[tsan] Treat non-barrier OSAtomic* functions as barriers to avoid false positives

[kubamracek]

Summary

The non-barrier versions of OSAtomic* functions are semantically mo_relaxed, but the two variants (e.g. OSAtomicAdd32 and OSAtomicAdd32Barrier) are actually aliases of each other, and we cannot have different interceptors for them, because they're actually the same function. Thus, we have to stay conservative and treat the non-barrier versions as mo_acq_rel.

[dvyukov]

LGTM with a nit.

lib/tsan/rtl/tsan_interceptors_mac.cc

35

Please use const int for there.
Constants generally lead to fewer issues during maintenance than text replacements.

lib/tsan/rtl/tsan_interceptors_mac.cc

 
 #include <libkern/OSAtomic.h>
 #include <xpc/xpc.h>
 
 typedef long long_t;  // NOLINT
 
 namespace __tsan {
 
+// The non-barrier versions of OSAtomic* functions are semantically mo_relaxed,
+// but the two variants (e.g. OSAtomicAdd32 and OSAtomicAdd32Barrier) are
+// actually aliases of each other, and we cannot have different interceptors for
+// them, because they're actually the same function.  Thus, we have to stay
+// conservative and treat the non-barrier versions as mo_acq_rel.
+#define ORDER_BARRIER mo_acq_rel
+#define ORDER_NONBARRIER mo_acq_rel
+
 #define OSATOMIC_INTERCEPTOR(return_t, t, tsan_t, f, tsan_atomic_f, mo) \
   TSAN_INTERCEPTOR(return_t, f, t x, volatile t *ptr) {                 \
     SCOPED_TSAN_INTERCEPTOR(f, x, ptr);                                 \
     return tsan_atomic_f((volatile tsan_t *)ptr, x, mo);                \
   }
 
 #define OSATOMIC_INTERCEPTOR_PLUS_X(return_t, t, tsan_t, f, tsan_atomic_f, mo) \
   TSAN_INTERCEPTOR(return_t, f, t x, volatile t *ptr) {                        \

 #define OSATOMIC_INTERCEPTOR_MINUS_1(return_t, t, tsan_t, f, tsan_atomic_f, \
                                      mo)                                    \
   TSAN_INTERCEPTOR(return_t, f, volatile t *ptr) {                          \
     SCOPED_TSAN_INTERCEPTOR(f, ptr);                                        \
     return tsan_atomic_f((volatile tsan_t *)ptr, 1, mo) - 1;                \
   }
 
 #define OSATOMIC_INTERCEPTORS_ARITHMETIC(f, tsan_atomic_f, m)                  \
-  m(int32_t, int32_t, a32, f##32, __tsan_atomic32_##tsan_atomic_f, mo_relaxed) \
+  m(int32_t, int32_t, a32, f##32, __tsan_atomic32_##tsan_atomic_f,             \
+    ORDER_NONBARRIER)                                                          \
   m(int32_t, int32_t, a32, f##32##Barrier, __tsan_atomic32_##tsan_atomic_f,    \
-    mo_acq_rel)                                                                \
+    ORDER_BARRIER)                                                             \
   m(int64_t, int64_t, a64, f##64, __tsan_atomic64_##tsan_atomic_f,             \
-    mo_relaxed)                                                                \
+    ORDER_NONBARRIER)                                                          \
   m(int64_t, int64_t, a64, f##64##Barrier, __tsan_atomic64_##tsan_atomic_f,    \
-    mo_acq_rel)
+    ORDER_BARRIER)
 
 #define OSATOMIC_INTERCEPTORS_BITWISE(f, tsan_atomic_f, m, m_orig)             \
   m(int32_t, uint32_t, a32, f##32, __tsan_atomic32_##tsan_atomic_f,            \
-    mo_relaxed)                                                                \
+    ORDER_NONBARRIER)                                                          \
   m(int32_t, uint32_t, a32, f##32##Barrier, __tsan_atomic32_##tsan_atomic_f,   \
-    mo_acq_rel)                                                                \
+    ORDER_BARRIER)                                                             \
   m_orig(int32_t, uint32_t, a32, f##32##Orig, __tsan_atomic32_##tsan_atomic_f, \
-    mo_relaxed)                                                                \
+    ORDER_NONBARRIER)                                                          \
   m_orig(int32_t, uint32_t, a32, f##32##OrigBarrier,                           \
-    __tsan_atomic32_##tsan_atomic_f, mo_acq_rel)
+    __tsan_atomic32_##tsan_atomic_f, ORDER_BARRIER)
 
 OSATOMIC_INTERCEPTORS_ARITHMETIC(OSAtomicAdd, fetch_add,
                                  OSATOMIC_INTERCEPTOR_PLUS_X)
 OSATOMIC_INTERCEPTORS_ARITHMETIC(OSAtomicIncrement, fetch_add,
                                  OSATOMIC_INTERCEPTOR_PLUS_1)
 OSATOMIC_INTERCEPTORS_ARITHMETIC(OSAtomicDecrement, fetch_sub,
                                  OSATOMIC_INTERCEPTOR_MINUS_1)
 OSATOMIC_INTERCEPTORS_BITWISE(OSAtomicOr, fetch_or, OSATOMIC_INTERCEPTOR_PLUS_X,
                               OSATOMIC_INTERCEPTOR)
 OSATOMIC_INTERCEPTORS_BITWISE(OSAtomicAnd, fetch_and,
                               OSATOMIC_INTERCEPTOR_PLUS_X, OSATOMIC_INTERCEPTOR)
 OSATOMIC_INTERCEPTORS_BITWISE(OSAtomicXor, fetch_xor,
                               OSATOMIC_INTERCEPTOR_PLUS_X, OSATOMIC_INTERCEPTOR)
 
 #define OSATOMIC_INTERCEPTORS_CAS(f, tsan_atomic_f, tsan_t, t)              \
   TSAN_INTERCEPTOR(bool, f, t old_value, t new_value, t volatile *ptr) {    \
     SCOPED_TSAN_INTERCEPTOR(f, old_value, new_value, ptr);                  \
     return tsan_atomic_f##_compare_exchange_strong(                         \
-        (tsan_t *)ptr, (tsan_t *)&old_value, (tsan_t)new_value, mo_relaxed, \
-        mo_relaxed);                                                        \
+        (tsan_t *)ptr, (tsan_t *)&old_value, (tsan_t)new_value,             \
+        ORDER_NONBARRIER, ORDER_NONBARRIER);                                \
   }                                                                         \
                                                                             \
   TSAN_INTERCEPTOR(bool, f##Barrier, t old_value, t new_value,              \
                    t volatile *ptr) {                                       \
     SCOPED_TSAN_INTERCEPTOR(f##Barrier, old_value, new_value, ptr);         \
     return tsan_atomic_f##_compare_exchange_strong(                         \
-        (tsan_t *)ptr, (tsan_t *)&old_value, (tsan_t)new_value, mo_acq_rel, \
-        mo_relaxed);                                                        \
+        (tsan_t *)ptr, (tsan_t *)&old_value, (tsan_t)new_value,             \
+        ORDER_BARRIER, ORDER_NONBARRIER);                                   \
   }
 
 OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwapInt, __tsan_atomic32, a32, int)
 OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwapLong, __tsan_atomic64, a64,
                           long_t)
 OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwapPtr, __tsan_atomic64, a64,
                           void *)
 OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwap32, __tsan_atomic32, a32,
                           int32_t)
 OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwap64, __tsan_atomic64, a64,
                           int64_t)
 
 #define OSATOMIC_INTERCEPTOR_BITOP(f, op, m, mo)              \
   TSAN_INTERCEPTOR(bool, f, uint32_t n, volatile void *ptr) { \
     SCOPED_TSAN_INTERCEPTOR(f, n, ptr);                       \
     char *byte_ptr = ((char *)ptr) + (n >> 3);                \
     char bit_index = n & 7;                                   \
     char mask = m;                                            \
     char orig_byte = op((a8 *)byte_ptr, mask, mo);            \
     return orig_byte & mask;                                  \
   }
 
-#define OSATOMIC_INTERCEPTORS_BITOP(f, op, m)      \
-  OSATOMIC_INTERCEPTOR_BITOP(f, op, m, mo_relaxed) \
-  OSATOMIC_INTERCEPTOR_BITOP(f##Barrier, op, m, mo_acq_rel)
+#define OSATOMIC_INTERCEPTORS_BITOP(f, op, m)                  \
+  OSATOMIC_INTERCEPTOR_BITOP(f, op, m, ORDER_NONBARRIER)       \
+  OSATOMIC_INTERCEPTOR_BITOP(f##Barrier, op, m, ORDER_BARRIER)
 
 OSATOMIC_INTERCEPTORS_BITOP(OSAtomicTestAndSet, __tsan_atomic8_fetch_or,
                             0x80u >> bit_index)
 OSATOMIC_INTERCEPTORS_BITOP(OSAtomicTestAndClear, __tsan_atomic8_fetch_and,
                             ~(0x80u >> bit_index))
 
 TSAN_INTERCEPTOR(void, OSAtomicEnqueue, OSQueueHead *list, void *item,
                  size_t offset) {