llvm-capstone/runtimes/CMakeLists.txt
Christopher Di Bella c5a20b5182 [llvm-libgcc] initial commit
Note: the term "libgcc" refers to the all of `libgcc.a`, `libgcc_eh.a`,
and `libgcc_s.so`.

Enabling libunwind as a replacement for libgcc on Linux has proven to be
challenging since libgcc_s.so is a required dependency in the [Linux
standard base][5]. Some software is transitively dependent on libgcc
because glibc makes hardcoded calls to functions in libgcc_s. For example,
the function `__GI___backtrace` eventually makes its way to a [hardcoded
dlopen to libgcc_s' _Unwind_Backtrace][1]. Since libgcc_{eh.a,s.so} and
libunwind have the same ABI, but different implementations, the two
libraries end up [cross-talking, which ultimately results in a
segfault][2].

To solve this problem, libunwind needs to build a “libgcc”. That is, link
the necessary functions from compiler-rt and libunwind into an archive
and shared object that advertise themselves as `libgcc.a`, `libgcc_eh.a`,
and `libgcc_s.so`, so that glibc’s baked calls are diverted to the
correct objects in memory. Fortunately for us, compiler-rt and libunwind
use the same ABI as the libgcc family, so the problem is solvable at the
llvm-project configuration level: no program source needs to be edited.
Thus, the end result is for a user to configure their LLVM build with a
flag that indicates they want to archive compiler-rt/unwind as libgcc.
We achieve this by compiling libunwind with all the symbols necessary
for compiler-rt to emulate the libgcc family, and then generate symlinks
named for our "libgcc" that point to their corresponding libunwind
counterparts.

We alternatively considered patching glibc so that the source doesn't
directly refer to libgcc, but rather _defaults_ to libgcc, so that a
system preferring compiler-rt/libunwind can point to these libraries
at the config stage instead. Even if we modified the Linux standard
base, this alternative won't work because binaries that are built using
libgcc will still end up having crosstalk between the differing
implementations.

This problem has been solved in this manner for [FreeBSD][3], and this
CL has been tested against [Chrome OS][4].

[1]: https://github.com/bminor/glibc/blob/master/sysdeps/arm/backtrace.c#L68
[2]: https://bugs.chromium.org/p/chromium/issues/detail?id=1162190#c16
[3]: https://github.com/freebsd/freebsd-src/tree/main/lib/libgcc_s
[4]: https://chromium-review.googlesource.com/c/chromiumos/overlays/chromiumos-overlay/+/2945947
[5]: https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/libgcc-s.html

Differential Revision: https://reviews.llvm.org/D108416
2022-02-16 17:06:45 +00:00

274 lines
10 KiB
CMake

# This file handles building LLVM runtime sub-projects.
cmake_minimum_required(VERSION 3.13.4)
project(Runtimes C CXX ASM)
set(LLVM_ALL_RUNTIMES "compiler-rt;libc;libcxx;libcxxabi;libunwind;openmp")
set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
"Semicolon-separated list of runtimes to build (${LLVM_ALL_RUNTIMES}), or \"all\".")
if(LLVM_ENABLE_RUNTIMES STREQUAL "all" )
set(LLVM_ENABLE_RUNTIMES ${LLVM_ALL_RUNTIMES})
endif()
foreach(proj ${LLVM_ENABLE_RUNTIMES})
set(proj_dir "${CMAKE_CURRENT_SOURCE_DIR}/../${proj}")
if(IS_DIRECTORY ${proj_dir} AND EXISTS ${proj_dir}/CMakeLists.txt)
list(APPEND runtimes ${proj_dir})
else()
message(FATAL_ERROR "LLVM_ENABLE_RUNTIMES requests ${proj} but directory not found: ${proj_dir}")
endif()
string(TOUPPER "${proj}" canon_name)
STRING(REGEX REPLACE "-" "_" canon_name ${canon_name})
set(LLVM_EXTERNAL_${canon_name}_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../${proj}")
endforeach()
function(runtime_register_component name)
set_property(GLOBAL APPEND PROPERTY SUB_COMPONENTS ${name})
endfunction()
find_package(LLVM PATHS "${LLVM_BINARY_DIR}" NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
find_package(Clang PATHS "${LLVM_BINARY_DIR}" NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
# Add path for custom and the LLVM build's modules to the CMake module path.
list(INSERT CMAKE_MODULE_PATH 0
"${CMAKE_CURRENT_SOURCE_DIR}/cmake"
"${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules"
"${LLVM_COMMON_CMAKE_UTILS}"
"${LLVM_COMMON_CMAKE_UTILS}/Modules"
"${CMAKE_CURRENT_SOURCE_DIR}/../llvm/cmake"
"${CMAKE_CURRENT_SOURCE_DIR}/../llvm/cmake/modules"
)
set(LLVM_THIRD_PARTY_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../third-party")
function(get_compiler_rt_path path)
foreach(entry ${runtimes})
get_filename_component(projName ${entry} NAME)
if("${projName}" MATCHES "compiler-rt")
set(${path} ${entry} PARENT_SCOPE)
return()
endif()
endforeach()
endfunction()
# Some of the runtimes will conditionally use the compiler-rt sanitizers
# to make this work smoothly we ensure that compiler-rt is added first in
# the list of sub-projects. This allows other sub-projects to have checks
# like `if(TARGET asan)` to enable building with asan.
get_compiler_rt_path(compiler_rt_path)
if(compiler_rt_path)
list(REMOVE_ITEM runtimes ${compiler_rt_path})
if(NOT DEFINED LLVM_BUILD_COMPILER_RT OR LLVM_BUILD_COMPILER_RT)
list(INSERT runtimes 0 ${compiler_rt_path})
endif()
endif()
# If building standalone by pointing CMake at this runtimes directory,
# LLVM_BINARY_DIR isn't set, find_package(LLVM) will fail and these
# intermediate paths are unset.
if (NOT LLVM_BINARY_DIR)
set(LLVM_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
endif()
if (NOT LLVM_FOUND)
set(LLVM_TOOLS_BINARY_DIR ${LLVM_BINARY_DIR}/bin)
set(LLVM_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/lib)
endif()
# Setting these variables will allow the sub-build to put their outputs into
# the library and bin directories of the top-level build.
set(LLVM_LIBRARY_OUTPUT_INTDIR ${LLVM_LIBRARY_DIR})
set(LLVM_RUNTIME_OUTPUT_INTDIR ${LLVM_TOOLS_BINARY_DIR})
# This variable makes sure that e.g. llvm-lit is found.
set(LLVM_MAIN_SRC_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../llvm)
set(LLVM_CMAKE_DIR ${LLVM_MAIN_SRC_DIR}/cmake/modules)
# This variable is used by individual runtimes to locate LLVM files.
set(LLVM_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../llvm)
include(CheckLibraryExists)
include(LLVMCheckCompilerLinkerFlag)
include(CheckCCompilerFlag)
include(CheckCXXCompilerFlag)
check_c_compiler_flag("" LLVM_RUNTIMES_LINKING_WORKS)
if (NOT LLVM_RUNTIMES_LINKING_WORKS)
# The compiler driver may be implicitly trying to link against libunwind,
# which might not work if libunwind doesn't exist yet. Try to check if
# --unwindlib=none is supported, and use that if possible.
# Don't add this if not necessary to fix linking, as it can break using
# e.g. ASAN/TSAN.
llvm_check_compiler_linker_flag(C "--unwindlib=none" LLVM_RUNTIMES_SUPPORT_UNWINDLIB_NONE_FLAG)
if (LLVM_RUNTIMES_SUPPORT_UNWINDLIB_NONE_FLAG)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} --unwindlib=none")
endif()
endif()
# Disable use of the installed C++ standard library when building runtimes.
# Check for -nostdlib++ first; if there's no C++ standard library yet,
# all check_cxx_compiler_flag commands will fail until we add -nostdlib++
# (or -nodefaultlibs).
llvm_check_compiler_linker_flag(C "-nostdlib++" LLVM_RUNTIMES_SUPPORT_NOSTDLIBXX_FLAG)
if (LLVM_RUNTIMES_SUPPORT_NOSTDLIBXX_FLAG)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdlib++")
endif()
check_cxx_compiler_flag(-nostdinc++ LLVM_RUNTIMES_SUPPORT_NOSTDINCXX_FLAG)
if (LLVM_RUNTIMES_SUPPORT_NOSTDINCXX_FLAG)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdinc++")
endif()
# Avoid checking whether the compiler is working.
set(LLVM_COMPILER_CHECKED ON)
# Handle common options used by all runtimes.
include(AddLLVM)
include(HandleLLVMOptions)
find_package(Python3 REQUIRED COMPONENTS Interpreter)
# Host triple is used by tests to check if they are running natively.
include(GetHostTriple)
get_host_triple(LLVM_HOST_TRIPLE)
set(LLVM_DEFAULT_TARGET_TRIPLE "${LLVM_HOST_TRIPLE}" CACHE STRING
"Default target for which the runtimes will be built.")
option(LLVM_INCLUDE_TESTS "Generate build targets for the runtimes unit tests." ON)
option(LLVM_INCLUDE_DOCS "Generate build targets for the runtimes documentation." ON)
option(LLVM_ENABLE_SPHINX "Use Sphinx to generate the runtimes documentation." OFF)
# Use libtool instead of ar if you are both on an Apple host, and targeting Apple.
if(CMAKE_HOST_APPLE AND APPLE)
include(UseLibtool)
endif()
# This can be used to detect whether we're in the runtimes build.
set(LLVM_RUNTIMES_BUILD ON)
foreach(entry ${runtimes})
get_filename_component(projName ${entry} NAME)
# TODO: Clean this up as part of an interface standardization
string(REPLACE "-" "_" canon_name ${projName})
string(TOUPPER ${canon_name} canon_name)
# TODO: compiler-rt has to use standalone build for now. We tried to remove
# this in D57992 but this broke the build because compiler-rt assumes that
# LLVM and Clang are configured in the same build to set up dependencies. We
# should clean up the compiler-rt build and remove this eventually.
if ("${canon_name}" STREQUAL "COMPILER_RT")
set(${canon_name}_STANDALONE_BUILD ON)
endif()
if(LLVM_RUNTIMES_LIBDIR_SUBDIR)
set(${canon_name}_LIBDIR_SUBDIR "${LLVM_RUNTIMES_LIBDIR_SUBDIR}" CACHE STRING "" FORCE)
endif()
# Setting a variable to let sub-projects detect which other projects
# will be included under here.
set(HAVE_${canon_name} ON)
endforeach()
if(LLVM_INCLUDE_TESTS)
set(LIT_ARGS_DEFAULT "-sv --show-xfail --show-unsupported")
if (MSVC OR XCODE)
set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
endif()
set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
endif()
# llvm-libgcc incorporates both compiler-rt and libunwind as subprojects with very
# specific flags, which causes clashes when they're independently built too.
if("llvm-libgcc" IN_LIST runtimes)
if("compiler-rt" IN_LIST runtimes OR "compiler-rt" IN_LIST LLVM_ENABLE_PROJECTS)
message(FATAL_ERROR
"Attempting to build both compiler-rt and llvm-libgcc will cause irreconcilable "
"target clashes. Please choose one or the other, but not both.")
endif()
if("libunwind" IN_LIST runtimes)
message(
FATAL_ERROR
"Attempting to build both libunwind and llvm-libgcc will cause irreconcilable "
"target clashes. Please choose one or the other, but not both.")
endif()
endif()
# We do this in two loops so that HAVE_* is set for each runtime before the
# other runtimes are added.
foreach(entry ${runtimes})
get_filename_component(projName ${entry} NAME)
# Between each sub-project we want to cache and clear the LIT properties
set_property(GLOBAL PROPERTY LLVM_LIT_TESTSUITES)
set_property(GLOBAL PROPERTY LLVM_LIT_PARAMS)
set_property(GLOBAL PROPERTY LLVM_LIT_DEPENDS)
set_property(GLOBAL PROPERTY LLVM_LIT_EXTRA_ARGS)
add_subdirectory(${entry} ${projName})
get_property(LLVM_LIT_TESTSUITES GLOBAL PROPERTY LLVM_LIT_TESTSUITES)
get_property(LLVM_LIT_PARAMS GLOBAL PROPERTY LLVM_LIT_PARAMS)
get_property(LLVM_LIT_DEPENDS GLOBAL PROPERTY LLVM_LIT_DEPENDS)
get_property(LLVM_LIT_EXTRA_ARGS GLOBAL PROPERTY LLVM_LIT_EXTRA_ARGS)
list(APPEND RUNTIMES_LIT_TESTSUITES ${LLVM_LIT_TESTSUITES})
list(APPEND RUNTIMES_LIT_PARAMS ${LLVM_LIT_PARAMS})
list(APPEND RUNTIMES_LIT_DEPENDS ${LLVM_LIT_DEPENDS})
list(APPEND RUNTIMES_LIT_EXTRA_ARGS ${LLVM_LIT_EXTRA_ARGS})
endforeach()
if(LLVM_INCLUDE_TESTS)
# Add a global check rule now that all subdirectories have been traversed
# and we know the total set of lit testsuites.
add_lit_target(check-runtimes
"Running all regression tests"
${RUNTIMES_LIT_TESTSUITES}
PARAMS ${RUNTIMES_LIT_PARAMS}
DEPENDS ${RUNTIMES_LIT_DEPENDS}
ARGS ${RUNTIMES_LIT_EXTRA_ARGS}
)
add_custom_target(runtimes-test-depends DEPENDS ${RUNTIMES_LIT_DEPENDS})
if (NOT HAVE_LLVM_LIT)
# If built by manually invoking cmake on this directory, we don't have
# llvm-lit. If invoked via llvm/runtimes, the toplevel llvm cmake
# invocation already generated the llvm-lit script.
add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/llvm-lit
${CMAKE_CURRENT_BINARY_DIR}/llvm-lit)
endif()
endif()
get_property(SUB_COMPONENTS GLOBAL PROPERTY SUB_COMPONENTS)
if(SUB_COMPONENTS)
list(REMOVE_DUPLICATES SUB_COMPONENTS)
foreach(component ${SUB_COMPONENTS})
if(NOT TARGET ${component})
message(SEND_ERROR "Missing target for runtime component ${component}!")
continue()
endif()
if(TARGET check-${component})
list(APPEND SUB_CHECK_TARGETS check-${component})
endif()
if(TARGET install-${component})
list(APPEND SUB_INSTALL_TARGETS install-${component})
endif()
if(TARGET install-${component}-stripped)
list(APPEND SUB_INSTALL_TARGETS install-${component}-stripped)
endif()
endforeach()
if(LLVM_RUNTIMES_TARGET)
configure_file(
${CMAKE_CURRENT_SOURCE_DIR}/Components.cmake.in
${LLVM_BINARY_DIR}/runtimes/${LLVM_RUNTIMES_TARGET}/Components.cmake)
else()
configure_file(
${CMAKE_CURRENT_SOURCE_DIR}/Components.cmake.in
${LLVM_BINARY_DIR}/runtimes/Components.cmake)
endif()
endif()