[mlir][cmake] Fix MLIR shared library installation (#152195)

When `LLVM_INSTALL_TOOLCHAIN_ONLY=ON`, the MLIR shared library
(`libMLIR*`) is not installed even though it is built with the
`INSTALL_WITH_TOOLCHAIN` argument to the `add_mlir_library` cmake
function. This patch ensures that `libMLIR*` is installed when
`LLVM_INSTALL_TOOLCHAIN_ONLY=ON`.

Patch verified
[here](#151247 (comment)).

fixes #151247

Author: brnorris03

mlir/cmake/modules/AddMLIR.cmake

@@ -388,6 +388,9 @@ function(add_mlir_library name)
 
   if(TARGET ${name})
     target_link_libraries(${name} INTERFACE ${LLVM_COMMON_LIBS})
+    if(ARG_INSTALL_WITH_TOOLCHAIN)
+      set_target_properties(${name} PROPERTIES MLIR_INSTALL_WITH_TOOLCHAIN TRUE)
+    endif()
     if(NOT ARG_DISABLE_INSTALL)
       add_mlir_library_install(${name})
     endif()
@@ -617,28 +620,29 @@ endfunction(add_mlir_aggregate)
 # This is usually done as part of add_mlir_library but is broken out for cases
 # where non-standard library builds can be installed.
 function(add_mlir_library_install name)
-  if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
-  get_target_export_arg(${name} MLIR export_to_mlirtargets UMBRELLA mlir-libraries)
-  install(TARGETS ${name}
-    COMPONENT ${name}
-    ${export_to_mlirtargets}
-    LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-    ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
-    # Note that CMake will create a directory like:
-    #   objects-${CMAKE_BUILD_TYPE}/obj.LibName
-    # and put object files there.
-    OBJECTS DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-  )
+  get_target_property(_install_with_toolchain ${name} MLIR_INSTALL_WITH_TOOLCHAIN)
+  if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR _install_with_toolchain)
+    get_target_export_arg(${name} MLIR export_to_mlirtargets UMBRELLA mlir-libraries)
+    install(TARGETS ${name}
+      COMPONENT ${name}
+      ${export_to_mlirtargets}
+      LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
+      ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+      # Note that CMake will create a directory like:
+      #   objects-${CMAKE_BUILD_TYPE}/obj.LibName
+      # and put object files there.
+      OBJECTS DESTINATION lib${LLVM_LIBDIR_SUFFIX}
+    )
 
-  if (NOT LLVM_ENABLE_IDE)
-    add_llvm_install_targets(install-${name}
-                            DEPENDS ${name}
-                            COMPONENT ${name})
-  endif()
-  set_property(GLOBAL APPEND PROPERTY MLIR_ALL_LIBS ${name})
+    if (NOT LLVM_ENABLE_IDE)
+      add_llvm_install_targets(install-${name}
+                              DEPENDS ${name}
+                              COMPONENT ${name})
+    endif()
+    set_property(GLOBAL APPEND PROPERTY MLIR_ALL_LIBS ${name})
+    set_property(GLOBAL APPEND PROPERTY MLIR_EXPORTS ${name})
   endif()
-  set_property(GLOBAL APPEND PROPERTY MLIR_EXPORTS ${name})
 endfunction()
 
 # Declare an mlir library which is part of the public C-API.