Skip to content

[flang-rt] Use --as-needed for linking flang-rt libraries. #130856

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Mar 14, 2025
Merged

[flang-rt] Use --as-needed for linking flang-rt libraries. #130856

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
76c2d56
[flang-rt] Use --as-needed for linking flang-rt libraries.
vzakhari Mar 11, 2025
8e21a00
Addressed review comments.
vzakhari Mar 12, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 6 additions & 1 deletion flang-rt/CMakeLists.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -245,6 +245,12 @@ check_cxx_compiler_flag("-UTESTFLAG" FLANG_RT_SUPPORTS_UNDEFINE_FLAG)
# Check whether -fno-lto is supported.
check_cxx_compiler_flag(-fno-lto FLANG_RT_HAS_FNO_LTO_FLAG)

# Check whether -Wl,--as-needed is supported.
check_linker_flag(C "-Wl,--as-needed" LINKER_SUPPORTS_AS_NEEDED)
if (LINKER_SUPPORTS_AS_NEEDED)
set(LINKER_AS_NEEDED_OPT "-Wl,--as-needed")
endif()

# Different platform may have different name for the POSIX thread library.
# For example, libpthread.a on AIX. Search for it as it is needed when
# building the shared flang_rt.runtime.so.
Expand Down Expand Up @@ -295,7 +301,6 @@ elseif (FLANG_RT_GCC_RESOURCE_DIR)
endif ()



#####################
# Build Preparation #
#####################
Expand Down
11 changes: 11 additions & 0 deletions flang-rt/cmake/modules/AddFlangRT.cmake
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -186,6 +186,17 @@ function (add_flangrt_library name)
else ()
set_target_properties(${tgtname} PROPERTIES FOLDER "Flang-RT/Libraries")
endif ()

# flang-rt libraries must not depend on libc++/libstdc++,
# so set the linker language to C to avoid the unnecessary
# library dependence. Note that libc++/libstdc++ may still
# come through CMAKE_CXX_IMPLICIT_LINK_LIBRARIES.
set_target_properties(${tgtname} PROPERTIES LINKER_LANGUAGE C)
# Use --as-needed to avoid unnecessary dependencies.
if (LINKER_AS_NEEDED_OPT)
set_property(TARGET ${tgtname} APPEND_STRING PROPERTY
LINK_FLAGS "${LINKER_AS_NEEDED_OPT}")
endif()
endforeach ()

# Define how to compile and link the library.
Expand Down