Cleaned up and fixed code comment handling a bit.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index fb5dd5934927de68c99ea4dc302c621a633d9268..3e8fd5c72fb582ac662e6be50f6172ff97f91739 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -370,7 +370,7 @@ bool LCodeGen::GenerateDeferredCode() {
       LDeferredCode* code = deferred_[i];
       __ bind(code->entry());
       if (NeedsDeferredFrame()) {
-        Comment(";;; Deferred build frame",
+        Comment(";;; Deferred build frame @%d: %s.",
                 code->instruction_index(),
                 code->instr()->Mnemonic());
         ASSERT(!frame_is_built_);
@@ -387,7 +387,7 @@ bool LCodeGen::GenerateDeferredCode() {
               code->instr()->Mnemonic());
       code->Generate();
       if (NeedsDeferredFrame()) {
-        Comment(";;; Deferred destroy frame",
+        Comment(";;; Deferred destroy frame @%d: %s.",
                 code->instruction_index(),
                 code->instr()->Mnemonic());
         ASSERT(frame_is_built_);
@@ -926,11 +926,9 @@ void LCodeGen::RecordPosition(int position) {
 
 
 void LCodeGen::DoLabel(LLabel* label) {
-  if (label->is_loop_header()) {
-    Comment(";;; B%d - LOOP entry", label->block_id());
-  } else {
-    Comment(";;; B%d", label->block_id());
-  }
+  Comment(";;; -------------------- B%d%s --------------------",
+          label->block_id(),
+          label->is_loop_header() ? " (loop header)" : "");
   __ bind(label->label());
   current_block_ = label->block_id();
   DoGap(label);