Patch to enhance the source code line information for profiler.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
===================================================================
--- src/x64/lithium-codegen-x64.cc	(revision 16062)
+++ src/x64/lithium-codegen-x64.cc	(working copy)
@@ -278,6 +278,8 @@
               instr->Mnemonic());
     }
 
+    RecordAndUpdatePosition(instr->position());
+
     instr->CompileToNative(this);
   }
   EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
@@ -331,6 +333,10 @@
   if (deferred_.length() > 0) {
     for (int i = 0; !is_aborted() && i < deferred_.length(); i++) {
       LDeferredCode* code = deferred_[i];
+
+      int pos = instructions_->at(code->instruction_index())->position();
+      RecordAndUpdatePosition(pos);
+
       Comment(";;; <@%d,#%d> "
               "-------------------- Deferred %s --------------------",
               code->instruction_index(),
@@ -859,6 +865,14 @@
 }
 
 
+void LCodeGen::RecordAndUpdatePosition(int position) {
+  if (position >= 0 && position != old_position_) {
+    masm()->positions_recorder()->RecordPosition(position);
+    old_position_ = position;
+  }
+}
+
+
 static const char* LabelType(LLabel* label) {
   if (label->is_loop_header()) return " (loop header)";
   if (label->is_osr_entry()) return " (OSR entry)";