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Enable linker dead stripping on Darwin #22839

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Merged
merged 2 commits into from
Feb 25, 2019
Merged

Enable linker dead stripping on Darwin #22839

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7dad371
Enable linker dead stripping on Darwin
vedantk Feb 23, 2019
6ed319d
Disable dead stripping in Debug builds
vedantk Feb 23, 2019
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14 changes: 14 additions & 0 deletions cmake/modules/AddSwift.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -488,6 +488,20 @@ function(_add_variant_link_flags)
endif()
endif()

# Enable dead stripping. Portions of this logic were copied from llvm's
# `add_link_opts` function (which, perhaps, should have been used here in the
# first place, but at this point it's hard to say whether that's feasible).
#
# TODO: Evaluate/enable -f{function,data}-sections --gc-sections for bfd,
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BFD is an unsupported linker (it cannot handle the protected semantics needed for swift)

# gold, and lld.
if(NOT CMAKE_BUILD_TYPE STREQUAL Debug)
if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
# See rdar://48283130: This gives 6MB+ size reductions for swift and
# SourceKitService, and much larger size reductions for sil-opt etc.
list(APPEND result "-Wl,-dead_strip")
endif()
endif()

set("${LFLAGS_RESULT_VAR_NAME}" "${result}" PARENT_SCOPE)
set("${LFLAGS_LINK_LIBRARIES_VAR_NAME}" "${link_libraries}" PARENT_SCOPE)
set("${LFLAGS_LIBRARY_SEARCH_DIRECTORIES_VAR_NAME}" "${library_search_directories}" PARENT_SCOPE)
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