[ignition,modules] Introduce bytecodes for loading/storing module variables.

src/code-stub-assembler.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/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 #include "src/ic/handler-configuration.h"
 #include "src/ic/stub-cache.h"
 
@@ skipping 1258 matching lines @@
                                              Node* value) {
   int offset = Context::SlotOffset(slot_index);
   return Store(MachineRepresentation::kTagged, context, IntPtrConstant(offset),
                value);
 }
 
 Node* CodeStubAssembler::LoadNativeContext(Node* context) {
   return LoadContextElement(context, Context::NATIVE_CONTEXT_INDEX);
 }
 
+Node* CodeStubAssembler::LoadModuleContext(Node* context) {
+  Variable var_context(this, MachineRepresentation::kTaggedPointer);
+  var_context.Bind(context);
+
+  Label loop_start(this, &var_context), loop_end(this);
+  Goto(&loop_start);
+  Bind(&loop_start);
+  {
+    Node* context_map = LoadMap(var_context.value());
+    Node* is_module_context =
+        WordEqual(context_map, LoadRoot(Heap::kModuleContextMapRootIndex));
+    GotoIf(is_module_context, &loop_end);
+
+    var_context.Bind(
+        LoadContextElement(var_context.value(), Context::PREVIOUS_INDEX));
+    Goto(&loop_start);
+  }
+  Bind(&loop_end);
+  return var_context.value();
+}
+
 Node* CodeStubAssembler::LoadJSArrayElementsMap(ElementsKind kind,
                                                 Node* native_context) {
   CSA_ASSERT(IsNativeContext(native_context));
   return LoadFixedArrayElement(native_context,
                                IntPtrConstant(Context::ArrayMapIndex(kind)));
 }
 
 Node* CodeStubAssembler::StoreHeapNumberValue(Node* object, Node* value) {
   return StoreObjectFieldNoWriteBarrier(object, HeapNumber::kValueOffset, value,
                                         MachineRepresentation::kFloat64);
@@ skipping 7433 matching lines @@
   Node* buffer_bit_field = LoadObjectField(
       buffer, JSArrayBuffer::kBitFieldOffset, MachineType::Uint32());
   Node* was_neutered_mask = Int32Constant(JSArrayBuffer::WasNeutered::kMask);
 
   return Word32NotEqual(Word32And(buffer_bit_field, was_neutered_mask),
                         Int32Constant(0));
 }
 
 }  // namespace internal
 }  // namespace v8