X87: Made the detailed reason for deopts mandatory on x87. Unified and improved things.

src/x87/lithium-codegen-x87.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X87
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 1395 matching lines @@
   int32_t mask = divisor < 0 ? -(divisor + 1) : (divisor - 1);
   Label dividend_is_not_negative, done;
   if (hmod->CheckFlag(HValue::kLeftCanBeNegative)) {
     __ test(dividend, dividend);
     __ j(not_sign, &dividend_is_not_negative, Label::kNear);
     // Note that this is correct even for kMinInt operands.
     __ neg(dividend);
     __ and_(dividend, mask);
     __ neg(dividend);
     if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
-      DeoptimizeIf(zero, instr);
+      DeoptimizeIf(zero, instr, "minus zero");
     }
     __ jmp(&done, Label::kNear);
   }
 
   __ bind(&dividend_is_not_negative);
   __ and_(dividend, mask);
   __ bind(&done);
 }
 
 
 void LCodeGen::DoModByConstI(LModByConstI* instr) {
   Register dividend = ToRegister(instr->dividend());
   int32_t divisor = instr->divisor();
   DCHECK(ToRegister(instr->result()).is(eax));
 
   if (divisor == 0) {
-    DeoptimizeIf(no_condition, instr);
+    DeoptimizeIf(no_condition, instr, "division by zero");
     return;
   }
 
   __ TruncatingDiv(dividend, Abs(divisor));
   __ imul(edx, edx, Abs(divisor));
   __ mov(eax, dividend);
   __ sub(eax, edx);
 
   // Check for negative zero.
   HMod* hmod = instr->hydrogen();
   if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
     Label remainder_not_zero;
     __ j(not_zero, &remainder_not_zero, Label::kNear);
     __ cmp(dividend, Immediate(0));
-    DeoptimizeIf(less, instr);
+    DeoptimizeIf(less, instr, "minus zero");
     __ bind(&remainder_not_zero);
   }
 }
 
 
 void LCodeGen::DoModI(LModI* instr) {
   HMod* hmod = instr->hydrogen();
 
   Register left_reg = ToRegister(instr->left());
   DCHECK(left_reg.is(eax));
   Register right_reg = ToRegister(instr->right());
   DCHECK(!right_reg.is(eax));
   DCHECK(!right_reg.is(edx));
   Register result_reg = ToRegister(instr->result());
   DCHECK(result_reg.is(edx));
 
   Label done;
   // Check for x % 0, idiv would signal a divide error. We have to
   // deopt in this case because we can't return a NaN.
   if (hmod->CheckFlag(HValue::kCanBeDivByZero)) {
     __ test(right_reg, Operand(right_reg));
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "division by zero");
   }
 
   // Check for kMinInt % -1, idiv would signal a divide error. We
   // have to deopt if we care about -0, because we can't return that.
   if (hmod->CheckFlag(HValue::kCanOverflow)) {
     Label no_overflow_possible;
     __ cmp(left_reg, kMinInt);
     __ j(not_equal, &no_overflow_possible, Label::kNear);
     __ cmp(right_reg, -1);
     if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
-      DeoptimizeIf(equal, instr);
+      DeoptimizeIf(equal, instr, "minus zero");
     } else {
       __ j(not_equal, &no_overflow_possible, Label::kNear);
       __ Move(result_reg, Immediate(0));
       __ jmp(&done, Label::kNear);
     }
     __ bind(&no_overflow_possible);
   }
 
   // Sign extend dividend in eax into edx:eax.
   __ cdq();
 
   // If we care about -0, test if the dividend is <0 and the result is 0.
   if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
     Label positive_left;
     __ test(left_reg, Operand(left_reg));
     __ j(not_sign, &positive_left, Label::kNear);
     __ idiv(right_reg);
     __ test(result_reg, Operand(result_reg));
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "minus zero");
     __ jmp(&done, Label::kNear);
     __ bind(&positive_left);
   }
   __ idiv(right_reg);
   __ bind(&done);
 }
 
 
 void LCodeGen::DoDivByPowerOf2I(LDivByPowerOf2I* instr) {
   Register dividend = ToRegister(instr->dividend());
   int32_t divisor = instr->divisor();
   Register result = ToRegister(instr->result());
   DCHECK(divisor == kMinInt || base::bits::IsPowerOfTwo32(Abs(divisor)));
   DCHECK(!result.is(dividend));
 
   // Check for (0 / -x) that will produce negative zero.
   HDiv* hdiv = instr->hydrogen();
   if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
     __ test(dividend, dividend);
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "minus zero");
   }
   // Check for (kMinInt / -1).
   if (hdiv->CheckFlag(HValue::kCanOverflow) && divisor == -1) {
     __ cmp(dividend, kMinInt);
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "overflow");
   }
   // Deoptimize if remainder will not be 0.
   if (!hdiv->CheckFlag(HInstruction::kAllUsesTruncatingToInt32) &&
       divisor != 1 && divisor != -1) {
     int32_t mask = divisor < 0 ? -(divisor + 1) : (divisor - 1);
     __ test(dividend, Immediate(mask));
-    DeoptimizeIf(not_zero, instr);
+    DeoptimizeIf(not_zero, instr, "lost precision");
   }
   __ Move(result, dividend);
   int32_t shift = WhichPowerOf2Abs(divisor);
   if (shift > 0) {
     // The arithmetic shift is always OK, the 'if' is an optimization only.
     if (shift > 1) __ sar(result, 31);
     __ shr(result, 32 - shift);
     __ add(result, dividend);
     __ sar(result, shift);
   }
   if (divisor < 0) __ neg(result);
 }
 
 
 void LCodeGen::DoDivByConstI(LDivByConstI* instr) {
   Register dividend = ToRegister(instr->dividend());
   int32_t divisor = instr->divisor();
   DCHECK(ToRegister(instr->result()).is(edx));
 
   if (divisor == 0) {
-    DeoptimizeIf(no_condition, instr);
+    DeoptimizeIf(no_condition, instr, "division by zero");
     return;
   }
 
   // Check for (0 / -x) that will produce negative zero.
   HDiv* hdiv = instr->hydrogen();
   if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
     __ test(dividend, dividend);
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "minus zero");
   }
 
   __ TruncatingDiv(dividend, Abs(divisor));
   if (divisor < 0) __ neg(edx);
 
   if (!hdiv->CheckFlag(HInstruction::kAllUsesTruncatingToInt32)) {
     __ mov(eax, edx);
     __ imul(eax, eax, divisor);
     __ sub(eax, dividend);
-    DeoptimizeIf(not_equal, instr);
+    DeoptimizeIf(not_equal, instr, "lost precision");
   }
 }
 
 
 // TODO(svenpanne) Refactor this to avoid code duplication with DoFlooringDivI.
 void LCodeGen::DoDivI(LDivI* instr) {
   HBinaryOperation* hdiv = instr->hydrogen();
   Register dividend = ToRegister(instr->dividend());
   Register divisor = ToRegister(instr->divisor());
   Register remainder = ToRegister(instr->temp());
   DCHECK(dividend.is(eax));
   DCHECK(remainder.is(edx));
   DCHECK(ToRegister(instr->result()).is(eax));
   DCHECK(!divisor.is(eax));
   DCHECK(!divisor.is(edx));
 
   // Check for x / 0.
   if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
     __ test(divisor, divisor);
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "division by zero");
   }
 
   // Check for (0 / -x) that will produce negative zero.
   if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
     Label dividend_not_zero;
     __ test(dividend, dividend);
     __ j(not_zero, &dividend_not_zero, Label::kNear);
     __ test(divisor, divisor);
-    DeoptimizeIf(sign, instr);
+    DeoptimizeIf(sign, instr, "minus zero");
     __ bind(&dividend_not_zero);
   }
 
   // Check for (kMinInt / -1).
   if (hdiv->CheckFlag(HValue::kCanOverflow)) {
     Label dividend_not_min_int;
     __ cmp(dividend, kMinInt);
     __ j(not_zero, &dividend_not_min_int, Label::kNear);
     __ cmp(divisor, -1);
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "overflow");
     __ bind(&dividend_not_min_int);
   }
 
   // Sign extend to edx (= remainder).
   __ cdq();
   __ idiv(divisor);
 
   if (!hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
     // Deoptimize if remainder is not 0.
     __ test(remainder, remainder);
-    DeoptimizeIf(not_zero, instr);
+    DeoptimizeIf(not_zero, instr, "lost precision");
   }
 }
 
 
 void LCodeGen::DoFlooringDivByPowerOf2I(LFlooringDivByPowerOf2I* instr) {
   Register dividend = ToRegister(instr->dividend());
   int32_t divisor = instr->divisor();
   DCHECK(dividend.is(ToRegister(instr->result())));
 
   // If the divisor is positive, things are easy: There can be no deopts and we
   // can simply do an arithmetic right shift.
   if (divisor == 1) return;
   int32_t shift = WhichPowerOf2Abs(divisor);
   if (divisor > 1) {
     __ sar(dividend, shift);
     return;
   }
 
   // If the divisor is negative, we have to negate and handle edge cases.
   __ neg(dividend);
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "minus zero");
   }
 
   // Dividing by -1 is basically negation, unless we overflow.
   if (divisor == -1) {
     if (instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
-      DeoptimizeIf(overflow, instr);
+      DeoptimizeIf(overflow, instr, "overflow");
     }
     return;
   }
 
   // If the negation could not overflow, simply shifting is OK.
   if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
     __ sar(dividend, shift);
     return;
   }
 
   Label not_kmin_int, done;
   __ j(no_overflow, &not_kmin_int, Label::kNear);
   __ mov(dividend, Immediate(kMinInt / divisor));
   __ jmp(&done, Label::kNear);
   __ bind(&not_kmin_int);
   __ sar(dividend, shift);
   __ bind(&done);
 }
 
 
 void LCodeGen::DoFlooringDivByConstI(LFlooringDivByConstI* instr) {
   Register dividend = ToRegister(instr->dividend());
   int32_t divisor = instr->divisor();
   DCHECK(ToRegister(instr->result()).is(edx));
 
   if (divisor == 0) {
-    DeoptimizeIf(no_condition, instr);
+    DeoptimizeIf(no_condition, instr, "division by zero");
     return;
   }
 
   // Check for (0 / -x) that will produce negative zero.
   HMathFloorOfDiv* hdiv = instr->hydrogen();
   if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
     __ test(dividend, dividend);
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "minus zero");
   }
 
   // Easy case: We need no dynamic check for the dividend and the flooring
   // division is the same as the truncating division.
   if ((divisor > 0 && !hdiv->CheckFlag(HValue::kLeftCanBeNegative)) ||
       (divisor < 0 && !hdiv->CheckFlag(HValue::kLeftCanBePositive))) {
     __ TruncatingDiv(dividend, Abs(divisor));
     if (divisor < 0) __ neg(edx);
     return;
   }
@@ skipping 26 matching lines @@
   Register result = ToRegister(instr->result());
   DCHECK(dividend.is(eax));
   DCHECK(remainder.is(edx));
   DCHECK(result.is(eax));
   DCHECK(!divisor.is(eax));
   DCHECK(!divisor.is(edx));
 
   // Check for x / 0.
   if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
     __ test(divisor, divisor);
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "division by zero");
   }
 
   // Check for (0 / -x) that will produce negative zero.
   if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
     Label dividend_not_zero;
     __ test(dividend, dividend);
     __ j(not_zero, &dividend_not_zero, Label::kNear);
     __ test(divisor, divisor);
-    DeoptimizeIf(sign, instr);
+    DeoptimizeIf(sign, instr, "minus zero");
     __ bind(&dividend_not_zero);
   }
 
   // Check for (kMinInt / -1).
   if (hdiv->CheckFlag(HValue::kCanOverflow)) {
     Label dividend_not_min_int;
     __ cmp(dividend, kMinInt);
     __ j(not_zero, &dividend_not_min_int, Label::kNear);
     __ cmp(divisor, -1);
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "overflow");
     __ bind(&dividend_not_min_int);
   }
 
   // Sign extend to edx (= remainder).
   __ cdq();
   __ idiv(divisor);
 
   Label done;
   __ test(remainder, remainder);
   __ j(zero, &done, Label::kNear);
@@ skipping 57 matching lines @@
       __ imul(left, left, constant);
     }
   } else {
     if (instr->hydrogen()->representation().IsSmi()) {
       __ SmiUntag(left);
     }
     __ imul(left, ToOperand(right));
   }
 
   if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
-    DeoptimizeIf(overflow, instr);
+    DeoptimizeIf(overflow, instr, "overflow");
   }
 
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     // Bail out if the result is supposed to be negative zero.
     Label done;
     __ test(left, Operand(left));
     __ j(not_zero, &done);
     if (right->IsConstantOperand()) {
       if (ToInteger32(LConstantOperand::cast(right)) < 0) {
-        DeoptimizeIf(no_condition, instr);
+        DeoptimizeIf(no_condition, instr, "minus zero");
       } else if (ToInteger32(LConstantOperand::cast(right)) == 0) {
         __ cmp(ToRegister(instr->temp()), Immediate(0));
-        DeoptimizeIf(less, instr);
+        DeoptimizeIf(less, instr, "minus zero");
       }
     } else {
       // Test the non-zero operand for negative sign.
       __ or_(ToRegister(instr->temp()), ToOperand(right));
-      DeoptimizeIf(sign, instr);
+      DeoptimizeIf(sign, instr, "minus zero");
     }
     __ bind(&done);
   }
 }
 
 
 void LCodeGen::DoBitI(LBitI* instr) {
   LOperand* left = instr->left();
   LOperand* right = instr->right();
   DCHECK(left->Equals(instr->result()));
@@ skipping 52 matching lines @@
       case Token::ROR:
         __ ror_cl(ToRegister(left));
         break;
       case Token::SAR:
         __ sar_cl(ToRegister(left));
         break;
       case Token::SHR:
         __ shr_cl(ToRegister(left));
         if (instr->can_deopt()) {
           __ test(ToRegister(left), ToRegister(left));
-          DeoptimizeIf(sign, instr);
+          DeoptimizeIf(sign, instr, "negative value");
         }
         break;
       case Token::SHL:
         __ shl_cl(ToRegister(left));
         break;
       default:
         UNREACHABLE();
         break;
     }
   } else {
     int value = ToInteger32(LConstantOperand::cast(right));
     uint8_t shift_count = static_cast<uint8_t>(value & 0x1F);
     switch (instr->op()) {
       case Token::ROR:
         if (shift_count == 0 && instr->can_deopt()) {
           __ test(ToRegister(left), ToRegister(left));
-          DeoptimizeIf(sign, instr);
+          DeoptimizeIf(sign, instr, "negative value");
         } else {
           __ ror(ToRegister(left), shift_count);
         }
         break;
       case Token::SAR:
         if (shift_count != 0) {
           __ sar(ToRegister(left), shift_count);
         }
         break;
       case Token::SHR:
         if (shift_count != 0) {
           __ shr(ToRegister(left), shift_count);
         } else if (instr->can_deopt()) {
           __ test(ToRegister(left), ToRegister(left));
-          DeoptimizeIf(sign, instr);
+          DeoptimizeIf(sign, instr, "negative value");
         }
         break;
       case Token::SHL:
         if (shift_count != 0) {
           if (instr->hydrogen_value()->representation().IsSmi() &&
               instr->can_deopt()) {
             if (shift_count != 1) {
               __ shl(ToRegister(left), shift_count - 1);
             }
             __ SmiTag(ToRegister(left));
-            DeoptimizeIf(overflow, instr);
+            DeoptimizeIf(overflow, instr, "overflow");
           } else {
             __ shl(ToRegister(left), shift_count);
           }
         }
         break;
       default:
         UNREACHABLE();
         break;
     }
   }
 }
 
 
 void LCodeGen::DoSubI(LSubI* instr) {
   LOperand* left = instr->left();
   LOperand* right = instr->right();
   DCHECK(left->Equals(instr->result()));
 
   if (right->IsConstantOperand()) {
     __ sub(ToOperand(left),
            ToImmediate(right, instr->hydrogen()->representation()));
   } else {
     __ sub(ToRegister(left), ToOperand(right));
   }
   if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
-    DeoptimizeIf(overflow, instr);
+    DeoptimizeIf(overflow, instr, "overflow");
   }
 }
 
 
 void LCodeGen::DoConstantI(LConstantI* instr) {
   __ Move(ToRegister(instr->result()), Immediate(instr->value()));
 }
 
 
 void LCodeGen::DoConstantS(LConstantS* instr) {
@@ skipping 39 matching lines @@
 void LCodeGen::DoDateField(LDateField* instr) {
   Register object = ToRegister(instr->date());
   Register result = ToRegister(instr->result());
   Register scratch = ToRegister(instr->temp());
   Smi* index = instr->index();
   Label runtime, done;
   DCHECK(object.is(result));
   DCHECK(object.is(eax));
 
   __ test(object, Immediate(kSmiTagMask));
-  DeoptimizeIf(zero, instr);
+  DeoptimizeIf(zero, instr, "Smi");
   __ CmpObjectType(object, JS_DATE_TYPE, scratch);
-  DeoptimizeIf(not_equal, instr);
+  DeoptimizeIf(not_equal, instr, "not a date object");
 
   if (index->value() == 0) {
     __ mov(result, FieldOperand(object, JSDate::kValueOffset));
   } else {
     if (index->value() < JSDate::kFirstUncachedField) {
       ExternalReference stamp = ExternalReference::date_cache_stamp(isolate());
       __ mov(scratch, Operand::StaticVariable(stamp));
       __ cmp(scratch, FieldOperand(object, JSDate::kCacheStampOffset));
       __ j(not_equal, &runtime, Label::kNear);
       __ mov(result, FieldOperand(object, JSDate::kValueOffset +
@@ skipping 109 matching lines @@
       __ lea(ToRegister(instr->result()), address);
     }
   } else {
     if (right->IsConstantOperand()) {
       __ add(ToOperand(left),
              ToImmediate(right, instr->hydrogen()->representation()));
     } else {
       __ add(ToRegister(left), ToOperand(right));
     }
     if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
-      DeoptimizeIf(overflow, instr);
+      DeoptimizeIf(overflow, instr, "overflow");
     }
   }
 }
 
 
 void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
   LOperand* left = instr->left();
   LOperand* right = instr->right();
   DCHECK(left->Equals(instr->result()));
   HMathMinMax::Operation operation = instr->hydrogen()->operation();
@@ skipping 224 matching lines @@
       }
 
       if (expected.Contains(ToBooleanStub::SMI)) {
         // Smis: 0 -> false, all other -> true.
         __ test(reg, Operand(reg));
         __ j(equal, instr->FalseLabel(chunk_));
         __ JumpIfSmi(reg, instr->TrueLabel(chunk_));
       } else if (expected.NeedsMap()) {
         // If we need a map later and have a Smi -> deopt.
         __ test(reg, Immediate(kSmiTagMask));
-        DeoptimizeIf(zero, instr);
+        DeoptimizeIf(zero, instr, "Smi");
       }
 
       Register map = no_reg;  // Keep the compiler happy.
       if (expected.NeedsMap()) {
         map = ToRegister(instr->temp());
         DCHECK(!map.is(reg));
         __ mov(map, FieldOperand(reg, HeapObject::kMapOffset));
 
         if (expected.CanBeUndetectable()) {
           // Undetectable -> false.
@@ skipping 36 matching lines @@
         __ fld_d(FieldOperand(reg, HeapNumber::kValueOffset));
         __ FCmp();
         __ j(zero, instr->FalseLabel(chunk_));
         __ jmp(instr->TrueLabel(chunk_));
         __ bind(&not_heap_number);
       }
 
       if (!expected.IsGeneric()) {
         // We've seen something for the first time -> deopt.
         // This can only happen if we are not generic already.
-        DeoptimizeIf(no_condition, instr);
+        DeoptimizeIf(no_condition, instr, "unexpected object");
       }
     }
   }
 }
 
 
 void LCodeGen::EmitGoto(int block) {
   if (!IsNextEmittedBlock(block)) {
     __ jmp(chunk_->GetAssemblyLabel(LookupDestination(block)));
   }
@@ skipping 618 matching lines @@
     info()->AddNoFrameRange(no_frame_start, masm_->pc_offset());
   }
 }
 
 
 void LCodeGen::DoLoadGlobalCell(LLoadGlobalCell* instr) {
   Register result = ToRegister(instr->result());
   __ mov(result, Operand::ForCell(instr->hydrogen()->cell().handle()));
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ cmp(result, factory()->the_hole_value());
-    DeoptimizeIf(equal, instr);
+    DeoptimizeIf(equal, instr, "hole");
   }
 }
 
 
 template <class T>
 void LCodeGen::EmitVectorLoadICRegisters(T* instr) {
   DCHECK(FLAG_vector_ics);
   Register vector = ToRegister(instr->temp_vector());
   DCHECK(vector.is(VectorLoadICDescriptor::VectorRegister()));
   __ mov(vector, instr->hydrogen()->feedback_vector());
@@ skipping 23 matching lines @@
 void LCodeGen::DoStoreGlobalCell(LStoreGlobalCell* instr) {
   Register value = ToRegister(instr->value());
   Handle<PropertyCell> cell_handle = instr->hydrogen()->cell().handle();
 
   // If the cell we are storing to contains the hole it could have
   // been deleted from the property dictionary. In that case, we need
   // to update the property details in the property dictionary to mark
   // it as no longer deleted. We deoptimize in that case.
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ cmp(Operand::ForCell(cell_handle), factory()->the_hole_value());
-    DeoptimizeIf(equal, instr);
+    DeoptimizeIf(equal, instr, "hole");
   }
 
   // Store the value.
   __ mov(Operand::ForCell(cell_handle), value);
   // Cells are always rescanned, so no write barrier here.
 }
 
 
 void LCodeGen::DoLoadContextSlot(LLoadContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
   __ mov(result, ContextOperand(context, instr->slot_index()));
 
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ cmp(result, factory()->the_hole_value());
     if (instr->hydrogen()->DeoptimizesOnHole()) {
-      DeoptimizeIf(equal, instr);
+      DeoptimizeIf(equal, instr, "hole");
     } else {
       Label is_not_hole;
       __ j(not_equal, &is_not_hole, Label::kNear);
       __ mov(result, factory()->undefined_value());
       __ bind(&is_not_hole);
     }
   }
 }
 
 
 void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register value = ToRegister(instr->value());
 
   Label skip_assignment;
 
   Operand target = ContextOperand(context, instr->slot_index());
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ cmp(target, factory()->the_hole_value());
     if (instr->hydrogen()->DeoptimizesOnHole()) {
-      DeoptimizeIf(equal, instr);
+      DeoptimizeIf(equal, instr, "hole");
     } else {
       __ j(not_equal, &skip_assignment, Label::kNear);
     }
   }
 
   __ mov(target, value);
   if (instr->hydrogen()->NeedsWriteBarrier()) {
     SmiCheck check_needed =
         instr->hydrogen()->value()->type().IsHeapObject()
             ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
@@ skipping 72 matching lines @@
   Register function = ToRegister(instr->function());
   Register temp = ToRegister(instr->temp());
   Register result = ToRegister(instr->result());
 
   // Get the prototype or initial map from the function.
   __ mov(result,
          FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
 
   // Check that the function has a prototype or an initial map.
   __ cmp(Operand(result), Immediate(factory()->the_hole_value()));
-  DeoptimizeIf(equal, instr);
+  DeoptimizeIf(equal, instr, "hole");
 
   // If the function does not have an initial map, we're done.
   Label done;
   __ CmpObjectType(result, MAP_TYPE, temp);
   __ j(not_equal, &done, Label::kNear);
 
   // Get the prototype from the initial map.
   __ mov(result, FieldOperand(result, Map::kPrototypeOffset));
 
   // All done.
@@ skipping 70 matching lines @@
         break;
       case EXTERNAL_INT32_ELEMENTS:
       case INT32_ELEMENTS:
         __ mov(result, operand);
         break;
       case EXTERNAL_UINT32_ELEMENTS:
       case UINT32_ELEMENTS:
         __ mov(result, operand);
         if (!instr->hydrogen()->CheckFlag(HInstruction::kUint32)) {
           __ test(result, Operand(result));
-          DeoptimizeIf(negative, instr);
+          DeoptimizeIf(negative, instr, "negative value");
         }
         break;
       case EXTERNAL_FLOAT32_ELEMENTS:
       case EXTERNAL_FLOAT64_ELEMENTS:
       case FLOAT32_ELEMENTS:
       case FLOAT64_ELEMENTS:
       case FAST_SMI_ELEMENTS:
       case FAST_ELEMENTS:
       case FAST_DOUBLE_ELEMENTS:
       case FAST_HOLEY_SMI_ELEMENTS:
       case FAST_HOLEY_ELEMENTS:
       case FAST_HOLEY_DOUBLE_ELEMENTS:
       case DICTIONARY_ELEMENTS:
       case SLOPPY_ARGUMENTS_ELEMENTS:
         UNREACHABLE();
         break;
     }
   }
 }
 
 
 void LCodeGen::DoLoadKeyedFixedDoubleArray(LLoadKeyed* instr) {
   if (instr->hydrogen()->RequiresHoleCheck()) {
     Operand hole_check_operand = BuildFastArrayOperand(
         instr->elements(), instr->key(),
         instr->hydrogen()->key()->representation(),
         FAST_DOUBLE_ELEMENTS,
         instr->base_offset() + sizeof(kHoleNanLower32));
     __ cmp(hole_check_operand, Immediate(kHoleNanUpper32));
-    DeoptimizeIf(equal, instr);
+    DeoptimizeIf(equal, instr, "hole");
   }
 
   Operand double_load_operand = BuildFastArrayOperand(
       instr->elements(),
       instr->key(),
       instr->hydrogen()->key()->representation(),
       FAST_DOUBLE_ELEMENTS,
       instr->base_offset());
   X87Mov(ToX87Register(instr->result()), double_load_operand);
 }
 
 
 void LCodeGen::DoLoadKeyedFixedArray(LLoadKeyed* instr) {
   Register result = ToRegister(instr->result());
 
   // Load the result.
   __ mov(result,
          BuildFastArrayOperand(instr->elements(), instr->key(),
                                instr->hydrogen()->key()->representation(),
                                FAST_ELEMENTS, instr->base_offset()));
 
   // Check for the hole value.
   if (instr->hydrogen()->RequiresHoleCheck()) {
     if (IsFastSmiElementsKind(instr->hydrogen()->elements_kind())) {
       __ test(result, Immediate(kSmiTagMask));
-      DeoptimizeIf(not_equal, instr);
+      DeoptimizeIf(not_equal, instr, "not a Smi");
     } else {
       __ cmp(result, factory()->the_hole_value());
-      DeoptimizeIf(equal, instr);
+      DeoptimizeIf(equal, instr, "hole");
     }
   }
 }
 
 
 void LCodeGen::DoLoadKeyed(LLoadKeyed* instr) {
   if (instr->is_typed_elements()) {
     DoLoadKeyedExternalArray(instr);
   } else if (instr->hydrogen()->representation().IsDouble()) {
     DoLoadKeyedFixedDoubleArray(instr);
@@ skipping 126 matching lines @@
   }
 
   // Normal function. Replace undefined or null with global receiver.
   __ cmp(receiver, factory()->null_value());
   __ j(equal, &global_object, Label::kNear);
   __ cmp(receiver, factory()->undefined_value());
   __ j(equal, &global_object, Label::kNear);
 
   // The receiver should be a JS object.
   __ test(receiver, Immediate(kSmiTagMask));
-  DeoptimizeIf(equal, instr);
+  DeoptimizeIf(equal, instr, "Smi");
   __ CmpObjectType(receiver, FIRST_SPEC_OBJECT_TYPE, scratch);
-  DeoptimizeIf(below, instr);
+  DeoptimizeIf(below, instr, "not a JavaScript object");
 
   __ jmp(&receiver_ok, Label::kNear);
   __ bind(&global_object);
   __ mov(receiver, FieldOperand(function, JSFunction::kContextOffset));
   const int global_offset = Context::SlotOffset(Context::GLOBAL_OBJECT_INDEX);
   __ mov(receiver, Operand(receiver, global_offset));
   const int proxy_offset = GlobalObject::kGlobalProxyOffset;
   __ mov(receiver, FieldOperand(receiver, proxy_offset));
   __ bind(&receiver_ok);
 }
 
 
 void LCodeGen::DoApplyArguments(LApplyArguments* instr) {
   Register receiver = ToRegister(instr->receiver());
   Register function = ToRegister(instr->function());
   Register length = ToRegister(instr->length());
   Register elements = ToRegister(instr->elements());
   DCHECK(receiver.is(eax));  // Used for parameter count.
   DCHECK(function.is(edi));  // Required by InvokeFunction.
   DCHECK(ToRegister(instr->result()).is(eax));
 
   // Copy the arguments to this function possibly from the
   // adaptor frame below it.
   const uint32_t kArgumentsLimit = 1 * KB;
   __ cmp(length, kArgumentsLimit);
-  DeoptimizeIf(above, instr);
+  DeoptimizeIf(above, instr, "too many arguments");
 
   __ push(receiver);
   __ mov(receiver, length);
 
   // Loop through the arguments pushing them onto the execution
   // stack.
   Label invoke, loop;
   // length is a small non-negative integer, due to the test above.
   __ test(length, Operand(length));
   __ j(zero, &invoke, Label::kNear);
@@ skipping 172 matching lines @@
   }
 
   RecordSafepointWithLazyDeopt(instr, RECORD_SIMPLE_SAFEPOINT);
 }
 
 
 void LCodeGen::DoDeferredMathAbsTaggedHeapNumber(LMathAbs* instr) {
   Register input_reg = ToRegister(instr->value());
   __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
          factory()->heap_number_map());
-  DeoptimizeIf(not_equal, instr);
+  DeoptimizeIf(not_equal, instr, "not a heap number");
 
   Label slow, allocated, done;
   Register tmp = input_reg.is(eax) ? ecx : eax;
   Register tmp2 = tmp.is(ecx) ? edx : input_reg.is(ecx) ? edx : ecx;
 
   // Preserve the value of all registers.
   PushSafepointRegistersScope scope(this);
 
   __ mov(tmp, FieldOperand(input_reg, HeapNumber::kExponentOffset));
   // Check the sign of the argument. If the argument is positive, just
@@ skipping 26 matching lines @@
   __ bind(&done);
 }
 
 
 void LCodeGen::EmitIntegerMathAbs(LMathAbs* instr) {
   Register input_reg = ToRegister(instr->value());
   __ test(input_reg, Operand(input_reg));
   Label is_positive;
   __ j(not_sign, &is_positive, Label::kNear);
   __ neg(input_reg);  // Sets flags.
-  DeoptimizeIf(negative, instr);
+  DeoptimizeIf(negative, instr, "overflow");
   __ bind(&is_positive);
 }
 
 
 void LCodeGen::DoMathAbs(LMathAbs* instr) {
   // Class for deferred case.
   class DeferredMathAbsTaggedHeapNumber FINAL : public LDeferredCode {
    public:
     DeferredMathAbsTaggedHeapNumber(LCodeGen* codegen,
                                     LMathAbs* instr,
@@ skipping 31 matching lines @@
 void LCodeGen::DoMathFloor(LMathFloor* instr) {
   Register output_reg = ToRegister(instr->result());
   X87Register input_reg = ToX87Register(instr->value());
   X87Fxch(input_reg);
 
   Label not_minus_zero, done;
   // Deoptimize on unordered.
   __ fldz();
   __ fld(1);
   __ FCmp();
-  DeoptimizeIf(parity_even, instr);
+  DeoptimizeIf(parity_even, instr, "NaN");
   __ j(below, &not_minus_zero, Label::kNear);
 
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     // Check for negative zero.
     __ j(not_equal, &not_minus_zero, Label::kNear);
     // +- 0.0.
     __ fld(0);
     __ FXamSign();
-    DeoptimizeIf(not_zero, instr);
+    DeoptimizeIf(not_zero, instr, "minus zero");
     __ Move(output_reg, Immediate(0));
     __ jmp(&done, Label::kFar);
   }
 
   // Positive input.
   // rc=01B, round down.
   __ bind(&not_minus_zero);
   __ fnclex();
   __ X87SetRC(0x0400);
   __ sub(esp, Immediate(kPointerSize));
   __ fist_s(Operand(esp, 0));
   __ pop(output_reg);
   __ X87CheckIA();
-  DeoptimizeIf(equal, instr);
+  DeoptimizeIf(equal, instr, "overflow");
   __ fnclex();
   __ X87SetRC(0x0000);
   __ bind(&done);
 }
 
 
 void LCodeGen::DoMathRound(LMathRound* instr) {
   X87Register input_reg = ToX87Register(instr->value());
   Register result = ToRegister(instr->result());
   X87Fxch(input_reg);
@@ skipping 126 matching lines @@
     __ push(exponent);
     __ fild_s(MemOperand(esp, 0));
     __ pop(exponent);
   } else if (exponent_type.IsTagged()) {
     Register exponent = ToRegister(instr->right());
     Register temp = exponent.is(ecx) ? eax : ecx;
     Label no_deopt, done;
     X87LoadForUsage(base);
     __ JumpIfSmi(exponent, &no_deopt);
     __ CmpObjectType(exponent, HEAP_NUMBER_TYPE, temp);
-    DeoptimizeIf(not_equal, instr);
+    DeoptimizeIf(not_equal, instr, "not a heap number");
     // Heap number(double)
     __ fld_d(FieldOperand(exponent, HeapNumber::kValueOffset));
     __ jmp(&done);
     // SMI
     __ bind(&no_deopt);
     __ SmiUntag(exponent);
     __ push(exponent);
     __ fild_s(MemOperand(esp, 0));
     __ pop(exponent);
     __ bind(&done);
@@ skipping 382 matching lines @@
                        instr->hydrogen()->index()->representation()));
   } else {
     __ cmp(ToRegister(instr->index()), ToOperand(instr->length()));
   }
   if (FLAG_debug_code && instr->hydrogen()->skip_check()) {
     Label done;
     __ j(NegateCondition(cc), &done, Label::kNear);
     __ int3();
     __ bind(&done);
   } else {
-    DeoptimizeIf(cc, instr);
+    DeoptimizeIf(cc, instr, "out of bounds");
   }
 }
 
 
 void LCodeGen::DoStoreKeyedExternalArray(LStoreKeyed* instr) {
   ElementsKind elements_kind = instr->elements_kind();
   LOperand* key = instr->key();
   if (!key->IsConstantOperand() &&
       ExternalArrayOpRequiresTemp(instr->hydrogen()->key()->representation(),
                                   elements_kind)) {
@@ skipping 172 matching lines @@
       CodeFactory::KeyedStoreIC(isolate(), instr->strict_mode()).code();
   CallCode(ic, RelocInfo::CODE_TARGET, instr);
 }
 
 
 void LCodeGen::DoTrapAllocationMemento(LTrapAllocationMemento* instr) {
   Register object = ToRegister(instr->object());
   Register temp = ToRegister(instr->temp());
   Label no_memento_found;
   __ TestJSArrayForAllocationMemento(object, temp, &no_memento_found);
-  DeoptimizeIf(equal, instr);
+  DeoptimizeIf(equal, instr, "memento found");
   __ bind(&no_memento_found);
 }
 
 
 void LCodeGen::DoTransitionElementsKind(LTransitionElementsKind* instr) {
   Register object_reg = ToRegister(instr->object());
 
   Handle<Map> from_map = instr->original_map();
   Handle<Map> to_map = instr->transitioned_map();
   ElementsKind from_kind = instr->from_kind();
@@ skipping 350 matching lines @@
   __ StoreToSafepointRegisterSlot(reg, eax);
 }
 
 
 void LCodeGen::DoSmiTag(LSmiTag* instr) {
   HChange* hchange = instr->hydrogen();
   Register input = ToRegister(instr->value());
   if (hchange->CheckFlag(HValue::kCanOverflow) &&
       hchange->value()->CheckFlag(HValue::kUint32)) {
     __ test(input, Immediate(0xc0000000));
-    DeoptimizeIf(not_zero, instr);
+    DeoptimizeIf(not_zero, instr, "overflow");
   }
   __ SmiTag(input);
   if (hchange->CheckFlag(HValue::kCanOverflow) &&
       !hchange->value()->CheckFlag(HValue::kUint32)) {
-    DeoptimizeIf(overflow, instr);
+    DeoptimizeIf(overflow, instr, "overflow");
   }
 }
 
 
 void LCodeGen::DoSmiUntag(LSmiUntag* instr) {
   LOperand* input = instr->value();
   Register result = ToRegister(input);
   DCHECK(input->IsRegister() && input->Equals(instr->result()));
   if (instr->needs_check()) {
     __ test(result, Immediate(kSmiTagMask));
-    DeoptimizeIf(not_zero, instr);
+    DeoptimizeIf(not_zero, instr, "not a Smi");
   } else {
     __ AssertSmi(result);
   }
   __ SmiUntag(result);
 }
 
 
 void LCodeGen::EmitNumberUntagDNoSSE2(LNumberUntagD* instr, Register input_reg,
                                       Register temp_reg, X87Register res_reg,
                                       NumberUntagDMode mode) {
   bool can_convert_undefined_to_nan =
       instr->hydrogen()->can_convert_undefined_to_nan();
   bool deoptimize_on_minus_zero = instr->hydrogen()->deoptimize_on_minus_zero();
 
   Label load_smi, done;
 
   X87PrepareToWrite(res_reg);
   if (mode == NUMBER_CANDIDATE_IS_ANY_TAGGED) {
     // Smi check.
     __ JumpIfSmi(input_reg, &load_smi);
 
     // Heap number map check.
     __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
            factory()->heap_number_map());
     if (!can_convert_undefined_to_nan) {
-      DeoptimizeIf(not_equal, instr);
+      DeoptimizeIf(not_equal, instr, "not a heap number");
     } else {
       Label heap_number, convert;
       __ j(equal, &heap_number);
 
       // Convert undefined (or hole) to NaN.
       __ cmp(input_reg, factory()->undefined_value());
-      DeoptimizeIf(not_equal, instr);
+      DeoptimizeIf(not_equal, instr, "not a heap number/undefined");
 
       __ bind(&convert);
       ExternalReference nan =
           ExternalReference::address_of_canonical_non_hole_nan();
       __ fld_d(Operand::StaticVariable(nan));
       __ jmp(&done, Label::kNear);
 
       __ bind(&heap_number);
     }
     // Heap number to x87 conversion.
     __ fld_d(FieldOperand(input_reg, HeapNumber::kValueOffset));
     if (deoptimize_on_minus_zero) {
       __ fldz();
       __ FCmp();
       __ fld_d(FieldOperand(input_reg, HeapNumber::kValueOffset));
       __ j(not_zero, &done, Label::kNear);
 
       // Use general purpose registers to check if we have -0.0
       __ mov(temp_reg, FieldOperand(input_reg, HeapNumber::kExponentOffset));
       __ test(temp_reg, Immediate(HeapNumber::kSignMask));
       __ j(zero, &done, Label::kNear);
 
       // Pop FPU stack before deoptimizing.
       __ fstp(0);
-      DeoptimizeIf(not_zero, instr);
+      DeoptimizeIf(not_zero, instr, "minus zero");
     }
     __ jmp(&done, Label::kNear);
   } else {
     DCHECK(mode == NUMBER_CANDIDATE_IS_SMI);
   }
 
   __ bind(&load_smi);
   // Clobbering a temp is faster than re-tagging the
   // input register since we avoid dependencies.
   __ mov(temp_reg, input_reg);
@@ skipping 32 matching lines @@
     __ jmp(done);
 
     __ bind(&check_bools);
     __ cmp(input_reg, factory()->true_value());
     __ j(not_equal, &check_false, Label::kNear);
     __ Move(input_reg, Immediate(1));
     __ jmp(done);
 
     __ bind(&check_false);
     __ cmp(input_reg, factory()->false_value());
-    DeoptimizeIf(not_equal, instr, "cannot truncate");
+    DeoptimizeIf(not_equal, instr, "not a heap number/undefined/true/false");
     __ Move(input_reg, Immediate(0));
   } else {
     // TODO(olivf) Converting a number on the fpu is actually quite slow. We
     // should first try a fast conversion and then bailout to this slow case.
     __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
            isolate()->factory()->heap_number_map());
     DeoptimizeIf(not_equal, instr, "not a heap number");
 
     __ sub(esp, Immediate(kPointerSize));
     __ fld_d(FieldOperand(input_reg, HeapNumber::kValueOffset));
@@ skipping 104 matching lines @@
   DCHECK(input->IsDoubleRegister());
   LOperand* result = instr->result();
   DCHECK(result->IsRegister());
   Register result_reg = ToRegister(result);
 
   if (instr->truncating()) {
     X87Register input_reg = ToX87Register(input);
     X87Fxch(input_reg);
     __ TruncateX87TOSToI(result_reg);
   } else {
-    Label bailout, done;
+    Label lost_precision, is_nan, minus_zero, done;
     X87Register input_reg = ToX87Register(input);
     X87Fxch(input_reg);
     __ X87TOSToI(result_reg, instr->hydrogen()->GetMinusZeroMode(),
-                 &bailout, Label::kNear);
+                 &lost_precision, &is_nan, &minus_zero, Label::kNear);
     __ jmp(&done, Label::kNear);
-    __ bind(&bailout);
-    DeoptimizeIf(no_condition, instr);
+    __ bind(&lost_precision);
+    DeoptimizeIf(no_condition, instr, "lost precision");
+    __ bind(&is_nan);
+    DeoptimizeIf(no_condition, instr, "NaN");
+    __ bind(&minus_zero);
+    DeoptimizeIf(no_condition, instr, "minus zero");
     __ bind(&done);
   }
 }
 
 
 void LCodeGen::DoDoubleToSmi(LDoubleToSmi* instr) {
   LOperand* input = instr->value();
   DCHECK(input->IsDoubleRegister());
   LOperand* result = instr->result();
   DCHECK(result->IsRegister());
   Register result_reg = ToRegister(result);
 
-  Label bailout, done;
+  Label lost_precision, is_nan, minus_zero, done;
   X87Register input_reg = ToX87Register(input);
   X87Fxch(input_reg);
   __ X87TOSToI(result_reg, instr->hydrogen()->GetMinusZeroMode(),
-      &bailout, Label::kNear);
+               &lost_precision, &is_nan, &minus_zero,
+               DeoptEveryNTimes() ? Label::kFar : Label::kNear);
   __ jmp(&done, Label::kNear);
-  __ bind(&bailout);
-  DeoptimizeIf(no_condition, instr);
+  __ bind(&lost_precision);
+  DeoptimizeIf(no_condition, instr, "lost precision");
+  __ bind(&is_nan);
+  DeoptimizeIf(no_condition, instr, "NaN");
+  __ bind(&minus_zero);
+  DeoptimizeIf(no_condition, instr, "minus zero");
   __ bind(&done);
-
   __ SmiTag(result_reg);
-  DeoptimizeIf(overflow, instr);
+  DeoptimizeIf(overflow, instr, "overflow");
 }
 
 
 void LCodeGen::DoCheckSmi(LCheckSmi* instr) {
   LOperand* input = instr->value();
   __ test(ToOperand(input), Immediate(kSmiTagMask));
-  DeoptimizeIf(not_zero, instr);
+  DeoptimizeIf(not_zero, instr, "not a Smi");
 }
 
 
 void LCodeGen::DoCheckNonSmi(LCheckNonSmi* instr) {
   if (!instr->hydrogen()->value()->type().IsHeapObject()) {
     LOperand* input = instr->value();
     __ test(ToOperand(input), Immediate(kSmiTagMask));
-    DeoptimizeIf(zero, instr);
+    DeoptimizeIf(zero, instr, "Smi");
   }
 }
 
 
 void LCodeGen::DoCheckInstanceType(LCheckInstanceType* instr) {
   Register input = ToRegister(instr->value());
   Register temp = ToRegister(instr->temp());
 
   __ mov(temp, FieldOperand(input, HeapObject::kMapOffset));
 
   if (instr->hydrogen()->is_interval_check()) {
     InstanceType first;
     InstanceType last;
     instr->hydrogen()->GetCheckInterval(&first, &last);
 
     __ cmpb(FieldOperand(temp, Map::kInstanceTypeOffset),
             static_cast<int8_t>(first));
 
     // If there is only one type in the interval check for equality.
     if (first == last) {
-      DeoptimizeIf(not_equal, instr);
+      DeoptimizeIf(not_equal, instr, "wrong instance type");
     } else {
-      DeoptimizeIf(below, instr);
+      DeoptimizeIf(below, instr, "wrong instance type");
       // Omit check for the last type.
       if (last != LAST_TYPE) {
         __ cmpb(FieldOperand(temp, Map::kInstanceTypeOffset),
                 static_cast<int8_t>(last));
-        DeoptimizeIf(above, instr);
+        DeoptimizeIf(above, instr, "wrong instance type");
       }
     }
   } else {
     uint8_t mask;
     uint8_t tag;
     instr->hydrogen()->GetCheckMaskAndTag(&mask, &tag);
 
     if (base::bits::IsPowerOfTwo32(mask)) {
       DCHECK(tag == 0 || base::bits::IsPowerOfTwo32(tag));
       __ test_b(FieldOperand(temp, Map::kInstanceTypeOffset), mask);
-      DeoptimizeIf(tag == 0 ? not_zero : zero, instr);
+      DeoptimizeIf(tag == 0 ? not_zero : zero, instr, "wrong instance type");
     } else {
       __ movzx_b(temp, FieldOperand(temp, Map::kInstanceTypeOffset));
       __ and_(temp, mask);
       __ cmp(temp, tag);
-      DeoptimizeIf(not_equal, instr);
+      DeoptimizeIf(not_equal, instr, "wrong instance type");
     }
   }
 }
 
 
 void LCodeGen::DoCheckValue(LCheckValue* instr) {
   Handle<HeapObject> object = instr->hydrogen()->object().handle();
   if (instr->hydrogen()->object_in_new_space()) {
     Register reg = ToRegister(instr->value());
     Handle<Cell> cell = isolate()->factory()->NewCell(object);
     __ cmp(reg, Operand::ForCell(cell));
   } else {
     Operand operand = ToOperand(instr->value());
     __ cmp(operand, object);
   }
-  DeoptimizeIf(not_equal, instr);
+  DeoptimizeIf(not_equal, instr, "value mismatch");
 }
 
 
 void LCodeGen::DoDeferredInstanceMigration(LCheckMaps* instr, Register object) {
   {
     PushSafepointRegistersScope scope(this);
     __ push(object);
     __ xor_(esi, esi);
     __ CallRuntimeSaveDoubles(Runtime::kTryMigrateInstance);
     RecordSafepointWithRegisters(
         instr->pointer_map(), 1, Safepoint::kNoLazyDeopt);
 
     __ test(eax, Immediate(kSmiTagMask));
   }
-  DeoptimizeIf(zero, instr);
+  DeoptimizeIf(zero, instr, "instance migration failed");
 }
 
 
 void LCodeGen::DoCheckMaps(LCheckMaps* instr) {
   class DeferredCheckMaps FINAL : public LDeferredCode {
    public:
     DeferredCheckMaps(LCodeGen* codegen,
                       LCheckMaps* instr,
                       Register object,
                       const X87Stack& x87_stack)
@@ skipping 35 matching lines @@
     Handle<Map> map = maps->at(i).handle();
     __ CompareMap(reg, map);
     __ j(equal, &success, Label::kNear);
   }
 
   Handle<Map> map = maps->at(maps->size() - 1).handle();
   __ CompareMap(reg, map);
   if (instr->hydrogen()->HasMigrationTarget()) {
     __ j(not_equal, deferred->entry());
   } else {
-    DeoptimizeIf(not_equal, instr);
+    DeoptimizeIf(not_equal, instr, "wrong map");
   }
 
   __ bind(&success);
 }
 
 
 void LCodeGen::DoClampDToUint8(LClampDToUint8* instr) {
   X87Register value_reg = ToX87Register(instr->unclamped());
   Register result_reg = ToRegister(instr->result());
   X87Fxch(value_reg);
@@ skipping 20 matching lines @@
   __ JumpIfSmi(input_reg, &is_smi);
 
   // Check for heap number
   __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
          factory()->heap_number_map());
   __ j(equal, &heap_number, Label::kNear);
 
   // Check for undefined. Undefined is converted to zero for clamping
   // conversions.
   __ cmp(input_reg, factory()->undefined_value());
-  DeoptimizeIf(not_equal, instr);
+  DeoptimizeIf(not_equal, instr, "not a heap number/undefined");
   __ jmp(&zero_result, Label::kNear);
 
   // Heap number
   __ bind(&heap_number);
 
   // Surprisingly, all of the hand-crafted bit-manipulations below are much
   // faster than the x86 FPU built-in instruction, especially since "banker's
   // rounding" would be additionally very expensive
 
   // Get exponent word.
@@ skipping 552 matching lines @@
   DCHECK(!environment->HasBeenRegistered());
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
 
   GenerateOsrPrologue();
 }
 
 
 void LCodeGen::DoForInPrepareMap(LForInPrepareMap* instr) {
   DCHECK(ToRegister(instr->context()).is(esi));
   __ cmp(eax, isolate()->factory()->undefined_value());
-  DeoptimizeIf(equal, instr);
+  DeoptimizeIf(equal, instr, "undefined");
 
   __ cmp(eax, isolate()->factory()->null_value());
-  DeoptimizeIf(equal, instr);
+  DeoptimizeIf(equal, instr, "null");
 
   __ test(eax, Immediate(kSmiTagMask));
-  DeoptimizeIf(zero, instr);
+  DeoptimizeIf(zero, instr, "Smi");
 
   STATIC_ASSERT(FIRST_JS_PROXY_TYPE == FIRST_SPEC_OBJECT_TYPE);
   __ CmpObjectType(eax, LAST_JS_PROXY_TYPE, ecx);
-  DeoptimizeIf(below_equal, instr);
+  DeoptimizeIf(below_equal, instr, "wrong instance type");
 
   Label use_cache, call_runtime;
   __ CheckEnumCache(&call_runtime);
 
   __ mov(eax, FieldOperand(eax, HeapObject::kMapOffset));
   __ jmp(&use_cache, Label::kNear);
 
   // Get the set of properties to enumerate.
   __ bind(&call_runtime);
   __ push(eax);
   CallRuntime(Runtime::kGetPropertyNamesFast, 1, instr);
 
   __ cmp(FieldOperand(eax, HeapObject::kMapOffset),
          isolate()->factory()->meta_map());
-  DeoptimizeIf(not_equal, instr);
+  DeoptimizeIf(not_equal, instr, "wrong map");
   __ bind(&use_cache);
 }
 
 
 void LCodeGen::DoForInCacheArray(LForInCacheArray* instr) {
   Register map = ToRegister(instr->map());
   Register result = ToRegister(instr->result());
   Label load_cache, done;
   __ EnumLength(result, map);
   __ cmp(result, Immediate(Smi::FromInt(0)));
   __ j(not_equal, &load_cache, Label::kNear);
   __ mov(result, isolate()->factory()->empty_fixed_array());
   __ jmp(&done, Label::kNear);
 
   __ bind(&load_cache);
   __ LoadInstanceDescriptors(map, result);
   __ mov(result,
          FieldOperand(result, DescriptorArray::kEnumCacheOffset));
   __ mov(result,
          FieldOperand(result, FixedArray::SizeFor(instr->idx())));
   __ bind(&done);
   __ test(result, result);
-  DeoptimizeIf(equal, instr);
+  DeoptimizeIf(equal, instr, "no cache");
 }
 
 
 void LCodeGen::DoCheckMapValue(LCheckMapValue* instr) {
   Register object = ToRegister(instr->value());
   __ cmp(ToRegister(instr->map()),
          FieldOperand(object, HeapObject::kMapOffset));
-  DeoptimizeIf(not_equal, instr);
+  DeoptimizeIf(not_equal, instr, "wrong map");
 }
 
 
 void LCodeGen::DoDeferredLoadMutableDouble(LLoadFieldByIndex* instr,
                                            Register object,
                                            Register index) {
   PushSafepointRegistersScope scope(this);
   __ push(object);
   __ push(index);
   __ xor_(esi, esi);
@@ skipping 74 matching lines @@
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X87