atomic: Add a spin_loop() hint

tavianator · May 15, 2024 · c964524 · c964524
1 parent 41c2f7a
commit c964524
Showing 1 changed file with 14 additions and 0 deletions.
diff --git a/src/atomic.h b/src/atomic.h
@@ -8,6 +8,7 @@
 #ifndef BFS_ATOMIC_H
 #define BFS_ATOMIC_H
 
+#include "prelude.h"
 #include "sanity.h"
 #include <stdatomic.h>
 
@@ -101,4 +102,17 @@
 #define signal_fence(order) \
 	atomic_signal_fence(memory_order_##order)
 
+/**
+ * A hint to the CPU to relax while it spins.
+ */
+#if __has_builtin(__builtin_ia32_pause)
+#  define spin_loop() __builtin_ia32_pause()
+#elif __has_builtin(__builtin_arm_yield)
+#  define spin_loop() __builtin_arm_yield()
+#elif __has_builtin(__builtin_riscv_pause)
+#  define spin_loop() __builtin_riscv_pause()
+#else
+#  define spin_loop() ((void)0)
+#endif
+
 #endif // BFS_ATOMIC_H