[libc-commits] [libc] 096f85e - [libc] add more APIs of cmgxchg variants (#91208)

[via libc-commits]

Author: Schrodinger ZHU Yifan
Date: 2024-05-06T18:55:18-04:00
New Revision: 096f85e827b6fdf52ff1f8d99aa8335a885b46a1

URL: https://github.com/llvm/llvm-project/commit/096f85e827b6fdf52ff1f8d99aa8335a885b46a1
DIFF: https://github.com/llvm/llvm-project/commit/096f85e827b6fdf52ff1f8d99aa8335a885b46a1.diff

LOG: [libc] add more APIs of cmgxchg variants (#91208)

Such APIs are useful in lock implementations

Added: 
    

Modified: 
    libc/src/__support/CPP/atomic.h

Removed: 
    


################################################################################
diff  --git a/libc/src/__support/CPP/atomic.h b/libc/src/__support/CPP/atomic.h
index 5e428940565b99..e273d998c07029 100644
--- a/libc/src/__support/CPP/atomic.h
+++ b/libc/src/__support/CPP/atomic.h
@@ -101,6 +101,36 @@ template <typename T> struct Atomic {
                                        int(mem_ord), int(mem_ord));
   }
 
+  // Atomic compare exchange (separate success and failure memory orders)
+  bool compare_exchange_strong(
+      T &expected, T desired, MemoryOrder success_order,
+      MemoryOrder failure_order,
+      [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
+    return __atomic_compare_exchange_n(&val, &expected, desired, false,
+                                       static_cast<int>(success_order),
+                                       static_cast<int>(failure_order));
+  }
+
+  // Atomic compare exchange (weak version)
+  bool compare_exchange_weak(
+      T &expected, T desired, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
+      [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
+    return __atomic_compare_exchange_n(&val, &expected, desired, true,
+                                       static_cast<int>(mem_ord),
+                                       static_cast<int>(mem_ord));
+  }
+
+  // Atomic compare exchange (weak version with separate success and failure
+  // memory orders)
+  bool compare_exchange_weak(
+      T &expected, T desired, MemoryOrder success_order,
+      MemoryOrder failure_order,
+      [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
+    return __atomic_compare_exchange_n(&val, &expected, desired, true,
+                                       static_cast<int>(success_order),
+                                       static_cast<int>(failure_order));
+  }
+
   T exchange(T desired, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
              [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
 #if __has_builtin(__scoped_atomic_exchange_n)