diff options
| author | Thiago Macieira <thiago.macieira@intel.com> | 2015-09-08 20:35:33 -0300 |
|---|---|---|
| committer | Thiago Macieira <thiago.macieira@intel.com> | 2015-12-04 05:20:26 +0000 |
| commit | 2398e225abdea36321670d34a8238b6e64dba281 (patch) | |
| tree | 4dc329448072cab5f1bd24e137104275289974ee /src | |
| parent | 6c222297ab19e1bc6b74c4290446c1cb61f6fda8 (diff) | |
Auto-detect whether 64-bit std::atomic really works
The C++ standard says it must, but some badly-configured toolchains seem
to be lacking support.
In particular, for some 32-bit platforms without native support for
them, GCC implements 64-bit atomics via out-of-line functions in
libatomic. If that library is missing... well, then std::atomic 64-bit
doesn't work and we mustn't try to use it.
This was found when trying to compile Qt 5.6 for MIPS 32-bit:
Linking library libQt5Core.so.5.6.0
.obj/qsimd.o: In function `std::__atomic_base<unsigned long long>::load(std::memory_order) const':
/opt/poky/1.7/sysroots/mips32r2-poky-linux/usr/include/c++/4.9.1/bits/atomic_base.h:500: undefined reference to `__atomic_load_8'
.obj/qsimd.o: In function `std::__atomic_base<unsigned long long>::store(unsigned long long, std::memory_order)':
/opt/poky/1.7/sysroots/mips32r2-poky-linux/usr/include/c++/4.9.1/bits/atomic_base.h:478: undefined reference to `__atomic_store_8'
Yocto bug report: https://bugzilla.yoctoproject.org/show_bug.cgi?id=8274
Change-Id: I42e7ef1a481840699a8dffff140224d6614e5c36
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 3d7586b760550b7d89594c8d7462fc30b868ecc6)
Reviewed-by: Dmitry Shachnev <mitya57@gmail.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/corelib/arch/arch.pri | 2 | ||||
| -rw-r--r-- | src/corelib/arch/qatomic_cxx11.h | 12 |
2 files changed, 9 insertions, 5 deletions
diff --git a/src/corelib/arch/arch.pri b/src/corelib/arch/arch.pri index 16fe8b8e5c..083d912331 100644 --- a/src/corelib/arch/arch.pri +++ b/src/corelib/arch/arch.pri @@ -10,6 +10,8 @@ HEADERS += \ arch/qatomic_gcc.h \ arch/qatomic_cxx11.h +atomic64-libatomic: LIBS += -latomic + unix { # fallback implementation when no other appropriate qatomic_*.h exists HEADERS += arch/qatomic_unix.h diff --git a/src/corelib/arch/qatomic_cxx11.h b/src/corelib/arch/qatomic_cxx11.h index 0e06ca951a..4136e09ce2 100644 --- a/src/corelib/arch/qatomic_cxx11.h +++ b/src/corelib/arch/qatomic_cxx11.h @@ -78,11 +78,13 @@ template<> struct QAtomicOpsSupport<8> { enum { IsSupported = 1 }; }; #define Q_ATOMIC_INT16_FETCH_AND_STORE_IS_ALWAYS_NATIVE #define Q_ATOMIC_INT16_FETCH_AND_ADD_IS_ALWAYS_NATIVE -#define Q_ATOMIC_INT64_IS_SUPPORTED -#define Q_ATOMIC_INT64_REFERENCE_COUNTING_IS_ALWAYS_NATIVE -#define Q_ATOMIC_INT64_TEST_AND_SET_IS_ALWAYS_NATIVE -#define Q_ATOMIC_INT64_FETCH_AND_STORE_IS_ALWAYS_NATIVE -#define Q_ATOMIC_INT64_FETCH_AND_ADD_IS_ALWAYS_NATIVE +#ifndef QT_NO_STD_ATOMIC64 +# define Q_ATOMIC_INT64_IS_SUPPORTED +# define Q_ATOMIC_INT64_REFERENCE_COUNTING_IS_ALWAYS_NATIVE +# define Q_ATOMIC_INT64_TEST_AND_SET_IS_ALWAYS_NATIVE +# define Q_ATOMIC_INT64_FETCH_AND_STORE_IS_ALWAYS_NATIVE +# define Q_ATOMIC_INT64_FETCH_AND_ADD_IS_ALWAYS_NATIVE +#endif template <typename X> struct QAtomicOps { |