Improved variable-related assembler comments in fullcode.

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 9380f190c365701af523d6c6d65cb155d78d1639..bd066e31d2cc8d7638650c74a6889ae2a76420a5 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -1444,7 +1444,7 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy) {
   // variables.
   switch (var->location()) {
     case Variable::UNALLOCATED: {
-      Comment cmnt(masm_, "Global variable");
+      Comment cmnt(masm_, "[ Global variable");
       // Use inline caching. Variable name is passed in rcx and the global
       // object on the stack.
       __ Move(rcx, var->name());
@@ -1457,7 +1457,8 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy) {
     case Variable::PARAMETER:
     case Variable::LOCAL:
     case Variable::CONTEXT: {
-      Comment cmnt(masm_, var->IsContextSlot() ? "Context slot" : "Stack slot");
+      Comment cmnt(masm_, var->IsContextSlot() ? "[ Context slot"
+                                               : "[ Stack slot");
       if (var->binding_needs_init()) {
         // var->scope() may be NULL when the proxy is located in eval code and
         // refers to a potential outside binding. Currently those bindings are
@@ -1519,12 +1520,12 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy) {
     }
 
     case Variable::LOOKUP: {
+      Comment cmnt(masm_, "[ Lookup slot");
       Label done, slow;
       // Generate code for loading from variables potentially shadowed
       // by eval-introduced variables.
       EmitDynamicLookupFastCase(var, NOT_INSIDE_TYPEOF, &slow, &done);
       __ bind(&slow);
-      Comment cmnt(masm_, "Lookup slot");
       __ push(rsi);  // Context.
       __ Push(var->name());
       __ CallRuntime(Runtime::kLoadContextSlot, 2);
@@ -4479,7 +4480,7 @@ void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
   ASSERT(!context()->IsTest());
 
   if (proxy != NULL && proxy->var()->IsUnallocated()) {
-    Comment cmnt(masm_, "Global variable");
+    Comment cmnt(masm_, "[ Global variable");
     __ Move(rcx, proxy->name());
     __ movp(rax, GlobalObjectOperand());
     // Use a regular load, not a contextual load, to avoid a reference
@@ -4488,6 +4489,7 @@ void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
     PrepareForBailout(expr, TOS_REG);
     context()->Plug(rax);
   } else if (proxy != NULL && proxy->var()->IsLookupSlot()) {
+    Comment cmnt(masm_, "[ Lookup slot");
     Label done, slow;
 
     // Generate code for loading from variables potentially shadowed