From 264c7fe3cd49d575ad9df7e6e14f19757a7b45f8 Mon Sep 17 00:00:00 2001
From: "svenpanne@chromium.org" <svenpanne@chromium.org>
Date: Fri, 19 Sep 2014 06:27:06 +0000
Subject: [PATCH] Emit comment with instruction+reason before deopt calls.

Note that we still need to migrate from sometimes emitting those
comments by hand to passing a reason explicitly, but this can be done
incrementally in separate CLs.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/582743002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24061 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/arm/lithium-codegen-arm.cc       |  25 ++++----
 src/arm/lithium-codegen-arm.h        |   5 +-
 src/arm64/lithium-codegen-arm64.cc   | 109 ++++++++++++++++++-----------------
 src/arm64/lithium-codegen-arm64.h    |  45 +++++++++------
 src/deoptimizer.h                    |  10 +++-
 src/ia32/lithium-codegen-ia32.cc     |  25 ++++----
 src/ia32/lithium-codegen-ia32.h      |   5 +-
 src/lithium-codegen.cc               |   6 ++
 src/lithium-codegen.h                |   1 +
 src/mips/lithium-codegen-mips.cc     |  18 +++---
 src/mips/lithium-codegen-mips.h      |   6 +-
 src/mips64/lithium-codegen-mips64.cc |  18 +++---
 src/mips64/lithium-codegen-mips64.h  |   6 +-
 src/x64/lithium-codegen-x64.cc       |  26 +++++----
 src/x64/lithium-codegen-x64.h        |   5 +-
 src/x87/lithium-codegen-x87.cc       |  25 ++++----
 src/x87/lithium-codegen-x87.h        |   5 +-
 17 files changed, 195 insertions(+), 145 deletions(-)

diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 87fcd60..b20f8b0 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -336,21 +336,23 @@ bool LCodeGen::GenerateDeoptJumpTable() {
 
     int length = deopt_jump_table_.length();
     for (int i = 0; i < length; i++) {
-      __ bind(&deopt_jump_table_[i].label);
+      Deoptimizer::JumpTableEntry* table_entry = &deopt_jump_table_[i];
+      __ bind(&table_entry->label);
 
-      Deoptimizer::BailoutType type = deopt_jump_table_[i].bailout_type;
+      Deoptimizer::BailoutType type = table_entry->bailout_type;
       DCHECK(type == deopt_jump_table_[0].bailout_type);
-      Address entry = deopt_jump_table_[i].address;
+      Address entry = table_entry->address;
       int id = Deoptimizer::GetDeoptimizationId(isolate(), entry, type);
       DCHECK(id != Deoptimizer::kNotDeoptimizationEntry);
       Comment(";;; jump table entry %d: deoptimization bailout %d.", i, id);
+      DeoptComment(table_entry->mnemonic, table_entry->reason);
 
       // Second-level deopt table entries are contiguous and small, so instead
       // of loading the full, absolute address of each one, load an immediate
       // offset which will be added to the base address later.
       __ mov(entry_offset, Operand(entry - base));
 
-      if (deopt_jump_table_[i].needs_frame) {
+      if (table_entry->needs_frame) {
         DCHECK(!info()->saves_caller_doubles());
         if (needs_frame.is_bound()) {
           __ b(&needs_frame);
@@ -847,6 +849,7 @@ void LCodeGen::RegisterEnvironmentForDeoptimization(LEnvironment* environment,
 
 
 void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
+                            const char* reason,
                             Deoptimizer::BailoutType bailout_type) {
   LEnvironment* environment = instr->environment();
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
@@ -904,6 +907,7 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
   // restore caller doubles.
   if (condition == al && frame_is_built_ &&
       !info()->saves_caller_doubles()) {
+    DeoptComment(instr->Mnemonic(), reason);
     __ Call(entry, RelocInfo::RUNTIME_ENTRY);
   } else {
     // We often have several deopts to the same entry, reuse the last
@@ -912,9 +916,8 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
         (deopt_jump_table_.last().address != entry) ||
         (deopt_jump_table_.last().bailout_type != bailout_type) ||
         (deopt_jump_table_.last().needs_frame != !frame_is_built_)) {
-      Deoptimizer::JumpTableEntry table_entry(entry,
-                                              bailout_type,
-                                              !frame_is_built_);
+      Deoptimizer::JumpTableEntry table_entry(entry, instr->Mnemonic(), reason,
+                                              bailout_type, !frame_is_built_);
       deopt_jump_table_.Add(table_entry, zone());
     }
     __ b(condition, &deopt_jump_table_.last().label);
@@ -922,11 +925,12 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
 }
 
 
-void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr) {
+void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
+                            const char* reason) {
   Deoptimizer::BailoutType bailout_type = info()->IsStub()
       ? Deoptimizer::LAZY
       : Deoptimizer::EAGER;
-  DeoptimizeIf(condition, instr, bailout_type);
+  DeoptimizeIf(condition, instr, reason, bailout_type);
 }
 
 
@@ -5665,8 +5669,7 @@ void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
     type = Deoptimizer::LAZY;
   }
 
-  Comment(";;; deoptimize: %s", instr->hydrogen()->reason());
-  DeoptimizeIf(al, instr, type);
+  DeoptimizeIf(al, instr, instr->hydrogen()->reason(), type);
 }
 
 
diff --git a/src/arm/lithium-codegen-arm.h b/src/arm/lithium-codegen-arm.h
index fc60916..a08768c 100644
--- a/src/arm/lithium-codegen-arm.h
+++ b/src/arm/lithium-codegen-arm.h
@@ -235,8 +235,9 @@ class LCodeGen: public LCodeGenBase {
   void RegisterEnvironmentForDeoptimization(LEnvironment* environment,
                                             Safepoint::DeoptMode mode);
   void DeoptimizeIf(Condition condition, LInstruction* instr,
-                    Deoptimizer::BailoutType bailout_type);
-  void DeoptimizeIf(Condition condition, LInstruction* instr);
+                    const char* reason, Deoptimizer::BailoutType bailout_type);
+  void DeoptimizeIf(Condition condition, LInstruction* instr,
+                    const char* reason = NULL);
 
   void AddToTranslation(LEnvironment* environment,
                         Translation* translation,
diff --git a/src/arm64/lithium-codegen-arm64.cc b/src/arm64/lithium-codegen-arm64.cc
index 0873c95..b083215 100644
--- a/src/arm64/lithium-codegen-arm64.cc
+++ b/src/arm64/lithium-codegen-arm64.cc
@@ -593,11 +593,8 @@ bool LCodeGen::GenerateCode() {
   // the frame (that is done in GeneratePrologue).
   FrameScope frame_scope(masm_, StackFrame::NONE);
 
-  return GeneratePrologue() &&
-      GenerateBody() &&
-      GenerateDeferredCode() &&
-      GenerateDeoptJumpTable() &&
-      GenerateSafepointTable();
+  return GeneratePrologue() && GenerateBody() && GenerateDeferredCode() &&
+         GenerateJumpTable() && GenerateSafepointTable();
 }
 
 
@@ -827,28 +824,30 @@ bool LCodeGen::GenerateDeferredCode() {
 }
 
 
-bool LCodeGen::GenerateDeoptJumpTable() {
+bool LCodeGen::GenerateJumpTable() {
   Label needs_frame, restore_caller_doubles, call_deopt_entry;
 
-  if (deopt_jump_table_.length() > 0) {
+  if (jump_table_.length() > 0) {
     Comment(";;; -------------------- Jump table --------------------");
-    Address base = deopt_jump_table_[0]->address;
+    Address base = jump_table_[0]->address;
 
     UseScratchRegisterScope temps(masm());
     Register entry_offset = temps.AcquireX();
 
-    int length = deopt_jump_table_.length();
+    int length = jump_table_.length();
     for (int i = 0; i < length; i++) {
-      __ Bind(&deopt_jump_table_[i]->label);
+      Deoptimizer::JumpTableEntry* table_entry = jump_table_[i];
+      __ Bind(&table_entry->label);
 
-      Deoptimizer::BailoutType type = deopt_jump_table_[i]->bailout_type;
-      Address entry = deopt_jump_table_[i]->address;
+      Deoptimizer::BailoutType type = table_entry->bailout_type;
+      Address entry = table_entry->address;
       int id = Deoptimizer::GetDeoptimizationId(isolate(), entry, type);
       if (id == Deoptimizer::kNotDeoptimizationEntry) {
         Comment(";;; jump table entry %d.", i);
       } else {
         Comment(";;; jump table entry %d: deoptimization bailout %d.", i, id);
       }
+      DeoptComment(table_entry->mnemonic, table_entry->reason);
 
       // Second-level deopt table entries are contiguous and small, so instead
       // of loading the full, absolute address of each one, load the base
@@ -859,7 +858,7 @@ bool LCodeGen::GenerateDeoptJumpTable() {
       // branch.
       bool last_entry = (i + 1) == length;
 
-      if (deopt_jump_table_[i]->needs_frame) {
+      if (table_entry->needs_frame) {
         DCHECK(!info()->saves_caller_doubles());
         if (!needs_frame.is_bound()) {
           // This variant of deopt can only be used with stubs. Since we don't
@@ -997,8 +996,8 @@ void LCodeGen::PopulateDeoptimizationLiteralsWithInlinedFunctions() {
 
 
 void LCodeGen::DeoptimizeBranch(
-    LInstruction* instr, BranchType branch_type, Register reg, int bit,
-    Deoptimizer::BailoutType* override_bailout_type) {
+    LInstruction* instr, const char* reason, BranchType branch_type,
+    Register reg, int bit, Deoptimizer::BailoutType* override_bailout_type) {
   LEnvironment* environment = instr->environment();
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
   Deoptimizer::BailoutType bailout_type =
@@ -1052,91 +1051,98 @@ void LCodeGen::DeoptimizeBranch(
   // Go through jump table if we need to build frame, or restore caller doubles.
   if (branch_type == always &&
       frame_is_built_ && !info()->saves_caller_doubles()) {
+    DeoptComment(instr->Mnemonic(), reason);
     __ Call(entry, RelocInfo::RUNTIME_ENTRY);
   } else {
     // We often have several deopts to the same entry, reuse the last
     // jump entry if this is the case.
-    if (deopt_jump_table_.is_empty() ||
-        (deopt_jump_table_.last()->address != entry) ||
-        (deopt_jump_table_.last()->bailout_type != bailout_type) ||
-        (deopt_jump_table_.last()->needs_frame != !frame_is_built_)) {
+    if (jump_table_.is_empty() || (jump_table_.last()->address != entry) ||
+        (jump_table_.last()->bailout_type != bailout_type) ||
+        (jump_table_.last()->needs_frame != !frame_is_built_)) {
       Deoptimizer::JumpTableEntry* table_entry =
-        new(zone()) Deoptimizer::JumpTableEntry(entry,
-                                                bailout_type,
-                                                !frame_is_built_);
-      deopt_jump_table_.Add(table_entry, zone());
+          new (zone()) Deoptimizer::JumpTableEntry(
+              entry, instr->Mnemonic(), reason, bailout_type, !frame_is_built_);
+      jump_table_.Add(table_entry, zone());
     }
-    __ B(&deopt_jump_table_.last()->label,
-         branch_type, reg, bit);
+    __ B(&jump_table_.last()->label, branch_type, reg, bit);
   }
 }
 
 
 void LCodeGen::Deoptimize(LInstruction* instr,
-                          Deoptimizer::BailoutType* override_bailout_type) {
-  DeoptimizeBranch(instr, always, NoReg, -1, override_bailout_type);
+                          Deoptimizer::BailoutType* override_bailout_type,
+                          const char* reason) {
+  DeoptimizeBranch(instr, reason, always, NoReg, -1, override_bailout_type);
 }
 
 
-void LCodeGen::DeoptimizeIf(Condition cond, LInstruction* instr) {
-  DeoptimizeBranch(instr, static_cast<BranchType>(cond));
+void LCodeGen::DeoptimizeIf(Condition cond, LInstruction* instr,
+                            const char* reason) {
+  DeoptimizeBranch(instr, reason, static_cast<BranchType>(cond));
 }
 
 
-void LCodeGen::DeoptimizeIfZero(Register rt, LInstruction* instr) {
-  DeoptimizeBranch(instr, reg_zero, rt);
+void LCodeGen::DeoptimizeIfZero(Register rt, LInstruction* instr,
+                                const char* reason) {
+  DeoptimizeBranch(instr, reason, reg_zero, rt);
 }
 
 
-void LCodeGen::DeoptimizeIfNotZero(Register rt, LInstruction* instr) {
-  DeoptimizeBranch(instr, reg_not_zero, rt);
+void LCodeGen::DeoptimizeIfNotZero(Register rt, LInstruction* instr,
+                                   const char* reason) {
+  DeoptimizeBranch(instr, reason, reg_not_zero, rt);
 }
 
 
-void LCodeGen::DeoptimizeIfNegative(Register rt, LInstruction* instr) {
+void LCodeGen::DeoptimizeIfNegative(Register rt, LInstruction* instr,
+                                    const char* reason) {
   int sign_bit = rt.Is64Bits() ? kXSignBit : kWSignBit;
-  DeoptimizeIfBitSet(rt, sign_bit, instr);
+  DeoptimizeIfBitSet(rt, sign_bit, instr, reason);
 }
 
 
-void LCodeGen::DeoptimizeIfSmi(Register rt, LInstruction* instr) {
-  DeoptimizeIfBitClear(rt, MaskToBit(kSmiTagMask), instr);
+void LCodeGen::DeoptimizeIfSmi(Register rt, LInstruction* instr,
+                               const char* reason) {
+  DeoptimizeIfBitClear(rt, MaskToBit(kSmiTagMask), instr, reason);
 }
 
 
-void LCodeGen::DeoptimizeIfNotSmi(Register rt, LInstruction* instr) {
-  DeoptimizeIfBitSet(rt, MaskToBit(kSmiTagMask), instr);
+void LCodeGen::DeoptimizeIfNotSmi(Register rt, LInstruction* instr,
+                                  const char* reason) {
+  DeoptimizeIfBitSet(rt, MaskToBit(kSmiTagMask), instr, reason);
 }
 
 
 void LCodeGen::DeoptimizeIfRoot(Register rt, Heap::RootListIndex index,
-                                LInstruction* instr) {
+                                LInstruction* instr, const char* reason) {
   __ CompareRoot(rt, index);
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, reason);
 }
 
 
 void LCodeGen::DeoptimizeIfNotRoot(Register rt, Heap::RootListIndex index,
-                                   LInstruction* instr) {
+                                   LInstruction* instr, const char* reason) {
   __ CompareRoot(rt, index);
-  DeoptimizeIf(ne, instr);
+  DeoptimizeIf(ne, instr, reason);
 }
 
 
-void LCodeGen::DeoptimizeIfMinusZero(DoubleRegister input,
-                                     LInstruction* instr) {
+void LCodeGen::DeoptimizeIfMinusZero(DoubleRegister input, LInstruction* instr,
+                                     const char* reason) {
   __ TestForMinusZero(input);
-  DeoptimizeIf(vs, instr);
+  DeoptimizeIf(vs, instr, reason);
 }
 
 
-void LCodeGen::DeoptimizeIfBitSet(Register rt, int bit, LInstruction* instr) {
-  DeoptimizeBranch(instr, reg_bit_set, rt, bit);
+void LCodeGen::DeoptimizeIfBitSet(Register rt, int bit, LInstruction* instr,
+                                  const char* reason) {
+  DeoptimizeBranch(instr, reason, reg_bit_set, rt, bit);
 }
 
 
-void LCodeGen::DeoptimizeIfBitClear(Register rt, int bit, LInstruction* instr) {
-  DeoptimizeBranch(instr, reg_bit_clear, rt, bit);
+void LCodeGen::DeoptimizeIfBitClear(Register rt, int bit, LInstruction* instr,
+                                    const char* reason) {
+  DeoptimizeBranch(instr, reason, reg_bit_clear, rt, bit);
 }
 
 
@@ -2685,8 +2691,7 @@ void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
     type = Deoptimizer::LAZY;
   }
 
-  Comment(";;; deoptimize: %s", instr->hydrogen()->reason());
-  Deoptimize(instr, &type);
+  Deoptimize(instr, &type, instr->hydrogen()->reason());
 }
 
 
diff --git a/src/arm64/lithium-codegen-arm64.h b/src/arm64/lithium-codegen-arm64.h
index 4ee8a8b..40fbc38 100644
--- a/src/arm64/lithium-codegen-arm64.h
+++ b/src/arm64/lithium-codegen-arm64.h
@@ -27,7 +27,7 @@ class LCodeGen: public LCodeGenBase {
   LCodeGen(LChunk* chunk, MacroAssembler* assembler, CompilationInfo* info)
       : LCodeGenBase(chunk, assembler, info),
         deoptimizations_(4, info->zone()),
-        deopt_jump_table_(4, info->zone()),
+        jump_table_(4, info->zone()),
         deoptimization_literals_(8, info->zone()),
         inlined_function_count_(0),
         scope_(info->scope()),
@@ -213,24 +213,35 @@ class LCodeGen: public LCodeGenBase {
                                    Register temp,
                                    LOperand* index,
                                    String::Encoding encoding);
-  void DeoptimizeBranch(LInstruction* instr, BranchType branch_type,
-                        Register reg = NoReg, int bit = -1,
+  void DeoptimizeBranch(LInstruction* instr, const char* reason,
+                        BranchType branch_type, Register reg = NoReg,
+                        int bit = -1,
                         Deoptimizer::BailoutType* override_bailout_type = NULL);
   void Deoptimize(LInstruction* instr,
-                  Deoptimizer::BailoutType* override_bailout_type = NULL);
-  void DeoptimizeIf(Condition cond, LInstruction* instr);
-  void DeoptimizeIfZero(Register rt, LInstruction* instr);
-  void DeoptimizeIfNotZero(Register rt, LInstruction* instr);
-  void DeoptimizeIfNegative(Register rt, LInstruction* instr);
-  void DeoptimizeIfSmi(Register rt, LInstruction* instr);
-  void DeoptimizeIfNotSmi(Register rt, LInstruction* instr);
+                  Deoptimizer::BailoutType* override_bailout_type = NULL,
+                  const char* reason = NULL);
+  void DeoptimizeIf(Condition cond, LInstruction* instr,
+                    const char* reason = NULL);
+  void DeoptimizeIfZero(Register rt, LInstruction* instr,
+                        const char* reason = NULL);
+  void DeoptimizeIfNotZero(Register rt, LInstruction* instr,
+                           const char* reason = NULL);
+  void DeoptimizeIfNegative(Register rt, LInstruction* instr,
+                            const char* reason = NULL);
+  void DeoptimizeIfSmi(Register rt, LInstruction* instr,
+                       const char* reason = NULL);
+  void DeoptimizeIfNotSmi(Register rt, LInstruction* instr,
+                          const char* reason = NULL);
   void DeoptimizeIfRoot(Register rt, Heap::RootListIndex index,
-                        LInstruction* instr);
+                        LInstruction* instr, const char* reason = NULL);
   void DeoptimizeIfNotRoot(Register rt, Heap::RootListIndex index,
-                           LInstruction* instr);
-  void DeoptimizeIfMinusZero(DoubleRegister input, LInstruction* instr);
-  void DeoptimizeIfBitSet(Register rt, int bit, LInstruction* instr);
-  void DeoptimizeIfBitClear(Register rt, int bit, LInstruction* instr);
+                           LInstruction* instr, const char* reason = NULL);
+  void DeoptimizeIfMinusZero(DoubleRegister input, LInstruction* instr,
+                             const char* reason = NULL);
+  void DeoptimizeIfBitSet(Register rt, int bit, LInstruction* instr,
+                          const char* reason = NULL);
+  void DeoptimizeIfBitClear(Register rt, int bit, LInstruction* instr,
+                            const char* reason = NULL);
 
   MemOperand PrepareKeyedExternalArrayOperand(Register key,
                                               Register base,
@@ -273,7 +284,7 @@ class LCodeGen: public LCodeGenBase {
   void GenerateBodyInstructionPre(LInstruction* instr) OVERRIDE;
   bool GeneratePrologue();
   bool GenerateDeferredCode();
-  bool GenerateDeoptJumpTable();
+  bool GenerateJumpTable();
   bool GenerateSafepointTable();
 
   // Generates the custom OSR entrypoint and sets the osr_pc_offset.
@@ -338,7 +349,7 @@ class LCodeGen: public LCodeGenBase {
   void EnsureSpaceForLazyDeopt(int space_needed) OVERRIDE;
 
   ZoneList<LEnvironment*> deoptimizations_;
-  ZoneList<Deoptimizer::JumpTableEntry*> deopt_jump_table_;
+  ZoneList<Deoptimizer::JumpTableEntry*> jump_table_;
   ZoneList<Handle<Object> > deoptimization_literals_;
   int inlined_function_count_;
   Scope* const scope_;
diff --git a/src/deoptimizer.h b/src/deoptimizer.h
index 90f5d5c..a0961fc 100644
--- a/src/deoptimizer.h
+++ b/src/deoptimizer.h
@@ -102,15 +102,19 @@ class Deoptimizer : public Malloced {
   static const int kBailoutTypesWithCodeEntry = SOFT + 1;
 
   struct JumpTableEntry : public ZoneObject {
-    inline JumpTableEntry(Address entry,
-                          Deoptimizer::BailoutType type,
+    inline JumpTableEntry(Address entry, const char* the_mnemonic,
+                          const char* the_reason, Deoptimizer::BailoutType type,
                           bool frame)
         : label(),
           address(entry),
+          mnemonic(the_mnemonic),
+          reason(the_reason),
           bailout_type(type),
-          needs_frame(frame) { }
+          needs_frame(frame) {}
     Label label;
     Address address;
+    const char* mnemonic;
+    const char* reason;
     Deoptimizer::BailoutType bailout_type;
     bool needs_frame;
   };
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 8d4e1cf..c11d74f 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -383,16 +383,18 @@ bool LCodeGen::GenerateJumpTable() {
     Comment(";;; -------------------- Jump table --------------------");
   }
   for (int i = 0; i < jump_table_.length(); i++) {
-    __ bind(&jump_table_[i].label);
-    Address entry = jump_table_[i].address;
-    Deoptimizer::BailoutType type = jump_table_[i].bailout_type;
+    Deoptimizer::JumpTableEntry* table_entry = &jump_table_[i];
+    __ bind(&table_entry->label);
+    Address entry = table_entry->address;
+    Deoptimizer::BailoutType type = table_entry->bailout_type;
     int id = Deoptimizer::GetDeoptimizationId(isolate(), entry, type);
     if (id == Deoptimizer::kNotDeoptimizationEntry) {
       Comment(";;; jump table entry %d.", i);
     } else {
       Comment(";;; jump table entry %d: deoptimization bailout %d.", i, id);
     }
-    if (jump_table_[i].needs_frame) {
+    DeoptComment(table_entry->mnemonic, table_entry->reason);
+    if (table_entry->needs_frame) {
       DCHECK(!info()->saves_caller_doubles());
       __ push(Immediate(ExternalReference::ForDeoptEntry(entry)));
       if (needs_frame.is_bound()) {
@@ -826,6 +828,7 @@ void LCodeGen::RegisterEnvironmentForDeoptimization(
 
 
 void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
+                            const char* reason,
                             Deoptimizer::BailoutType bailout_type) {
   LEnvironment* environment = instr->environment();
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
@@ -869,6 +872,7 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
 
   DCHECK(info()->IsStub() || frame_is_built_);
   if (cc == no_condition && frame_is_built_) {
+    DeoptComment(instr->Mnemonic(), reason);
     __ call(entry, RelocInfo::RUNTIME_ENTRY);
   } else {
     // We often have several deopts to the same entry, reuse the last
@@ -877,9 +881,8 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
         jump_table_.last().address != entry ||
         jump_table_.last().needs_frame != !frame_is_built_ ||
         jump_table_.last().bailout_type != bailout_type) {
-      Deoptimizer::JumpTableEntry table_entry(entry,
-                                              bailout_type,
-                                              !frame_is_built_);
+      Deoptimizer::JumpTableEntry table_entry(entry, instr->Mnemonic(), reason,
+                                              bailout_type, !frame_is_built_);
       jump_table_.Add(table_entry, zone());
     }
     if (cc == no_condition) {
@@ -891,11 +894,12 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
 }
 
 
-void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr) {
+void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
+                            const char* reason) {
   Deoptimizer::BailoutType bailout_type = info()->IsStub()
       ? Deoptimizer::LAZY
       : Deoptimizer::EAGER;
-  DeoptimizeIf(cc, instr, bailout_type);
+  DeoptimizeIf(cc, instr, reason, bailout_type);
 }
 
 
@@ -5463,8 +5467,7 @@ void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
   if (info()->IsStub() && type == Deoptimizer::EAGER) {
     type = Deoptimizer::LAZY;
   }
-  Comment(";;; deoptimize: %s", instr->hydrogen()->reason());
-  DeoptimizeIf(no_condition, instr, type);
+  DeoptimizeIf(no_condition, instr, instr->hydrogen()->reason(), type);
 }
 
 
diff --git a/src/ia32/lithium-codegen-ia32.h b/src/ia32/lithium-codegen-ia32.h
index b38d679..555cf8c 100644
--- a/src/ia32/lithium-codegen-ia32.h
+++ b/src/ia32/lithium-codegen-ia32.h
@@ -209,9 +209,10 @@ class LCodeGen: public LCodeGenBase {
 
   void RegisterEnvironmentForDeoptimization(LEnvironment* environment,
                                             Safepoint::DeoptMode mode);
-  void DeoptimizeIf(Condition cc, LInstruction* instr,
+  void DeoptimizeIf(Condition cc, LInstruction* instr, const char* reason,
                     Deoptimizer::BailoutType bailout_type);
-  void DeoptimizeIf(Condition cc, LInstruction* instr);
+  void DeoptimizeIf(Condition cc, LInstruction* instr,
+                    const char* reason = NULL);
 
   bool DeoptEveryNTimes() {
     return FLAG_deopt_every_n_times != 0 && !info()->IsStub();
diff --git a/src/lithium-codegen.cc b/src/lithium-codegen.cc
index 90efa53..8640116 100644
--- a/src/lithium-codegen.cc
+++ b/src/lithium-codegen.cc
@@ -147,6 +147,12 @@ void LCodeGenBase::Comment(const char* format, ...) {
 }
 
 
+void LCodeGenBase::DeoptComment(const char* mnemonic, const char* reason) {
+  Comment(";;; deoptimize %s: %s", mnemonic,
+          reason == NULL ? "unknown reason" : reason);
+}
+
+
 int LCodeGenBase::GetNextEmittedBlock() const {
   for (int i = current_block_ + 1; i < graph()->blocks()->length(); ++i) {
     if (!graph()->blocks()->at(i)->IsReachable()) continue;
diff --git a/src/lithium-codegen.h b/src/lithium-codegen.h
index 1eb963e..d57e614 100644
--- a/src/lithium-codegen.h
+++ b/src/lithium-codegen.h
@@ -33,6 +33,7 @@ class LCodeGenBase BASE_EMBEDDED {
   HGraph* graph() const;
 
   void FPRINTF_CHECKING Comment(const char* format, ...);
+  void DeoptComment(const char* mnemonic, const char* reason);
 
   bool GenerateBody();
   virtual void GenerateBodyInstructionPre(LInstruction* instr) {}
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index faf0342..6d73c83 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -821,7 +821,8 @@ void LCodeGen::RegisterEnvironmentForDeoptimization(LEnvironment* environment,
 
 void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
                             Deoptimizer::BailoutType bailout_type,
-                            Register src1, const Operand& src2) {
+                            Register src1, const Operand& src2,
+                            const char* reason) {
   LEnvironment* environment = instr->environment();
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
   DCHECK(environment->HasBeenRegistered());
@@ -867,6 +868,7 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
   // restore caller doubles.
   if (condition == al && frame_is_built_ &&
       !info()->saves_caller_doubles()) {
+    DeoptComment(instr->Mnemonic(), reason);
     __ Call(entry, RelocInfo::RUNTIME_ENTRY, condition, src1, src2);
   } else {
     // We often have several deopts to the same entry, reuse the last
@@ -875,9 +877,8 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
         (deopt_jump_table_.last().address != entry) ||
         (deopt_jump_table_.last().bailout_type != bailout_type) ||
         (deopt_jump_table_.last().needs_frame != !frame_is_built_)) {
-      Deoptimizer::JumpTableEntry table_entry(entry,
-                                              bailout_type,
-                                              !frame_is_built_);
+      Deoptimizer::JumpTableEntry table_entry(entry, instr->Mnemonic(), reason,
+                                              bailout_type, !frame_is_built_);
       deopt_jump_table_.Add(table_entry, zone());
     }
     __ Branch(&deopt_jump_table_.last().label, condition, src1, src2);
@@ -886,11 +887,12 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
 
 
 void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
-                            Register src1, const Operand& src2) {
+                            Register src1, const Operand& src2,
+                            const char* reason) {
   Deoptimizer::BailoutType bailout_type = info()->IsStub()
       ? Deoptimizer::LAZY
       : Deoptimizer::EAGER;
-  DeoptimizeIf(condition, instr, bailout_type, src1, src2);
+  DeoptimizeIf(condition, instr, bailout_type, src1, src2, reason);
 }
 
 
@@ -5676,8 +5678,8 @@ void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
     type = Deoptimizer::LAZY;
   }
 
-  Comment(";;; deoptimize: %s", instr->hydrogen()->reason());
-  DeoptimizeIf(al, instr, type, zero_reg, Operand(zero_reg));
+  DeoptimizeIf(al, instr, type, zero_reg, Operand(zero_reg),
+               instr->hydrogen()->reason());
 }
 
 
diff --git a/src/mips/lithium-codegen-mips.h b/src/mips/lithium-codegen-mips.h
index b8b9e7d..ca25c89 100644
--- a/src/mips/lithium-codegen-mips.h
+++ b/src/mips/lithium-codegen-mips.h
@@ -231,10 +231,12 @@ class LCodeGen: public LCodeGenBase {
   void DeoptimizeIf(Condition condition, LInstruction* instr,
                     Deoptimizer::BailoutType bailout_type,
                     Register src1 = zero_reg,
-                    const Operand& src2 = Operand(zero_reg));
+                    const Operand& src2 = Operand(zero_reg),
+                    const char* reason = NULL);
   void DeoptimizeIf(Condition condition, LInstruction* instr,
                     Register src1 = zero_reg,
-                    const Operand& src2 = Operand(zero_reg));
+                    const Operand& src2 = Operand(zero_reg),
+                    const char* reason = NULL);
 
   void AddToTranslation(LEnvironment* environment,
                         Translation* translation,
diff --git a/src/mips64/lithium-codegen-mips64.cc b/src/mips64/lithium-codegen-mips64.cc
index d060d16..965486c 100644
--- a/src/mips64/lithium-codegen-mips64.cc
+++ b/src/mips64/lithium-codegen-mips64.cc
@@ -774,7 +774,8 @@ void LCodeGen::RegisterEnvironmentForDeoptimization(LEnvironment* environment,
 
 void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
                             Deoptimizer::BailoutType bailout_type,
-                            Register src1, const Operand& src2) {
+                            Register src1, const Operand& src2,
+                            const char* reason) {
   LEnvironment* environment = instr->environment();
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
   DCHECK(environment->HasBeenRegistered());
@@ -820,6 +821,7 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
   // restore caller doubles.
   if (condition == al && frame_is_built_ &&
       !info()->saves_caller_doubles()) {
+    DeoptComment(instr->Mnemonic(), reason);
     __ Call(entry, RelocInfo::RUNTIME_ENTRY, condition, src1, src2);
   } else {
     // We often have several deopts to the same entry, reuse the last
@@ -828,9 +830,8 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
         (deopt_jump_table_.last().address != entry) ||
         (deopt_jump_table_.last().bailout_type != bailout_type) ||
         (deopt_jump_table_.last().needs_frame != !frame_is_built_)) {
-      Deoptimizer::JumpTableEntry table_entry(entry,
-                                              bailout_type,
-                                              !frame_is_built_);
+      Deoptimizer::JumpTableEntry table_entry(entry, instr->Mnemonic(), reason,
+                                              bailout_type, !frame_is_built_);
       deopt_jump_table_.Add(table_entry, zone());
     }
     __ Branch(&deopt_jump_table_.last().label, condition, src1, src2);
@@ -839,11 +840,12 @@ void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
 
 
 void LCodeGen::DeoptimizeIf(Condition condition, LInstruction* instr,
-                            Register src1, const Operand& src2) {
+                            Register src1, const Operand& src2,
+                            const char* reason) {
   Deoptimizer::BailoutType bailout_type = info()->IsStub()
       ? Deoptimizer::LAZY
       : Deoptimizer::EAGER;
-  DeoptimizeIf(condition, instr, bailout_type, src1, src2);
+  DeoptimizeIf(condition, instr, bailout_type, src1, src2, reason);
 }
 
 
@@ -5712,8 +5714,8 @@ void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
     type = Deoptimizer::LAZY;
   }
 
-  Comment(";;; deoptimize: %s", instr->hydrogen()->reason());
-  DeoptimizeIf(al, instr, type, zero_reg, Operand(zero_reg));
+  DeoptimizeIf(al, instr, type, zero_reg, Operand(zero_reg),
+               instr->hydrogen()->reason());
 }
 
 
diff --git a/src/mips64/lithium-codegen-mips64.h b/src/mips64/lithium-codegen-mips64.h
index 9457b9d..b2193ae 100644
--- a/src/mips64/lithium-codegen-mips64.h
+++ b/src/mips64/lithium-codegen-mips64.h
@@ -232,10 +232,12 @@ class LCodeGen: public LCodeGenBase {
   void DeoptimizeIf(Condition condition, LInstruction* instr,
                     Deoptimizer::BailoutType bailout_type,
                     Register src1 = zero_reg,
-                    const Operand& src2 = Operand(zero_reg));
+                    const Operand& src2 = Operand(zero_reg),
+                    const char* reason = NULL);
   void DeoptimizeIf(Condition condition, LInstruction* instr,
                     Register src1 = zero_reg,
-                    const Operand& src2 = Operand(zero_reg));
+                    const Operand& src2 = Operand(zero_reg),
+                    const char* reason = NULL);
 
   void AddToTranslation(LEnvironment* environment,
                         Translation* translation,
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 9f1c396..46456a1 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -303,16 +303,18 @@ bool LCodeGen::GenerateJumpTable() {
     Comment(";;; -------------------- Jump table --------------------");
   }
   for (int i = 0; i < jump_table_.length(); i++) {
-    __ bind(&jump_table_[i].label);
-    Address entry = jump_table_[i].address;
-    Deoptimizer::BailoutType type = jump_table_[i].bailout_type;
+    Deoptimizer::JumpTableEntry* table_entry = &jump_table_[i];
+    __ bind(&table_entry->label);
+    Address entry = table_entry->address;
+    Deoptimizer::BailoutType type = table_entry->bailout_type;
     int id = Deoptimizer::GetDeoptimizationId(isolate(), entry, type);
     if (id == Deoptimizer::kNotDeoptimizationEntry) {
       Comment(";;; jump table entry %d.", i);
     } else {
       Comment(";;; jump table entry %d: deoptimization bailout %d.", i, id);
     }
-    if (jump_table_[i].needs_frame) {
+    DeoptComment(table_entry->mnemonic, table_entry->reason);
+    if (table_entry->needs_frame) {
       DCHECK(!info()->saves_caller_doubles());
       __ Move(kScratchRegister, ExternalReference::ForDeoptEntry(entry));
       if (needs_frame.is_bound()) {
@@ -730,6 +732,7 @@ void LCodeGen::RegisterEnvironmentForDeoptimization(LEnvironment* environment,
 
 
 void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
+                            const char* reason,
                             Deoptimizer::BailoutType bailout_type) {
   LEnvironment* environment = instr->environment();
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
@@ -779,6 +782,7 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
   // restore caller doubles.
   if (cc == no_condition && frame_is_built_ &&
       !info()->saves_caller_doubles()) {
+    DeoptComment(instr->Mnemonic(), reason);
     __ call(entry, RelocInfo::RUNTIME_ENTRY);
   } else {
     // We often have several deopts to the same entry, reuse the last
@@ -787,9 +791,8 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
         jump_table_.last().address != entry ||
         jump_table_.last().needs_frame != !frame_is_built_ ||
         jump_table_.last().bailout_type != bailout_type) {
-      Deoptimizer::JumpTableEntry table_entry(entry,
-                                              bailout_type,
-                                              !frame_is_built_);
+      Deoptimizer::JumpTableEntry table_entry(entry, instr->Mnemonic(), reason,
+                                              bailout_type, !frame_is_built_);
       jump_table_.Add(table_entry, zone());
     }
     if (cc == no_condition) {
@@ -801,11 +804,12 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
 }
 
 
-void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr) {
+void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
+                            const char* reason) {
   Deoptimizer::BailoutType bailout_type = info()->IsStub()
       ? Deoptimizer::LAZY
       : Deoptimizer::EAGER;
-  DeoptimizeIf(cc, instr, bailout_type);
+  DeoptimizeIf(cc, instr, reason, bailout_type);
 }
 
 
@@ -5647,9 +5651,7 @@ void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
   if (info()->IsStub() && type == Deoptimizer::EAGER) {
     type = Deoptimizer::LAZY;
   }
-
-  Comment(";;; deoptimize: %s", instr->hydrogen()->reason());
-  DeoptimizeIf(no_condition, instr, type);
+  DeoptimizeIf(no_condition, instr, instr->hydrogen()->reason(), type);
 }
 
 
diff --git a/src/x64/lithium-codegen-x64.h b/src/x64/lithium-codegen-x64.h
index e1876b8..bf10e34 100644
--- a/src/x64/lithium-codegen-x64.h
+++ b/src/x64/lithium-codegen-x64.h
@@ -206,9 +206,10 @@ class LCodeGen: public LCodeGenBase {
                                     int argc);
   void RegisterEnvironmentForDeoptimization(LEnvironment* environment,
                                             Safepoint::DeoptMode mode);
-  void DeoptimizeIf(Condition cc, LInstruction* instr,
+  void DeoptimizeIf(Condition cc, LInstruction* instr, const char* reason,
                     Deoptimizer::BailoutType bailout_type);
-  void DeoptimizeIf(Condition cc, LInstruction* instr);
+  void DeoptimizeIf(Condition cc, LInstruction* instr,
+                    const char* reason = NULL);
 
   bool DeoptEveryNTimes() {
     return FLAG_deopt_every_n_times != 0 && !info()->IsStub();
diff --git a/src/x87/lithium-codegen-x87.cc b/src/x87/lithium-codegen-x87.cc
index 67f8a78..ac67bb2 100644
--- a/src/x87/lithium-codegen-x87.cc
+++ b/src/x87/lithium-codegen-x87.cc
@@ -364,16 +364,18 @@ bool LCodeGen::GenerateJumpTable() {
     Comment(";;; -------------------- Jump table --------------------");
   }
   for (int i = 0; i < jump_table_.length(); i++) {
-    __ bind(&jump_table_[i].label);
-    Address entry = jump_table_[i].address;
-    Deoptimizer::BailoutType type = jump_table_[i].bailout_type;
+    Deoptimizer::JumpTableEntry* table_entry = &jump_table_[i];
+    __ bind(&table_entry->label);
+    Address entry = table_entry->address;
+    Deoptimizer::BailoutType type = table_entry->bailout_type;
     int id = Deoptimizer::GetDeoptimizationId(isolate(), entry, type);
     if (id == Deoptimizer::kNotDeoptimizationEntry) {
       Comment(";;; jump table entry %d.", i);
     } else {
       Comment(";;; jump table entry %d: deoptimization bailout %d.", i, id);
     }
-    if (jump_table_[i].needs_frame) {
+    DeoptComment(table_entry->mnemonic, table_entry->reason);
+    if (table_entry->needs_frame) {
       DCHECK(!info()->saves_caller_doubles());
       __ push(Immediate(ExternalReference::ForDeoptEntry(entry)));
       if (needs_frame.is_bound()) {
@@ -1008,6 +1010,7 @@ void LCodeGen::RegisterEnvironmentForDeoptimization(
 
 
 void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
+                            const char* reason,
                             Deoptimizer::BailoutType bailout_type) {
   LEnvironment* environment = instr->environment();
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
@@ -1062,6 +1065,7 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
 
   DCHECK(info()->IsStub() || frame_is_built_);
   if (cc == no_condition && frame_is_built_) {
+    DeoptComment(instr->Mnemonic(), reason);
     __ call(entry, RelocInfo::RUNTIME_ENTRY);
   } else {
     // We often have several deopts to the same entry, reuse the last
@@ -1070,9 +1074,8 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
         jump_table_.last().address != entry ||
         jump_table_.last().needs_frame != !frame_is_built_ ||
         jump_table_.last().bailout_type != bailout_type) {
-      Deoptimizer::JumpTableEntry table_entry(entry,
-                                              bailout_type,
-                                              !frame_is_built_);
+      Deoptimizer::JumpTableEntry table_entry(entry, instr->Mnemonic(), reason,
+                                              bailout_type, !frame_is_built_);
       jump_table_.Add(table_entry, zone());
     }
     if (cc == no_condition) {
@@ -1084,11 +1087,12 @@ void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
 }
 
 
-void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr) {
+void LCodeGen::DeoptimizeIf(Condition cc, LInstruction* instr,
+                            const char* reason) {
   Deoptimizer::BailoutType bailout_type = info()->IsStub()
       ? Deoptimizer::LAZY
       : Deoptimizer::EAGER;
-  DeoptimizeIf(cc, instr, bailout_type);
+  DeoptimizeIf(cc, instr, reason, bailout_type);
 }
 
 
@@ -5528,8 +5532,7 @@ void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
   if (info()->IsStub() && type == Deoptimizer::EAGER) {
     type = Deoptimizer::LAZY;
   }
-  Comment(";;; deoptimize: %s", instr->hydrogen()->reason());
-  DeoptimizeIf(no_condition, instr, type);
+  DeoptimizeIf(no_condition, instr, instr->hydrogen()->reason(), type);
 }
 
 
diff --git a/src/x87/lithium-codegen-x87.h b/src/x87/lithium-codegen-x87.h
index ca2179a..080a468 100644
--- a/src/x87/lithium-codegen-x87.h
+++ b/src/x87/lithium-codegen-x87.h
@@ -234,9 +234,10 @@ class LCodeGen: public LCodeGenBase {
 
   void RegisterEnvironmentForDeoptimization(LEnvironment* environment,
                                             Safepoint::DeoptMode mode);
-  void DeoptimizeIf(Condition cc, LInstruction* instr,
+  void DeoptimizeIf(Condition cc, LInstruction* instr, const char* reason,
                     Deoptimizer::BailoutType bailout_type);
-  void DeoptimizeIf(Condition cc, LInstruction* instr);
+  void DeoptimizeIf(Condition cc, LInstruction* instr,
+                    const char* reason = NULL);
 
   bool DeoptEveryNTimes() {
     return FLAG_deopt_every_n_times != 0 && !info()->IsStub();
-- 
2.7.4