[wasm] Fix TSan reports for feedback vector size access

By using atomic accessors.

Change-Id: I7ff8660aa118c809da9ce6ff851ebd5080a7b1c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3217197
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77318}

src/wasm/module-instantiate.cc

@@ -6,6 +6,7 @@
 
 #include "src/api/api.h"
 #include "src/asmjs/asm-js.h"
+#include "src/base/atomicops.h"
 #include "src/base/platform/wrappers.h"
 #include "src/logging/counters-scopes.h"
 #include "src/logging/metrics.h"
@@ -715,7 +716,8 @@ MaybeHandle<WasmInstanceObject> InstanceBuilder::Build() {
     instance->set_feedback_vectors(*vectors);
     for (int i = 0; i < num_functions; i++) {
       int func_index = module_->num_imported_functions + i;
-      int slots = module_->functions[func_index].feedback_slots;
+      int slots =
+          base::Relaxed_Load(&module_->functions[func_index].feedback_slots);
       if (slots == 0) continue;
       if (FLAG_trace_wasm_speculative_inlining) {
         PrintF("[Function %d (declared %d): allocating %d feedback slots]\n",

src/wasm/wasm-code-manager.cc

@@ -8,6 +8,7 @@
 #include <iomanip>
 #include <numeric>
 
+#include "src/base/atomicops.h"
 #include "src/base/build_config.h"
 #include "src/base/iterator.h"
 #include "src/base/macros.h"
@@ -2268,10 +2269,13 @@ std::vector<std::unique_ptr<WasmCode>> NativeModule::AddCompiledCode(
     total_code_space += RoundUp<kCodeAlignment>(result.code_desc.instr_size);
     if (result.result_tier == ExecutionTier::kLiftoff) {
       int index = result.func_index;
-      DCHECK(module()->functions[index].feedback_slots == 0 ||
-             module()->functions[index].feedback_slots ==
-                 result.feedback_vector_slots);
-      module()->functions[index].feedback_slots = result.feedback_vector_slots;
+      int* slots = &module()->functions[index].feedback_slots;
+#if DEBUG
+      int current_value = base::Relaxed_Load(slots);
+      DCHECK(current_value == 0 ||
+             current_value == result.feedback_vector_slots);
+#endif
+      base::Relaxed_Store(slots, result.feedback_vector_slots);
     }
   }
   base::Vector<byte> code_space;