[MLIR] Fix build without native arch

[nikic]

Summary

D125214 split off a MLIRExecutionEngineUtils library that is used by MLIRGPUTransforms. However, currently the entire ExecutionEngine directory is skipped if the LLVM_NATIVE_ARCH target is not available.

Move the check for LLVM_NATIVE_ARCH, such that MLIRExecutionEngineUtils always gets build, and only the JIT-related libraries are omitted without native arch.

mlir/lib/CMakeLists.txt

 add_subdirectory(Pass)
 add_subdirectory(Reducer)
 add_subdirectory(Rewrite)
 add_subdirectory(Support)
 add_subdirectory(TableGen)
 add_subdirectory(Target)
 add_subdirectory(Tools)
 add_subdirectory(Transforms)
-
-# Only enable the ExecutionEngine if the native target is configured in.
-if(TARGET ${LLVM_NATIVE_ARCH})
-  add_subdirectory(ExecutionEngine)
-endif()

mlir/lib/ExecutionEngine/CMakeLists.txt

 # Exclude these from libMLIR.so because the JIT infrastructure
 # is a big dependency which most don't need.
 
 set(LLVM_OPTIONAL_SOURCES
   AsyncRuntime.cpp
   CRunnerUtils.cpp
   CudaRuntimeWrappers.cpp
   SparseTensorUtils.cpp
   ExecutionEngine.cpp
   RocmRuntimeWrappers.cpp
   RunnerUtils.cpp
   OptUtils.cpp
   JitRunner.cpp
   )
 
-if(LLVM_USE_INTEL_JITEVENTS)
-  set(LLVM_JIT_LISTENER_LIB
-      IntelJITEvents)
-endif(LLVM_USE_INTEL_JITEVENTS)
-
-if(LLVM_USE_PERF)
-  set(LLVM_JIT_LISTENER_LIB
-      PerfJITEvents)
-endif(LLVM_USE_PERF)
-
 # Use a separate library for OptUtils, to avoid pulling in the entire JIT and
 # codegen infrastructure. Unlike MLIRExecutionEngine, this is part of
 # libMLIR.so.
 add_mlir_library(MLIRExecutionEngineUtils
   OptUtils.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${MLIR_MAIN_INCLUDE_DIR}/mlir/ExecutionEngine
add_mlir_library(MLIRExecutionEngineUtils
   InstCombine
   ScalarOpts
   Vectorize
   TransformUtils
   IPO
   Passes
   )
 
+# Only enable the ExecutionEngine if the native target is configured in.
+if(NOT TARGET ${LLVM_NATIVE_ARCH})
+  return()
+endif()
+
+if(LLVM_USE_INTEL_JITEVENTS)
+  set(LLVM_JIT_LISTENER_LIB
+      IntelJITEvents)
+endif(LLVM_USE_INTEL_JITEVENTS)
+
+if(LLVM_USE_PERF)
+  set(LLVM_JIT_LISTENER_LIB
+      PerfJITEvents)
+endif(LLVM_USE_PERF)
+
 add_mlir_library(MLIRExecutionEngine
   ExecutionEngine.cpp
 
   EXCLUDE_FROM_LIBMLIR
 
   ADDITIONAL_HEADER_DIRS
   ${MLIR_MAIN_INCLUDE_DIR}/mlir/ExecutionEngine