[TurboFan] Make TSAN happy with background Code reads

Perform relaxed reads/writes on the builtin index.

Bug: v8:11478, v8:7790
Change-Id: I488fd30e6635f39bb46440e9d5230ab311825e7d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2716290Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73012}

src/objects/code-inl.h

@@ -492,14 +492,14 @@ inline HandlerTable::CatchPrediction Code::GetBuiltinCatchPrediction() {
 }
 
 int Code::builtin_index() const {
-  int index = ReadField<int>(kBuiltinIndexOffset);
+  int index = RELAXED_READ_INT_FIELD(*this, kBuiltinIndexOffset);
   DCHECK(index == Builtins::kNoBuiltinId || Builtins::IsBuiltinId(index));
   return index;
 }
 
 void Code::set_builtin_index(int index) {
   DCHECK(index == Builtins::kNoBuiltinId || Builtins::IsBuiltinId(index));
-  WriteField<int>(kBuiltinIndexOffset, index);
+  RELAXED_WRITE_INT_FIELD(*this, kBuiltinIndexOffset, index);
 }
 
 bool Code::is_builtin() const {

src/objects/object-macros.h

@@ -553,7 +553,15 @@
 #define RELAXED_WRITE_INT32_FIELD(p, offset, value)             \
   base::Relaxed_Store(                                          \
       reinterpret_cast<base::Atomic32*>(FIELD_ADDR(p, offset)), \
-      static_cast<base::Atomic32>(value));
+      static_cast<base::Atomic32>(value))
+
+static_assert(sizeof(int) == sizeof(int32_t),
+              "sizeof int must match sizeof int32_t");
+
+#define RELAXED_READ_INT_FIELD(p, offset) RELAXED_READ_INT32_FIELD(p, offset)
+
+#define RELAXED_WRITE_INT_FIELD(p, offset, value) \
+  RELAXED_WRITE_INT32_FIELD(p, offset, value)
 
 #define RELAXED_READ_BYTE_FIELD(p, offset) \
   static_cast<byte>(base::Relaxed_Load(    \