From 57fc8ecdbaa7fbb1a13907ca3f7a3cb9f9459d27 Mon Sep 17 00:00:00 2001 From: Sergej Jaskiewicz <jaskiewiczs@icloud.com> Date: Fri, 6 Dec 2019 17:26:35 +0300 Subject: [PATCH] Reland "Enable `-funwind-tables` flag when building libunwind" Summary: Relands https://reviews.llvm.org/D70815. The original commit set `CMAKE_TRY_COMPILE_TARGET_TYPE` to `STATIC_LIBRARY` globally in libunwind/CMakeLists.txt, which effectively disabled the linking step in CMake checks. This broke some builds (see 938c70b86c7d2165f8c28d5700e9c1ac1263307e). Here we set CMAKE_TRY_COMPILE_TARGET_TYPE to STATIC_LIBRARY only when checking for presence of the `-funwind-tables` flag, and then set it back to the original value so it doesn't affect other checks. Reviewers: mstorsjo, jfb Subscribers: mgorny, christof, libcxx-commits Tags: #libc Differential Revision: https://reviews.llvm.org/D71117 --- libunwind/CMakeLists.txt | 22 ++++++++++++++++++++++ libunwind/cmake/config-ix.cmake | 11 +++++++++++ libunwind/test/CMakeLists.txt | 1 + libunwind/test/libunwind/test/config.py | 10 ++++++++++ libunwind/test/lit.site.cfg.in | 1 + libunwind/test/signal_frame.pass.cpp | 4 ++-- 6 files changed, 47 insertions(+), 2 deletions(-) diff --git a/libunwind/CMakeLists.txt b/libunwind/CMakeLists.txt index 08095d1333a5..6dd0a15405b5 100644 --- a/libunwind/CMakeLists.txt +++ b/libunwind/CMakeLists.txt @@ -291,7 +291,29 @@ endif() add_cxx_compile_flags_if_supported(-fstrict-aliasing) add_cxx_compile_flags_if_supported(-EHsc) +# Don't run the linker in this CMake check. +# +# The reason why this was added is that when building libunwind for +# ARM Linux, we need to pass the -funwind-tables flag in order for it to +# work properly with ARM EHABI. +# +# However, when performing CMake checks, adding this flag causes the check +# to produce a false negative, because the compiler generates calls +# to __aeabi_unwind_cpp_pr0, which is defined in libunwind itself, +# which isn't built yet, so the linker complains about undefined symbols. +# +# This leads to libunwind not being built with this flag, which makes +# libunwind quite useless in this setup. +set(_previous_CMAKE_TRY_COMPILE_TARGET_TYPE ${CMAKE_TRY_COMPILE_TARGET_TYPE}) +set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY) add_compile_flags_if_supported(-funwind-tables) +set(CMAKE_TRY_COMPILE_TARGET_TYPE ${_previous_CMAKE_TRY_COMPILE_TARGET_TYPE}) + +if (LIBUNWIND_USES_ARM_EHABI AND NOT LIBUNWIND_SUPPORTS_FUNWIND_TABLES_FLAG) + message(SEND_ERROR "The -funwind-tables flag must be supported " + "because this target uses ARM Exception Handling ABI") +endif() + add_cxx_compile_flags_if_supported(-fno-exceptions) add_cxx_compile_flags_if_supported(-fno-rtti) diff --git a/libunwind/cmake/config-ix.cmake b/libunwind/cmake/config-ix.cmake index 02d2f13f2e28..0d833e996ca1 100644 --- a/libunwind/cmake/config-ix.cmake +++ b/libunwind/cmake/config-ix.cmake @@ -2,6 +2,7 @@ include(CMakePushCheckState) include(CheckCCompilerFlag) include(CheckCXXCompilerFlag) include(CheckLibraryExists) +include(CheckSymbolExists) include(CheckCSourceCompiles) check_library_exists(c fopen "" LIBUNWIND_HAS_C_LIB) @@ -73,3 +74,13 @@ check_cxx_compiler_flag(-nostdinc++ LIBUNWIND_HAS_NOSTDINCXX_FLAG) # Check libraries check_library_exists(dl dladdr "" LIBUNWIND_HAS_DL_LIB) check_library_exists(pthread pthread_once "" LIBUNWIND_HAS_PTHREAD_LIB) + +# Check symbols +check_symbol_exists(__arm__ "" LIBUNWIND_TARGET_ARM) +check_symbol_exists(__USING_SJLJ_EXCEPTIONS__ "" LIBUNWIND_USES_SJLJ_EXCEPTIONS) +check_symbol_exists(__ARM_DWARF_EH__ "" LIBUNWIND_USES_DWARF_EH) + +if(LIBUNWIND_TARGET_ARM AND NOT LIBUNWIND_USES_SJLJ_EXCEPTIONS AND NOT LIBUNWIND_USES_DWARF_EH) + # This condition is copied from __libunwind_config.h + set(LIBUNWIND_USES_ARM_EHABI ON) +endif() diff --git a/libunwind/test/CMakeLists.txt b/libunwind/test/CMakeLists.txt index d902e3e82941..40d4acd4e8c2 100644 --- a/libunwind/test/CMakeLists.txt +++ b/libunwind/test/CMakeLists.txt @@ -16,6 +16,7 @@ pythonize_bool(LIBCXX_ENABLE_SHARED) pythonize_bool(LIBUNWIND_ENABLE_SHARED) pythonize_bool(LIBUNWIND_ENABLE_THREADS) pythonize_bool(LIBUNWIND_ENABLE_EXCEPTIONS) +pythonize_bool(LIBUNWIND_USES_ARM_EHABI) pythonize_bool(LIBUNWIND_USE_COMPILER_RT) pythonize_bool(LIBUNWIND_BUILD_EXTERNAL_THREAD_LIBRARY) set(LIBUNWIND_TARGET_INFO "libcxx.test.target_info.LocalTI" CACHE STRING diff --git a/libunwind/test/libunwind/test/config.py b/libunwind/test/libunwind/test/config.py index 05e3f3cc21f3..41ca3f9b4a44 100644 --- a/libunwind/test/libunwind/test/config.py +++ b/libunwind/test/libunwind/test/config.py @@ -37,6 +37,8 @@ class Configuration(LibcxxConfiguration): super(Configuration, self).configure_features() if not self.get_lit_bool('enable_exceptions', True): self.config.available_features.add('libcxxabi-no-exceptions') + if self.get_lit_bool('arm_ehabi', False): + self.config.available_features.add('libunwind-arm-ehabi') def configure_compile_flags(self): self.cxx.compile_flags += ['-DLIBUNWIND_NO_TIMER'] @@ -66,3 +68,11 @@ class Configuration(LibcxxConfiguration): def configure_compile_flags_rtti(self): pass + + def configure_link_flags_cxx_library(self): + # libunwind tests should not link with libc++ + pass + + def configure_link_flags_abi_library(self): + # libunwind tests should not link with libc++abi + pass diff --git a/libunwind/test/lit.site.cfg.in b/libunwind/test/lit.site.cfg.in index 34da72ac1068..37f90a90efdb 100644 --- a/libunwind/test/lit.site.cfg.in +++ b/libunwind/test/lit.site.cfg.in @@ -19,6 +19,7 @@ config.executor = "@LIBUNWIND_EXECUTOR@" config.libunwind_shared = @LIBUNWIND_ENABLE_SHARED@ config.enable_shared = @LIBCXX_ENABLE_SHARED@ config.enable_exceptions = @LIBUNWIND_ENABLE_EXCEPTIONS@ +config.arm_ehabi = @LIBUNWIND_USES_ARM_EHABI@ config.host_triple = "@LLVM_HOST_TRIPLE@" config.target_triple = "@TARGET_TRIPLE@" config.use_target = bool("@LIBUNWIND_TARGET_TRIPLE@") diff --git a/libunwind/test/signal_frame.pass.cpp b/libunwind/test/signal_frame.pass.cpp index a6f3f483bea5..a899461fafb4 100644 --- a/libunwind/test/signal_frame.pass.cpp +++ b/libunwind/test/signal_frame.pass.cpp @@ -9,6 +9,8 @@ // Ensure that functions marked as signal frames are reported as such. +// UNSUPPORTED: libunwind-arm-ehabi + #include <assert.h> #include <stdlib.h> #include <libunwind.h> @@ -20,9 +22,7 @@ void test() { unw_getcontext(&uc); unw_init_local(&cursor, &uc); assert(unw_step(&cursor) > 0); -#if !defined(_LIBUNWIND_ARM_EHABI) assert(unw_is_signal_frame(&cursor)); -#endif } int main() {