I wrote:
> So about like this, then.
After actually testing (by removing the ARM stanza on a macOS machine),
it seems that placement doesn't work, because of the default definition
of S_UNLOCK at the bottom of the "#if defined(__GNUC__)" stuff. Putting
it inside that test works, and seems like it should be fine, since this
is a GCC-ism.
regards, tom lane
diff --git a/src/include/storage/s_lock.h b/src/include/storage/s_lock.h
index 4225d9b7fc..8b19ab160f 100644
--- a/src/include/storage/s_lock.h
+++ b/src/include/storage/s_lock.h
@@ -293,29 +293,6 @@ spin_delay(void)
#endif /* __arm__ || __arm || __aarch64__ */
-/*
- * RISC-V likewise uses __sync_lock_test_and_set(int *, int) if available.
- */
-#if defined(__riscv)
-#ifdef HAVE_GCC__SYNC_INT32_TAS
-#define HAS_TEST_AND_SET
-
-#define TAS(lock) tas(lock)
-
-typedef int slock_t;
-
-static __inline__ int
-tas(volatile slock_t *lock)
-{
- return __sync_lock_test_and_set(lock, 1);
-}
-
-#define S_UNLOCK(lock) __sync_lock_release(lock)
-
-#endif /* HAVE_GCC__SYNC_INT32_TAS */
-#endif /* __riscv */
-
-
/* S/390 and S/390x Linux (32- and 64-bit zSeries) */
#if defined(__s390__) || defined(__s390x__)
#define HAS_TEST_AND_SET
@@ -619,6 +596,50 @@ tas(volatile slock_t *lock)
#endif /* __hppa || __hppa__ */
+/*
+ * If we have no platform-specific knowledge, but we found that the compiler
+ * provides __sync_lock_test_and_set(), use that. Prefer the int-width
+ * version over the char-width version if we have both, on the rather dubious
+ * grounds that that's known to be more likely to work in the ARM ecosystem.
+ * (But we dealt with ARM above.)
+ */
+#if !defined(HAS_TEST_AND_SET)
+
+#if defined(HAVE_GCC__SYNC_INT32_TAS)
+#define HAS_TEST_AND_SET
+
+#define TAS(lock) tas(lock)
+
+typedef int slock_t;
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+ return __sync_lock_test_and_set(lock, 1);
+}
+
+#define S_UNLOCK(lock) __sync_lock_release(lock)
+
+#elif defined(HAVE_GCC__SYNC_CHAR_TAS)
+#define HAS_TEST_AND_SET
+
+#define TAS(lock) tas(lock)
+
+typedef char slock_t;
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+ return __sync_lock_test_and_set(lock, 1);
+}
+
+#define S_UNLOCK(lock) __sync_lock_release(lock)
+
+#endif /* HAVE_GCC__SYNC_INT32_TAS */
+
+#endif /* !defined(HAS_TEST_AND_SET) */
+
+
/*
* Default implementation of S_UNLOCK() for gcc/icc.
*
