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libswift: build support for the initial libswift
* add the (still empty) libswift package * add build support for libswift in CMake * add libswift to swift-frontend and sil-opt The build can be controlled with the LIBSWIFT_BUILD_MODE cmake variable: by default it’s “DISABLE”, which means that libswift is not built. If it’s “HOSTTOOLS”, libswift is built with a pre-installed toolchain on the host system.
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‎CMakeLists.txt

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@@ -191,6 +191,10 @@ set(SWIFT_TOOLS_ENABLE_LTO OFF CACHE STRING "Build Swift tools with LTO. One
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option only affects the tools that run on the host (the compiler), and has
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no effect on the target libraries (the standard library and the runtime).")
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option(SWIFT_TOOLS_ENABLE_LIBSWIFT
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"Enable building libswift and linking libswift into the compiler itself."
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FALSE)
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# The following only works with the Ninja generator in CMake >= 3.0.
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set(SWIFT_PARALLEL_LINK_JOBS "" CACHE STRING
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"Define the maximum number of linker jobs for swift.")
@@ -891,6 +895,7 @@ if(SWIFT_INCLUDE_TOOLS)
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message(STATUS " Build type: ${CMAKE_BUILD_TYPE}")
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message(STATUS " Assertions: ${LLVM_ENABLE_ASSERTIONS}")
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message(STATUS " LTO: ${SWIFT_TOOLS_ENABLE_LTO}")
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message(STATUS " libswift: ${SWIFT_TOOLS_ENABLE_LIBSWIFT}")
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message(STATUS "")
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else()
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message(STATUS "Not building host Swift tools")
@@ -1034,6 +1039,11 @@ add_subdirectory(include)
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if(SWIFT_INCLUDE_TOOLS)
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add_subdirectory(lib)
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# "libswift" must come before "tools".
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# It adds libswift module names to the global property "libswift_modules"
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# which is used in add_swift_host_tool for the lldb workaround.
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add_subdirectory(libswift)
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# Always include this after including stdlib/!
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# Refer to the large comment above the add_subdirectory(stdlib) call.
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# https://bugs.swift.org/browse/SR-5975

‎cmake/modules/AddSwift.cmake

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@@ -607,6 +607,121 @@ function(add_swift_host_library name)
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endif()
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endfunction()
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# Add a module of libswift
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#
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# Creates a target to compile a module which is part of libswift.
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# Adds the module name to the global property "libswift_modules".
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#
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# This is a temporary workaround until it's possible to compile libswift with
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# cmake's builtin swift support.
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function(add_libswift_module module)
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cmake_parse_arguments(ALSM
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""
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"DEPENDS"
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""
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${ARGN})
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set(sources ${ALSM_UNPARSED_ARGUMENTS})
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list(TRANSFORM sources PREPEND "${CMAKE_CURRENT_SOURCE_DIR}/")
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set(target_name "LibSwift${module}")
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# Add a target which depends on the actual compilation target, which
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# will be created in add_libswift.
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# This target is mainly used to add properties, like the list of source files.
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add_custom_target(
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${target_name}
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SOURCES ${sources}
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COMMENT "libswift module ${module}")
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set_property(TARGET ${target_name} PROPERTY "module_name" ${module})
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set_property(TARGET ${target_name} PROPERTY "module_depends" ${ALSM_DEPENDS})
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get_property(modules GLOBAL PROPERTY "libswift_modules")
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set_property(GLOBAL PROPERTY "libswift_modules" ${modules} ${module})
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endfunction()
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# Add source files to a libswift module.
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#
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# This is a temporary workaround until it's possible to compile libswift with
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# cmake's builtin swift support.
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function(libswift_sources module)
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cmake_parse_arguments(LSS
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""
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""
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""
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${ARGN})
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set(sources ${LSS_UNPARSED_ARGUMENTS})
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list(TRANSFORM sources PREPEND "${CMAKE_CURRENT_SOURCE_DIR}/")
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set(target_name "LibSwift${module}")
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set_property(TARGET "LibSwift${module}" APPEND PROPERTY SOURCES ${sources})
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endfunction()
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# Add the libswift library.
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#
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# Adds targets to compile all modules of libswift and a target for the
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# libswift library itself.
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#
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# This is a temporary workaround until it's possible to compile libswift with
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# cmake's builtin swift support.
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function(add_libswift name)
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if(CMAKE_BUILD_TYPE STREQUAL Debug)
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set(libswift_compile_options "-g")
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else()
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set(libswift_compile_options "-O" "-cross-module-optimization")
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endif()
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set(build_dir ${CMAKE_CURRENT_BINARY_DIR})
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if(SWIFT_HOST_VARIANT_SDK IN_LIST SWIFT_APPLE_PLATFORMS)
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set(deployment_version "${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_DEPLOYMENT_VERSION}")
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endif()
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get_versioned_target_triple(target ${SWIFT_HOST_VARIANT_SDK}
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${SWIFT_HOST_VARIANT_ARCH} "${deployment_version}")
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get_property(modules GLOBAL PROPERTY "libswift_modules")
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foreach(module ${modules})
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set(module_target "LibSwift${module}")
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get_target_property(module ${module_target} "module_name")
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get_target_property(sources ${module_target} SOURCES)
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get_target_property(dependencies ${module_target} "module_depends")
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if(dependencies)
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list(TRANSFORM dependencies PREPEND "LibSwift")
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else()
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set(dependencies "")
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endif()
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set(module_obj_file "${build_dir}/${module}.o")
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set(module_file "${build_dir}/${module}.swiftmodule")
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set_property(TARGET ${module_target} PROPERTY "module_file" "${module_file}")
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set(all_obj_files ${all_obj_files} ${module_obj_file})
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# Compile the libswift module into an object file
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add_custom_command_target(dep_target OUTPUT ${module_obj_file}
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WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
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DEPENDS ${sources} ${dependencies}
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COMMAND ${CMAKE_Swift_COMPILER} "-c" "-o" ${module_obj_file}
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"-sdk" "${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${SWIFT_HOST_VARIANT_ARCH}_PATH}"
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"-target" ${target}
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"-module-name" ${module} "-emit-module"
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"-emit-module-path" "${build_dir}/${module}.swiftmodule"
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"-parse-as-library" ${sources}
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"-wmo" ${libswift_compile_options}
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"-I" "${CMAKE_SOURCE_DIR}/include/swift"
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"-I" "${build_dir}"
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COMMENT "Building libswift module ${module}")
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add_dependencies(${module_target} ${dep_target})
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endforeach()
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# Create a static libswift library containing all module object files.
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add_library(${name} STATIC ${all_obj_files})
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set_target_properties(${name} PROPERTIES LINKER_LANGUAGE CXX)
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endfunction()
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macro(add_swift_tool_subdirectory name)
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add_llvm_subdirectory(SWIFT TOOL ${name})
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endmacro()
@@ -616,7 +731,7 @@ macro(add_swift_lib_subdirectory name)
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endmacro()
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function(add_swift_host_tool executable)
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set(options)
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set(options HAS_LIBSWIFT)
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set(single_parameter_options SWIFT_COMPONENT)
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set(multiple_parameter_options LLVM_LINK_COMPONENTS)
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@@ -668,6 +783,24 @@ function(add_swift_host_tool executable)
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get_filename_component(TOOLCHAIN_BIN_DIR ${CMAKE_Swift_COMPILER} DIRECTORY)
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get_filename_component(TOOLCHAIN_LIB_DIR "${TOOLCHAIN_BIN_DIR}/../lib/swift/macosx" ABSOLUTE)
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target_link_directories(${executable} PUBLIC ${TOOLCHAIN_LIB_DIR})
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if (ASHT_HAS_LIBSWIFT AND SWIFT_TOOLS_ENABLE_LIBSWIFT)
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# Workaround to make lldb happy: we have to explicitly add all libswift modules
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# to the linker command line.
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set(libswift_ast_path_flags "-Wl")
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get_property(modules GLOBAL PROPERTY "libswift_modules")
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foreach(module ${modules})
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get_target_property(module_file "LibSwift${module}" "module_file")
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string(APPEND libswift_ast_path_flags ",-add_ast_path,${module_file}")
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endforeach()
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set_property(TARGET ${executable} APPEND_STRING PROPERTY
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LINK_FLAGS ${libswift_ast_path_flags})
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# Workaround for a linker crash related to autolinking: rdar://77839981
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set_property(TARGET ${executable} APPEND_STRING PROPERTY
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LINK_FLAGS " -lobjc ")
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endif()
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endif()
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# Lists of rpaths that we are going to add to our executables.
@@ -687,6 +820,22 @@ function(add_swift_host_tool executable)
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set_target_properties(${executable} PROPERTIES
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BUILD_WITH_INSTALL_RPATH YES
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INSTALL_RPATH "${RPATH_LIST}")
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elseif(SWIFT_HOST_VARIANT_SDK STREQUAL "LINUX")
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if (ASHT_HAS_LIBSWIFT AND SWIFT_TOOLS_ENABLE_LIBSWIFT)
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# At build time and and run time, link against the swift libraries in the
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# installed host toolchain.
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get_filename_component(swift_bin_dir ${CMAKE_Swift_COMPILER} DIRECTORY)
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get_filename_component(swift_dir ${swift_bin_dir} DIRECTORY)
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set(host_lib_dir "${swift_dir}/lib/swift/linux")
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target_link_libraries(${executable} PRIVATE "swiftCore")
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target_link_directories(${executable} PRIVATE ${host_lib_dir})
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set_target_properties(${executable} PROPERTIES
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BUILD_WITH_INSTALL_RPATH YES
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INSTALL_RPATH "${host_lib_dir}")
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endif()
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endif()
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llvm_update_compile_flags(${executable})

‎include/swift/Basic/InitializeLibSwift.h

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//===--- InitializeLibSwift.h -----------------------------------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_BASIC_INITIALIZELIBSWIFT_H
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#define SWIFT_BASIC_INITIALIZELIBSWIFT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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void initializeLibSwift();
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#ifdef __cplusplus
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}
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#endif
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#endif // SWIFT_BASIC_INITIALIZELIBSWIFT_H

‎lib/Immediate/Immediate.cpp

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@@ -237,26 +237,42 @@ int swift::RunImmediately(CompilerInstance &CI,
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//
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// This must be done here, before any library loading has been done, to avoid
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// racing with the static initializers in user code.
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// Setup interpreted process arguments.
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using ArgOverride = void (*)(const char **, int);
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#if defined(_WIN32)
240243
auto stdlib = loadSwiftRuntime(Context.SearchPathOpts.RuntimeLibraryPaths);
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if (!stdlib) {
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CI.getDiags().diagnose(SourceLoc(),
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diag::error_immediate_mode_missing_stdlib);
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return -1;
245248
}
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// Setup interpreted process arguments.
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using ArgOverride = void (*)(const char **, int);
249-
#if defined(_WIN32)
250249
auto module = static_cast<HMODULE>(stdlib);
251250
auto emplaceProcessArgs = reinterpret_cast<ArgOverride>(
252251
GetProcAddress(module, "_swift_stdlib_overrideUnsafeArgvArgc"));
253252
if (emplaceProcessArgs == nullptr)
254253
return -1;
255254
#else
255+
// In case the compiler is built with libswift, it already has the stdlib
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// linked to. First try to lookup the symbol with the standard library
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// resolving.
256258
auto emplaceProcessArgs
257-
= (ArgOverride)dlsym(stdlib, "_swift_stdlib_overrideUnsafeArgvArgc");
258-
if (dlerror())
259-
return -1;
259+
= (ArgOverride)dlsym(RTLD_DEFAULT, "_swift_stdlib_overrideUnsafeArgvArgc");
260+
261+
if (dlerror()) {
262+
// If this does not work (= not build with libswift), we have to explicitly
263+
// load the stdlib.
264+
auto stdlib = loadSwiftRuntime(Context.SearchPathOpts.RuntimeLibraryPaths);
265+
if (!stdlib) {
266+
CI.getDiags().diagnose(SourceLoc(),
267+
diag::error_immediate_mode_missing_stdlib);
268+
return -1;
269+
}
270+
dlerror();
271+
emplaceProcessArgs
272+
= (ArgOverride)dlsym(stdlib, "_swift_stdlib_overrideUnsafeArgvArgc");
273+
if (dlerror())
274+
return -1;
275+
}
260276
#endif
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262278
SmallVector<const char *, 32> argBuf;

‎libswift/CMakeLists.txt

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# This source file is part of the Swift.org open source project
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#
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# Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
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# Licensed under Apache License v2.0 with Runtime Library Exception
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#
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# See http://swift.org/LICENSE.txt for license information
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# See http://swift.org/CONTRIBUTORS.txt for Swift project authors
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if (NOT SWIFT_TOOLS_ENABLE_LIBSWIFT)
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# A dummy libswift if libswift is disabled
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add_swift_host_library(libswift OBJECT LibSwiftStubs.cpp)
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else()
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project(LibSwift LANGUAGES C CXX Swift)
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if (NOT CMAKE_Swift_COMPILER)
16+
message(FATAL_ERROR "Need a swift toolchain for building libswift")
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endif()
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add_subdirectory(Sources)
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add_libswift("libswift")
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endif()
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‎libswift/LibSwiftStubs.cpp

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//===--- LibSwiftStubs.cpp ------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
6+
// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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extern "C" {
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void initializeLibSwift();
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}
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void initializeLibSwift() {}
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‎libswift/Package.swift

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// swift-tools-version:5.3
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import PackageDescription
4+
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let package = Package(
6+
name: "libswift",
7+
platforms: [
8+
.macOS("10.9"),
9+
],
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products: [
11+
.library(
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name: "Swift",
13+
type: .static,
14+
targets: ["SIL", "Optimizer"]),
15+
],
16+
dependencies: [
17+
],
18+
// Note that all modules must be added to LIBSWIFT_MODULES in the top-level
19+
// CMakeLists.txt file to get debugging working.
20+
targets: [
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.target(
22+
name: "SIL",
23+
dependencies: [],
24+
swiftSettings: [SwiftSetting.unsafeFlags([
25+
"-I", "../include/swift",
26+
"-cross-module-optimization"
27+
])]),
28+
.target(
29+
name: "Optimizer",
30+
dependencies: ["SIL"],
31+
swiftSettings: [SwiftSetting.unsafeFlags([
32+
"-I", "../include/swift",
33+
"-cross-module-optimization"
34+
])]),
35+
]
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)

‎libswift/README.md

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# Swift implemented in Swift
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_Libswift_ is the part of the Swift compiler, which is implemented in Swift.
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With _libswift_ it is possible to add SIL optimization passes written in Swift. It allows to gradually migrate the SIL optimizer from C++ to Swift.
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## Building
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_Libswift_ is a static library and it is built as part of the swift compiler using build-script and CMake.
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To enable _libswift_, add the build-script option `--libswift`.
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In this early stage of development _libswift_ is disabled by default. Right now _libswift_ does not contain any optimizations or features which are not available in the existing optimizer. Therefore a compiler with disabled _libswift_ still behaves as a compiler with enabled _libswift_. This will change soon.
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When _libswift_ is enabled, it is built with a Swift toolchain (5.3 or newer), which must be installed on the host system. The `swiftc` compiler driver is expected to be in the command search path.
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Currently the `swift-frontend` and `sil-opt` tools use _libswift_. Tools, which don't use any optimization passes from _libswift_ don't need to link _libswift_. For example, all tools, which compile Swift source code, but don't optimize it, like SourceKit or lldb, don't need to link _libswift_. As long as `initializeLibSwift()` is not called there is no dependency on _libswift_.
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This also means that currently it is not possible to implement mandatory passes in _libswift_, because this would break tools which compile Swift code but don't use _libswift_. When we want to implement mandatory passes in _libswift_ in the future, we'll need to link _libswift_ to all those tools.
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