Patch to enhance the source code line information for profiler.

src/arm/lithium-arm.h

Index: src/arm/lithium-arm.h
===================================================================
--- src/arm/lithium-arm.h	(revision 16062)
+++ src/arm/lithium-arm.h	(working copy)
@@ -209,9 +209,12 @@
 class LInstruction: public ZoneObject {
  public:
   LInstruction()
-      :  environment_(NULL),
-         hydrogen_value_(NULL),
-         is_call_(false) { }
+      : environment_(NULL),
+        hydrogen_value_(NULL),
+        bit_field_(IsCallBits::encode(false)) {
+    set_position(RelocInfo::kNoPosition);
+  }
+
   virtual ~LInstruction() { }
 
   virtual void CompileToNative(LCodeGen* generator) = 0;
@@ -250,20 +253,30 @@
   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_; }
 
   virtual void SetDeferredLazyDeoptimizationEnvironment(LEnvironment* env) { }
 
-  void MarkAsCall() { is_call_ = true; }
+  void MarkAsCall() { bit_field_ = IsCallBits::update(bit_field_, true); }
+  bool IsCall() const { return IsCallBits::decode(bit_field_); }
 
   // 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 IsCall(); }
+  bool ClobbersRegisters() const { return IsCall(); }
+  bool ClobbersDoubleRegisters() const { return IsCall(); }
 
   // Interface to the register allocator and iterators.
-  bool IsMarkedAsCall() const { return is_call_; }
+  bool IsMarkedAsCall() const { return IsCall(); }
 
   virtual bool HasResult() const = 0;
   virtual LOperand* result() const = 0;
@@ -287,10 +300,13 @@
   virtual int TempCount() = 0;
   virtual LOperand* TempAt(int i) = 0;
 
+  class IsCallBits: public BitField<bool, 0, 1> {};
+  class PositionBits: public BitField<int, 1, 31> {};
+
   LEnvironment* environment_;
   SetOncePointer<LPointerMap> pointer_map_;
   HValue* hydrogen_value_;
-  bool is_call_;
+  int bit_field_;
 };