[libcxx] r260235 - Introduce a cmake module to figure out whether we need to link with libatomic.
Vasileios Kalintiris via cfe-commits
cfe-commits at lists.llvm.org
Tue Feb 16 06:44:15 PST 2016
I changed the type of message from fatal_error to warning in r260961. While the test for atomics works fine in most cases, it fails because we include <cstdint> and <atomic>, and the user's host compiler might not provide them during a bootstrap (see PR26631 and PR26622).
Does anyone have any idea how to tackle this problem? As suggested by the bug reports, we could include the headers provided by libc++. However, I'm not sure whether we are supposed to do that during configuration time.
- Vasileios
<http://llvm.org/viewvc/llvm-project/?view=rev&revision=260961>
________________________________
From: Eric Fiselier [eric at efcs.ca]
Sent: 11 February 2016 16:08
To: Daniel Sanders
Cc: Vasileios Kalintiris; hans at chromium.org; mclow.lists at gmail.com; cfe-commits at lists.llvm.org
Subject: Re: [libcxx] r260235 - Introduce a cmake module to figure out whether we need to link with libatomic.
> we need to rename HAVE_CXX_ATOMICS_WITH_LIB to something like LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB.
Fixed in r260531.
I think we will eventually want to merge the following commits, assuming they don't regress the build, especially with the -gcc-toolchain option.
- [libcxx] r260515 - Re-commit "Introduce a cmake module to figure out whether we need to link with libatomic."
- [libcxx] r260524 - Fix r260515 - Correct typos in CMake changes
- [libcxx] r260531 - Rename CheckLibcxxAtomic.cmake variable result names so they don't clash with LLVM
@Marshall Any objections?
On Thu, Feb 11, 2016 at 2:18 AM, Daniel Sanders via cfe-commits <cfe-commits at lists.llvm.org<mailto:cfe-commits at lists.llvm.org>> wrote:
Hi,
In my latests rc2+patches build I've also found that we need to rename HAVE_CXX_ATOMICS_WITH_LIB to something like LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB. It's currently re-using the result of LLVM's check which doesn't include 64-bit atomics.
________________________________________
From: Vasileios Kalintiris
Sent: 09 February 2016 23:50
To: hans at chromium.org<mailto:hans at chromium.org>
Cc: cfe-commits at lists.llvm.org<mailto:cfe-commits at lists.llvm.org>; Daniel Sanders; mclow.lists at gmail.com<mailto:mclow.lists at gmail.com>
Subject: RE: [libcxx] r260235 - Introduce a cmake module to figure out whether we need to link with libatomic.
Hi Hans,
Please wait before merging this as it breaks LLVM bootstraps when using the -gcc-toolchain option and the system's default gcc installation does not provide libatomic. We have to check LIBCXX_GCC_TOOLCHAIN in our test. I'll create a patch tomorrow and I'll let you know when it's okay to merge them. In the meantime, I reverted it in r260323.
- Vasileios
________________________________________
From: Vasileios Kalintiris
Sent: 09 February 2016 18:56
To: hans at chromium.org<mailto:hans at chromium.org>
Cc: cfe-commits at lists.llvm.org<mailto:cfe-commits at lists.llvm.org>; Daniel Sanders; mclow.lists at gmail.com<mailto:mclow.lists at gmail.com>
Subject: RE: [libcxx] r260235 - Introduce a cmake module to figure out whether we need to link with libatomic.
Hi Hans,
Can we merge this on the 3.8 release branch? It fixes libcxx builds on MIPS by linking with libatomic when needed. Also, all the x86_64 and ARM buildbots for libcxx look good.
Thanks,
Vasileios
________________________________________
From: cfe-commits [cfe-commits-bounces at lists.llvm.org<mailto:cfe-commits-bounces at lists.llvm.org>] on behalf of Vasileios Kalintiris via cfe-commits [cfe-commits at lists.llvm.org<mailto:cfe-commits at lists.llvm.org>]
Sent: 09 February 2016 17:00
To: cfe-commits at lists.llvm.org<mailto:cfe-commits at lists.llvm.org>
Subject: [libcxx] r260235 - Introduce a cmake module to figure out whether we need to link with libatomic.
Author: vkalintiris
Date: Tue Feb 9 11:00:38 2016
New Revision: 260235
URL: http://llvm.org/viewvc/llvm-project?rev=260235&view=rev
Log:
Introduce a cmake module to figure out whether we need to link with libatomic.
Summary:
This fixes the tests under std/atomics for 32-bit MIPS CPUs where the
8-byte atomic operations call into the libatomic library.
Reviewers: dsanders, mclow.lists, EricWF, jroelofs, joerg
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D16613
Added:
libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake
Modified:
libcxx/trunk/cmake/config-ix.cmake
libcxx/trunk/lib/CMakeLists.txt
libcxx/trunk/test/CMakeLists.txt
libcxx/trunk/test/libcxx/test/target_info.py
libcxx/trunk/test/lit.site.cfg.in<http://lit.site.cfg.in>
Added: libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake?rev=260235&view=auto
==============================================================================
--- libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake (added)
+++ libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake Tue Feb 9 11:00:38 2016
@@ -0,0 +1,38 @@
+INCLUDE(CheckCXXSourceCompiles)
+
+# Sometimes linking against libatomic is required for atomic ops, if
+# the platform doesn't support lock-free atomics.
+#
+# We could modify LLVM's CheckAtomic module and have it check for 64-bit
+# atomics instead. However, we would like to avoid careless uses of 64-bit
+# atomics inside LLVM over time on 32-bit platforms.
+
+function(check_cxx_atomics varname)
+ set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+ set(CMAKE_REQUIRED_FLAGS "-std=c++11")
+ check_cxx_source_compiles("
+#include <cstdint>
+#include <atomic>
+std::atomic<uintptr_t> x;
+std::atomic<uintmax_t> y;
+int main() {
+ return x + y;
+}
+" ${varname})
+ set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
+endfunction(check_cxx_atomics)
+
+check_cxx_atomics(HAVE_CXX_ATOMICS_WITHOUT_LIB)
+# If not, check if the library exists, and atomics work with it.
+if(NOT HAVE_CXX_ATOMICS_WITHOUT_LIB)
+ check_library_exists(atomic __atomic_fetch_add_8 "" HAVE_LIBATOMIC)
+ if(HAVE_LIBATOMIC)
+ list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
+ check_cxx_atomics(HAVE_CXX_ATOMICS_WITH_LIB)
+ if (NOT HAVE_CXX_ATOMICS_WITH_LIB)
+ message(FATAL_ERROR "Host compiler must support std::atomic!")
+ endif()
+ else()
+ message(FATAL_ERROR "Host compiler appears to require libatomic, but cannot find it.")
+ endif()
+endif()
Modified: libcxx/trunk/cmake/config-ix.cmake
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/cmake/config-ix.cmake?rev=260235&r1=260234&r2=260235&view=diff
==============================================================================
--- libcxx/trunk/cmake/config-ix.cmake (original)
+++ libcxx/trunk/cmake/config-ix.cmake Tue Feb 9 11:00:38 2016
@@ -1,5 +1,6 @@
include(CheckLibraryExists)
include(CheckCXXCompilerFlag)
+include(CheckLibcxxAtomic)
# Check compiler flags
@@ -17,3 +18,7 @@ check_library_exists(c fopen "" LIBCXX_H
check_library_exists(m ccos "" LIBCXX_HAS_M_LIB)
check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB)
check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB)
+
+if (NOT HAVE_CXX_ATOMICS_WITHOUT_LIB)
+ set(LIBCXX_HAS_ATOMIC_LIB True)
+endif()
Modified: libcxx/trunk/lib/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/lib/CMakeLists.txt?rev=260235&r1=260234&r2=260235&view=diff
==============================================================================
--- libcxx/trunk/lib/CMakeLists.txt (original)
+++ libcxx/trunk/lib/CMakeLists.txt Tue Feb 9 11:00:38 2016
@@ -79,6 +79,7 @@ add_library_flags_if(LIBCXX_HAS_C_LIB c)
add_library_flags_if(LIBCXX_HAS_M_LIB m)
add_library_flags_if(LIBCXX_HAS_RT_LIB rt)
add_library_flags_if(LIBCXX_HAS_GCC_S_LIB gcc_s)
+add_library_flags_if(LIBCXX_HAS_ATOMIC_LIB atomic)
# Setup flags.
add_flags_if_supported(-fPIC)
Modified: libcxx/trunk/test/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/CMakeLists.txt?rev=260235&r1=260234&r2=260235&view=diff
==============================================================================
--- libcxx/trunk/test/CMakeLists.txt (original)
+++ libcxx/trunk/test/CMakeLists.txt Tue Feb 9 11:00:38 2016
@@ -15,6 +15,7 @@ pythonize_bool(LIBCXX_ENABLE_SHARED)
pythonize_bool(LIBCXX_BUILD_32_BITS)
pythonize_bool(LIBCXX_GENERATE_COVERAGE)
pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER)
+pythonize_bool(LIBCXX_HAS_ATOMIC_LIB)
# The tests shouldn't link to any ABI library when it has been linked into
# libc++ statically or via a linker script.
Modified: libcxx/trunk/test/libcxx/test/target_info.py
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/libcxx/test/target_info.py?rev=260235&r1=260234&r2=260235&view=diff
==============================================================================
--- libcxx/trunk/test/libcxx/test/target_info.py (original)
+++ libcxx/trunk/test/libcxx/test/target_info.py Tue Feb 9 11:00:38 2016
@@ -172,6 +172,9 @@ class LinuxLocalTI(DefaultTargetInfo):
flags += ['-lunwind', '-ldl']
else:
flags += ['-lgcc_s', '-lgcc']
+ use_libatomic = self.full_config.get_lit_bool('use_libatomic', False)
+ if use_libatomic:
+ flags += ['-latomic']
san = self.full_config.get_lit_conf('use_sanitizer', '').strip()
if san:
# The libraries and their order are taken from the
Modified: libcxx/trunk/test/lit.site.cfg.in<http://lit.site.cfg.in>
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/lit.site.cfg.in?rev=260235&r1=260234&r2=260235&view=diff
==============================================================================
--- libcxx/trunk/test/lit.site.cfg.in<http://lit.site.cfg.in> (original)
+++ libcxx/trunk/test/lit.site.cfg.in<http://lit.site.cfg.in> Tue Feb 9 11:00:38 2016
@@ -20,6 +20,7 @@ config.generate_coverage = "@LIBC
config.target_info = "@LIBCXX_TARGET_INFO@"
config.executor = "@LIBCXX_EXECUTOR@"
config.llvm_unwinder = "@LIBCXXABI_USE_LLVM_UNWINDER@"
+config.use_libatomic = "@LIBCXX_HAS_ATOMIC_LIB@"
# Let the main config do the real work.
lit_config.load_config(config, "@LIBCXX_SOURCE_DIR@/test/lit.cfg")
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