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

src/code-stub-assembler.cc

Index: src/code-stub-assembler.cc
diff --git a/src/code-stub-assembler.cc b/src/code-stub-assembler.cc
index 970dc4f54230a7f30747f82b016bf90b0f6e7a3c..4847366c3ef1f05be572b94de07c3c87d58a8a59 100644
--- a/src/code-stub-assembler.cc
+++ b/src/code-stub-assembler.cc
@@ -1276,6 +1276,27 @@ 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);
+

[Benedikt Meurer, 2016/11/04 16:45:58]

Nit: Please add some kind of assert here. It'd be nice to catch bugs via an
assert instead of an endless loop once the native context is reached.

+    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));