Patch to enhance the source code line information for profiler.

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
===================================================================
--- src/x64/lithium-x64.h	(revision 15993)
+++ src/x64/lithium-x64.h	(working copy)
@@ -207,10 +207,10 @@
 
 class LInstruction: public ZoneObject {
  public:
-  LInstruction()
-      :  environment_(NULL),
-         hydrogen_value_(NULL),
-         is_call_(false) { }
+  LInstruction() : environment_(NULL), hydrogen_value_(NULL) {
+    bit_field_ = IsCallBits::encode(false) |
+        PositionBits::encode(RelocInfo::kNoPosition + 1);
+  }
 
   virtual ~LInstruction() { }
 
@@ -250,20 +250,31 @@
   LPointerMap* pointer_map() const { return pointer_map_.get(); }
   bool HasPointerMap() const { return pointer_map_.is_set(); }
 
+  // The 31 bits PositionBits is used to store the int position value. And the
+  // position value may be RelocInfo::kNoPosition (-1). The accessor always
+  // +1/-1 so that the encoded value of position in bit_field_ is always >= 0
+  // and can fit into the 31 bits PositionBits.
+  void set_position(int pos) {
+    bit_field_ = PositionBits::update(bit_field_, pos + 1);
+  }
+  int position() { return PositionBits::decode(bit_field_) - 1; }
+
   void set_hydrogen_value(HValue* value) { hydrogen_value_ = value; }
   HValue* hydrogen_value() const { return hydrogen_value_; }
 
-  void MarkAsCall() { is_call_ = true; }
+  void MarkAsCall() { bit_field_ = IsCallBits::update(bit_field_, true); }
 
   // Interface to the register allocator and iterators.
-  bool ClobbersTemps() const { return is_call_; }
-  bool ClobbersRegisters() const { return is_call_; }
-  bool ClobbersDoubleRegisters() const { return is_call_; }
+  bool ClobbersTemps() const { return IsCallBits::decode(bit_field_); }
+  bool ClobbersRegisters() const { return IsCallBits::decode(bit_field_); }
+  bool ClobbersDoubleRegisters() const {
+    return IsCallBits::decode(bit_field_);
+  }
 
   virtual void SetDeferredLazyDeoptimizationEnvironment(LEnvironment* env) { }
 
   // Interface to the register allocator and iterators.
-  bool IsMarkedAsCall() const { return is_call_; }
+  bool IsMarkedAsCall() const { return IsCallBits::decode(bit_field_); }
 
   virtual bool HasResult() const = 0;
   virtual LOperand* result() const = 0;
@@ -290,7 +301,9 @@
   LEnvironment* environment_;
   SetOncePointer<LPointerMap> pointer_map_;
   HValue* hydrogen_value_;
-  bool is_call_;
+  int bit_field_;
+  class IsCallBits: public BitField<bool, 0, 1> {};
+  class PositionBits: public BitField<int, 1, 31> {};
 };