From 8f170a66e7badc4044f2d0bc19ae9611f0cd4cec Mon Sep 17 00:00:00 2001
From: "vegorov@chromium.org"
 <vegorov@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Thu, 13 Feb 2014 16:09:28 +0000
Subject: [PATCH] Improve positions tracking inside the HGraphBuilder.

Instead of tracking simple absolute offset from the start of the script like other places do, track a pair of (inlining id, offset from the start of inlined function).

This enables us to pinpoint with inlining path an instruction came from. Previously in multi-script environments we emitted positions that made very little sense because inside a single optimized function they would point to different scripts without a way to distinguish them.

Start dumping the source of every inlined function to make possible IR viewing tools with integrated source views as there was previously no way to acquire this information from IR dumps. We also dump source position at which each inlining occured.

Tracked positions are written into hydrogen.cfg as pos:<inlining-id>_<offset>.

Flag --emit-opt-code-positions is renamed by this change into --hydrogen-track-positions to better convey it's meaning.

In addition this change assigned global unique identifier to each optimization performed inside isolate. This allows to precisely match compilation artifacts (e.g. IR and disassembly) and deoptimizations.

BUG=
R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/140683011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19360 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/arm/lithium-arm.cc                 |   1 -
 src/arm/lithium-arm.h                  |   2 -
 src/arm/lithium-codegen-arm.cc         |   4 +-
 src/codegen.cc                         |   2 +
 src/compiler.cc                        |  14 ++-
 src/compiler.h                         |   5 +
 src/deoptimizer.cc                     |  13 +-
 src/flag-definitions.h                 |   7 +-
 src/hydrogen-instructions.cc           |  21 +++-
 src/hydrogen-instructions.h            | 124 +++++++++++++-----
 src/hydrogen-representation-changes.cc |   5 +-
 src/hydrogen.cc                        | 224 ++++++++++++++++++++++++++-------
 src/hydrogen.h                         |  89 ++++++++++---
 src/ia32/lithium-codegen-ia32.cc       |   4 +-
 src/isolate.cc                         |   3 +-
 src/isolate.h                          |  10 ++
 src/lithium-codegen.cc                 |   8 +-
 src/mips/lithium-codegen-mips.cc       |   4 +-
 src/objects.h                          |   4 +-
 src/x64/lithium-codegen-x64.cc         |   4 +-
 20 files changed, 417 insertions(+), 131 deletions(-)

diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index 38509a6..8eb5eb7 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -840,7 +840,6 @@ void LChunkBuilder::DoBasicBlock(HBasicBlock* block, HBasicBlock* next_block) {
 void LChunkBuilder::VisitInstruction(HInstruction* current) {
   HInstruction* old_current = current_instruction_;
   current_instruction_ = current;
-  if (current->has_position()) position_ = current->position();
 
   LInstruction* instr = NULL;
   if (current->CanReplaceWithDummyUses()) {
diff --git a/src/arm/lithium-arm.h b/src/arm/lithium-arm.h
index 29a1766..982ac2c 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -2580,7 +2580,6 @@ class LChunkBuilder V8_FINAL : public LChunkBuilderBase {
         current_block_(NULL),
         next_block_(NULL),
         allocator_(allocator),
-        position_(RelocInfo::kNoPosition),
         instruction_pending_deoptimization_environment_(NULL),
         pending_deoptimization_ast_id_(BailoutId::None()) { }
 
@@ -2717,7 +2716,6 @@ class LChunkBuilder V8_FINAL : public LChunkBuilderBase {
   HBasicBlock* current_block_;
   HBasicBlock* next_block_;
   LAllocator* allocator_;
-  int position_;
   LInstruction* instruction_pending_deoptimization_environment_;
   BailoutId pending_deoptimization_ast_id_;
 
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 54ec589..424f2e6 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -277,7 +277,8 @@ bool LCodeGen::GenerateDeferredCode() {
 
       HValue* value =
           instructions_->at(code->instruction_index())->hydrogen_value();
-      RecordAndWritePosition(value->position());
+      RecordAndWritePosition(
+          chunk()->graph()->SourcePositionToScriptPosition(value->position()));
 
       Comment(";;; <@%d,#%d> "
               "-------------------- Deferred %s --------------------",
@@ -906,6 +907,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
       translations_.CreateByteArray(isolate()->factory());
   data->SetTranslationByteArray(*translations);
   data->SetInlinedFunctionCount(Smi::FromInt(inlined_function_count_));
+  data->SetOptimizationId(Smi::FromInt(info_->optimization_id()));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);
diff --git a/src/codegen.cc b/src/codegen.cc
index 13ce221..f6c3668 100644
--- a/src/codegen.cc
+++ b/src/codegen.cc
@@ -165,6 +165,8 @@ void CodeGenerator::PrintCode(Handle<Code> code, CompilationInfo* info) {
             function->debug_name()->ToCString().get(), tracing_scope.file());
       }
       PrintF(tracing_scope.file(), "--- Optimized code ---\n");
+      PrintF(tracing_scope.file(),
+             "optimization_id = %d\n", info->optimization_id());
     } else {
       PrintF(tracing_scope.file(), "--- Code ---\n");
     }
diff --git a/src/compiler.cc b/src/compiler.cc
index 6ebbe41..003c5ab 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -60,7 +60,8 @@ CompilationInfo::CompilationInfo(Handle<Script> script,
       script_(script),
       osr_ast_id_(BailoutId::None()),
       parameter_count_(0),
-      this_has_uses_(true) {
+      this_has_uses_(true),
+      optimization_id_(-1) {
   Initialize(script->GetIsolate(), BASE, zone);
 }
 
@@ -72,7 +73,8 @@ CompilationInfo::CompilationInfo(Handle<SharedFunctionInfo> shared_info,
       script_(Handle<Script>(Script::cast(shared_info->script()))),
       osr_ast_id_(BailoutId::None()),
       parameter_count_(0),
-      this_has_uses_(true) {
+      this_has_uses_(true),
+      optimization_id_(-1) {
   Initialize(script_->GetIsolate(), BASE, zone);
 }
 
@@ -86,7 +88,8 @@ CompilationInfo::CompilationInfo(Handle<JSFunction> closure,
       context_(closure->context()),
       osr_ast_id_(BailoutId::None()),
       parameter_count_(0),
-      this_has_uses_(true) {
+      this_has_uses_(true),
+      optimization_id_(-1) {
   Initialize(script_->GetIsolate(), BASE, zone);
 }
 
@@ -98,7 +101,8 @@ CompilationInfo::CompilationInfo(HydrogenCodeStub* stub,
              IsLazy::encode(true)),
       osr_ast_id_(BailoutId::None()),
       parameter_count_(0),
-      this_has_uses_(true) {
+      this_has_uses_(true),
+      optimization_id_(-1) {
   Initialize(isolate, STUB, zone);
   code_stub_ = stub;
 }
@@ -405,7 +409,7 @@ OptimizedCompileJob::Status OptimizedCompileJob::CreateGraph() {
   // Type-check the function.
   AstTyper::Run(info());
 
-  graph_builder_ = FLAG_emit_opt_code_positions
+  graph_builder_ = FLAG_hydrogen_track_positions
       ? new(info()->zone()) HOptimizedGraphBuilderWithPositions(info())
       : new(info()->zone()) HOptimizedGraphBuilder(info());
 
diff --git a/src/compiler.h b/src/compiler.h
index 9d1baa3..f7ff09c 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -227,6 +227,7 @@ class CompilationInfo {
     SetMode(OPTIMIZE);
     osr_ast_id_ = osr_ast_id;
     unoptimized_code_ = unoptimized;
+    optimization_id_ = isolate()->NextOptimizationId();
   }
   void DisableOptimization();
 
@@ -315,6 +316,8 @@ class CompilationInfo {
     return osr_ast_id_ == osr_ast_id && function.is_identical_to(closure_);
   }
 
+  int optimization_id() const { return optimization_id_; }
+
  protected:
   CompilationInfo(Handle<Script> script,
                   Zone* zone);
@@ -450,6 +453,8 @@ class CompilationInfo {
 
   Handle<Foreign> object_wrapper_;
 
+  int optimization_id_;
+
   DISALLOW_COPY_AND_ASSIGN(CompilationInfo);
 };
 
diff --git a/src/deoptimizer.cc b/src/deoptimizer.cc
index f07aab8..68b10d9 100644
--- a/src/deoptimizer.cc
+++ b/src/deoptimizer.cc
@@ -731,6 +731,12 @@ void Deoptimizer::DoComputeOutputFrames() {
     LOG(isolate(), CodeDeoptEvent(compiled_code_));
   }
   ElapsedTimer timer;
+
+  // Determine basic deoptimization information.  The optimized frame is
+  // described by the input data.
+  DeoptimizationInputData* input_data =
+      DeoptimizationInputData::cast(compiled_code_->deoptimization_data());
+
   if (trace_scope_ != NULL) {
     timer.Start();
     PrintF(trace_scope_->file(),
@@ -739,7 +745,8 @@ void Deoptimizer::DoComputeOutputFrames() {
            reinterpret_cast<intptr_t>(function_));
     PrintFunctionName();
     PrintF(trace_scope_->file(),
-           " @%d, FP to SP delta: %d]\n",
+           " (opt #%d) @%d, FP to SP delta: %d]\n",
+           input_data->OptimizationId()->value(),
            bailout_id_,
            fp_to_sp_delta_);
     if (bailout_type_ == EAGER || bailout_type_ == SOFT) {
@@ -747,10 +754,6 @@ void Deoptimizer::DoComputeOutputFrames() {
     }
   }
 
-  // Determine basic deoptimization information.  The optimized frame is
-  // described by the input data.
-  DeoptimizationInputData* input_data =
-      DeoptimizationInputData::cast(compiled_code_->deoptimization_data());
   BailoutId node_id = input_data->AstId(bailout_id_);
   ByteArray* translations = input_data->TranslationByteArray();
   unsigned translation_index =
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 7befbdc..1819be0 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -823,6 +823,9 @@ DEFINE_bool(redirect_code_traces, false,
 DEFINE_string(redirect_code_traces_to, NULL,
             "output deopt information and disassembly into the given file")
 
+DEFINE_bool(hydrogen_track_positions, false,
+            "track source code positions when building IR")
+
 //
 // Disassembler only flags
 //
@@ -855,8 +858,6 @@ DEFINE_bool(print_unopt_code, false, "print unoptimized code before "
             "printing optimized code based on it")
 DEFINE_bool(print_code_verbose, false, "print more information for code")
 DEFINE_bool(print_builtin_code, false, "print generated code for builtins")
-DEFINE_bool(emit_opt_code_positions, false,
-            "annotate optimize code with source code positions")
 
 #ifdef ENABLE_DISASSEMBLER
 DEFINE_bool(sodium, false, "print generated code output suitable for use with "
@@ -865,7 +866,7 @@ DEFINE_bool(sodium, false, "print generated code output suitable for use with "
 DEFINE_implication(sodium, print_code_stubs)
 DEFINE_implication(sodium, print_code)
 DEFINE_implication(sodium, print_opt_code)
-DEFINE_implication(sodium, emit_opt_code_positions)
+DEFINE_implication(sodium, hydrogen_track_positions)
 DEFINE_implication(sodium, code_comments)
 
 DEFINE_bool(print_all_code, false, "enable all flags related to printing code")
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 00087e4..fdd43cc 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -682,6 +682,19 @@ void HValue::ComputeInitialRange(Zone* zone) {
 }
 
 
+void HSourcePosition::PrintTo(FILE* out) {
+  if (IsUnknown()) {
+    PrintF(out, "<?>");
+  } else {
+    if (FLAG_hydrogen_track_positions) {
+      PrintF(out, "<%d:%d>", inlining_id(), position());
+    } else {
+      PrintF(out, "<0:%d>", raw());
+    }
+  }
+}
+
+
 void HInstruction::PrintTo(StringStream* stream) {
   PrintMnemonicTo(stream);
   PrintDataTo(stream);
@@ -738,8 +751,7 @@ void HInstruction::InsertBefore(HInstruction* next) {
   next_ = next;
   previous_ = prev;
   SetBlock(next->block());
-  if (position() == RelocInfo::kNoPosition &&
-      next->position() != RelocInfo::kNoPosition) {
+  if (!has_position() && next->has_position()) {
     set_position(next->position());
   }
 }
@@ -776,8 +788,7 @@ void HInstruction::InsertAfter(HInstruction* previous) {
   if (block->last() == previous) {
     block->set_last(this);
   }
-  if (position() == RelocInfo::kNoPosition &&
-      previous->position() != RelocInfo::kNoPosition) {
+  if (!has_position() && previous->has_position()) {
     set_position(previous->position());
   }
 }
@@ -1649,7 +1660,7 @@ Range* HConstant::InferRange(Zone* zone) {
 }
 
 
-int HPhi::position() const {
+HSourcePosition HPhi::position() const {
   return block()->first()->position();
 }
 
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index a290080..86624d0 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -546,6 +546,61 @@ class DecompositionResult V8_FINAL BASE_EMBEDDED {
 typedef EnumSet<GVNFlag, int32_t> GVNFlagSet;
 
 
+// This class encapsulates encoding and decoding of sources positions from
+// which hydrogen values originated.
+// When FLAG_track_hydrogen_positions is set this object encodes the
+// identifier of the inlining and absolute offset from the start of the
+// inlined function.
+// When the flag is not set we simply track absolute offset from the
+// script start.
+class HSourcePosition {
+ public:
+  HSourcePosition(const HSourcePosition& other) : value_(other.value_) { }
+
+  static HSourcePosition Unknown() {
+    return HSourcePosition(RelocInfo::kNoPosition);
+  }
+
+  bool IsUnknown() const { return value_ == RelocInfo::kNoPosition; }
+
+  int position() const { return PositionField::decode(value_); }
+  void set_position(int position) {
+    if (FLAG_hydrogen_track_positions) {
+      value_ = static_cast<int>(PositionField::update(value_, position));
+    } else {
+      value_ = position;
+    }
+  }
+
+  int inlining_id() const { return InliningIdField::decode(value_); }
+  void set_inlining_id(int inlining_id) {
+    if (FLAG_hydrogen_track_positions) {
+      value_ = static_cast<int>(InliningIdField::update(value_, inlining_id));
+    }
+  }
+
+  int raw() const { return value_; }
+
+  void PrintTo(FILE* f);
+
+ private:
+  typedef BitField<int, 0, 9> InliningIdField;
+
+  // Offset from the start of the inlined function.
+  typedef BitField<int, 9, 22> PositionField;
+
+  // On HPositionInfo can use this constructor.
+  explicit HSourcePosition(int value) : value_(value) { }
+
+  friend class HPositionInfo;
+
+  // If FLAG_hydrogen_track_positions is set contains bitfields InliningIdField
+  // and PositionField.
+  // Otherwise contains absolute offset from the script start.
+  int value_;
+};
+
+
 class HValue : public ZoneObject {
  public:
   static const int kNoNumber = -1;
@@ -627,8 +682,12 @@ class HValue : public ZoneObject {
         flags_(0) {}
   virtual ~HValue() {}
 
-  virtual int position() const { return RelocInfo::kNoPosition; }
-  virtual int operand_position(int index) const { return position(); }
+  virtual HSourcePosition position() const {
+    return HSourcePosition::Unknown();
+  }
+  virtual HSourcePosition operand_position(int index) const {
+    return position();
+  }
 
   HBasicBlock* block() const { return block_; }
   void SetBlock(HBasicBlock* block);
@@ -1085,25 +1144,22 @@ class HValue : public ZoneObject {
 // In the first case it contains intruction's position as a tagged value.
 // In the second case it points to an array which contains instruction's
 // position and operands' positions.
-// TODO(vegorov): what we really want to track here is a combination of
-// source position and a script id because cross script inlining can easily
-// result in optimized functions composed of several scripts.
 class HPositionInfo {
  public:
   explicit HPositionInfo(int pos) : data_(TagPosition(pos)) { }
 
-  int position() const {
+  HSourcePosition position() const {
     if (has_operand_positions()) {
-      return static_cast<int>(operand_positions()[kInstructionPosIndex]);
+      return operand_positions()[kInstructionPosIndex];
     }
-    return static_cast<int>(UntagPosition(data_));
+    return HSourcePosition(static_cast<int>(UntagPosition(data_)));
   }
 
-  void set_position(int pos) {
+  void set_position(HSourcePosition pos) {
     if (has_operand_positions()) {
       operand_positions()[kInstructionPosIndex] = pos;
     } else {
-      data_ = TagPosition(pos);
+      data_ = TagPosition(pos.raw());
     }
   }
 
@@ -1113,27 +1169,27 @@ class HPositionInfo {
     }
 
     const int length = kFirstOperandPosIndex + operand_count;
-    intptr_t* positions =
-        zone->NewArray<intptr_t>(length);
+    HSourcePosition* positions =
+        zone->NewArray<HSourcePosition>(length);
     for (int i = 0; i < length; i++) {
-      positions[i] = RelocInfo::kNoPosition;
+      positions[i] = HSourcePosition::Unknown();
     }
 
-    const int pos = position();
+    const HSourcePosition pos = position();
     data_ = reinterpret_cast<intptr_t>(positions);
     set_position(pos);
 
     ASSERT(has_operand_positions());
   }
 
-  int operand_position(int idx) const {
+  HSourcePosition operand_position(int idx) const {
     if (!has_operand_positions()) {
       return position();
     }
-    return static_cast<int>(*operand_position_slot(idx));
+    return *operand_position_slot(idx);
   }
 
-  void set_operand_position(int idx, int pos) {
+  void set_operand_position(int idx, HSourcePosition pos) {
     *operand_position_slot(idx) = pos;
   }
 
@@ -1141,7 +1197,7 @@ class HPositionInfo {
   static const intptr_t kInstructionPosIndex = 0;
   static const intptr_t kFirstOperandPosIndex = 1;
 
-  intptr_t* operand_position_slot(int idx) const {
+  HSourcePosition* operand_position_slot(int idx) const {
     ASSERT(has_operand_positions());
     return &(operand_positions()[kFirstOperandPosIndex + idx]);
   }
@@ -1150,9 +1206,9 @@ class HPositionInfo {
     return !IsTaggedPosition(data_);
   }
 
-  intptr_t* operand_positions() const {
+  HSourcePosition* operand_positions() const {
     ASSERT(has_operand_positions());
-    return reinterpret_cast<intptr_t*>(data_);
+    return reinterpret_cast<HSourcePosition*>(data_);
   }
 
   static const intptr_t kPositionTag = 1;
@@ -1200,23 +1256,23 @@ class HInstruction : public HValue {
   }
 
   // The position is a write-once variable.
-  virtual int position() const V8_OVERRIDE {
-    return position_.position();
+  virtual HSourcePosition position() const V8_OVERRIDE {
+    return HSourcePosition(position_.position());
   }
   bool has_position() const {
-    return position_.position() != RelocInfo::kNoPosition;
+    return !position().IsUnknown();
   }
-  void set_position(int position) {
+  void set_position(HSourcePosition position) {
     ASSERT(!has_position());
-    ASSERT(position != RelocInfo::kNoPosition);
+    ASSERT(!position.IsUnknown());
     position_.set_position(position);
   }
 
-  virtual int operand_position(int index) const V8_OVERRIDE {
-    const int pos = position_.operand_position(index);
-    return (pos != RelocInfo::kNoPosition) ? pos : position();
+  virtual HSourcePosition operand_position(int index) const V8_OVERRIDE {
+    const HSourcePosition pos = position_.operand_position(index);
+    return pos.IsUnknown() ? position() : pos;
   }
-  void set_operand_position(Zone* zone, int index, int pos) {
+  void set_operand_position(Zone* zone, int index, HSourcePosition pos) {
     ASSERT(0 <= index && index < OperandCount());
     position_.ensure_storage_for_operand_positions(zone, OperandCount());
     position_.set_operand_position(index, pos);
@@ -3163,7 +3219,7 @@ class HPhi V8_FINAL : public HValue {
   bool IsReceiver() const { return merged_index_ == 0; }
   bool HasMergedIndex() const { return merged_index_ != kInvalidMergedIndex; }
 
-  virtual int position() const V8_OVERRIDE;
+  virtual HSourcePosition position() const V8_OVERRIDE;
 
   int merged_index() const { return merged_index_; }
 
@@ -3668,7 +3724,9 @@ class HBinaryOperation : public HTemplateInstruction<3> {
     return representation();
   }
 
-  void SetOperandPositions(Zone* zone, int left_pos, int right_pos) {
+  void SetOperandPositions(Zone* zone,
+                           HSourcePosition left_pos,
+                           HSourcePosition right_pos) {
     set_operand_position(zone, 1, left_pos);
     set_operand_position(zone, 2, right_pos);
   }
@@ -4123,7 +4181,9 @@ class HCompareNumericAndBranch : public HTemplateControlInstruction<2, 2> {
   }
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
 
-  void SetOperandPositions(Zone* zone, int left_pos, int right_pos) {
+  void SetOperandPositions(Zone* zone,
+                           HSourcePosition left_pos,
+                           HSourcePosition right_pos) {
     set_operand_position(zone, 0, left_pos);
     set_operand_position(zone, 1, right_pos);
   }
diff --git a/src/hydrogen-representation-changes.cc b/src/hydrogen-representation-changes.cc
index 07fc8be..7d0720c 100644
--- a/src/hydrogen-representation-changes.cc
+++ b/src/hydrogen-representation-changes.cc
@@ -61,10 +61,11 @@ void HRepresentationChangesPhase::InsertRepresentationChangeForUse(
   if (new_value == NULL) {
     new_value = new(graph()->zone()) HChange(
         value, to, is_truncating_to_smi, is_truncating_to_int);
-    if (use_value->operand_position(use_index) != RelocInfo::kNoPosition) {
+    if (!use_value->operand_position(use_index).IsUnknown()) {
       new_value->set_position(use_value->operand_position(use_index));
     } else {
-      ASSERT(!FLAG_emit_opt_code_positions || !graph()->info()->IsOptimizing());
+      ASSERT(!FLAG_hydrogen_track_positions ||
+             !graph()->info()->IsOptimizing());
     }
   }
 
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index a197727..e59048a 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -143,12 +143,13 @@ void HBasicBlock::RemovePhi(HPhi* phi) {
 }
 
 
-void HBasicBlock::AddInstruction(HInstruction* instr, int position) {
+void HBasicBlock::AddInstruction(HInstruction* instr,
+                                 HSourcePosition position) {
   ASSERT(!IsStartBlock() || !IsFinished());
   ASSERT(!instr->IsLinked());
   ASSERT(!IsFinished());
 
-  if (position != RelocInfo::kNoPosition) {
+  if (!position.IsUnknown()) {
     instr->set_position(position);
   }
   if (first_ == NULL) {
@@ -156,10 +157,10 @@ void HBasicBlock::AddInstruction(HInstruction* instr, int position) {
     ASSERT(!last_environment()->ast_id().IsNone());
     HBlockEntry* entry = new(zone()) HBlockEntry();
     entry->InitializeAsFirst(this);
-    if (position != RelocInfo::kNoPosition) {
+    if (!position.IsUnknown()) {
       entry->set_position(position);
     } else {
-      ASSERT(!FLAG_emit_opt_code_positions ||
+      ASSERT(!FLAG_hydrogen_track_positions ||
              !graph()->info()->IsOptimizing());
     }
     first_ = last_ = entry;
@@ -212,7 +213,7 @@ HSimulate* HBasicBlock::CreateSimulate(BailoutId ast_id,
 }
 
 
-void HBasicBlock::Finish(HControlInstruction* end, int position) {
+void HBasicBlock::Finish(HControlInstruction* end, HSourcePosition position) {
   ASSERT(!IsFinished());
   AddInstruction(end, position);
   end_ = end;
@@ -223,7 +224,7 @@ void HBasicBlock::Finish(HControlInstruction* end, int position) {
 
 
 void HBasicBlock::Goto(HBasicBlock* block,
-                       int position,
+                       HSourcePosition position,
                        FunctionState* state,
                        bool add_simulate) {
   bool drop_extra = state != NULL &&
@@ -246,7 +247,7 @@ void HBasicBlock::Goto(HBasicBlock* block,
 
 void HBasicBlock::AddLeaveInlined(HValue* return_value,
                                   FunctionState* state,
-                                  int position) {
+                                  HSourcePosition position) {
   HBasicBlock* target = state->function_return();
   bool drop_extra = state->inlining_kind() == NORMAL_RETURN;
 
@@ -1044,7 +1045,8 @@ void HGraphBuilder::IfBuilder::End() {
   while (current != NULL) {
     if (current->deopt_ && current->block_ != NULL) {
       current->block_->FinishExit(
-          HAbnormalExit::New(builder_->zone(), NULL), RelocInfo::kNoPosition);
+          HAbnormalExit::New(builder_->zone(), NULL),
+          HSourcePosition::Unknown());
     }
     current = current->next_;
   }
@@ -1177,9 +1179,10 @@ HGraph* HGraphBuilder::CreateGraph() {
 
 HInstruction* HGraphBuilder::AddInstruction(HInstruction* instr) {
   ASSERT(current_block() != NULL);
-  ASSERT(!FLAG_emit_opt_code_positions ||
-         position_ != RelocInfo::kNoPosition || !info_->IsOptimizing());
-  current_block()->AddInstruction(instr, position_);
+  ASSERT(!FLAG_hydrogen_track_positions ||
+         !position_.IsUnknown() ||
+         !info_->IsOptimizing());
+  current_block()->AddInstruction(instr, source_position());
   if (graph()->IsInsideNoSideEffectsScope()) {
     instr->SetFlag(HValue::kHasNoObservableSideEffects);
   }
@@ -1188,9 +1191,10 @@ HInstruction* HGraphBuilder::AddInstruction(HInstruction* instr) {
 
 
 void HGraphBuilder::FinishCurrentBlock(HControlInstruction* last) {
-  ASSERT(!FLAG_emit_opt_code_positions || !info_->IsOptimizing() ||
-         position_ != RelocInfo::kNoPosition);
-  current_block()->Finish(last, position_);
+  ASSERT(!FLAG_hydrogen_track_positions ||
+         !info_->IsOptimizing() ||
+         !position_.IsUnknown());
+  current_block()->Finish(last, source_position());
   if (last->IsReturn() || last->IsAbnormalExit()) {
     set_current_block(NULL);
   }
@@ -1198,9 +1202,9 @@ void HGraphBuilder::FinishCurrentBlock(HControlInstruction* last) {
 
 
 void HGraphBuilder::FinishExitCurrentBlock(HControlInstruction* instruction) {
-  ASSERT(!FLAG_emit_opt_code_positions || !info_->IsOptimizing() ||
-         position_ != RelocInfo::kNoPosition);
-  current_block()->FinishExit(instruction, position_);
+  ASSERT(!FLAG_hydrogen_track_positions || !info_->IsOptimizing() ||
+         !position_.IsUnknown());
+  current_block()->FinishExit(instruction, source_position());
   if (instruction->IsReturn() || instruction->IsAbnormalExit()) {
     set_current_block(NULL);
   }
@@ -1224,7 +1228,7 @@ void HGraphBuilder::AddSimulate(BailoutId id,
                                 RemovableSimulate removable) {
   ASSERT(current_block() != NULL);
   ASSERT(!graph()->IsInsideNoSideEffectsScope());
-  current_block()->AddNewSimulate(id, position_, removable);
+  current_block()->AddNewSimulate(id, source_position(), removable);
 }
 
 
@@ -2976,7 +2980,7 @@ HValue* HGraphBuilder::AddLoadJSBuiltin(Builtins::JavaScript builtin) {
 HOptimizedGraphBuilder::HOptimizedGraphBuilder(CompilationInfo* info)
     : HGraphBuilder(info),
       function_state_(NULL),
-      initial_function_state_(this, info, NORMAL_RETURN),
+      initial_function_state_(this, info, NORMAL_RETURN, 0),
       ast_context_(NULL),
       break_scope_(NULL),
       inlined_count_(0),
@@ -2988,7 +2992,7 @@ HOptimizedGraphBuilder::HOptimizedGraphBuilder(CompilationInfo* info)
   // to know it's the initial state.
   function_state_= &initial_function_state_;
   InitializeAstVisitor(info->zone());
-  if (FLAG_emit_opt_code_positions) {
+  if (FLAG_hydrogen_track_positions) {
     SetSourcePosition(info->shared_info()->start_position());
   }
 }
@@ -3057,7 +3061,8 @@ HBasicBlock* HOptimizedGraphBuilder::BuildLoopEntry(
 }
 
 
-void HBasicBlock::FinishExit(HControlInstruction* instruction, int position) {
+void HBasicBlock::FinishExit(HControlInstruction* instruction,
+                             HSourcePosition position) {
   Finish(instruction, position);
   ClearEnvironment();
 }
@@ -3080,7 +3085,9 @@ HGraph::HGraph(CompilationInfo* info)
       type_change_checksum_(0),
       maximum_environment_size_(0),
       no_side_effects_scope_count_(0),
-      disallow_adding_new_values_(false) {
+      disallow_adding_new_values_(false),
+      next_inline_id_(0),
+      inlined_functions_(5, info->zone()) {
   if (info->IsStub()) {
     HydrogenCodeStub* stub = info->code_stub();
     CodeStubInterfaceDescriptor* descriptor =
@@ -3088,6 +3095,7 @@ HGraph::HGraph(CompilationInfo* info)
     start_environment_ =
         new(zone_) HEnvironment(zone_, descriptor->environment_length());
   } else {
+    TraceInlinedFunction(info->shared_info(), HSourcePosition::Unknown());
     start_environment_ =
         new(zone_) HEnvironment(NULL, info->scope(), info->closure(), zone_);
   }
@@ -3115,6 +3123,81 @@ void HGraph::FinalizeUniqueness() {
 }
 
 
+int HGraph::TraceInlinedFunction(
+    Handle<SharedFunctionInfo> shared,
+    HSourcePosition position) {
+  if (!FLAG_hydrogen_track_positions) {
+    return 0;
+  }
+
+  int id = 0;
+  for (; id < inlined_functions_.length(); id++) {
+    if (inlined_functions_[id].shared().is_identical_to(shared)) {
+      break;
+    }
+  }
+
+  if (id == inlined_functions_.length()) {
+    inlined_functions_.Add(InlinedFunctionInfo(shared), zone());
+
+    if (!shared->script()->IsUndefined()) {
+      Handle<Script> script(Script::cast(shared->script()));
+      if (!script->source()->IsUndefined()) {
+        CodeTracer::Scope tracing_scope(isolate()->GetCodeTracer());
+        PrintF(tracing_scope.file(),
+               "--- FUNCTION SOURCE (%s) id{%d,%d} ---\n",
+               shared->DebugName()->ToCString().get(),
+               info()->optimization_id(),
+               id);
+
+        {
+          ConsStringIteratorOp op;
+          StringCharacterStream stream(String::cast(script->source()),
+                                       &op,
+                                       shared->start_position());
+          // fun->end_position() points to the last character in the stream. We
+          // need to compensate by adding one to calculate the length.
+          int source_len =
+              shared->end_position() - shared->start_position() + 1;
+          for (int i = 0; i < source_len; i++) {
+            if (stream.HasMore()) {
+              PrintF(tracing_scope.file(), "%c", stream.GetNext());
+            }
+          }
+        }
+
+        PrintF(tracing_scope.file(), "\n--- END ---\n");
+      }
+    }
+  }
+
+  int inline_id = next_inline_id_++;
+
+  if (inline_id != 0) {
+    CodeTracer::Scope tracing_scope(isolate()->GetCodeTracer());
+    PrintF(tracing_scope.file(), "INLINE (%s) id{%d,%d} AS %d AT ",
+           shared->DebugName()->ToCString().get(),
+           info()->optimization_id(),
+           id,
+           inline_id);
+    position.PrintTo(tracing_scope.file());
+    PrintF(tracing_scope.file(), "\n");
+  }
+
+  return inline_id;
+}
+
+
+int HGraph::SourcePositionToScriptPosition(HSourcePosition pos) {
+  if (!FLAG_hydrogen_track_positions || pos.IsUnknown()) {
+    return pos.raw();
+  }
+
+  return inlined_functions_[pos.inlining_id()].start_position() +
+      pos.position();
+}
+
+
 // Block ordering was implemented with two mutually recursive methods,
 // HGraph::Postorder and HGraph::PostorderLoopBlocks.
 // The recursion could lead to stack overflow so the algorithm has been
@@ -3493,7 +3576,8 @@ void HGraph::CollectPhis() {
 // a (possibly inlined) function.
 FunctionState::FunctionState(HOptimizedGraphBuilder* owner,
                              CompilationInfo* info,
-                             InliningKind inlining_kind)
+                             InliningKind inlining_kind,
+                             int inlining_id)
     : owner_(owner),
       compilation_info_(info),
       call_context_(NULL),
@@ -3503,6 +3587,8 @@ FunctionState::FunctionState(HOptimizedGraphBuilder* owner,
       entry_(NULL),
       arguments_object_(NULL),
       arguments_elements_(NULL),
+      inlining_id_(inlining_id),
+      outer_source_position_(HSourcePosition::Unknown()),
       outer_(owner->function_state()) {
   if (outer_ != NULL) {
     // State for an inline function.
@@ -3526,12 +3612,27 @@ FunctionState::FunctionState(HOptimizedGraphBuilder* owner,
 
   // Push on the state stack.
   owner->set_function_state(this);
+
+  if (FLAG_hydrogen_track_positions) {
+    outer_source_position_ = owner->source_position();
+    owner->EnterInlinedSource(
+      info->shared_info()->start_position(),
+      inlining_id);
+    owner->SetSourcePosition(info->shared_info()->start_position());
+  }
 }
 
 
 FunctionState::~FunctionState() {
   delete test_context_;
   owner_->set_function_state(outer_);
+
+  if (FLAG_hydrogen_track_positions) {
+    owner_->set_source_position(outer_source_position_);
+    owner_->EnterInlinedSource(
+      outer_->compilation_info()->shared_info()->start_position(),
+      outer_->inlining_id());
+  }
 }
 
 
@@ -4344,7 +4445,9 @@ void HOptimizedGraphBuilder::VisitSwitchStatement(SwitchStatement* stmt) {
     Type* combined_type = clause->compare_type();
     HControlInstruction* compare = BuildCompareInstruction(
         Token::EQ_STRICT, tag_value, label_value, tag_type, label_type,
-        combined_type, stmt->tag()->position(), clause->label()->position(),
+        combined_type,
+        ScriptPositionToSourcePosition(stmt->tag()->position()),
+        ScriptPositionToSourcePosition(clause->label()->position()),
         clause->id());
 
     HBasicBlock* next_test_block = graph()->CreateBasicBlock();
@@ -6065,7 +6168,7 @@ void HOptimizedGraphBuilder::VisitThrow(Throw* expr) {
   CHECK_ALIVE(VisitForValue(expr->exception()));
 
   HValue* value = environment()->Pop();
-  if (!FLAG_emit_opt_code_positions) SetSourcePosition(expr->position());
+  if (!FLAG_hydrogen_track_positions) SetSourcePosition(expr->position());
   Add<HPushArgument>(value);
   Add<HCallRuntime>(isolate()->factory()->empty_string(),
                     Runtime::FunctionForId(Runtime::kThrow), 1);
@@ -6997,7 +7100,8 @@ bool HOptimizedGraphBuilder::TryInline(Handle<JSFunction> target,
                                        HValue* implicit_return_value,
                                        BailoutId ast_id,
                                        BailoutId return_id,
-                                       InliningKind inlining_kind) {
+                                       InliningKind inlining_kind,
+                                       HSourcePosition position) {
   int nodes_added = InliningAstSize(target);
   if (nodes_added == kNotInlinable) return false;
 
@@ -7129,11 +7233,13 @@ bool HOptimizedGraphBuilder::TryInline(Handle<JSFunction> target,
   ASSERT(target_shared->has_deoptimization_support());
   AstTyper::Run(&target_info);
 
+  int function_id = graph()->TraceInlinedFunction(target_shared, position);
+
   // Save the pending call context. Set up new one for the inlined function.
   // The function state is new-allocated because we need to delete it
   // in two different places.
   FunctionState* target_state = new FunctionState(
-      this, &target_info, inlining_kind);
+      this, &target_info, inlining_kind, function_id);
 
   HConstant* undefined = graph()->GetConstantUndefined();
 
@@ -7280,7 +7386,8 @@ bool HOptimizedGraphBuilder::TryInlineCall(Call* expr) {
                    NULL,
                    expr->id(),
                    expr->ReturnId(),
-                   NORMAL_RETURN);
+                   NORMAL_RETURN,
+                   ScriptPositionToSourcePosition(expr->position()));
 }
 
 
@@ -7291,7 +7398,8 @@ bool HOptimizedGraphBuilder::TryInlineConstruct(CallNew* expr,
                    implicit_return_value,
                    expr->id(),
                    expr->ReturnId(),
-                   CONSTRUCT_CALL_RETURN);
+                   CONSTRUCT_CALL_RETURN,
+                   ScriptPositionToSourcePosition(expr->position()));
 }
 
 
@@ -7305,7 +7413,8 @@ bool HOptimizedGraphBuilder::TryInlineGetter(Handle<JSFunction> getter,
                    NULL,
                    ast_id,
                    return_id,
-                   GETTER_CALL_RETURN);
+                   GETTER_CALL_RETURN,
+                   source_position());
 }
 
 
@@ -7319,7 +7428,8 @@ bool HOptimizedGraphBuilder::TryInlineSetter(Handle<JSFunction> setter,
                    1,
                    implicit_return_value,
                    id, assignment_id,
-                   SETTER_CALL_RETURN);
+                   SETTER_CALL_RETURN,
+                   source_position());
 }
 
 
@@ -7331,7 +7441,8 @@ bool HOptimizedGraphBuilder::TryInlineApply(Handle<JSFunction> function,
                    NULL,
                    expr->id(),
                    expr->ReturnId(),
-                   NORMAL_RETURN);
+                   NORMAL_RETURN,
+                   ScriptPositionToSourcePosition(expr->position()));
 }
 
 
@@ -7879,6 +7990,8 @@ void HOptimizedGraphBuilder::VisitCall(Call* expr) {
     CHECK_ALIVE(PushLoad(prop, receiver, key));
     HValue* function = Pop();
 
+    if (FLAG_hydrogen_track_positions) SetSourcePosition(expr->position());
+
     // Push the function under the receiver.
     environment()->SetExpressionStackAt(0, function);
 
@@ -8151,7 +8264,7 @@ void HOptimizedGraphBuilder::VisitCallNew(CallNew* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
-  if (!FLAG_emit_opt_code_positions) SetSourcePosition(expr->position());
+  if (!FLAG_hydrogen_track_positions) SetSourcePosition(expr->position());
   int argument_count = expr->arguments()->length() + 1;  // Plus constructor.
   Factory* factory = isolate()->factory();
 
@@ -8694,7 +8807,7 @@ void HOptimizedGraphBuilder::VisitCountOperation(CountOperation* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
-  if (!FLAG_emit_opt_code_positions) SetSourcePosition(expr->position());
+  if (!FLAG_hydrogen_track_positions) SetSourcePosition(expr->position());
   Expression* target = expr->expression();
   VariableProxy* proxy = target->AsVariableProxy();
   Property* prop = target->AsProperty();
@@ -9361,9 +9474,11 @@ void HOptimizedGraphBuilder::VisitArithmeticExpression(BinaryOperation* expr) {
       BuildBinaryOperation(expr, left, right,
           ast_context()->IsEffect() ? NO_PUSH_BEFORE_SIMULATE
                                     : PUSH_BEFORE_SIMULATE);
-  if (FLAG_emit_opt_code_positions && result->IsBinaryOperation()) {
+  if (FLAG_hydrogen_track_positions && result->IsBinaryOperation()) {
     HBinaryOperation::cast(result)->SetOperandPositions(
-        zone(), expr->left()->position(), expr->right()->position());
+        zone(),
+        ScriptPositionToSourcePosition(expr->left()->position()),
+        ScriptPositionToSourcePosition(expr->right()->position()));
   }
   return ast_context()->ReturnValue(result);
 }
@@ -9397,7 +9512,7 @@ void HOptimizedGraphBuilder::VisitCompareOperation(CompareOperation* expr) {
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
 
-  if (!FLAG_emit_opt_code_positions) SetSourcePosition(expr->position());
+  if (!FLAG_hydrogen_track_positions) SetSourcePosition(expr->position());
 
   // Check for a few fast cases. The AST visiting behavior must be in sync
   // with the full codegen: We don't push both left and right values onto
@@ -9432,7 +9547,7 @@ void HOptimizedGraphBuilder::VisitCompareOperation(CompareOperation* expr) {
   CHECK_ALIVE(VisitForValue(expr->left()));
   CHECK_ALIVE(VisitForValue(expr->right()));
 
-  if (FLAG_emit_opt_code_positions) SetSourcePosition(expr->position());
+  if (FLAG_hydrogen_track_positions) SetSourcePosition(expr->position());
 
   HValue* right = Pop();
   HValue* left = Pop();
@@ -9494,7 +9609,9 @@ void HOptimizedGraphBuilder::VisitCompareOperation(CompareOperation* expr) {
 
   HControlInstruction* compare = BuildCompareInstruction(
       op, left, right, left_type, right_type, combined_type,
-      expr->left()->position(), expr->right()->position(), expr->id());
+      ScriptPositionToSourcePosition(expr->left()->position()),
+      ScriptPositionToSourcePosition(expr->right()->position()),
+      expr->id());
   if (compare == NULL) return;  // Bailed out.
   return ast_context()->ReturnControl(compare, expr->id());
 }
@@ -9507,8 +9624,8 @@ HControlInstruction* HOptimizedGraphBuilder::BuildCompareInstruction(
     Type* left_type,
     Type* right_type,
     Type* combined_type,
-    int left_position,
-    int right_position,
+    HSourcePosition left_position,
+    HSourcePosition right_position,
     BailoutId bailout_id) {
   // Cases handled below depend on collected type feedback. They should
   // soft deoptimize when there is no type feedback.
@@ -9533,7 +9650,7 @@ HControlInstruction* HOptimizedGraphBuilder::BuildCompareInstruction(
         AddCheckMap(operand_to_check, map);
         HCompareObjectEqAndBranch* result =
             New<HCompareObjectEqAndBranch>(left, right);
-        if (FLAG_emit_opt_code_positions) {
+        if (FLAG_hydrogen_track_positions) {
           result->set_operand_position(zone(), 0, left_position);
           result->set_operand_position(zone(), 1, right_position);
         }
@@ -9584,7 +9701,7 @@ HControlInstruction* HOptimizedGraphBuilder::BuildCompareInstruction(
       HCompareNumericAndBranch* result =
           New<HCompareNumericAndBranch>(left, right, op);
       result->set_observed_input_representation(left_rep, right_rep);
-      if (FLAG_emit_opt_code_positions) {
+      if (FLAG_hydrogen_track_positions) {
         result->SetOperandPositions(zone(), left_position, right_position);
       }
       return result;
@@ -9600,7 +9717,7 @@ void HOptimizedGraphBuilder::HandleLiteralCompareNil(CompareOperation* expr,
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   ASSERT(expr->op() == Token::EQ || expr->op() == Token::EQ_STRICT);
-  if (!FLAG_emit_opt_code_positions) SetSourcePosition(expr->position());
+  if (!FLAG_hydrogen_track_positions) SetSourcePosition(expr->position());
   CHECK_ALIVE(VisitForValue(sub_expr));
   HValue* value = Pop();
   if (expr->op() == Token::EQ_STRICT) {
@@ -10837,7 +10954,10 @@ void HTracer::TraceCompilation(CompilationInfo* info) {
   if (info->IsOptimizing()) {
     Handle<String> name = info->function()->debug_name();
     PrintStringProperty("name", name->ToCString().get());
-    PrintStringProperty("method", name->ToCString().get());
+    PrintIndent();
+    trace_.Add("method \"%s:%d\"\n",
+               name->ToCString().get(),
+               info->optimization_id());
   } else {
     CodeStub::Major major_key = info->code_stub()->MajorKey();
     PrintStringProperty("name", CodeStub::MajorName(major_key, false));
@@ -10951,14 +11071,22 @@ void HTracer::Trace(const char* name, HGraph* graph, LChunk* chunk) {
       Tag HIR_tag(this, "HIR");
       for (HInstructionIterator it(current); !it.Done(); it.Advance()) {
         HInstruction* instruction = it.Current();
-        int bci = FLAG_emit_opt_code_positions && instruction->has_position() ?
-            instruction->position() : 0;
         int uses = instruction->UseCount();
         PrintIndent();
-        trace_.Add("%d %d ", bci, uses);
+        trace_.Add("0 %d ", uses);
         instruction->PrintNameTo(&trace_);
         trace_.Add(" ");
         instruction->PrintTo(&trace_);
+        if (FLAG_hydrogen_track_positions &&
+            instruction->has_position() &&
+            instruction->position().raw() != 0) {
+          const HSourcePosition pos = instruction->position();
+          trace_.Add(" pos:");
+          if (pos.inlining_id() != 0) {
+            trace_.Add("%d_", pos.inlining_id());
+          }
+          trace_.Add("%d", pos.position());
+        }
         trace_.Add(" <|@\n");
       }
     }
diff --git a/src/hydrogen.h b/src/hydrogen.h
index b3d51e7..5f1ef79 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -110,7 +110,7 @@ class HBasicBlock V8_FINAL : public ZoneObject {
   bool IsFinished() const { return end_ != NULL; }
   void AddPhi(HPhi* phi);
   void RemovePhi(HPhi* phi);
-  void AddInstruction(HInstruction* instr, int position);
+  void AddInstruction(HInstruction* instr, HSourcePosition position);
   bool Dominates(HBasicBlock* other) const;
   bool EqualToOrDominates(HBasicBlock* other) const;
   int LoopNestingDepth() const;
@@ -137,7 +137,7 @@ class HBasicBlock V8_FINAL : public ZoneObject {
   int PredecessorIndexOf(HBasicBlock* predecessor) const;
   HPhi* AddNewPhi(int merged_index);
   HSimulate* AddNewSimulate(BailoutId ast_id,
-                            int position,
+                            HSourcePosition position,
                             RemovableSimulate removable = FIXED_SIMULATE) {
     HSimulate* instr = CreateSimulate(ast_id, removable);
     AddInstruction(instr, position);
@@ -186,13 +186,13 @@ class HBasicBlock V8_FINAL : public ZoneObject {
   friend class HGraphBuilder;
 
   HSimulate* CreateSimulate(BailoutId ast_id, RemovableSimulate removable);
-  void Finish(HControlInstruction* last, int position);
-  void FinishExit(HControlInstruction* instruction, int position);
+  void Finish(HControlInstruction* last, HSourcePosition position);
+  void FinishExit(HControlInstruction* instruction, HSourcePosition position);
   void Goto(HBasicBlock* block,
-            int position,
+            HSourcePosition position,
             FunctionState* state = NULL,
             bool add_simulate = true);
-  void GotoNoSimulate(HBasicBlock* block, int position) {
+  void GotoNoSimulate(HBasicBlock* block, HSourcePosition position) {
     Goto(block, position, NULL, false);
   }
 
@@ -200,7 +200,7 @@ class HBasicBlock V8_FINAL : public ZoneObject {
   // instruction and updating the bailout environment.
   void AddLeaveInlined(HValue* return_value,
                        FunctionState* state,
-                       int position);
+                       HSourcePosition position);
 
  private:
   void RegisterPredecessor(HBasicBlock* pred);
@@ -471,6 +471,16 @@ class HGraph V8_FINAL : public ZoneObject {
   void DecrementInNoSideEffectsScope() { no_side_effects_scope_count_--; }
   bool IsInsideNoSideEffectsScope() { return no_side_effects_scope_count_ > 0; }
 
+  // If we are tracking source positions then this function assigns a unique
+  // identifier to each inlining and dumps function source if it was inlined
+  // for the first time during the current optimization.
+  int TraceInlinedFunction(Handle<SharedFunctionInfo> shared,
+                           HSourcePosition position);
+
+  // Converts given HSourcePosition to the absolute offset from the start of
+  // the corresponding script.
+  int SourcePositionToScriptPosition(HSourcePosition position);
+
  private:
   HConstant* ReinsertConstantIfNecessary(HConstant* constant);
   HConstant* GetConstant(SetOncePointer<HConstant>* pointer,
@@ -516,6 +526,23 @@ class HGraph V8_FINAL : public ZoneObject {
   int no_side_effects_scope_count_;
   bool disallow_adding_new_values_;
 
+  class InlinedFunctionInfo {
+   public:
+    explicit InlinedFunctionInfo(Handle<SharedFunctionInfo> shared)
+      : shared_(shared), start_position_(shared->start_position()) {
+    }
+
+    Handle<SharedFunctionInfo> shared() const { return shared_; }
+    int start_position() const { return start_position_; }
+
+   private:
+    Handle<SharedFunctionInfo> shared_;
+    int start_position_;
+  };
+
+  int next_inline_id_;
+  ZoneList<InlinedFunctionInfo> inlined_functions_;
+
   DISALLOW_COPY_AND_ASSIGN(HGraph);
 };
 
@@ -882,7 +909,8 @@ class FunctionState V8_FINAL {
  public:
   FunctionState(HOptimizedGraphBuilder* owner,
                 CompilationInfo* info,
-                InliningKind inlining_kind);
+                InliningKind inlining_kind,
+                int inlining_id);
   ~FunctionState();
 
   CompilationInfo* compilation_info() { return compilation_info_; }
@@ -912,6 +940,8 @@ class FunctionState V8_FINAL {
 
   bool arguments_pushed() { return arguments_elements() != NULL; }
 
+  int inlining_id() const { return inlining_id_; }
+
  private:
   HOptimizedGraphBuilder* owner_;
 
@@ -941,6 +971,9 @@ class FunctionState V8_FINAL {
   HArgumentsObject* arguments_object_;
   HArgumentsElements* arguments_elements_;
 
+  int inlining_id_;
+  HSourcePosition outer_source_position_;
+
   FunctionState* outer_;
 };
 
@@ -1024,7 +1057,8 @@ class HGraphBuilder {
       : info_(info),
         graph_(NULL),
         current_block_(NULL),
-        position_(RelocInfo::kNoPosition) {}
+        position_(HSourcePosition::Unknown()),
+        start_position_(0) {}
   virtual ~HGraphBuilder() {}
 
   HBasicBlock* current_block() const { return current_block_; }
@@ -1054,7 +1088,7 @@ class HGraphBuilder {
             HBasicBlock* target,
             FunctionState* state = NULL,
             bool add_simulate = true) {
-    from->Goto(target, position_, state, add_simulate);
+    from->Goto(target, source_position(), state, add_simulate);
   }
   void Goto(HBasicBlock* target,
             FunctionState* state = NULL,
@@ -1070,7 +1104,7 @@ class HGraphBuilder {
   void AddLeaveInlined(HBasicBlock* block,
                        HValue* return_value,
                        FunctionState* state) {
-    block->AddLeaveInlined(return_value, state, position_);
+    block->AddLeaveInlined(return_value, state, source_position());
   }
   void AddLeaveInlined(HValue* return_value, FunctionState* state) {
     return AddLeaveInlined(current_block(), return_value, state);
@@ -1276,8 +1310,6 @@ class HGraphBuilder {
 
   void AddSimulate(BailoutId id, RemovableSimulate removable = FIXED_SIMULATE);
 
-  int position() const { return position_; }
-
  protected:
   virtual bool BuildGraph() = 0;
 
@@ -1778,6 +1810,27 @@ class HGraphBuilder {
  protected:
   void SetSourcePosition(int position) {
     ASSERT(position != RelocInfo::kNoPosition);
+    position_.set_position(position - start_position_);
+  }
+
+  void EnterInlinedSource(int start_position, int id) {
+    if (FLAG_hydrogen_track_positions) {
+      start_position_ = start_position;
+      position_.set_inlining_id(id);
+    }
+  }
+
+  // Convert the given absolute offset from the start of the script to
+  // the HSourcePosition assuming that this position corresponds to the
+  // same function as current position_.
+  HSourcePosition ScriptPositionToSourcePosition(int position) {
+    HSourcePosition pos = position_;
+    pos.set_position(position - start_position_);
+    return pos;
+  }
+
+  HSourcePosition source_position() { return position_; }
+  void set_source_position(HSourcePosition position) {
     position_ = position;
   }
 
@@ -1805,7 +1858,8 @@ class HGraphBuilder {
   CompilationInfo* info_;
   HGraph* graph_;
   HBasicBlock* current_block_;
-  int position_;
+  HSourcePosition position_;
+  int start_position_;
 };
 
 
@@ -2209,7 +2263,8 @@ class HOptimizedGraphBuilder : public HGraphBuilder, public AstVisitor {
                  HValue* implicit_return_value,
                  BailoutId ast_id,
                  BailoutId return_id,
-                 InliningKind inlining_kind);
+                 InliningKind inlining_kind,
+                 HSourcePosition position);
 
   bool TryInlineCall(Call* expr);
   bool TryInlineConstruct(CallNew* expr, HValue* implicit_return_value);
@@ -2419,8 +2474,8 @@ class HOptimizedGraphBuilder : public HGraphBuilder, public AstVisitor {
                                                Type* left_type,
                                                Type* right_type,
                                                Type* combined_type,
-                                               int left_position,
-                                               int right_position,
+                                               HSourcePosition left_position,
+                                               HSourcePosition right_position,
                                                BailoutId bailout_id);
 
   HInstruction* BuildStringCharCodeAt(HValue* string,
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 18ef79a..2fd00d0 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -476,7 +476,8 @@ bool LCodeGen::GenerateDeferredCode() {
 
       HValue* value =
           instructions_->at(code->instruction_index())->hydrogen_value();
-      RecordAndWritePosition(value->position());
+      RecordAndWritePosition(
+          chunk()->graph()->SourcePositionToScriptPosition(value->position()));
 
       Comment(";;; <@%d,#%d> "
               "-------------------- Deferred %s --------------------",
@@ -1178,6 +1179,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
       translations_.CreateByteArray(isolate()->factory());
   data->SetTranslationByteArray(*translations);
   data->SetInlinedFunctionCount(Smi::FromInt(inlined_function_count_));
+  data->SetOptimizationId(Smi::FromInt(info_->optimization_id()));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);
diff --git a/src/isolate.cc b/src/isolate.cc
index 3b4a62b..a008b6a 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1564,7 +1564,8 @@ Isolate::Isolate()
       sweeper_thread_(NULL),
       num_sweeper_threads_(0),
       max_available_threads_(0),
-      stress_deopt_count_(0) {
+      stress_deopt_count_(0),
+      next_optimization_id_(0) {
   id_ = NoBarrier_AtomicIncrement(&isolate_counter_, 1);
   TRACE_ISOLATE(constructor);
 
diff --git a/src/isolate.h b/src/isolate.h
index a9b0cd4..ef1dd30 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -1108,6 +1108,14 @@ class Isolate {
   // Given an address occupied by a live code object, return that object.
   Object* FindCodeObject(Address a);
 
+  int NextOptimizationId() {
+    int id = next_optimization_id_++;
+    if (!Smi::IsValid(next_optimization_id_)) {
+      next_optimization_id_ = 0;
+    }
+    return id;
+  }
+
  private:
   Isolate();
 
@@ -1340,6 +1348,8 @@ class Isolate {
   // Counts deopt points if deopt_every_n_times is enabled.
   unsigned int stress_deopt_count_;
 
+  int next_optimization_id_;
+
   friend class ExecutionAccess;
   friend class HandleScopeImplementer;
   friend class IsolateInitializer;
diff --git a/src/lithium-codegen.cc b/src/lithium-codegen.cc
index 5786a05..9eecedc 100644
--- a/src/lithium-codegen.cc
+++ b/src/lithium-codegen.cc
@@ -107,11 +107,9 @@ bool LCodeGenBase::GenerateBody() {
     GenerateBodyInstructionPre(instr);
 
     HValue* value = instr->hydrogen_value();
-    if (value->position() != RelocInfo::kNoPosition) {
-      ASSERT(!graph()->info()->IsOptimizing() ||
-             !FLAG_emit_opt_code_positions ||
-             value->position() != RelocInfo::kNoPosition);
-      RecordAndWritePosition(value->position());
+    if (!value->position().IsUnknown()) {
+      RecordAndWritePosition(
+        chunk()->graph()->SourcePositionToScriptPosition(value->position()));
     }
 
     instr->CompileToNative(codegen);
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index 604b164..e4fbe1f 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -267,7 +267,8 @@ bool LCodeGen::GenerateDeferredCode() {
 
       HValue* value =
           instructions_->at(code->instruction_index())->hydrogen_value();
-      RecordAndWritePosition(value->position());
+      RecordAndWritePosition(
+          chunk()->graph()->SourcePositionToScriptPosition(value->position()));
 
       Comment(";;; <@%d,#%d> "
               "-------------------- Deferred %s --------------------",
@@ -859,6 +860,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
       translations_.CreateByteArray(isolate()->factory());
   data->SetTranslationByteArray(*translations);
   data->SetInlinedFunctionCount(Smi::FromInt(inlined_function_count_));
+  data->SetOptimizationId(Smi::FromInt(info_->optimization_id()));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);
diff --git a/src/objects.h b/src/objects.h
index bb98576..b17db2a 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4995,7 +4995,8 @@ class DeoptimizationInputData: public FixedArray {
   static const int kLiteralArrayIndex = 2;
   static const int kOsrAstIdIndex = 3;
   static const int kOsrPcOffsetIndex = 4;
-  static const int kFirstDeoptEntryIndex = 5;
+  static const int kOptimizationIdIndex = 5;
+  static const int kFirstDeoptEntryIndex = 6;
 
   // Offsets of deopt entry elements relative to the start of the entry.
   static const int kAstIdRawOffset = 0;
@@ -5018,6 +5019,7 @@ class DeoptimizationInputData: public FixedArray {
   DEFINE_ELEMENT_ACCESSORS(LiteralArray, FixedArray)
   DEFINE_ELEMENT_ACCESSORS(OsrAstId, Smi)
   DEFINE_ELEMENT_ACCESSORS(OsrPcOffset, Smi)
+  DEFINE_ELEMENT_ACCESSORS(OptimizationId, Smi)
 
 #undef DEFINE_ELEMENT_ACCESSORS
 
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index dafbd25..9c12a51 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -328,7 +328,8 @@ bool LCodeGen::GenerateDeferredCode() {
 
       HValue* value =
           instructions_->at(code->instruction_index())->hydrogen_value();
-      RecordAndWritePosition(value->position());
+      RecordAndWritePosition(
+          chunk()->graph()->SourcePositionToScriptPosition(value->position()));
 
       Comment(";;; <@%d,#%d> "
               "-------------------- Deferred %s --------------------",
@@ -791,6 +792,7 @@ void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
       translations_.CreateByteArray(isolate()->factory());
   data->SetTranslationByteArray(*translations);
   data->SetInlinedFunctionCount(Smi::FromInt(inlined_function_count_));
+  data->SetOptimizationId(Smi::FromInt(info_->optimization_id()));
 
   Handle<FixedArray> literals =
       factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);
-- 
2.7.4