Revert "Revert "[wasm] Complete separation of compilation and instantiation""

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/conversions.h"
 #include "src/debug/debug.h"
@@ skipping 21 matching lines @@
   DCHECK(deopt_data->length() == 2);
   JSObject* module_object = JSObject::cast(deopt_data->get(0));
   RUNTIME_ASSERT(!module_object->IsNull(isolate));
 
   Address old_mem_start, new_mem_start;
   uint32_t old_size, new_size;
   const int kWasmMemArrayBuffer = 2;
 
   // Get mem buffer associated with module object
   Object* obj = module_object->GetInternalField(kWasmMemArrayBuffer);
-  Handle<JSArrayBuffer> old_buffer =
-      Handle<JSArrayBuffer>(JSArrayBuffer::cast(obj));
 
-  if (old_buffer->byte_length()->Number() == 0) {
+  if (obj->IsUndefined(isolate)) {
     // If module object does not have linear memory associated with it,
     // Allocate new array buffer of given size.
-    old_mem_start = static_cast<Address>(old_buffer->backing_store());
+    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;
     if (delta_pages > wasm::WasmModule::kMaxMemPages) {
       THROW_NEW_ERROR_RETURN_FAILURE(
           isolate, NewRangeError(MessageTemplate::kWasmTrapMemOutOfBounds));
     }
     new_mem_start =
         static_cast<Address>(isolate->array_buffer_allocator()->Allocate(
             static_cast<uint32_t>(new_size)));
     if (new_mem_start == NULL) {
       THROW_NEW_ERROR_RETURN_FAILURE(
           isolate, NewRangeError(MessageTemplate::kWasmTrapMemAllocationFail));
     }
 #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>(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) {
       THROW_NEW_ERROR_RETURN_FAILURE(
           isolate, NewRangeError(MessageTemplate::kWasmTrapMemOutOfBounds));
     }
     new_mem_start = static_cast<Address>(realloc(old_mem_start, new_size));
     if (new_mem_start == NULL) {
       THROW_NEW_ERROR_RETURN_FAILURE(
           isolate, NewRangeError(MessageTemplate::kWasmTrapMemAllocationFail));
@@ skipping 13 matching lines @@
 
   RUNTIME_ASSERT(wasm::UpdateWasmModuleMemory(
       module_object, old_mem_start, new_mem_start, old_size, new_size));
 
   return *isolate->factory()->NewNumberFromUint(old_size /
                                                 wasm::WasmModule::kPageSize);
 }
 
 }  // namespace internal
 }  // namespace v8