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llvm-mirror/lib/Target/CMakeLists.txt
Tom Stellard fb33bc86b6 CMake: Make most target symbols hidden by default
Summary:
For builds with LLVM_BUILD_LLVM_DYLIB=ON and BUILD_SHARED_LIBS=OFF
this change makes all symbols in the target specific libraries hidden
by default.

A new macro called LLVM_EXTERNAL_VISIBILITY has been added to mark symbols in these
libraries public, which is mainly needed for the definitions of the
LLVMInitialize* functions.

This patch reduces the number of public symbols in libLLVM.so by about
25%.  This should improve load times for the dynamic library and also
make abi checker tools, like abidiff require less memory when analyzing
libLLVM.so

One side-effect of this change is that for builds with
LLVM_BUILD_LLVM_DYLIB=ON and LLVM_LINK_LLVM_DYLIB=ON some unittests that
access symbols that are no longer public will need to be statically linked.

Before and after public symbol counts (using gcc 8.2.1, ld.bfd 2.31.1):
nm before/libLLVM-9svn.so | grep ' [A-Zuvw] ' | wc -l
36221
nm after/libLLVM-9svn.so | grep ' [A-Zuvw] ' | wc -l
26278

Reviewers: chandlerc, beanz, mgorny, rnk, hans

Reviewed By: rnk, hans

Subscribers: merge_guards_bot, luismarques, smeenai, ldionne, lenary, s.egerton, pzheng, sameer.abuasal, MaskRay, wuzish, echristo, Jim, hiraditya, michaelplatings, chapuni, jholewinski, arsenm, dschuff, jyknight, dylanmckay, sdardis, nemanjai, jvesely, javed.absar, sbc100, jgravelle-google, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, zzheng, edward-jones, mgrang, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, kristina, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D54439
2020-01-14 19:46:52 -08:00

34 lines
1.1 KiB
CMake

list(APPEND LLVM_COMMON_DEPENDS intrinsics_gen)
list(APPEND LLVM_TABLEGEN_FLAGS -I ${LLVM_MAIN_SRC_DIR}/lib/Target)
add_llvm_component_library(LLVMTarget
Target.cpp
TargetIntrinsicInfo.cpp
TargetLoweringObjectFile.cpp
TargetMachine.cpp
TargetMachineC.cpp
ADDITIONAL_HEADER_DIRS
${LLVM_MAIN_INCLUDE_DIR}/llvm/Target
)
# When building shared objects for each target there are some internal APIs
# that are used across shared objects which we can't hide.
if (NOT BUILD_SHARED_LIBS AND NOT APPLE)
# Set default visibility to hidden, so we don't export all the Target classes
# in libLLVM.so.
set(CMAKE_CXX_VISIBILITY_PRESET hidden)
endif()
foreach(t ${LLVM_TARGETS_TO_BUILD})
message(STATUS "Targeting ${t}")
add_subdirectory(${t})
endforeach()
# Currently we do not allow libraries from lib to reference targets directly.
# This property is used to enforce that convention. It is important because the
# logic in llvm_map_components_to_libnames is order dependent on the target
# libraries being created.
set_property(GLOBAL PROPERTY LLVM_TARGETS_CONFIGURED On)