen project ofn)
   # Validate calling context.
   if(NOT ${project}_TABLEGEN_EXE)
     message(FATAL_ERROR "${project}_TABLEGEN_EXE not set")
   endif()
add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${ofn}
     ${tblgen_change_flag}
     ${additional_cmdline}
     # The file in LLVM_TARGET_DEFINITIONS may be not in the current
     # directory and local_tds may not contain it, so we must
     # explicitly list it here:
     DEPENDS ${${project}_TABLEGEN_TARGET} ${${project}_TABLEGEN_EXE}
       ${local_tds} ${global_tds}
     ${LLVM_TARGET_DEFINITIONS_ABSOLUTE}
+    ${LLVM_TARGET_DEPENDS}
     COMMENT "Building ${ofn}..."
     )
 
   # `make clean' must remove all those generated files:
   set_property(DIRECTORY APPEND PROPERTY ADDITIONAL_MAKE_CLEAN_FILES ${ofn})
 
   set(TABLEGEN_OUTPUT ${TABLEGEN_OUTPUT} ${CMAKE_CURRENT_BINARY_DIR}/${ofn} PARENT_SCOPE)
   set_source_files_properties(${CMAKE_CURRENT_BINARY_DIR}/${ofn} PROPERTIES

mlir/include/mlir/Dialect/Linalg/IR/CMakeLists.txt

add_custom_command(
     ${MLIR_LINALG_ODS_GEN_TARGET}
     VERBATIM)
   add_custom_target(
     MLIR${output_file}TcIncGen
     DEPENDS
     ${MLIR_LINALG_ODS_GEN_EXE}
     ${MLIR_LINALG_ODS_GEN_TARGET}
     ${GEN_ODS_FILE} ${GEN_CPP_FILE})
+  # Setup the file dependencies needed for the subsequent tablegen step.
+  # TODO: Once there is only one way of generating named ops remove this parent
+  # scope manipulation and implement the tablegen generation in the same scope.
+  set(LLVM_TARGET_DEPENDS ${LLVM_TARGET_DEPENDS} ${GEN_ODS_FILE} PARENT_SCOPE)
 endfunction()
 
 # Declare a function to generate ODS with mlir-linalg-ods-yaml-gen
 function(add_linalg_ods_yaml_gen yaml_ast_file output_file)
   set(YAML_AST_SOURCE ${CMAKE_CURRENT_SOURCE_DIR}/${yaml_ast_file})
   set(GEN_ODS_FILE ${CMAKE_CURRENT_BINARY_DIR}/${output_file}.yamlgen.td)
   set(GEN_CPP_FILE ${CMAKE_CURRENT_BINARY_DIR}/${output_file}.yamlgen.cpp.inc)
   set_source_files_properties(
add_custom_command(
     ${MLIR_LINALG_ODS_YAML_GEN_EXE}
     ${MLIR_LINALG_ODS_YAML_GEN_TARGET})
   add_custom_target(
     MLIR${output_file}YamlIncGen
     DEPENDS
     ${MLIR_LINALG_ODS_YAML_GEN_EXE}
     ${MLIR_LINALG_ODS_YAML_GEN_TARGET}
     ${GEN_ODS_FILE} ${GEN_CPP_FILE})
+  # Setup the file dependencies needed for the subsequent tablegen step.
+  # TODO: Once there is only one way of generating named ops remove this parent
+  # scope manipulation and implement the tablegen generation in the same scope.
+  set(LLVM_TARGET_DEPENDS ${LLVM_TARGET_DEPENDS} ${GEN_ODS_FILE} PARENT_SCOPE)
 endfunction()
 
 # TODO: Delete tc generation and replace with the YAML variant once all ops are
-# ported.
+# ported. At the same time, move the YAML and TableGen generation to the same
+# scope to avoid the at a distance dependency manipulation via
+# LLVM_TARGET_DEPENDS.
+set(LLVM_TARGET_DEPENDS "")
 add_linalg_ods_tc_gen(LinalgNamedStructuredOpsSpec.tc LinalgNamedStructuredOps)
 add_linalg_ods_yaml_gen(LinalgNamedStructuredOps.yaml LinalgNamedStructuredOps)
 
 # Provide a short name for all external dependency that needs to
 # include Linalg in ODS
 add_custom_target(LinalgOdsGen
   DEPENDS
   MLIRLinalgNamedStructuredOpsTcIncGen