[llvm-branch-commits] [libcxx] b8f8e45 - [libc++] Simplify how we define the linker script for libc++
Tom Stellard via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Fri Aug 5 01:05:33 PDT 2022
Author: Louis Dionne
Date: 2022-08-05T01:04:08-07:00
New Revision: b8f8e4530c47754f0384c9a824ae9917a449436c
URL: https://github.com/llvm/llvm-project/commit/b8f8e4530c47754f0384c9a824ae9917a449436c
DIFF: https://github.com/llvm/llvm-project/commit/b8f8e4530c47754f0384c9a824ae9917a449436c.diff
LOG: [libc++] Simplify how we define the linker script for libc++
Trying to be generic didn't work properly because we had to special-case
some interface libraries that we didn't want in the linker script. Instead,
only look at the ABI and the unwinding libraries explicitly.
This should solve the issue reported by @dim in [1].
[1]: https://discourse.llvm.org/t/15-0-0-rc1-has-been-tagged/64174/22
Differential Revision: https://reviews.llvm.org/D131037
(cherry picked from commit b7fb8563974d83f9eb8191fdfbebfd04147a2cbd)
Added:
Modified:
libcxx/src/CMakeLists.txt
Removed:
libcxx/cmake/Modules/DefineLinkerScript.cmake
################################################################################
diff --git a/libcxx/cmake/Modules/DefineLinkerScript.cmake b/libcxx/cmake/Modules/DefineLinkerScript.cmake
deleted file mode 100644
index 71a43086727c7..0000000000000
--- a/libcxx/cmake/Modules/DefineLinkerScript.cmake
+++ /dev/null
@@ -1,56 +0,0 @@
-# This function defines a linker script in place of the symlink traditionally
-# created for shared libraries.
-#
-# More specifically, this function goes through the PUBLIC and INTERFACE
-# library dependencies of <target> and gathers them into a linker script,
-# such that those libraries are linked against when the shared library for
-# <target> is linked against.
-#
-# Arguments:
-# <target>: A target representing a shared library. A linker script will be
-# created in place of that target's TARGET_LINKER_FILE, which is
-# the symlink pointing to the actual shared library (usually
-# libFoo.so pointing to libFoo.so.1, which itself points to
-# libFoo.so.1.0).
-
-function(define_linker_script target)
- if (NOT TARGET "${target}")
- message(FATAL_ERROR "The provided target '${target}' is not actually a target.")
- endif()
-
- get_target_property(target_type "${target}" TYPE)
- if (NOT "${target_type}" STREQUAL "SHARED_LIBRARY")
- message(FATAL_ERROR "The provided target '${target}' is not a shared library (its type is '${target_type}').")
- endif()
-
- set(symlink "$<TARGET_LINKER_FILE:${target}>")
- set(soname "$<TARGET_SONAME_FILE_NAME:${target}>")
-
- get_target_property(interface_libs "${target}" INTERFACE_LINK_LIBRARIES)
-
- set(link_libraries)
- if (interface_libs)
- foreach(lib IN LISTS interface_libs)
- if ("${lib}" MATCHES "cxx-headers|ParallelSTL")
- continue()
- endif()
- # If ${lib} is not a target, we use a dummy target which we know will
- # have an OUTPUT_NAME property so that CMake doesn't fail when evaluating
- # the non-selected branch of the `IF`. It doesn't matter what it evaluates
- # to because it's not selected, but it must not cause an error.
- # See https://gitlab.kitware.com/cmake/cmake/-/issues/21045.
- set(output_name_tgt "$<IF:$<TARGET_EXISTS:${lib}>,${lib},${target}>")
- set(libname "$<IF:$<TARGET_EXISTS:${lib}>,$<TARGET_PROPERTY:${output_name_tgt},OUTPUT_NAME>,${lib}>")
- list(APPEND link_libraries "${CMAKE_LINK_LIBRARY_FLAG}${libname}")
- endforeach()
- endif()
- string(REPLACE ";" " " link_libraries "${link_libraries}")
-
- set(linker_script "INPUT(${soname} ${link_libraries})")
- add_custom_command(TARGET "${target}" POST_BUILD
- COMMAND "${CMAKE_COMMAND}" -E remove "${symlink}"
- COMMAND "${CMAKE_COMMAND}" -E echo "${linker_script}" > "${symlink}"
- COMMENT "Generating linker script: '${linker_script}' as file ${symlink}"
- VERBATIM
- )
-endfunction()
diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt
index 61c60f9345998..9abf548abbb95 100644
--- a/libcxx/src/CMakeLists.txt
+++ b/libcxx/src/CMakeLists.txt
@@ -212,20 +212,6 @@ if (LIBCXX_ENABLE_SHARED)
cxx_add_common_build_flags(cxx_shared)
cxx_set_common_defines(cxx_shared)
- # Link against LLVM libunwind
- # Note that we do need to link against libunwind directly to ensure that the correct
- # dependencies are recorded when creating a linker script.
- # TODO: Look into modifying the linker script creation to recursively consider interface libraries
- if (LIBCXXABI_USE_LLVM_UNWINDER)
- if (LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY)
- # libunwind is already included in libc++abi
- elseif (TARGET unwind_shared OR HAVE_LIBUNWIND)
- target_link_libraries(cxx_shared PUBLIC unwind_shared)
- else()
- target_link_libraries(cxx_shared PUBLIC unwind)
- endif()
- endif()
-
# Link against libc++abi
if (LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
target_link_libraries(cxx_shared PRIVATE libcxx-abi-shared-objects)
@@ -254,8 +240,30 @@ if (LIBCXX_ENABLE_SHARED)
# Generate a linker script in place of a libc++.so symlink.
if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
- include(DefineLinkerScript)
- define_linker_script(cxx_shared)
+ set(link_libraries)
+
+ set(imported_libname "$<TARGET_PROPERTY:libcxx-abi-shared,IMPORTED_LIBNAME>")
+ set(output_name "$<TARGET_PROPERTY:libcxx-abi-shared,OUTPUT_NAME>")
+ string(APPEND link_libraries "${CMAKE_LINK_LIBRARY_FLAG}$<IF:$<BOOL:${imported_libname}>,${imported_libname},${output_name}>")
+
+ # TODO: Move to the same approach as above for the unwind library
+ if (LIBCXXABI_USE_LLVM_UNWINDER)
+ if (LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY)
+ # libunwind is already included in libc++abi
+ elseif (TARGET unwind_shared OR HAVE_LIBUNWIND)
+ string(APPEND link_libraries " ${CMAKE_LINK_LIBRARY_FLAG}$<TARGET_PROPERTY:unwind_shared,OUTPUT_NAME>")
+ else()
+ string(APPEND link_libraries " ${CMAKE_LINK_LIBRARY_FLAG}unwind")
+ endif()
+ endif()
+
+ set(linker_script "INPUT($<TARGET_SONAME_FILE_NAME:cxx_shared> ${link_libraries})")
+ add_custom_command(TARGET cxx_shared POST_BUILD
+ COMMAND "${CMAKE_COMMAND}" -E remove "$<TARGET_LINKER_FILE:cxx_shared>"
+ COMMAND "${CMAKE_COMMAND}" -E echo "${linker_script}" > "$<TARGET_LINKER_FILE:cxx_shared>"
+ COMMENT "Generating linker script: '${linker_script}' as file $<TARGET_LINKER_FILE:cxx_shared>"
+ VERBATIM
+ )
endif()
list(APPEND LIBCXX_BUILD_TARGETS "cxx_shared")
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