[mlir] Fix MLIR dylib CMake config when LLVM_BUILD_LLVM_DYLIB is OFF

mlir/CMakeLists.txt

@@ -172,8 +172,11 @@ set(MLIR_INSTALL_AGGREGATE_OBJECTS 1 CACHE BOOL
 
 set(MLIR_BUILD_MLIR_C_DYLIB 0 CACHE BOOL "Builds libMLIR-C shared library.")
 
-set(MLIR_LINK_MLIR_DYLIB ${LLVM_LINK_LLVM_DYLIB} CACHE BOOL
-    "Link tools against libMLIR.so")
+option(MLIR_BUILD_MLIR_DYLIB "Builds the libMLIR shared library" OFF)
+option(MLIR_LINK_MLIR_DYLIB "Link tools against libMLIR.so" ${LLVM_LINK_LLVM_DYLIB})
+if (MLIR_LINK_MLIR_DYLIB)
+  set(MLIR_BUILD_MLIR_DYLIB ON)
+endif()
 
 configure_file(
   ${MLIR_MAIN_INCLUDE_DIR}/mlir/Config/mlir-config.h.cmake
@@ -235,6 +238,15 @@ set(MLIR_PDLL_TABLEGEN_TARGET "${MLIR_PDLL_TABLEGEN_TARGET}" CACHE INTERNAL "")
 set(MLIR_SRC_SHARDER_TABLEGEN_EXE "${MLIR_SRC_SHARDER_TABLEGEN_EXE}" CACHE INTERNAL "")
 set(MLIR_SRC_SHARDER_TABLEGEN_TARGET "${MLIR_SRC_SHARDER_TABLEGEN_TARGET}" CACHE INTERNAL "")
 
+# Add MLIR dylib target here, as calls to mlir_target_link_libraries (used by
+# individual libs below) assume that such a target may exist,
+# but we cannot define the actual dylib until after all individual libs
+# are defined.
+if (MLIR_BUILD_MLIR_DYLIB)
+  add_library(MLIRDylib INTERFACE)
+  add_mlir_library_install(MLIRDylib)
+endif()
+
 add_subdirectory(include/mlir)
 add_subdirectory(lib)
 # C API needs all dialects for registration, but should be built before tests.

mlir/cmake/modules/AddMLIR.cmake

@@ -354,11 +354,11 @@ function(add_mlir_library name)
     # Yes, because the target "obj.${name}" is referenced.
     set(NEEDS_OBJECT_LIB ON)
   endif ()
-  if(LLVM_BUILD_LLVM_DYLIB AND NOT ARG_EXCLUDE_FROM_LIBMLIR AND NOT XCODE)
+  if(MLIR_BUILD_MLIR_DYLIB AND NOT ARG_EXCLUDE_FROM_LIBMLIR AND NOT XCODE)
     # Yes, because in addition to the shared library, the object files are
     # needed for linking into libMLIR.so (see mlir/tools/mlir-shlib/CMakeLists.txt).
     # For XCode, -force_load is used instead.
-    # Windows is not supported (LLVM_BUILD_LLVM_DYLIB=ON will cause an error).
+    # Windows is not supported (MLIR_BUILD_MLIR_DYLIB=ON will cause an error).
     set(NEEDS_OBJECT_LIB ON)
     set_property(GLOBAL APPEND PROPERTY MLIR_STATIC_LIBS ${name})
     set_property(GLOBAL APPEND PROPERTY MLIR_LLVM_LINK_COMPONENTS ${ARG_LINK_COMPONENTS})
@@ -745,7 +745,7 @@ function(mlir_target_link_libraries target type)
   endif()
 
   if (MLIR_LINK_MLIR_DYLIB)
-    target_link_libraries(${target} ${type} MLIR)
+    target_link_libraries(${target} ${type} MLIRDylib)
   else()
     target_link_libraries(${target} ${type} ${ARGN})
   endif()

mlir/lib/ExecutionEngine/CMakeLists.txt

@@ -103,7 +103,7 @@ mlir_target_link_libraries(MLIRExecutionEngine PUBLIC
   MLIRTargetLLVMIRExport
   )
 
-if(LLVM_BUILD_LLVM_DYLIB AND NOT (WIN32 OR MINGW OR CYGWIN)) # Does not build on windows currently, see #106859
+if(MLIR_BUILD_MLIR_DYLIB AND NOT (WIN32 OR MINGW OR CYGWIN)) # Does not build on windows currently, see #106859
   # Build a shared library for the execution engine. Some downstream projects
   # use this library to build their own CPU runners while preserving dynamic
   # linkage.

mlir/tools/mlir-shlib/CMakeLists.txt

@@ -30,7 +30,7 @@ if(MLIR_LINK_MLIR_DYLIB)
   set(INSTALL_WITH_TOOLCHAIN INSTALL_WITH_TOOLCHAIN)
 endif()
 
-if(LLVM_BUILD_LLVM_DYLIB)
+if(MLIR_BUILD_MLIR_DYLIB)
   add_mlir_library(
     MLIR
     SHARED
@@ -45,6 +45,7 @@ if(LLVM_BUILD_LLVM_DYLIB)
     ${mlir_llvm_link_components}
   )
   target_link_libraries(MLIR PRIVATE ${LLVM_PTHREAD_LIB})
+  target_link_libraries(MLIRDylib INTERFACE MLIR)
 endif()
 
 #message("Libraries included in libMLIR.so: ${mlir_libs}")