[wasm] Remove dangerous ByteArray::data accessor.

src/wasm/wasm-module.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <memory>
 
 #include "src/base/atomic-utils.h"
 #include "src/code-stubs.h"
 
 #include "src/macro-assembler.h"
@@ skipping 496 matching lines @@
   if (target->IsJSFunction()) {
     Handle<JSFunction> func = Handle<JSFunction>::cast(target);
     export_wrapper_code = handle(func->code());
     if (export_wrapper_code->kind() == Code::JS_TO_WASM_FUNCTION) {
       int exported_param_count =
           Smi::cast(func->GetInternalField(kInternalArity))->value();
       Handle<ByteArray> exportedSig = Handle<ByteArray>(
           ByteArray::cast(func->GetInternalField(kInternalSignature)));
       if (exported_param_count == param_count &&
           exportedSig->length() == sig_data->length() &&
-          memcmp(exportedSig->data(), sig_data->data(),
-                 exportedSig->length()) == 0) {
+          memcmp(exportedSig->GetDataStartAddress(),
+                 sig_data->GetDataStartAddress(), exportedSig->length()) == 0) {
         isMatch = true;
       }
     }
   }
   if (isMatch) {
     int wasm_count = 0;
     int const mask = RelocInfo::ModeMask(RelocInfo::CODE_TARGET);
     for (RelocIterator it(*export_wrapper_code, mask); !it.done(); it.next()) {
       RelocInfo* rinfo = it.rinfo();
       Address target_address = rinfo->target_address();
       Code* target = Code::GetCodeFromTargetAddress(target_address);
       if (target->kind() == Code::WASM_FUNCTION) {
         ++wasm_count;
         code = handle(target);
       }
     }
     DCHECK(wasm_count == 1);
     return code;
   } else {
     // Copy the signature to avoid a raw pointer into a heap object when
     // GC can happen.
     Zone zone(isolate->allocator());
     MachineRepresentation* reps =
         zone.NewArray<MachineRepresentation>(sig_data_size);
-    memcpy(reps, sig_data->data(),
+    memcpy(reps, sig_data->GetDataStartAddress(),
            sizeof(MachineRepresentation) * sig_data_size);
     FunctionSig sig(ret_count, param_count, reps);
 
     return compiler::CompileWasmToJSWrapper(isolate, target, &sig, index,
                                             module_name, function_name);
   }
 }
 
 void InitializeParallelCompilation(
     Isolate* isolate, const std::vector<WasmFunction>& functions,
@@ skipping 1359 matching lines @@
   WasmCompiledModule* compiled_module =
       WasmCompiledModule::cast(instance->GetInternalField(kWasmCompiledModule));
   CHECK(compiled_module->has_weak_module_object());
   CHECK(compiled_module->ptr_to_weak_module_object()->cleared());
 }
 
 }  // namespace testing
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8