Author: compnerd
Date: Mon Aug 29 16:33:37 2016
New Revision: 280015
URL: http://llvm.org/viewvc/llvm-project?rev=280015&view=rev
Log:
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!
Modified:
libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake
libcxx/trunk/cmake/config-ix.cmake
Modified: libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake
URL:
http://llvm.org/viewvc/llvm-project/libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake?rev=280015&r1=280014&r2=280015&view=diff
==============================================================================
--- libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake (original)
+++ libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake Mon Aug 29 16:33:37 2016
@@ -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 "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all")
+ endif()
check_cxx_source_compiles("
#include <cstdint>
#include <atomic>
Modified: libcxx/trunk/cmake/config-ix.cmake
URL:
http://llvm.org/viewvc/llvm-project/libcxx/trunk/cmake/config-ix.cmake?rev=280015&r1=280014&r2=280015&view=diff
==============================================================================
--- libcxx/trunk/cmake/config-ix.cmake (original)
+++ libcxx/trunk/cmake/config-ix.cmake Mon Aug 29 16:33:37 2016
@@ -1,5 +1,34 @@
include(CheckLibraryExists)
include(CheckCXXCompilerFlag)
+
+check_library_exists(c fopen "" LIBCXX_HAS_C_LIB)
+if (NOT LIBCXX_USE_COMPILER_RT)
+ check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB)
+endif()
+
+# libc++ is built with -nodefaultlibs, so we want all our checks to also
+# use this option, otherwise we may end up with an inconsistency between
+# the flags we think we require during configuration (if the checks are
+# performed without -nodefaultlibs) and the flags that are actually
+# required during compilation (which has the -nodefaultlibs). libc is
+# required for the link to go through. We remove sanitizers from the
+# configuration checks to avoid spurious link errors.
+check_cxx_compiler_flag(-nodefaultlibs LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG)
+if (LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG)
+ set(CMAKE_REQUIRED_FLAGS "${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-
# 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()
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