[wasm] Support mutable imported anyref globals in interpreter.

This adds support for loading and storing mutable imported globals
having a reference type in the interpreter. It expands existing test
coverage to the interpreter.

R=clemensh@chromium.org
TEST=mjsunit/wasm/anyref-globals-interpreter
BUG=v8:8091,v8:7581

Change-Id: I78e0c5c73664a183e1d92ec91eadf8b9a93e4787
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1559743Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60701}

src/wasm/wasm-interpreter.cc

@@ -2039,6 +2039,7 @@ class ThreadImpl {
   }
 
   byte* GetGlobalPtr(const WasmGlobal* global) {
+    DCHECK(!ValueTypes::IsReferenceType(global->type));
     if (global->mutability && global->imported) {
       return reinterpret_cast<byte*>(
           instance_object_->imported_mutable_globals()[global->index]);
@@ -2047,6 +2048,24 @@ class ThreadImpl {
     }
   }
 
+  void GetGlobalBufferAndIndex(const WasmGlobal* global,
+                               Handle<FixedArray>* buffer, uint32_t* index) {
+    DCHECK(ValueTypes::IsReferenceType(global->type));
+    if (global->mutability && global->imported) {
+      *buffer =
+          handle(FixedArray::cast(
+                     instance_object_->imported_mutable_globals_buffers()->get(
+                         global->index)),
+                 isolate_);
+      Address idx = instance_object_->imported_mutable_globals()[global->index];
+      DCHECK_LE(idx, std::numeric_limits<uint32_t>::max());
+      *index = static_cast<uint32_t>(idx);
+    } else {
+      *buffer = handle(instance_object_->tagged_globals_buffer(), isolate_);
+      *index = global->offset;
+    }
+  }
+
   bool ExecuteSimdOp(WasmOpcode opcode, Decoder* decoder, InterpreterCode* code,
                      pc_t pc, int& len) {
     switch (opcode) {
@@ -3046,11 +3065,11 @@ class ThreadImpl {
             case kWasmAnyFunc:
             case kWasmExceptRef: {
               HandleScope handle_scope(isolate_);  // Avoid leaking handles.
-              DCHECK(!global->mutability || !global->imported);
-              Push(WasmValue(
-                  handle(instance_object_->tagged_globals_buffer()->get(
-                             global->offset),
-                         isolate_)));
+              Handle<FixedArray> global_buffer;    // The buffer of the global.
+              uint32_t global_index = 0;           // The index into the buffer.
+              GetGlobalBufferAndIndex(global, &global_buffer, &global_index);
+              Handle<Object> value(global_buffer->get(global_index), isolate_);
+              Push(WasmValue(value));
               break;
             }
             default:
@@ -3077,9 +3096,10 @@ class ThreadImpl {
             case kWasmAnyFunc:
             case kWasmExceptRef: {
               HandleScope handle_scope(isolate_);  // Avoid leaking handles.
-              DCHECK(!global->mutability || !global->imported);
-              instance_object_->tagged_globals_buffer()->set(
-                  global->offset, *Pop().to_anyref());
+              Handle<FixedArray> global_buffer;    // The buffer of the global.
+              uint32_t global_index = 0;           // The index into the buffer.
+              GetGlobalBufferAndIndex(global, &global_buffer, &global_index);
+              global_buffer->set(global_index, *Pop().to_anyref());
               break;
             }
             default:

test/mjsunit/wasm/anyref-globals-interpreter.js

+// Copyright 2019 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.
+
+// Flags: --experimental-wasm-anyref --expose-gc
+// Flags: --wasm-interpret-all
+
+// This is just a wrapper for an existing reference types test case that runs
+// with the --wasm-interpret-all flag added. If we ever decide to add a test
+// variant for this, then we can remove this file.
+
+load("test/mjsunit/wasm/anyref-globals.js");