Fix 'undefined reference to __atomic_load/store/cas_16' error (gcc-7/x64)

Issue #34 (libatomic_ops).

* src/atomic_ops/sysdeps/gcc/x86.h [!AO_DISABLE_GCC_ATOMICS
&& !__APPLE_CC__ && !__clang__ && AO_GNUC_PREREQ(7, 0)
&& !AO_PREFER_BUILTIN_ATOMICS && !AO_THREAD_SANITIZER
&& !__MINGW32__] (AO_SKIPATOMIC_double_compare_and_swap_ANY,
AO_SKIPATOMIC_DOUBLE_LOAD_STORE_ANY): Define macro; add comment.

diff --git a/src/atomic_ops/sysdeps/gcc/x86.h b/src/atomic_ops/sysdeps/gcc/x86.h
index d7c06c52e8f35234656f210846ef6f55bff7f142..b4ca39ff88176db25dbe8f101db1837f41cccd8d 100644 (file)
--- a/src/atomic_ops/sysdeps/gcc/x86.h
+++ b/src/atomic_ops/sysdeps/gcc/x86.h
@@ -67,7 +67,15 @@
 #       define AO_SKIPATOMIC_DOUBLE_LOAD_STORE_ANY
 #     endif
 #   endif /* __x86_64__ */
-# endif /* __clang__ */
+
+# elif AO_GNUC_PREREQ(7, 0) && !defined(AO_PREFER_BUILTIN_ATOMICS) \
+       && !defined(AO_THREAD_SANITIZER) && !defined(__MINGW32__)
+    /* gcc-7.x/x64 (gcc-7.2, at least) requires -latomic flag in case   */
+    /* of double-word atomic operations use (but not in case of TSan).  */
+    /* TODO: Revise it for the future gcc-7 releases. */
+#   define AO_SKIPATOMIC_double_compare_and_swap_ANY
+#   define AO_SKIPATOMIC_DOUBLE_LOAD_STORE_ANY
+# endif /* __GNUC__ && !__clang__ */
 
 # ifdef AO_SKIPATOMIC_DOUBLE_LOAD_STORE_ANY
 #   define AO_SKIPATOMIC_double_load