From c8ae8f2fb187fc690764e576d5dcc31637b1109c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Verschelde?= <rverschelde@gmail.com>
Date: Sun, 1 Sep 2019 12:19:44 +0200
Subject: [PATCH] Revert "Add __atomic_* operators support for atomic
 operations"

---
 core/safe_refcount.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/core/safe_refcount.h b/core/safe_refcount.h
index 0b65ffb9ca3..54f540b0c72 100644
--- a/core/safe_refcount.h
+++ b/core/safe_refcount.h
@@ -97,8 +97,8 @@ static _ALWAYS_INLINE_ T atomic_exchange_if_greater(volatile T *pw, volatile V v
 
 /* Implementation for GCC & Clang */
 
-#include <stdbool.h>
-#include <atomic>
+// GCC guarantees atomic intrinsics for sizes of 1, 2, 4 and 8 bytes.
+// Clang states it supports GCC atomic builtins.
 
 template <class T>
 static _ALWAYS_INLINE_ T atomic_conditional_increment(volatile T *pw) {
@@ -107,7 +107,7 @@ static _ALWAYS_INLINE_ T atomic_conditional_increment(volatile T *pw) {
 		T tmp = static_cast<T const volatile &>(*pw);
 		if (tmp == 0)
 			return 0; // if zero, can't add to it anymore
-		if (__atomic_compare_exchange_n(pw, &tmp, tmp + 1, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) == true)
+		if (__sync_val_compare_and_swap(pw, tmp, tmp + 1) == tmp)
 			return tmp + 1;
 	}
 }
@@ -115,25 +115,25 @@ static _ALWAYS_INLINE_ T atomic_conditional_increment(volatile T *pw) {
 template <class T>
 static _ALWAYS_INLINE_ T atomic_decrement(volatile T *pw) {
 
-	return __atomic_sub_fetch(pw, 1, __ATOMIC_SEQ_CST);
+	return __sync_sub_and_fetch(pw, 1);
 }
 
 template <class T>
 static _ALWAYS_INLINE_ T atomic_increment(volatile T *pw) {
 
-	return __atomic_add_fetch(pw, 1, __ATOMIC_SEQ_CST);
+	return __sync_add_and_fetch(pw, 1);
 }
 
 template <class T, class V>
 static _ALWAYS_INLINE_ T atomic_sub(volatile T *pw, volatile V val) {
 
-	return __atomic_sub_fetch(pw, val, __ATOMIC_SEQ_CST);
+	return __sync_sub_and_fetch(pw, val);
 }
 
 template <class T, class V>
 static _ALWAYS_INLINE_ T atomic_add(volatile T *pw, volatile V val) {
 
-	return __atomic_add_fetch(pw, val, __ATOMIC_SEQ_CST);
+	return __sync_add_and_fetch(pw, val);
 }
 
 template <class T, class V>
@@ -143,7 +143,7 @@ static _ALWAYS_INLINE_ T atomic_exchange_if_greater(volatile T *pw, volatile V v
 		T tmp = static_cast<T const volatile &>(*pw);
 		if (tmp >= val)
 			return tmp; // already greater, or equal
-		if (__atomic_compare_exchange_n(pw, &tmp, val, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) == true)
+		if (__sync_val_compare_and_swap(pw, tmp, val) == tmp)
 			return val;
 	}
 }