libswift: add support for Android and OpenBSD in the CMake config

Add a new libswift build mode for cross-compilation in the process, that currently
only works for non-Darwin hosts.

Author: finagolfin

CMakeLists.txt

@@ -190,6 +190,8 @@ cmake_dependent_option(LIBSWIFT_BUILD_MODE "How to build libswift. Possible valu
     BOOTSTRAPPING: libswift is built with a 2-stage bootstrapping process
     BOOTSTRAPPING-WITH-HOSTLIBS:   libswift is built with a 2-stage bootstrapping process,
                    but the compiler links against the host system swift libs (macOS only)
+    CROSSCOMPILE:  libswift is cross-compiled with a native host compiler, provided in
+                   `SWIFT_NATIVE_SWIFT_TOOLS_PATH` (non-Darwin only)
     CROSSCOMPILE-WITH-HOSTLIBS:    libswift is built with a bootstrapping-with-hostlibs compiled
                                    compiler, provided in `SWIFT_NATIVE_SWIFT_TOOLS_PATH`"
   OFF "NOT CMAKE_GENERATOR STREQUAL \"Xcode\"" OFF)
@@ -616,6 +618,8 @@ elseif(LIBSWIFT_BUILD_MODE MATCHES "BOOTSTRAPPING.*")
   set(SWIFT_EXEC_FOR_LIBSWIFT "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/swiftc")
   if(LIBSWIFT_BUILD_MODE STREQUAL "BOOTSTRAPPING-WITH-HOSTLIBS")
     set(LIBSWIFT_BUILD_MODE "CROSSCOMPILE-WITH-HOSTLIBS")
+  elseif(LIBSWIFT_BUILD_MODE STREQUAL "BOOTSTRAPPING")
+    set(LIBSWIFT_BUILD_MODE "CROSSCOMPILE")
   else()
     set(LIBSWIFT_BUILD_MODE "HOSTTOOLS")
   endif()

cmake/modules/AddSwift.cmake

@@ -739,6 +739,10 @@ function(add_libswift name)
       get_filename_component(swift_exec_bin_dir ${ALS_SWIFT_EXEC} DIRECTORY)
       set(sdk_option ${sdk_option} "-resource-dir" "${swift_exec_bin_dir}/../bootstrapping0/lib/swift")
     endif()
+  elseif(${LIBSWIFT_BUILD_MODE} STREQUAL "CROSSCOMPILE")
+    set(sdk_option "-sdk" "${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${SWIFT_HOST_VARIANT_ARCH}_PATH}")
+    get_filename_component(swift_exec_bin_dir ${ALS_SWIFT_EXEC} DIRECTORY)
+    set(sdk_option ${sdk_option} "-resource-dir" "${swift_exec_bin_dir}/../lib/swift")
   endif()
   get_versioned_target_triple(target ${SWIFT_HOST_VARIANT_SDK}
       ${SWIFT_HOST_VARIANT_ARCH} "${deployment_version}")
@@ -973,22 +977,28 @@ function(add_swift_host_tool executable)
       BUILD_WITH_INSTALL_RPATH YES
       INSTALL_RPATH "${RPATH_LIST}")
 
-  elseif(SWIFT_HOST_VARIANT_SDK STREQUAL "LINUX" AND ASHT_HAS_LIBSWIFT AND LIBSWIFT_BUILD_MODE)
+  elseif(SWIFT_HOST_VARIANT_SDK MATCHES "LINUX|ANDROID|OPENBSD" AND ASHT_HAS_LIBSWIFT AND LIBSWIFT_BUILD_MODE)
     set(swiftrt "swiftImageRegistrationObject${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_OBJECT_FORMAT}-${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}-${SWIFT_HOST_VARIANT_ARCH}")
-    if(LIBSWIFT_BUILD_MODE STREQUAL "HOSTTOOLS")
+    if(${LIBSWIFT_BUILD_MODE} MATCHES "HOSTTOOLS|CROSSCOMPILE")
       # At build time and and run time, link against the swift libraries in the
       # installed host toolchain.
       get_filename_component(swift_bin_dir ${SWIFT_EXEC_FOR_LIBSWIFT} DIRECTORY)
       get_filename_component(swift_dir ${swift_bin_dir} DIRECTORY)
-      set(host_lib_dir "${swift_dir}/lib/swift/linux")
+      set(host_lib_dir "${swift_dir}/lib/swift/${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}")
 
       target_link_libraries(${executable} PRIVATE ${swiftrt})
       target_link_libraries(${executable} PRIVATE "swiftCore")
 
       target_link_directories(${executable} PRIVATE ${host_lib_dir})
-      set_target_properties(${executable} PROPERTIES
-        BUILD_WITH_INSTALL_RPATH YES
-        INSTALL_RPATH  "${host_lib_dir}")
+      if(LIBSWIFT_BUILD_MODE STREQUAL "HOSTTOOLS")
+        set_target_properties(${executable} PROPERTIES
+          BUILD_WITH_INSTALL_RPATH YES
+          INSTALL_RPATH  "${host_lib_dir}")
+      else()
+        set_target_properties(${executable} PROPERTIES
+          BUILD_WITH_INSTALL_RPATH YES
+          INSTALL_RPATH  "$ORIGIN/../lib/swift/${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}")
+      endif()
 
     elseif(LIBSWIFT_BUILD_MODE STREQUAL "BOOTSTRAPPING")
       # At build time link against the built swift libraries from the
@@ -1004,7 +1014,7 @@ function(add_swift_host_tool executable)
       # bootstrapping stage.
       set_target_properties(${executable} PROPERTIES
         BUILD_WITH_INSTALL_RPATH YES
-        INSTALL_RPATH  "$ORIGIN/../lib/swift/${SWIFT_SDK_LINUX_LIB_SUBDIR}")
+        INSTALL_RPATH  "$ORIGIN/../lib/swift/${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}")
 
     elseif(LIBSWIFT_BUILD_MODE STREQUAL "BOOTSTRAPPING-WITH-HOSTLIBS")
       message(FATAL_ERROR "LIBSWIFT_BUILD_MODE 'BOOTSTRAPPING-WITH-HOSTLIBS' not supported on Linux")

libswift/CMakeLists.txt

@@ -20,7 +20,7 @@ else()
 
   add_subdirectory(Sources)
 
-  if(${LIBSWIFT_BUILD_MODE} MATCHES "HOSTTOOLS|CROSSCOMPILE-WITH-HOSTLIBS")
+  if(${LIBSWIFT_BUILD_MODE} MATCHES "HOSTTOOLS|CROSSCOMPILE")
 
     if (NOT SWIFT_EXEC_FOR_LIBSWIFT)
       message(FATAL_ERROR "Need a swift toolchain for building libswift")

stdlib/cmake/modules/SwiftSource.cmake

@@ -734,7 +734,7 @@ function(_compile_swift_files
       # stdlib in the current stage is not built yet.
       if(${SWIFT_HOST_VARIANT_SDK} IN_LIST SWIFT_APPLE_PLATFORMS)
         set(set_environment_args "${CMAKE_COMMAND}" "-E" "env" "DYLD_LIBRARY_PATH=${bs_lib_dir}")
-      elseif(SWIFT_HOST_VARIANT_SDK STREQUAL "LINUX")
+      elseif(SWIFT_HOST_VARIANT_SDK MATCHES "LINUX|ANDROID|OPENBSD")
         set(set_environment_args "${CMAKE_COMMAND}" "-E" "env" "LD_LIBRARY_PATH=${bs_lib_dir}")
       else()
         message(FATAL_ERROR "TODO: bootstrapping support for ${SWIFT_HOST_VARIANT_SDK}")