[wasm] Use WeakFixedArray for list of instances sharing a WasmMemoryObject.

src/wasm/module-compiler.cc

 // Copyright 2017 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 <src/wasm/module-compiler.h>
 
 #include <atomic>
 
 #include "src/asmjs/asm-js.h"
 #include "src/assembler-inl.h"
@@ skipping 1004 matching lines @@
 
   //--------------------------------------------------------------------------
   // Set up the exports object for the new instance.
   //--------------------------------------------------------------------------
   ProcessExports(code_table, instance, compiled_module_);
   if (thrower_->error()) return {};
 
   //--------------------------------------------------------------------------
   // Add instance to Memory object
   //--------------------------------------------------------------------------
-  DCHECK(instance->IsWasmInstanceObject());
   if (instance->has_memory_object()) {
-    instance->memory_object()->AddInstance(isolate_, instance);
+    Handle<WasmMemoryObject> memory(instance->memory_object(), isolate_);
+    WasmMemoryObject::AddInstance(isolate_, memory, instance);
   }
 
   //--------------------------------------------------------------------------
   // Initialize the indirect function tables.
   //--------------------------------------------------------------------------
   if (function_table_count > 0) LoadTableSegments(code_table, instance);
 
   // Patch all code with the relocations registered in code_specialization.
   code_specialization.RelocateDirectCalls(instance);
   code_specialization.ApplyToWholeInstance(*instance, SKIP_ICACHE_FLUSH);
@@ skipping 622 matching lines @@
           memory_object = WasmMemoryObject::New(
               isolate_,
               (instance->has_memory_buffer())
                   ? handle(instance->memory_buffer())
                   : Handle<JSArrayBuffer>::null(),
               (module_->max_mem_pages != 0) ? module_->max_mem_pages : -1);
           instance->set_memory_object(*memory_object);
         } else {
           memory_object =
               Handle<WasmMemoryObject>(instance->memory_object(), isolate_);
-          memory_object->ResetInstancesLink(isolate_);
         }
 
         desc.set_value(memory_object);
         break;
       }
       case kExternalGlobal: {
         // Export the value of the global variable as a number.
         WasmGlobal& global = module_->globals[exp.index];
         double num = 0;
         switch (global.type) {
@@ skipping 673 matching lines @@
     HandleScope scope(job_->isolate_);
     Handle<WasmModuleObject> result =
         WasmModuleObject::New(job_->isolate_, job_->compiled_module_);
     // {job_} is deleted in AsyncCompileSucceeded, therefore the {return}.
     return job_->AsyncCompileSucceeded(result);
   }
 };
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8