[wasm] Call a runtime function for a MemorySize instruction.

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 {
 
+RUNTIME_FUNCTION(Runtime_WasmMemorySize) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(0, args.length());
+
+  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* owning_instance = wasm::GetOwningWasmInstance(code);
+    CHECK_NOT_NULL(owning_instance);
+    module_instance = handle(JSObject::cast(owning_instance), isolate);
+  }
+  return *isolate->factory()->NewNumberFromInt(
+      wasm::GetInstanceMemorySize(isolate, module_instance));
+}
+
 RUNTIME_FUNCTION(Runtime_WasmGrowMemory) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_UINT32_ARG_CHECKED(delta_pages, 0);
   Handle<JSObject> module_instance;
   {
     // Get the module JSObject
     DisallowHeapAllocation no_allocation;
     const Address entry = Isolate::c_entry_fp(isolate->thread_local_top());
     Address pc =
@@ skipping 32 matching lines @@
   Object* exception = args[0];
   // The unwinder will only deliver exceptions to wasm if the exception is a
   // Number or a Smi (which we have just converted to a Number.) This logic
   // lives in Isolate::is_catchable_by_wasm(Object*).
   CHECK(exception->IsNumber());
   return exception;
 }
 
 }  // namespace internal
 }  // namespace v8