From 3d7586b760550b7d89594c8d7462fc30b868ecc6 Mon Sep 17 00:00:00 2001 From: Thiago Macieira Date: Tue, 8 Sep 2015 20:35:33 -0300 Subject: 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::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::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 Reviewed-by: Lars Knoll Reviewed-by: Thiago Macieira --- src/corelib/arch/qatomic_cxx11.h | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'src/corelib/arch/qatomic_cxx11.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 struct QAtomicOps { -- cgit v1.2.3