From e3f0c9323039bd1148a8e36a31b468a871971fbb Mon Sep 17 00:00:00 2001
From: Lioncash <mathew1800@gmail.com>
Date: Tue, 28 Jul 2020 04:32:39 -0400
Subject: common/atomic_ops: Don't cast away volatile from pointers

Preserves the volatility of the pointers being casted.
---
 src/common/atomic_ops.cpp | 37 +++++++++++++++++++++----------------
 src/common/atomic_ops.h   | 10 +++++-----
 2 files changed, 26 insertions(+), 21 deletions(-)

(limited to 'src/common')

diff --git a/src/common/atomic_ops.cpp b/src/common/atomic_ops.cpp
index 1098e21ff..1612d0e67 100644
--- a/src/common/atomic_ops.cpp
+++ b/src/common/atomic_ops.cpp
@@ -14,50 +14,55 @@ namespace Common {
 
 #if _MSC_VER
 
-bool AtomicCompareAndSwap(u8 volatile* pointer, u8 value, u8 expected) {
-    u8 result = _InterlockedCompareExchange8((char*)pointer, value, expected);
+bool AtomicCompareAndSwap(volatile u8* pointer, u8 value, u8 expected) {
+    const u8 result =
+        _InterlockedCompareExchange8(reinterpret_cast<volatile char*>(pointer), value, expected);
     return result == expected;
 }
 
-bool AtomicCompareAndSwap(u16 volatile* pointer, u16 value, u16 expected) {
-    u16 result = _InterlockedCompareExchange16((short*)pointer, value, expected);
+bool AtomicCompareAndSwap(volatile u16* pointer, u16 value, u16 expected) {
+    const u16 result =
+        _InterlockedCompareExchange16(reinterpret_cast<volatile short*>(pointer), value, expected);
     return result == expected;
 }
 
-bool AtomicCompareAndSwap(u32 volatile* pointer, u32 value, u32 expected) {
-    u32 result = _InterlockedCompareExchange((long*)pointer, value, expected);
+bool AtomicCompareAndSwap(volatile u32* pointer, u32 value, u32 expected) {
+    const u32 result =
+        _InterlockedCompareExchange(reinterpret_cast<volatile long*>(pointer), value, expected);
     return result == expected;
 }
 
-bool AtomicCompareAndSwap(u64 volatile* pointer, u64 value, u64 expected) {
-    u64 result = _InterlockedCompareExchange64((__int64*)pointer, value, expected);
+bool AtomicCompareAndSwap(volatile u64* pointer, u64 value, u64 expected) {
+    const u64 result = _InterlockedCompareExchange64(reinterpret_cast<volatile __int64*>(pointer),
+                                                     value, expected);
     return result == expected;
 }
 
-bool AtomicCompareAndSwap(u64 volatile* pointer, u128 value, u128 expected) {
-    return _InterlockedCompareExchange128((__int64*)pointer, value[1], value[0],
-                                          (__int64*)expected.data()) != 0;
+bool AtomicCompareAndSwap(volatile u64* pointer, u128 value, u128 expected) {
+    return _InterlockedCompareExchange128(reinterpret_cast<volatile __int64*>(pointer), value[1],
+                                          value[0],
+                                          reinterpret_cast<__int64*>(expected.data())) != 0;
 }
 
 #else
 
-bool AtomicCompareAndSwap(u8 volatile* pointer, u8 value, u8 expected) {
+bool AtomicCompareAndSwap(volatile u8* pointer, u8 value, u8 expected) {
     return __sync_bool_compare_and_swap(pointer, expected, value);
 }
 
-bool AtomicCompareAndSwap(u16 volatile* pointer, u16 value, u16 expected) {
+bool AtomicCompareAndSwap(volatile u16* pointer, u16 value, u16 expected) {
     return __sync_bool_compare_and_swap(pointer, expected, value);
 }
 
-bool AtomicCompareAndSwap(u32 volatile* pointer, u32 value, u32 expected) {
+bool AtomicCompareAndSwap(volatile u32* pointer, u32 value, u32 expected) {
     return __sync_bool_compare_and_swap(pointer, expected, value);
 }
 
-bool AtomicCompareAndSwap(u64 volatile* pointer, u64 value, u64 expected) {
+bool AtomicCompareAndSwap(volatile u64* pointer, u64 value, u64 expected) {
     return __sync_bool_compare_and_swap(pointer, expected, value);
 }
 
-bool AtomicCompareAndSwap(u64 volatile* pointer, u128 value, u128 expected) {
+bool AtomicCompareAndSwap(volatile u64* pointer, u128 value, u128 expected) {
     unsigned __int128 value_a;
     unsigned __int128 expected_a;
     std::memcpy(&value_a, value.data(), sizeof(u128));
diff --git a/src/common/atomic_ops.h b/src/common/atomic_ops.h
index e6181d521..8d6b73c00 100644
--- a/src/common/atomic_ops.h
+++ b/src/common/atomic_ops.h
@@ -8,10 +8,10 @@
 
 namespace Common {
 
-bool AtomicCompareAndSwap(u8 volatile* pointer, u8 value, u8 expected);
-bool AtomicCompareAndSwap(u16 volatile* pointer, u16 value, u16 expected);
-bool AtomicCompareAndSwap(u32 volatile* pointer, u32 value, u32 expected);
-bool AtomicCompareAndSwap(u64 volatile* pointer, u64 value, u64 expected);
-bool AtomicCompareAndSwap(u64 volatile* pointer, u128 value, u128 expected);
+bool AtomicCompareAndSwap(volatile u8* pointer, u8 value, u8 expected);
+bool AtomicCompareAndSwap(volatile u16* pointer, u16 value, u16 expected);
+bool AtomicCompareAndSwap(volatile u32* pointer, u32 value, u32 expected);
+bool AtomicCompareAndSwap(volatile u64* pointer, u64 value, u64 expected);
+bool AtomicCompareAndSwap(volatile u64* pointer, u128 value, u128 expected);
 
 } // namespace Common
-- 
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