[wasm] reuse the first compiled module

src/runtime/runtime-wasm.cc

 // Copyright 2016 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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/assembler.h"
 #include "src/compiler/wasm-compiler.h"
 #include "src/conversions.h"
 #include "src/debug/debug.h"
 #include "src/factory.h"
 #include "src/frames-inl.h"
 #include "src/objects-inl.h"
 #include "src/v8memory.h"
 #include "src/wasm/wasm-module.h"
 
 namespace v8 {
 namespace internal {
 
-namespace {
-const int kWasmMemArrayBuffer = 2;
-}
-
 RUNTIME_FUNCTION(Runtime_WasmGrowMemory) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   uint32_t delta_pages = 0;
   CHECK(args[0]->ToUint32(&delta_pages));
-  Handle<JSObject> module_object;
+  Handle<JSObject> module_instance;
 
   {
     // Get the module JSObject
     DisallowHeapAllocation no_allocation;
     const Address entry = Isolate::c_entry_fp(isolate->thread_local_top());
     Address pc =
         Memory::Address_at(entry + StandardFrameConstants::kCallerPCOffset);
     Code* code =
         isolate->inner_pointer_to_code_cache()->GetCacheEntry(pc)->code;
     Object* undefined = *isolate->factory()->undefined_value();
     Object* owning_instance = wasm::GetOwningWasmInstance(undefined, code);
     CHECK_NOT_NULL(owning_instance);
     CHECK_NE(owning_instance, undefined);
-    module_object = handle(JSObject::cast(owning_instance), isolate);
+    module_instance = handle(JSObject::cast(owning_instance), isolate);
   }
 
   Address old_mem_start, new_mem_start;
   uint32_t old_size, new_size;
 
   // Get mem buffer associated with module object
-  Handle<Object> obj(module_object->GetInternalField(kWasmMemArrayBuffer),
-                     isolate);
-
-  if (obj->IsUndefined(isolate)) {
+  MaybeHandle<JSArrayBuffer> maybe_mem_buffer =
+      wasm::GetInstanceMemory(isolate, module_instance);
+  Handle<JSArrayBuffer> old_buffer;
+  if (!maybe_mem_buffer.ToHandle(&old_buffer)) {
     // If module object does not have linear memory associated with it,
     // Allocate new array buffer of given size.
     old_mem_start = nullptr;
     old_size = 0;
     // TODO(gdeepti): Fix bounds check to take into account size of memtype.
     new_size = delta_pages * wasm::WasmModule::kPageSize;
     // The code generated in the wasm compiler guarantees this precondition.
     DCHECK(delta_pages <= wasm::WasmModule::kMaxMemPages);
     new_mem_start =
         static_cast<Address>(isolate->array_buffer_allocator()->Allocate(
             static_cast<uint32_t>(new_size)));
     if (new_mem_start == NULL) {
       return *isolate->factory()->NewNumberFromInt(-1);
     }
 #if DEBUG
     // Double check the API allocator actually zero-initialized the memory.
     for (size_t i = old_size; i < new_size; i++) {
       DCHECK_EQ(0, new_mem_start[i]);
     }
 #endif
   } else {
-    Handle<JSArrayBuffer> old_buffer = Handle<JSArrayBuffer>::cast(obj);
     old_mem_start = static_cast<Address>(old_buffer->backing_store());
     old_size = old_buffer->byte_length()->Number();
     // If the old memory was zero-sized, we should have been in the
     // "undefined" case above.
     DCHECK_NOT_NULL(old_mem_start);
     DCHECK_NE(0, old_size);
 
     new_size = old_size + delta_pages * wasm::WasmModule::kPageSize;
     if (new_size >
         wasm::WasmModule::kMaxMemPages * wasm::WasmModule::kPageSize) {
       return *isolate->factory()->NewNumberFromInt(-1);
     }
     new_mem_start = static_cast<Address>(realloc(old_mem_start, new_size));
     if (new_mem_start == NULL) {
       return *isolate->factory()->NewNumberFromInt(-1);
     }
     old_buffer->set_is_external(true);
     isolate->heap()->UnregisterArrayBuffer(*old_buffer);
     // Zero initializing uninitialized memory from realloc
     memset(new_mem_start + old_size, 0, new_size - old_size);
   }
 
   Handle<JSArrayBuffer> buffer = isolate->factory()->NewJSArrayBuffer();
   JSArrayBuffer::Setup(buffer, isolate, false, new_mem_start, new_size);
   buffer->set_is_neuterable(false);
 
   // Set new buffer to be wasm memory
-  module_object->SetInternalField(kWasmMemArrayBuffer, *buffer);
 
-  CHECK(wasm::UpdateWasmModuleMemory(module_object, old_mem_start,
+  wasm::SetInstanceMemory(module_instance, *buffer);
+
+  CHECK(wasm::UpdateWasmModuleMemory(module_instance, old_mem_start,
                                      new_mem_start, old_size, new_size));
 
   return *isolate->factory()->NewNumberFromInt(old_size /
                                                wasm::WasmModule::kPageSize);
 }
 
 RUNTIME_FUNCTION(Runtime_WasmThrowTypeError) {
   HandleScope scope(isolate);
   DCHECK_EQ(0, args.length());
   THROW_NEW_ERROR_RETURN_FAILURE(
       isolate, NewTypeError(MessageTemplate::kWasmTrapTypeError));
 }
 }  // namespace internal
 }  // namespace v8