From eb930a502cd38fa45188b72eb4287d8aebb6b415 Mon Sep 17 00:00:00 2001 From: Saleem Abdulrasool Date: Mon, 29 Aug 2016 21:33:37 +0000 Subject: [PATCH] libc++: perform configuration checks with -nodefaultlibs We're compiling libc++ with -nodefaultlibs, so we should also pass this option during the configuration checks to ensure those checks are consistent with the actual build. The primary motivation here is to ease cross-compilation against a non-standard set of C++ libraries. Previously, the configuration checks would attempt to link against the standard C++ libraries, which would cause link failures when cross-compiling, even though the actual library link would go through correctly (because of the use of -nodefaultlibs and explicitly specifying any needed libraries). This is more correct even ignoring the motivation, however. Patch by Shoaib Meenai! git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@280015 91177308-0d34-0410-b5e6-96231b3b80d8 --- cmake/Modules/CheckLibcxxAtomic.cmake | 5 +++- cmake/config-ix.cmake | 33 +++++++++++++++++++++++---- 2 files changed, 33 insertions(+), 5 deletions(-) diff --git a/cmake/Modules/CheckLibcxxAtomic.cmake b/cmake/Modules/CheckLibcxxAtomic.cmake index 4ff343236..7d01a9bd1 100644 --- a/cmake/Modules/CheckLibcxxAtomic.cmake +++ b/cmake/Modules/CheckLibcxxAtomic.cmake @@ -9,10 +9,13 @@ INCLUDE(CheckCXXSourceCompiles) function(check_cxx_atomics varname) set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS}) - set(CMAKE_REQUIRED_FLAGS "-std=c++11 -nostdinc++ -isystem ${LIBCXX_SOURCE_DIR}/include") + set(CMAKE_REQUIRED_FLAGS "-nodefaultlibs -std=c++11 -nostdinc++ -isystem ${LIBCXX_SOURCE_DIR}/include") if (${LIBCXX_GCC_TOOLCHAIN}) set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} --gcc-toolchain=${LIBCXX_GCC_TOOLCHAIN}") endif() + if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize) + set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all") + endif() check_cxx_source_compiles(" #include #include diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake index bbbe7c6d9..fa3a07f4f 100644 --- a/cmake/config-ix.cmake +++ b/cmake/config-ix.cmake @@ -1,5 +1,34 @@ include(CheckLibraryExists) include(CheckCXXCompilerFlag) + +check_library_exists(c fopen "" LIBCXX_HAS_C_LIB) +if (NOT LIBCXX_USE_COMPILER_RT) + check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB) +endif() + +# libc++ is built with -nodefaultlibs, so we want all our checks to also +# use this option, otherwise we may end up with an inconsistency between +# the flags we think we require during configuration (if the checks are +# performed without -nodefaultlibs) and the flags that are actually +# required during compilation (which has the -nodefaultlibs). libc is +# required for the link to go through. We remove sanitizers from the +# configuration checks to avoid spurious link errors. +check_cxx_compiler_flag(-nodefaultlibs LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG) +if (LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG) + set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nodefaultlibs") + if (LIBCXX_HAS_C_LIB) + list(APPEND CMAKE_REQUIRED_LIBRARIES c) + endif () + if (LIBCXX_USE_COMPILER_RT) + list(APPEND CMAKE_REQUIRED_LIBRARIES -rtlib=compiler-rt) + elseif (LIBCXX_HAS_GCC_S_LIB) + list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s) + endif () + if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize) + set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all") + endif () +endif () + include(CheckLibcxxAtomic) # Check compiler flags @@ -14,9 +43,5 @@ check_cxx_compiler_flag(/GR- LIBCXX_HAS_NO_GR_FLAG) # Check libraries check_library_exists(pthread pthread_create "" LIBCXX_HAS_PTHREAD_LIB) -check_library_exists(c fopen "" LIBCXX_HAS_C_LIB) check_library_exists(m ccos "" LIBCXX_HAS_M_LIB) check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB) -if (NOT LIBCXX_USE_COMPILER_RT) - check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB) -endif()