Add MLIR_INSTALL_AGGREGATE_OBJECTS and default it to ON.

[stellaraccident]

Summary

• Package maintainers can opt to disable installation of these objects.
• Per discussion on https://reviews.llvm.org/D111504

[kwk]

LGTM

mlir/CMakeLists.txt

 
 option(MLIR_INCLUDE_TESTS
        "Generate build targets for the MLIR unit tests."
        ${LLVM_INCLUDE_TESTS})
 
 option(MLIR_INCLUDE_INTEGRATION_TESTS
        "Generate build targets for the MLIR integration tests.")
 
+set(MLIR_INSTALL_AGGREGATE_OBJECTS 1 CACHE BOOL
+    "Installs object files needed for add_mlir_aggregate to work out of \
+    tree. Package maintainers can disable this to exclude these assets if \
+    not desired. Enabling this will result in object files being written \
+    under lib/objects-{CMAKE_BUILD_TYPE}.")
+
 #-------------------------------------------------------------------------------
 # Python Bindings Configuration
 # Requires:
 #   The pybind11 library can be found (set with -DPYBIND_DIR=...)
 #   The python executable is correct (set with -DPython3_EXECUTABLE=...)
 #-------------------------------------------------------------------------------
 
 set(MLIR_ENABLE_BINDINGS_PYTHON 0 CACHE BOOL

mlir/cmake/modules/AddMLIR.cmake

set_target_properties(${name} PROPERTIES
       MLIR_AGGREGATE_OBJECTS "${AGGREGATE_OBJECTS}"
       MLIR_AGGREGATE_DEPS "${AGGREGATE_DEPS}"
       MLIR_AGGREGATE_OBJECT_LIB_IMPORTED "${AGGREGATE_OBJECT_LIB}"
       MLIR_AGGREGATE_DEP_LIBS_IMPORTED "${CURRENT_LINK_LIBRARIES}"
     )
 
     # In order for out-of-tree projects to build aggregates of this library,
     # we need to install the OBJECT library.
-    if(NOT ARG_DISABLE_INSTALL)
+    if(MLIR_INSTALL_AGGREGATE_OBJECTS AND NOT ARG_DISABLE_INSTALL)
       add_mlir_library_install(obj.${name})
     endif()
   endif()
 endfunction(add_mlir_library)
 
 # Sets a variable with a transformed list of link libraries such individual
 # libraries will be dynamically excluded when evaluated on a final library
 # which defines an MLIR_AGGREGATE_EXCLUDE_LIBS which contains any of the
if(NOT _is_imported)
       # In the context of this aggregate, resolve the list of OBJECTS and DEPS
       # that each library advertises and patch it into the whole.
       set(_local_objects $<TARGET_GENEX_EVAL:${name},$<TARGET_PROPERTY:${lib},MLIR_AGGREGATE_OBJECTS>>)
       set(_local_deps $<TARGET_GENEX_EVAL:${name},$<TARGET_PROPERTY:${lib},MLIR_AGGREGATE_DEPS>>)
     else()
       # It is an imported target, which can only have flat strings populated
       # (no generator expressions).
       # Rebuild the generator expressions from the imported flat string lists.
+      if(NOT MLIR_INSTALL_AGGREGATE_OBJECTS)
+        message(SEND_ERROR "Cannot build aggregate from imported targets which were not installed via MLIR_INSTALL_AGGREGATE_OBJECTS (for ${lib}).")
+      endif()
+
       get_property(_has_object_lib_prop TARGET ${lib} PROPERTY MLIR_AGGREGATE_OBJECT_LIB_IMPORTED SET)
       get_property(_has_dep_libs_prop TARGET ${lib} PROPERTY MLIR_AGGREGATE_DEP_LIBS_IMPORTED SET)
       if(NOT _has_object_lib_prop OR NOT _has_dep_libs_prop)
         message(SEND_ERROR "Cannot create an aggregate out of imported ${lib}: It is missing properties indicating that it was built for aggregation")
       endif()
       get_target_property(_imp_local_object_lib ${lib} MLIR_AGGREGATE_OBJECT_LIB_IMPORTED)
       get_target_property(_imp_dep_libs ${lib} MLIR_AGGREGATE_DEP_LIBS_IMPORTED)
       set(_local_objects)

mlir/cmake/modules/MLIRConfig.cmake.in

 # This file allows users to call find_package(MLIR) and pick up our targets.
 
 @MLIR_CONFIG_CODE@
 
 find_package(LLVM REQUIRED CONFIG
              HINTS "@MLIR_CONFIG_LLVM_CMAKE_DIR@")
 
 set(MLIR_EXPORTED_TARGETS "@MLIR_EXPORTS@")
 set(MLIR_CMAKE_DIR "@MLIR_CONFIG_CMAKE_DIR@")
 set(MLIR_INCLUDE_DIRS "@MLIR_CONFIG_INCLUDE_DIRS@")
 set(MLIR_TABLEGEN_EXE "@MLIR_TABLEGEN_EXE@")
+set(MLIR_INSTALL_AGGREGATE_OBJECTS "@MLIR_INSTALL_AGGREGATE_OBJECTS@")
 
 # For mlir_tablegen()
 set(MLIR_INCLUDE_DIR "@MLIR_INCLUDE_DIR@")
 set(MLIR_MAIN_SRC_DIR "@MLIR_MAIN_SRC_DIR@")
 
 set_property(GLOBAL PROPERTY MLIR_ALL_LIBS "@MLIR_ALL_LIBS@")
 set_property(GLOBAL PROPERTY MLIR_DIALECT_LIBS "@MLIR_DIALECT_LIBS@")
 set_property(GLOBAL PROPERTY MLIR_CONVERSION_LIBS "@MLIR_CONVERSION_LIBS@")