[flang] Move LLVM_ENABLE_RUNTIMES definition above uses (llvm#138136)

Author: DavidTruby

llvm/CMakeLists.txt

@@ -138,6 +138,23 @@ foreach(proj ${LLVM_ENABLE_PROJECTS})
   endif()
 endforeach()
 
+# Select the runtimes to build
+#
+# As we migrate runtimes to using the bootstrapping build, the set of default runtimes
+# should grow as we remove those runtimes from LLVM_ENABLE_PROJECTS above.
+set(LLVM_DEFAULT_RUNTIMES "libcxx;libcxxabi;libunwind")
+set(LLVM_SUPPORTED_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc;offload;flang-rt")
+set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
+  "Semicolon-separated list of runtimes to build, or \"all\" (${LLVM_DEFAULT_RUNTIMES}). Supported runtimes are ${LLVM_SUPPORTED_RUNTIMES}.")
+if(LLVM_ENABLE_RUNTIMES STREQUAL "all")
+  set(LLVM_ENABLE_RUNTIMES ${LLVM_DEFAULT_RUNTIMES})
+endif()
+foreach(proj IN LISTS LLVM_ENABLE_RUNTIMES)
+  if (NOT "${proj}" IN_LIST LLVM_SUPPORTED_RUNTIMES)
+    message(FATAL_ERROR "Runtime \"${proj}\" is not a supported runtime. Supported runtimes are: ${LLVM_SUPPORTED_RUNTIMES}")
+  endif()
+endforeach()
+
 if ("flang" IN_LIST LLVM_ENABLE_PROJECTS)
   if (NOT "mlir" IN_LIST LLVM_ENABLE_PROJECTS)
     message(STATUS "Enabling MLIR as a dependency to flang")
@@ -190,23 +207,6 @@ if ("flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
   endif ()
 endif ()
 
-# Select the runtimes to build
-#
-# As we migrate runtimes to using the bootstrapping build, the set of default runtimes
-# should grow as we remove those runtimes from LLVM_ENABLE_PROJECTS above.
-set(LLVM_DEFAULT_RUNTIMES "libcxx;libcxxabi;libunwind")
-set(LLVM_SUPPORTED_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc;offload;flang-rt")
-set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
-  "Semicolon-separated list of runtimes to build, or \"all\" (${LLVM_DEFAULT_RUNTIMES}). Supported runtimes are ${LLVM_SUPPORTED_RUNTIMES}.")
-if(LLVM_ENABLE_RUNTIMES STREQUAL "all")
-  set(LLVM_ENABLE_RUNTIMES ${LLVM_DEFAULT_RUNTIMES})
-endif()
-foreach(proj IN LISTS LLVM_ENABLE_RUNTIMES)
-  if (NOT "${proj}" IN_LIST LLVM_SUPPORTED_RUNTIMES)
-    message(FATAL_ERROR "Runtime \"${proj}\" is not a supported runtime. Supported runtimes are: ${LLVM_SUPPORTED_RUNTIMES}")
-  endif()
-endforeach()
-
 # Set a shorthand option to enable the GPU build of the 'libc' project.
 option(LIBC_GPU_BUILD "Enable the 'libc' project targeting the GPU" OFF)
 if(LIBC_GPU_BUILD)