From d5c2b473a831ca9e2a93bda30dc131b4fee7314f Mon Sep 17 00:00:00 2001
From: Merry <git@mary.rs>
Date: Sun, 7 May 2023 15:12:05 +0100
Subject: [PATCH] spin_lock: Use std::call_once

---
 src/dynarmic/common/spin_lock_arm64.cpp | 14 +++++---------
 src/dynarmic/common/spin_lock_x64.cpp   | 14 +++++---------
 2 files changed, 10 insertions(+), 18 deletions(-)

diff --git a/src/dynarmic/common/spin_lock_arm64.cpp b/src/dynarmic/common/spin_lock_arm64.cpp
index 36871449..db58accb 100644
--- a/src/dynarmic/common/spin_lock_arm64.cpp
+++ b/src/dynarmic/common/spin_lock_arm64.cpp
@@ -3,6 +3,8 @@
  * SPDX-License-Identifier: 0BSD
  */
 
+#include <mutex>
+
 #include <oaknut/code_block.hpp>
 #include <oaknut/oaknut.hpp>
 
@@ -43,11 +45,11 @@ struct SpinLockImpl {
     oaknut::CodeBlock mem;
     oaknut::CodeGenerator code;
 
-    bool initialized = false;
     void (*lock)(volatile int*);
     void (*unlock)(volatile int*);
 };
 
+std::once_flag flag;
 SpinLockImpl impl;
 
 SpinLockImpl::SpinLockImpl()
@@ -66,23 +68,17 @@ void SpinLockImpl::Initialize() {
     code.RET();
 
     mem.protect();
-
-    initialized = true;
 }
 
 }  // namespace
 
 void SpinLock::Lock() {
-    if (!impl.initialized) [[unlikely]] {
-        impl.Initialize();
-    }
+    std::call_once(flag, &SpinLockImpl::Initialize, impl);
     impl.lock(&storage);
 }
 
 void SpinLock::Unlock() {
-    if (!impl.initialized) [[unlikely]] {
-        impl.Initialize();
-    }
+    std::call_once(flag, &SpinLockImpl::Initialize, impl);
     impl.unlock(&storage);
 }
 
diff --git a/src/dynarmic/common/spin_lock_x64.cpp b/src/dynarmic/common/spin_lock_x64.cpp
index 9f0daa63..fdea94f4 100644
--- a/src/dynarmic/common/spin_lock_x64.cpp
+++ b/src/dynarmic/common/spin_lock_x64.cpp
@@ -3,6 +3,8 @@
  * SPDX-License-Identifier: 0BSD
  */
 
+#include <mutex>
+
 #include <xbyak/xbyak.h>
 
 #include "dynarmic/backend/x64/abi.h"
@@ -38,11 +40,11 @@ struct SpinLockImpl {
 
     Xbyak::CodeGenerator code;
 
-    bool initialized = false;
     void (*lock)(volatile int*);
     void (*unlock)(volatile int*);
 };
 
+std::once_flag flag;
 SpinLockImpl impl;
 
 void SpinLockImpl::Initialize() {
@@ -57,23 +59,17 @@ void SpinLockImpl::Initialize() {
     unlock = code.getCurr<void (*)(volatile int*)>();
     EmitSpinLockUnlock(code, ABI_PARAM1, code.eax);
     code.ret();
-
-    initialized = true;
 }
 
 }  // namespace
 
 void SpinLock::Lock() {
-    if (!impl.initialized) [[unlikely]] {
-        impl.Initialize();
-    }
+    std::call_once(flag, &SpinLockImpl::Initialize, impl);
     impl.lock(&storage);
 }
 
 void SpinLock::Unlock() {
-    if (!impl.initialized) [[unlikely]] {
-        impl.Initialize();
-    }
+    std::call_once(flag, &SpinLockImpl::Initialize, impl);
     impl.unlock(&storage);
 }