mdbx: fix/refine the use of C11 atomics.

Change-Id: I5d925d4625b06296fd82f4b35ee36be682e7b2d3

.github/actions/spelling/expect.txt

@@ -208,6 +208,7 @@ csrc
 CSRSS
 css
 cstdarg
+cstdatomic
 cstddef
 cstdint
 cstr

src/core.c

@@ -780,12 +780,24 @@ static __always_inline void atomic_yield(void) {
 #if MDBX_64BIT_CAS
 static __always_inline bool atomic_cas64(volatile uint64_t *p, uint64_t c,
                                          uint64_t v) {
-#if defined(ATOMIC_VAR_INIT) || defined(ATOMIC_LLONG_LOCK_FREE)
+#if !defined(__STDC_NO_ATOMICS__) &&                                           \
+    (defined(ATOMIC_VAR_INIT) || defined(ATOMIC_LLONG_LOCK_FREE) ||            \
+     __has_extension(c_atomic))
   STATIC_ASSERT(sizeof(long long) >= sizeof(uint64_t));
-#ifndef __COVERITY__
+#ifdef ATOMIC_LLONG_LOCK_FREE
-  STATIC_ASSERT(atomic_is_lock_free(p));
+  STATIC_ASSERT(ATOMIC_LLONG_LOCK_FREE > 0);
-#endif /* Workaround for Coverity */
+#if ATOMIC_LLONG_LOCK_FREE < 2
-  return atomic_compare_exchange_strong((_Atomic uint64_t *)p, &c, v);
+  assert(atomic_is_lock_free(p));
+#endif
+#else
+  assert(atomic_is_lock_free(p));
+#endif
+#ifdef __clang__
+  STATIC_ASSERT(sizeof(_Atomic uint64_t) == sizeof(uint64_t));
+  return atomic_compare_exchange_strong((_Atomic volatile uint64_t *)p, &c, v);
+#else
+  return atomic_compare_exchange_strong(p, &c, v);
+#endif
 #elif defined(__GNUC__) || defined(__clang__)
   return __sync_bool_compare_and_swap(p, c, v);
 #elif defined(_MSC_VER)
@@ -801,12 +813,24 @@ static __always_inline bool atomic_cas64(volatile uint64_t *p, uint64_t c,
 
 static __always_inline bool atomic_cas32(volatile uint32_t *p, uint32_t c,
                                          uint32_t v) {
-#if defined(ATOMIC_VAR_INIT) || defined(ATOMIC_INT_LOCK_FREE)
+#if !defined(__STDC_NO_ATOMICS__) &&                                           \
+    (defined(ATOMIC_VAR_INIT) || defined(ATOMIC_INT_LOCK_FREE) ||              \
+     __has_extension(c_atomic))
   STATIC_ASSERT(sizeof(int) >= sizeof(uint32_t));
-#ifndef __COVERITY__
+#ifdef ATOMIC_INT_LOCK_FREE
-  STATIC_ASSERT(atomic_is_lock_free(p));
+  STATIC_ASSERT(ATOMIC_INT_LOCK_FREE > 0);
-#endif /* Workaround for Coverity */
+#if ATOMIC_INT_LOCK_FREE < 2
-  return atomic_compare_exchange_strong((_Atomic uint32_t *)p, &c, v);
+  assert(atomic_is_lock_free(p));
+#endif
+#else
+  assert(atomic_is_lock_free(p));
+#endif
+#ifdef __clang__
+  STATIC_ASSERT(sizeof(_Atomic uint32_t) == sizeof(uint32_t));
+  return atomic_compare_exchange_strong((_Atomic volatile uint32_t *)p, &c, v);
+#else
+  return atomic_compare_exchange_strong(p, &c, v);
+#endif
 #elif defined(__GNUC__) || defined(__clang__)
   return __sync_bool_compare_and_swap(p, c, v);
 #elif defined(_MSC_VER)
@@ -820,12 +844,24 @@ static __always_inline bool atomic_cas32(volatile uint32_t *p, uint32_t c,
 }
 
 static __always_inline uint32_t atomic_add32(volatile uint32_t *p, uint32_t v) {
-#if defined(ATOMIC_VAR_INIT) || defined(ATOMIC_INT_LOCK_FREE)
+#if !defined(__STDC_NO_ATOMICS__) &&                                           \
+    (defined(ATOMIC_VAR_INIT) || defined(ATOMIC_INT_LOCK_FREE) ||              \
+     __has_extension(c_atomic))
   STATIC_ASSERT(sizeof(int) >= sizeof(uint32_t));
-#ifndef __COVERITY__
+#ifdef ATOMIC_INT_LOCK_FREE
-  STATIC_ASSERT(atomic_is_lock_free(p));
+  STATIC_ASSERT(ATOMIC_INT_LOCK_FREE > 0);
-#endif /* Workaround for Coverity */
+#if ATOMIC_INT_LOCK_FREE < 2
-  return atomic_fetch_add((_Atomic uint32_t *)p, v);
+  assert(atomic_is_lock_free(p));
+#endif
+#else
+  assert(atomic_is_lock_free(p));
+#endif
+#ifdef __clang__
+  STATIC_ASSERT(sizeof(_Atomic uint32_t) == sizeof(uint32_t));
+  return atomic_fetch_add((_Atomic volatile uint32_t *)p, v);
+#else
+  return atomic_fetch_add(p, v);
+#endif
 #elif defined(__GNUC__) || defined(__clang__)
   return __sync_fetch_and_add(p, v);
 #elif defined(_MSC_VER)

src/osal.h

@@ -459,6 +459,35 @@ typedef union MDBX_srwlock {
 #ifdef __cplusplus
 extern void mdbx_osal_jitter(bool tiny);
 #else
+
+/*----------------------------------------------------------------------------*/
+/* Atomics */
+
+#if defined(__cplusplus) && !defined(__STDC_NO_ATOMICS__) && __has_include(<cstdatomic>)
+#include <cstdatomic>
+#elif !defined(__cplusplus) && (__STDC_VERSION__ >= 201112L) &&                \
+    !defined(__STDC_NO_ATOMICS__) &&                                           \
+    (__GNUC_PREREQ(4, 9) || __CLANG_PREREQ(3, 8) ||                            \
+     !(defined(__GNUC__) || defined(__clang__)))
+#include <stdatomic.h>
+#elif defined(__GNUC__) || defined(__clang__)
+/* LY: nothing required */
+#elif defined(_MSC_VER)
+#pragma warning(disable : 4163) /* 'xyz': not available as an intrinsic */
+#pragma warning(disable : 4133) /* 'function': incompatible types - from       \
+                                   'size_t' to 'LONGLONG' */
+#pragma warning(disable : 4244) /* 'return': conversion from 'LONGLONG' to     \
+                                   'std::size_t', possible loss of data */
+#pragma warning(disable : 4267) /* 'function': conversion from 'size_t' to     \
+                                   'long', possible loss of data */
+#pragma intrinsic(_InterlockedExchangeAdd, _InterlockedCompareExchange)
+#pragma intrinsic(_InterlockedExchangeAdd64, _InterlockedCompareExchange64)
+#elif defined(__APPLE__)
+#include <libkern/OSAtomic.h>
+#else
+#error FIXME atomic-ops
+#endif
+
 /*----------------------------------------------------------------------------*/
 /* Memory/Compiler barriers, cache coherence */
 
@@ -500,8 +529,8 @@ static __maybe_unused __inline void mdbx_compiler_barrier(void) {
 }
 
 static __maybe_unused __inline void mdbx_memory_barrier(void) {
-#if __has_extension(c_atomic) || __has_extension(cxx_atomic)
+#if __has_extension(c_atomic) && !defined(__STDC_NO_ATOMICS__)
-  __c11_atomic_thread_fence(__ATOMIC_SEQ_CST);
+  atomic_thread_fence(__ATOMIC_SEQ_CST);
 #elif defined(__ATOMIC_SEQ_CST)
   __atomic_thread_fence(__ATOMIC_SEQ_CST);
 #elif defined(__clang__) || defined(__GNUC__)
@@ -898,32 +927,6 @@ MDBX_INTERNAL_VAR MDBX_RegGetValueA mdbx_RegGetValueA;
 
 #endif /* Windows */
 
-/*----------------------------------------------------------------------------*/
-/* Atomics */
-
-#if !defined(__cplusplus) && (__STDC_VERSION__ >= 201112L) &&                  \
-    !defined(__STDC_NO_ATOMICS__) &&                                           \
-    (__GNUC_PREREQ(4, 9) || __CLANG_PREREQ(3, 8) ||                            \
-     !(defined(__GNUC__) || defined(__clang__)))
-#include <stdatomic.h>
-#elif defined(__GNUC__) || defined(__clang__)
-/* LY: nothing required */
-#elif defined(_MSC_VER)
-#pragma warning(disable : 4163) /* 'xyz': not available as an intrinsic */
-#pragma warning(disable : 4133) /* 'function': incompatible types - from       \
-                                   'size_t' to 'LONGLONG' */
-#pragma warning(disable : 4244) /* 'return': conversion from 'LONGLONG' to     \
-                                   'std::size_t', possible loss of data */
-#pragma warning(disable : 4267) /* 'function': conversion from 'size_t' to     \
-                                   'long', possible loss of data */
-#pragma intrinsic(_InterlockedExchangeAdd, _InterlockedCompareExchange)
-#pragma intrinsic(_InterlockedExchangeAdd64, _InterlockedCompareExchange64)
-#elif defined(__APPLE__)
-#include <libkern/OSAtomic.h>
-#else
-#error FIXME atomic-ops
-#endif
-
 #endif /* !__cplusplus */
 
 /*----------------------------------------------------------------------------*/