Make the detailed reason for deopts mandatory on all platforms.

src/arm/lithium-codegen-arm.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"
 
 #include "src/arm/lithium-codegen-arm.h"
 #include "src/arm/lithium-gap-resolver-arm.h"
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 1140 matching lines @@
   int32_t mask = divisor < 0 ? -(divisor + 1) : (divisor - 1);
   Label dividend_is_not_negative, done;
   if (hmod->CheckFlag(HValue::kLeftCanBeNegative)) {
     __ cmp(dividend, Operand::Zero());
     __ b(pl, &dividend_is_not_negative);
     // Note that this is correct even for kMinInt operands.
     __ rsb(dividend, dividend, Operand::Zero());
     __ and_(dividend, dividend, Operand(mask));
     __ rsb(dividend, dividend, Operand::Zero(), SetCC);
     if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "minus zero");
     }
     __ b(&done);
   }
 
   __ bind(&dividend_is_not_negative);
   __ and_(dividend, dividend, Operand(mask));
   __ bind(&done);
 }
 
 
 void LCodeGen::DoModByConstI(LModByConstI* instr) {
   Register dividend = ToRegister(instr->dividend());
   int32_t divisor = instr->divisor();
   Register result = ToRegister(instr->result());
   DCHECK(!dividend.is(result));
 
   if (divisor == 0) {
-    DeoptimizeIf(al, instr);
+    DeoptimizeIf(al, instr, "division by zero");
     return;
   }
 
   __ TruncatingDiv(result, dividend, Abs(divisor));
   __ mov(ip, Operand(Abs(divisor)));
   __ smull(result, ip, result, ip);
   __ sub(result, dividend, result, SetCC);
 
   // Check for negative zero.
   HMod* hmod = instr->hydrogen();
   if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
     Label remainder_not_zero;
     __ b(ne, &remainder_not_zero);
     __ cmp(dividend, Operand::Zero());
-    DeoptimizeIf(lt, instr);
+    DeoptimizeIf(lt, instr, "minus zero");
     __ bind(&remainder_not_zero);
   }
 }
 
 
 void LCodeGen::DoModI(LModI* instr) {
   HMod* hmod = instr->hydrogen();
   if (CpuFeatures::IsSupported(SUDIV)) {
     CpuFeatureScope scope(masm(), SUDIV);
 
     Register left_reg = ToRegister(instr->left());
     Register right_reg = ToRegister(instr->right());
     Register result_reg = ToRegister(instr->result());
 
     Label done;
     // Check for x % 0, sdiv might signal an exception. We have to deopt in this
     // case because we can't return a NaN.
     if (hmod->CheckFlag(HValue::kCanBeDivByZero)) {
       __ cmp(right_reg, Operand::Zero());
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "division by zero");
     }
 
     // Check for kMinInt % -1, sdiv will return kMinInt, which is not what we
     // want. 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, Operand(kMinInt));
       __ b(ne, &no_overflow_possible);
       __ cmp(right_reg, Operand(-1));
       if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
-        DeoptimizeIf(eq, instr);
+        DeoptimizeIf(eq, instr, "minus zero");
       } else {
         __ b(ne, &no_overflow_possible);
         __ mov(result_reg, Operand::Zero());
         __ jmp(&done);
       }
       __ bind(&no_overflow_possible);
     }
 
     // For 'r3 = r1 % r2' we can have the following ARM code:
     //   sdiv r3, r1, r2
     //   mls r3, r3, r2, r1
 
     __ sdiv(result_reg, left_reg, right_reg);
     __ Mls(result_reg, result_reg, right_reg, left_reg);
 
     // If we care about -0, test if the dividend is <0 and the result is 0.
     if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
       __ cmp(result_reg, Operand::Zero());
       __ b(ne, &done);
       __ cmp(left_reg, Operand::Zero());
-      DeoptimizeIf(lt, instr);
+      DeoptimizeIf(lt, instr, "minus zero");
     }
     __ bind(&done);
 
   } else {
     // General case, without any SDIV support.
     Register left_reg = ToRegister(instr->left());
     Register right_reg = ToRegister(instr->right());
     Register result_reg = ToRegister(instr->result());
     Register scratch = scratch0();
     DCHECK(!scratch.is(left_reg));
     DCHECK(!scratch.is(right_reg));
     DCHECK(!scratch.is(result_reg));
     DwVfpRegister dividend = ToDoubleRegister(instr->temp());
     DwVfpRegister divisor = ToDoubleRegister(instr->temp2());
     DCHECK(!divisor.is(dividend));
     LowDwVfpRegister quotient = double_scratch0();
     DCHECK(!quotient.is(dividend));
     DCHECK(!quotient.is(divisor));
 
     Label done;
     // Check for x % 0, we have to deopt in this case because we can't return a
     // NaN.
     if (hmod->CheckFlag(HValue::kCanBeDivByZero)) {
       __ cmp(right_reg, Operand::Zero());
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "division by zero");
     }
 
     __ Move(result_reg, left_reg);
     // Load the arguments in VFP registers. The divisor value is preloaded
     // before. Be careful that 'right_reg' is only live on entry.
     // TODO(svenpanne) The last comments seems to be wrong nowadays.
     __ vmov(double_scratch0().low(), left_reg);
     __ vcvt_f64_s32(dividend, double_scratch0().low());
     __ vmov(double_scratch0().low(), right_reg);
     __ vcvt_f64_s32(divisor, double_scratch0().low());
 
     // We do not care about the sign of the divisor. Note that we still handle
     // the kMinInt % -1 case correctly, though.
     __ vabs(divisor, divisor);
     // Compute the quotient and round it to a 32bit integer.
     __ vdiv(quotient, dividend, divisor);
     __ vcvt_s32_f64(quotient.low(), quotient);
     __ vcvt_f64_s32(quotient, quotient.low());
 
     // Compute the remainder in result.
     __ vmul(double_scratch0(), divisor, quotient);
     __ vcvt_s32_f64(double_scratch0().low(), double_scratch0());
     __ vmov(scratch, double_scratch0().low());
     __ sub(result_reg, left_reg, scratch, SetCC);
 
     // If we care about -0, test if the dividend is <0 and the result is 0.
     if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
       __ b(ne, &done);
       __ cmp(left_reg, Operand::Zero());
-      DeoptimizeIf(mi, instr);
+      DeoptimizeIf(mi, instr, "minus zero");
     }
     __ 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) {
     __ cmp(dividend, Operand::Zero());
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "minus zero");
   }
   // Check for (kMinInt / -1).
   if (hdiv->CheckFlag(HValue::kCanOverflow) && divisor == -1) {
     __ cmp(dividend, Operand(kMinInt));
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, 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);
     __ tst(dividend, Operand(mask));
-    DeoptimizeIf(ne, instr);
+    DeoptimizeIf(ne, instr, "lost precision");
   }
 
   if (divisor == -1) {  // Nice shortcut, not needed for correctness.
     __ rsb(result, dividend, Operand(0));
     return;
   }
   int32_t shift = WhichPowerOf2Abs(divisor);
   if (shift == 0) {
     __ mov(result, dividend);
   } else if (shift == 1) {
     __ add(result, dividend, Operand(dividend, LSR, 31));
   } else {
     __ mov(result, Operand(dividend, ASR, 31));
     __ add(result, dividend, Operand(result, LSR, 32 - shift));
   }
   if (shift > 0) __ mov(result, Operand(result, ASR, shift));
   if (divisor < 0) __ rsb(result, result, Operand(0));
 }
 
 
 void LCodeGen::DoDivByConstI(LDivByConstI* instr) {
   Register dividend = ToRegister(instr->dividend());
   int32_t divisor = instr->divisor();
   Register result = ToRegister(instr->result());
   DCHECK(!dividend.is(result));
 
   if (divisor == 0) {
-    DeoptimizeIf(al, instr);
+    DeoptimizeIf(al, 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) {
     __ cmp(dividend, Operand::Zero());
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "minus zero");
   }
 
   __ TruncatingDiv(result, dividend, Abs(divisor));
   if (divisor < 0) __ rsb(result, result, Operand::Zero());
 
   if (!hdiv->CheckFlag(HInstruction::kAllUsesTruncatingToInt32)) {
     __ mov(ip, Operand(divisor));
     __ smull(scratch0(), ip, result, ip);
     __ sub(scratch0(), scratch0(), dividend, SetCC);
-    DeoptimizeIf(ne, instr);
+    DeoptimizeIf(ne, 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 result = ToRegister(instr->result());
 
   // Check for x / 0.
   if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
     __ cmp(divisor, Operand::Zero());
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "division by zero");
   }
 
   // Check for (0 / -x) that will produce negative zero.
   if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
     Label positive;
     if (!instr->hydrogen_value()->CheckFlag(HValue::kCanBeDivByZero)) {
       // Do the test only if it hadn't be done above.
       __ cmp(divisor, Operand::Zero());
     }
     __ b(pl, &positive);
     __ cmp(dividend, Operand::Zero());
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "minus zero");
     __ bind(&positive);
   }
 
   // Check for (kMinInt / -1).
   if (hdiv->CheckFlag(HValue::kCanOverflow) &&
       (!CpuFeatures::IsSupported(SUDIV) ||
        !hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32))) {
     // We don't need to check for overflow when truncating with sdiv
     // support because, on ARM, sdiv kMinInt, -1 -> kMinInt.
     __ cmp(dividend, Operand(kMinInt));
     __ cmp(divisor, Operand(-1), eq);
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "overflow");
   }
 
   if (CpuFeatures::IsSupported(SUDIV)) {
     CpuFeatureScope scope(masm(), SUDIV);
     __ sdiv(result, dividend, divisor);
   } else {
     DoubleRegister vleft = ToDoubleRegister(instr->temp());
     DoubleRegister vright = double_scratch0();
     __ vmov(double_scratch0().low(), dividend);
     __ vcvt_f64_s32(vleft, double_scratch0().low());
     __ vmov(double_scratch0().low(), divisor);
     __ vcvt_f64_s32(vright, double_scratch0().low());
     __ vdiv(vleft, vleft, vright);  // vleft now contains the result.
     __ vcvt_s32_f64(double_scratch0().low(), vleft);
     __ vmov(result, double_scratch0().low());
   }
 
   if (!hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
     // Compute remainder and deopt if it's not zero.
     Register remainder = scratch0();
     __ Mls(remainder, result, divisor, dividend);
     __ cmp(remainder, Operand::Zero());
-    DeoptimizeIf(ne, instr);
+    DeoptimizeIf(ne, instr, "lost precision");
   }
 }
 
 
 void LCodeGen::DoMultiplyAddD(LMultiplyAddD* instr) {
   DwVfpRegister addend = ToDoubleRegister(instr->addend());
   DwVfpRegister multiplier = ToDoubleRegister(instr->multiplier());
   DwVfpRegister multiplicand = ToDoubleRegister(instr->multiplicand());
 
   // This is computed in-place.
@@ skipping 30 matching lines @@
   // can simply do an arithmetic right shift.
   int32_t shift = WhichPowerOf2Abs(divisor);
   if (divisor > 1) {
     __ mov(result, Operand(dividend, ASR, shift));
     return;
   }
 
   // If the divisor is negative, we have to negate and handle edge cases.
   __ rsb(result, dividend, Operand::Zero(), SetCC);
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "minus zero");
   }
 
   // Dividing by -1 is basically negation, unless we overflow.
   if (divisor == -1) {
     if (instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
-      DeoptimizeIf(vs, instr);
+      DeoptimizeIf(vs, instr, "overflow");
     }
     return;
   }
 
   // If the negation could not overflow, simply shifting is OK.
   if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
     __ mov(result, Operand(result, ASR, shift));
     return;
   }
 
   __ mov(result, Operand(kMinInt / divisor), LeaveCC, vs);
   __ mov(result, Operand(result, ASR, shift), LeaveCC, vc);
 }
 
 
 void LCodeGen::DoFlooringDivByConstI(LFlooringDivByConstI* instr) {
   Register dividend = ToRegister(instr->dividend());
   int32_t divisor = instr->divisor();
   Register result = ToRegister(instr->result());
   DCHECK(!dividend.is(result));
 
   if (divisor == 0) {
-    DeoptimizeIf(al, instr);
+    DeoptimizeIf(al, 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) {
     __ cmp(dividend, Operand::Zero());
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, 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(result, dividend, Abs(divisor));
     if (divisor < 0) __ rsb(result, result, Operand::Zero());
     return;
   }
@@ skipping 20 matching lines @@
 // TODO(svenpanne) Refactor this to avoid code duplication with DoDivI.
 void LCodeGen::DoFlooringDivI(LFlooringDivI* instr) {
   HBinaryOperation* hdiv = instr->hydrogen();
   Register left = ToRegister(instr->dividend());
   Register right = ToRegister(instr->divisor());
   Register result = ToRegister(instr->result());
 
   // Check for x / 0.
   if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
     __ cmp(right, Operand::Zero());
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "division by zero");
   }
 
   // Check for (0 / -x) that will produce negative zero.
   if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
     Label positive;
     if (!instr->hydrogen_value()->CheckFlag(HValue::kCanBeDivByZero)) {
       // Do the test only if it hadn't be done above.
       __ cmp(right, Operand::Zero());
     }
     __ b(pl, &positive);
     __ cmp(left, Operand::Zero());
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "minus zero");
     __ bind(&positive);
   }
 
   // Check for (kMinInt / -1).
   if (hdiv->CheckFlag(HValue::kCanOverflow) &&
       (!CpuFeatures::IsSupported(SUDIV) ||
        !hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32))) {
     // We don't need to check for overflow when truncating with sdiv
     // support because, on ARM, sdiv kMinInt, -1 -> kMinInt.
     __ cmp(left, Operand(kMinInt));
     __ cmp(right, Operand(-1), eq);
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "overflow");
   }
 
   if (CpuFeatures::IsSupported(SUDIV)) {
     CpuFeatureScope scope(masm(), SUDIV);
     __ sdiv(result, left, right);
   } else {
     DoubleRegister vleft = ToDoubleRegister(instr->temp());
     DoubleRegister vright = double_scratch0();
     __ vmov(double_scratch0().low(), left);
     __ vcvt_f64_s32(vleft, double_scratch0().low());
@@ skipping 25 matching lines @@
     instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero);
   bool overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
 
   if (right_op->IsConstantOperand()) {
     int32_t constant = ToInteger32(LConstantOperand::cast(right_op));
 
     if (bailout_on_minus_zero && (constant < 0)) {
       // The case of a null constant will be handled separately.
       // If constant is negative and left is null, the result should be -0.
       __ cmp(left, Operand::Zero());
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "minus zero");
     }
 
     switch (constant) {
       case -1:
         if (overflow) {
           __ rsb(result, left, Operand::Zero(), SetCC);
-          DeoptimizeIf(vs, instr);
+          DeoptimizeIf(vs, instr, "overflow");
         } else {
           __ rsb(result, left, Operand::Zero());
         }
         break;
       case 0:
         if (bailout_on_minus_zero) {
           // If left is strictly negative and the constant is null, the
           // result is -0. Deoptimize if required, otherwise return 0.
           __ cmp(left, Operand::Zero());
-          DeoptimizeIf(mi, instr);
+          DeoptimizeIf(mi, instr, "minus zero");
         }
         __ mov(result, Operand::Zero());
         break;
       case 1:
         __ Move(result, left);
         break;
       default:
         // Multiplying by powers of two and powers of two plus or minus
         // one can be done faster with shifted operands.
         // For other constants we emit standard code.
@@ skipping 29 matching lines @@
     if (overflow) {
       Register scratch = scratch0();
       // scratch:result = left * right.
       if (instr->hydrogen()->representation().IsSmi()) {
         __ SmiUntag(result, left);
         __ smull(result, scratch, result, right);
       } else {
         __ smull(result, scratch, left, right);
       }
       __ cmp(scratch, Operand(result, ASR, 31));
-      DeoptimizeIf(ne, instr);
+      DeoptimizeIf(ne, instr, "overflow");
     } else {
       if (instr->hydrogen()->representation().IsSmi()) {
         __ SmiUntag(result, left);
         __ mul(result, result, right);
       } else {
         __ mul(result, left, right);
       }
     }
 
     if (bailout_on_minus_zero) {
       Label done;
       __ teq(left, Operand(right));
       __ b(pl, &done);
       // Bail out if the result is minus zero.
       __ cmp(result, Operand::Zero());
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "minus zero");
       __ bind(&done);
     }
   }
 }
 
 
 void LCodeGen::DoBitI(LBitI* instr) {
   LOperand* left_op = instr->left();
   LOperand* right_op = instr->right();
   DCHECK(left_op->IsRegister());
@@ skipping 42 matching lines @@
     switch (instr->op()) {
       case Token::ROR:
         __ mov(result, Operand(left, ROR, scratch));
         break;
       case Token::SAR:
         __ mov(result, Operand(left, ASR, scratch));
         break;
       case Token::SHR:
         if (instr->can_deopt()) {
           __ mov(result, Operand(left, LSR, scratch), SetCC);
-          DeoptimizeIf(mi, instr);
+          DeoptimizeIf(mi, instr, "negative value");
         } else {
           __ mov(result, Operand(left, LSR, scratch));
         }
         break;
       case Token::SHL:
         __ mov(result, Operand(left, LSL, scratch));
         break;
       default:
         UNREACHABLE();
         break;
@@ skipping 16 matching lines @@
         } else {
           __ Move(result, left);
         }
         break;
       case Token::SHR:
         if (shift_count != 0) {
           __ mov(result, Operand(left, LSR, shift_count));
         } else {
           if (instr->can_deopt()) {
             __ tst(left, Operand(0x80000000));
-            DeoptimizeIf(ne, instr);
+            DeoptimizeIf(ne, instr, "negative value");
           }
           __ Move(result, left);
         }
         break;
       case Token::SHL:
         if (shift_count != 0) {
           if (instr->hydrogen_value()->representation().IsSmi() &&
               instr->can_deopt()) {
             if (shift_count != 1) {
               __ mov(result, Operand(left, LSL, shift_count - 1));
               __ SmiTag(result, result, SetCC);
             } else {
               __ SmiTag(result, left, SetCC);
             }
-            DeoptimizeIf(vs, instr);
+            DeoptimizeIf(vs, instr, "overflow");
           } else {
             __ mov(result, Operand(left, LSL, shift_count));
           }
         } else {
           __ Move(result, left);
         }
         break;
       default:
         UNREACHABLE();
         break;
@@ skipping 11 matching lines @@
 
   if (right->IsStackSlot()) {
     Register right_reg = EmitLoadRegister(right, ip);
     __ sub(ToRegister(result), ToRegister(left), Operand(right_reg), set_cond);
   } else {
     DCHECK(right->IsRegister() || right->IsConstantOperand());
     __ sub(ToRegister(result), ToRegister(left), ToOperand(right), set_cond);
   }
 
   if (can_overflow) {
-    DeoptimizeIf(vs, instr);
+    DeoptimizeIf(vs, instr, "overflow");
   }
 }
 
 
 void LCodeGen::DoRSubI(LRSubI* instr) {
   LOperand* left = instr->left();
   LOperand* right = instr->right();
   LOperand* result = instr->result();
   bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
   SBit set_cond = can_overflow ? SetCC : LeaveCC;
 
   if (right->IsStackSlot()) {
     Register right_reg = EmitLoadRegister(right, ip);
     __ rsb(ToRegister(result), ToRegister(left), Operand(right_reg), set_cond);
   } else {
     DCHECK(right->IsRegister() || right->IsConstantOperand());
     __ rsb(ToRegister(result), ToRegister(left), ToOperand(right), set_cond);
   }
 
   if (can_overflow) {
-    DeoptimizeIf(vs, instr);
+    DeoptimizeIf(vs, instr, "overflow");
   }
 }
 
 
 void LCodeGen::DoConstantI(LConstantI* instr) {
   __ mov(ToRegister(instr->result()), Operand(instr->value()));
 }
 
 
 void LCodeGen::DoConstantS(LConstantS* instr) {
@@ skipping 33 matching lines @@
   Register result = ToRegister(instr->result());
   Register scratch = ToRegister(instr->temp());
   Smi* index = instr->index();
   Label runtime, done;
   DCHECK(object.is(result));
   DCHECK(object.is(r0));
   DCHECK(!scratch.is(scratch0()));
   DCHECK(!scratch.is(object));
 
   __ SmiTst(object);
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, "Smi");
   __ CompareObjectType(object, scratch, scratch, JS_DATE_TYPE);
-  DeoptimizeIf(ne, instr);
+  DeoptimizeIf(ne, instr, "not a date object");
 
   if (index->value() == 0) {
     __ ldr(result, FieldMemOperand(object, JSDate::kValueOffset));
   } else {
     if (index->value() < JSDate::kFirstUncachedField) {
       ExternalReference stamp = ExternalReference::date_cache_stamp(isolate());
       __ mov(scratch, Operand(stamp));
       __ ldr(scratch, MemOperand(scratch));
       __ ldr(scratch0(), FieldMemOperand(object, JSDate::kCacheStampOffset));
       __ cmp(scratch, scratch0());
@@ skipping 96 matching lines @@
 
   if (right->IsStackSlot()) {
     Register right_reg = EmitLoadRegister(right, ip);
     __ add(ToRegister(result), ToRegister(left), Operand(right_reg), set_cond);
   } else {
     DCHECK(right->IsRegister() || right->IsConstantOperand());
     __ add(ToRegister(result), ToRegister(left), ToOperand(right), set_cond);
   }
 
   if (can_overflow) {
-    DeoptimizeIf(vs, instr);
+    DeoptimizeIf(vs, instr, "overflow");
   }
 }
 
 
 void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
   LOperand* left = instr->left();
   LOperand* right = instr->right();
   HMathMinMax::Operation operation = instr->hydrogen()->operation();
   if (instr->hydrogen()->representation().IsSmiOrInteger32()) {
     Condition condition = (operation == HMathMinMax::kMathMin) ? le : ge;
@@ skipping 205 matching lines @@
       }
 
       if (expected.Contains(ToBooleanStub::SMI)) {
         // Smis: 0 -> false, all other -> true.
         __ cmp(reg, Operand::Zero());
         __ b(eq, instr->FalseLabel(chunk_));
         __ JumpIfSmi(reg, instr->TrueLabel(chunk_));
       } else if (expected.NeedsMap()) {
         // If we need a map later and have a Smi -> deopt.
         __ SmiTst(reg);
-        DeoptimizeIf(eq, instr);
+        DeoptimizeIf(eq, instr, "Smi");
       }
 
       const Register map = scratch0();
       if (expected.NeedsMap()) {
         __ ldr(map, FieldMemOperand(reg, HeapObject::kMapOffset));
 
         if (expected.CanBeUndetectable()) {
           // Undetectable -> false.
           __ ldrb(ip, FieldMemOperand(map, Map::kBitFieldOffset));
           __ tst(ip, Operand(1 << Map::kIsUndetectable));
@@ skipping 35 matching lines @@
         __ VFPCompareAndSetFlags(dbl_scratch, 0.0);
         __ cmp(r0, r0, vs);  // NaN -> false.
         __ b(eq, instr->FalseLabel(chunk_));  // +0, -0 -> false.
         __ b(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(al, instr);
+        DeoptimizeIf(al, instr, "unexpected object");
       }
     }
   }
 }
 
 
 void LCodeGen::EmitGoto(int block) {
   if (!IsNextEmittedBlock(block)) {
     __ jmp(chunk_->GetAssemblyLabel(LookupDestination(block)));
   }
@@ skipping 624 matching lines @@
 }
 
 
 void LCodeGen::DoLoadGlobalCell(LLoadGlobalCell* instr) {
   Register result = ToRegister(instr->result());
   __ mov(ip, Operand(Handle<Object>(instr->hydrogen()->cell().handle())));
   __ ldr(result, FieldMemOperand(ip, Cell::kValueOffset));
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ LoadRoot(ip, Heap::kTheHoleValueRootIndex);
     __ cmp(result, ip);
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, 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()));
   __ Move(vector, instr->hydrogen()->feedback_vector());
@@ skipping 29 matching lines @@
 
   // 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.
   if (instr->hydrogen()->RequiresHoleCheck()) {
     // We use a temp to check the payload (CompareRoot might clobber ip).
     Register payload = ToRegister(instr->temp());
     __ ldr(payload, FieldMemOperand(cell, Cell::kValueOffset));
     __ CompareRoot(payload, Heap::kTheHoleValueRootIndex);
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "hole");
   }
 
   // Store the value.
   __ str(value, FieldMemOperand(cell, Cell::kValueOffset));
   // Cells are always rescanned, so no write barrier here.
 }
 
 
 void LCodeGen::DoLoadContextSlot(LLoadContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
   __ ldr(result, ContextOperand(context, instr->slot_index()));
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ LoadRoot(ip, Heap::kTheHoleValueRootIndex);
     __ cmp(result, ip);
     if (instr->hydrogen()->DeoptimizesOnHole()) {
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "hole");
     } else {
       __ mov(result, Operand(factory()->undefined_value()), LeaveCC, eq);
     }
   }
 }
 
 
 void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register value = ToRegister(instr->value());
   Register scratch = scratch0();
   MemOperand target = ContextOperand(context, instr->slot_index());
 
   Label skip_assignment;
 
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ ldr(scratch, target);
     __ LoadRoot(ip, Heap::kTheHoleValueRootIndex);
     __ cmp(scratch, ip);
     if (instr->hydrogen()->DeoptimizesOnHole()) {
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "hole");
     } else {
       __ b(ne, &skip_assignment);
     }
   }
 
   __ str(value, target);
   if (instr->hydrogen()->NeedsWriteBarrier()) {
     SmiCheck check_needed =
         instr->hydrogen()->value()->type().IsHeapObject()
             ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
@@ skipping 59 matching lines @@
   Register function = ToRegister(instr->function());
   Register result = ToRegister(instr->result());
 
   // Get the prototype or initial map from the function.
   __ ldr(result,
          FieldMemOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
 
   // Check that the function has a prototype or an initial map.
   __ LoadRoot(ip, Heap::kTheHoleValueRootIndex);
   __ cmp(result, ip);
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, "hole");
 
   // If the function does not have an initial map, we're done.
   Label done;
   __ CompareObjectType(result, scratch, scratch, MAP_TYPE);
   __ b(ne, &done);
 
   // Get the prototype from the initial map.
   __ ldr(result, FieldMemOperand(result, Map::kPrototypeOffset));
 
   // All done.
@@ skipping 105 matching lines @@
         break;
       case EXTERNAL_INT32_ELEMENTS:
       case INT32_ELEMENTS:
         __ ldr(result, mem_operand);
         break;
       case EXTERNAL_UINT32_ELEMENTS:
       case UINT32_ELEMENTS:
         __ ldr(result, mem_operand);
         if (!instr->hydrogen()->CheckFlag(HInstruction::kUint32)) {
           __ cmp(result, Operand(0x80000000));
-          DeoptimizeIf(cs, instr);
+          DeoptimizeIf(cs, instr, "negative value");
         }
         break;
       case FLOAT32_ELEMENTS:
       case FLOAT64_ELEMENTS:
       case EXTERNAL_FLOAT32_ELEMENTS:
       case EXTERNAL_FLOAT64_ELEMENTS:
       case FAST_HOLEY_DOUBLE_ELEMENTS:
       case FAST_HOLEY_ELEMENTS:
       case FAST_HOLEY_SMI_ELEMENTS:
       case FAST_DOUBLE_ELEMENTS:
@@ skipping 32 matching lines @@
     int shift_size = (instr->hydrogen()->key()->representation().IsSmi())
         ? (element_size_shift - kSmiTagSize) : element_size_shift;
     __ add(scratch, scratch, Operand(key, LSL, shift_size));
   }
 
   __ vldr(result, scratch, 0);
 
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ ldr(scratch, MemOperand(scratch, sizeof(kHoleNanLower32)));
     __ cmp(scratch, Operand(kHoleNanUpper32));
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "hole");
   }
 }
 
 
 void LCodeGen::DoLoadKeyedFixedArray(LLoadKeyed* instr) {
   Register elements = ToRegister(instr->elements());
   Register result = ToRegister(instr->result());
   Register scratch = scratch0();
   Register store_base = scratch;
   int offset = instr->base_offset();
@@ skipping 13 matching lines @@
     } else {
       __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
     }
   }
   __ ldr(result, MemOperand(store_base, offset));
 
   // Check for the hole value.
   if (instr->hydrogen()->RequiresHoleCheck()) {
     if (IsFastSmiElementsKind(instr->hydrogen()->elements_kind())) {
       __ SmiTst(result);
-      DeoptimizeIf(ne, instr);
+      DeoptimizeIf(ne, instr, "not a Smi");
     } else {
       __ LoadRoot(scratch, Heap::kTheHoleValueRootIndex);
       __ cmp(result, scratch);
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "hole");
     }
   }
 }
 
 
 void LCodeGen::DoLoadKeyed(LLoadKeyed* instr) {
   if (instr->is_typed_elements()) {
     DoLoadKeyedExternalArray(instr);
   } else if (instr->hydrogen()->representation().IsDouble()) {
     DoLoadKeyedFixedDoubleArray(instr);
@@ skipping 121 matching lines @@
   // Normal function. Replace undefined or null with global receiver.
   __ LoadRoot(scratch, Heap::kNullValueRootIndex);
   __ cmp(receiver, scratch);
   __ b(eq, &global_object);
   __ LoadRoot(scratch, Heap::kUndefinedValueRootIndex);
   __ cmp(receiver, scratch);
   __ b(eq, &global_object);
 
   // Deoptimize if the receiver is not a JS object.
   __ SmiTst(receiver);
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, "Smi");
   __ CompareObjectType(receiver, scratch, scratch, FIRST_SPEC_OBJECT_TYPE);
-  DeoptimizeIf(lt, instr);
+  DeoptimizeIf(lt, instr, "not a JavaScript object");
 
   __ b(&result_in_receiver);
   __ bind(&global_object);
   __ ldr(result, FieldMemOperand(function, JSFunction::kContextOffset));
   __ ldr(result,
          ContextOperand(result, Context::GLOBAL_OBJECT_INDEX));
   __ ldr(result, FieldMemOperand(result, GlobalObject::kGlobalProxyOffset));
 
   if (result.is(receiver)) {
     __ bind(&result_in_receiver);
@@ skipping 14 matching lines @@
   Register elements = ToRegister(instr->elements());
   Register scratch = scratch0();
   DCHECK(receiver.is(r0));  // Used for parameter count.
   DCHECK(function.is(r1));  // Required by InvokeFunction.
   DCHECK(ToRegister(instr->result()).is(r0));
 
   // Copy the arguments to this function possibly from the
   // adaptor frame below it.
   const uint32_t kArgumentsLimit = 1 * KB;
   __ cmp(length, Operand(kArgumentsLimit));
-  DeoptimizeIf(hi, instr);
+  DeoptimizeIf(hi, instr, "too many arguments");
 
   // Push the receiver and use the register to keep the original
   // number of arguments.
   __ push(receiver);
   __ mov(receiver, length);
   // The arguments are at a one pointer size offset from elements.
   __ add(elements, elements, Operand(1 * kPointerSize));
 
   // Loop through the arguments pushing them onto the execution
   // stack.
@@ skipping 109 matching lines @@
   DCHECK(instr->context() != NULL);
   DCHECK(ToRegister(instr->context()).is(cp));
   Register input = ToRegister(instr->value());
   Register result = ToRegister(instr->result());
   Register scratch = scratch0();
 
   // Deoptimize if not a heap number.
   __ ldr(scratch, FieldMemOperand(input, HeapObject::kMapOffset));
   __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
   __ cmp(scratch, Operand(ip));
-  DeoptimizeIf(ne, instr);
+  DeoptimizeIf(ne, instr, "not a heap number");
 
   Label done;
   Register exponent = scratch0();
   scratch = no_reg;
   __ ldr(exponent, FieldMemOperand(input, HeapNumber::kExponentOffset));
   // Check the sign of the argument. If the argument is positive, just
   // return it.
   __ tst(exponent, Operand(HeapNumber::kSignMask));
   // Move the input to the result if necessary.
   __ Move(result, input);
@@ skipping 47 matching lines @@
 void LCodeGen::EmitIntegerMathAbs(LMathAbs* instr) {
   Register input = ToRegister(instr->value());
   Register result = ToRegister(instr->result());
   __ cmp(input, Operand::Zero());
   __ Move(result, input, pl);
   // We can make rsb conditional because the previous cmp instruction
   // will clear the V (overflow) flag and rsb won't set this flag
   // if input is positive.
   __ rsb(result, input, Operand::Zero(), SetCC, mi);
   // Deoptimize on overflow.
-  DeoptimizeIf(vs, instr);
+  DeoptimizeIf(vs, instr, "overflow");
 }
 
 
 void LCodeGen::DoMathAbs(LMathAbs* instr) {
   // Class for deferred case.
   class DeferredMathAbsTaggedHeapNumber FINAL : public LDeferredCode {
    public:
     DeferredMathAbsTaggedHeapNumber(LCodeGen* codegen, LMathAbs* instr)
         : LDeferredCode(codegen), instr_(instr) { }
     virtual void Generate() OVERRIDE {
@@ skipping 25 matching lines @@
 }
 
 
 void LCodeGen::DoMathFloor(LMathFloor* instr) {
   DwVfpRegister input = ToDoubleRegister(instr->value());
   Register result = ToRegister(instr->result());
   Register input_high = scratch0();
   Label done, exact;
 
   __ TryInt32Floor(result, input, input_high, double_scratch0(), &done, &exact);
-  DeoptimizeIf(al, instr);
+  DeoptimizeIf(al, instr, "lost precision or NaN");
 
   __ bind(&exact);
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     // Test for -0.
     __ cmp(result, Operand::Zero());
     __ b(ne, &done);
     __ cmp(input_high, Operand::Zero());
-    DeoptimizeIf(mi, instr);
+    DeoptimizeIf(mi, instr, "minus zero");
   }
   __ bind(&done);
 }
 
 
 void LCodeGen::DoMathRound(LMathRound* instr) {
   DwVfpRegister input = ToDoubleRegister(instr->value());
   Register result = ToRegister(instr->result());
   DwVfpRegister double_scratch1 = ToDoubleRegister(instr->temp());
   DwVfpRegister input_plus_dot_five = double_scratch1;
   Register input_high = scratch0();
   DwVfpRegister dot_five = double_scratch0();
   Label convert, done;
 
   __ Vmov(dot_five, 0.5, scratch0());
   __ vabs(double_scratch1, input);
   __ VFPCompareAndSetFlags(double_scratch1, dot_five);
   // If input is in [-0.5, -0], the result is -0.
   // If input is in [+0, +0.5[, the result is +0.
   // If the input is +0.5, the result is 1.
   __ b(hi, &convert);  // Out of [-0.5, +0.5].
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     __ VmovHigh(input_high, input);
     __ cmp(input_high, Operand::Zero());
-    DeoptimizeIf(mi, instr);  // [-0.5, -0].
+    // [-0.5, -0].
+    DeoptimizeIf(mi, instr, "minus zero");
   }
   __ VFPCompareAndSetFlags(input, dot_five);
   __ mov(result, Operand(1), LeaveCC, eq);  // +0.5.
   // Remaining cases: [+0, +0.5[ or [-0.5, +0.5[, depending on
   // flag kBailoutOnMinusZero.
   __ mov(result, Operand::Zero(), LeaveCC, ne);
   __ b(&done);
 
   __ bind(&convert);
   __ vadd(input_plus_dot_five, input, dot_five);
   // Reuse dot_five (double_scratch0) as we no longer need this value.
   __ TryInt32Floor(result, input_plus_dot_five, input_high, double_scratch0(),
                    &done, &done);
-  DeoptimizeIf(al, instr);
+  DeoptimizeIf(al, instr, "lost precision or NaN");
   __ bind(&done);
 }
 
 
 void LCodeGen::DoMathFround(LMathFround* instr) {
   DwVfpRegister input_reg = ToDoubleRegister(instr->value());
   DwVfpRegister output_reg = ToDoubleRegister(instr->result());
   LowDwVfpRegister scratch = double_scratch0();
   __ vcvt_f32_f64(scratch.low(), input_reg);
   __ vcvt_f64_f32(output_reg, scratch.low());
@@ skipping 43 matching lines @@
   if (exponent_type.IsSmi()) {
     MathPowStub stub(isolate(), MathPowStub::TAGGED);
     __ CallStub(&stub);
   } else if (exponent_type.IsTagged()) {
     Label no_deopt;
     __ JumpIfSmi(tagged_exponent, &no_deopt);
     DCHECK(!r6.is(tagged_exponent));
     __ ldr(r6, FieldMemOperand(tagged_exponent, HeapObject::kMapOffset));
     __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
     __ cmp(r6, Operand(ip));
-    DeoptimizeIf(ne, instr);
+    DeoptimizeIf(ne, instr, "not a heap number");
     __ bind(&no_deopt);
     MathPowStub stub(isolate(), MathPowStub::TAGGED);
     __ CallStub(&stub);
   } else if (exponent_type.IsInteger32()) {
     MathPowStub stub(isolate(), MathPowStub::INTEGER);
     __ CallStub(&stub);
   } else {
     DCHECK(exponent_type.IsDouble());
     MathPowStub stub(isolate(), MathPowStub::DOUBLE);
     __ CallStub(&stub);
@@ skipping 331 matching lines @@
     Register index = ToRegister(instr->index());
     Operand length = ToOperand(instr->length());
     __ cmp(index, length);
   }
   if (FLAG_debug_code && instr->hydrogen()->skip_check()) {
     Label done;
     __ b(NegateCondition(cc), &done);
     __ stop("eliminated bounds check failed");
     __ bind(&done);
   } else {
-    DeoptimizeIf(cc, instr);
+    DeoptimizeIf(cc, instr, "out of bounds");
   }
 }
 
 
 void LCodeGen::DoStoreKeyedExternalArray(LStoreKeyed* instr) {
   Register external_pointer = ToRegister(instr->elements());
   Register key = no_reg;
   ElementsKind elements_kind = instr->elements_kind();
   bool key_is_constant = instr->key()->IsConstantOperand();
   int constant_key = 0;
@@ skipping 227 matching lines @@
   }
   __ bind(&not_applicable);
 }
 
 
 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(eq, instr);
+  DeoptimizeIf(eq, instr, "memento found");
   __ bind(&no_memento_found);
 }
 
 
 void LCodeGen::DoStringAdd(LStringAdd* instr) {
   DCHECK(ToRegister(instr->context()).is(cp));
   DCHECK(ToRegister(instr->left()).is(r1));
   DCHECK(ToRegister(instr->right()).is(r0));
   StringAddStub stub(isolate(),
                      instr->hydrogen()->flags(),
@@ skipping 313 matching lines @@
 }
 
 
 void LCodeGen::DoSmiTag(LSmiTag* instr) {
   HChange* hchange = instr->hydrogen();
   Register input = ToRegister(instr->value());
   Register output = ToRegister(instr->result());
   if (hchange->CheckFlag(HValue::kCanOverflow) &&
       hchange->value()->CheckFlag(HValue::kUint32)) {
     __ tst(input, Operand(0xc0000000));
-    DeoptimizeIf(ne, instr);
+    DeoptimizeIf(ne, instr, "overflow");
   }
   if (hchange->CheckFlag(HValue::kCanOverflow) &&
       !hchange->value()->CheckFlag(HValue::kUint32)) {
     __ SmiTag(output, input, SetCC);
-    DeoptimizeIf(vs, instr);
+    DeoptimizeIf(vs, instr, "overflow");
   } else {
     __ SmiTag(output, input);
   }
 }
 
 
 void LCodeGen::DoSmiUntag(LSmiUntag* instr) {
   Register input = ToRegister(instr->value());
   Register result = ToRegister(instr->result());
   if (instr->needs_check()) {
     STATIC_ASSERT(kHeapObjectTag == 1);
     // If the input is a HeapObject, SmiUntag will set the carry flag.
     __ SmiUntag(result, input, SetCC);
-    DeoptimizeIf(cs, instr);
+    DeoptimizeIf(cs, instr, "not a Smi");
   } else {
     __ SmiUntag(result, input);
   }
 }
 
 
 void LCodeGen::EmitNumberUntagD(LNumberUntagD* instr, Register input_reg,
                                 DwVfpRegister result_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();
 
   Register scratch = scratch0();
   SwVfpRegister flt_scratch = double_scratch0().low();
   DCHECK(!result_reg.is(double_scratch0()));
   Label convert, load_smi, done;
   if (mode == NUMBER_CANDIDATE_IS_ANY_TAGGED) {
     // Smi check.
     __ UntagAndJumpIfSmi(scratch, input_reg, &load_smi);
     // Heap number map check.
     __ ldr(scratch, FieldMemOperand(input_reg, HeapObject::kMapOffset));
     __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
     __ cmp(scratch, Operand(ip));
     if (can_convert_undefined_to_nan) {
       __ b(ne, &convert);
     } else {
-      DeoptimizeIf(ne, instr);
+      DeoptimizeIf(ne, instr, "not a heap number");
     }
     // load heap number
     __ vldr(result_reg, input_reg, HeapNumber::kValueOffset - kHeapObjectTag);
     if (deoptimize_on_minus_zero) {
       __ VmovLow(scratch, result_reg);
       __ cmp(scratch, Operand::Zero());
       __ b(ne, &done);
       __ VmovHigh(scratch, result_reg);
       __ cmp(scratch, Operand(HeapNumber::kSignMask));
-      DeoptimizeIf(eq, instr);
+      DeoptimizeIf(eq, instr, "minus zero");
     }
     __ jmp(&done);
     if (can_convert_undefined_to_nan) {
       __ bind(&convert);
       // Convert undefined (and hole) to NaN.
       __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
       __ cmp(input_reg, Operand(ip));
-      DeoptimizeIf(ne, instr);
+      DeoptimizeIf(ne, instr, "not a heap number/undefined");
       __ LoadRoot(scratch, Heap::kNanValueRootIndex);
       __ vldr(result_reg, scratch, HeapNumber::kValueOffset - kHeapObjectTag);
       __ jmp(&done);
     }
   } else {
     __ SmiUntag(scratch, input_reg);
     DCHECK(mode == NUMBER_CANDIDATE_IS_SMI);
   }
   // Smi to double register conversion
   __ bind(&load_smi);
@@ skipping 47 matching lines @@
     __ bind(&check_bools);
     __ LoadRoot(ip, Heap::kTrueValueRootIndex);
     __ cmp(scratch2, Operand(ip));
     __ b(ne, &check_false);
     __ mov(input_reg, Operand(1));
     __ b(&done);
 
     __ bind(&check_false);
     __ LoadRoot(ip, Heap::kFalseValueRootIndex);
     __ cmp(scratch2, Operand(ip));
-    DeoptimizeIf(ne, instr, "cannot truncate");
+    DeoptimizeIf(ne, instr, "not a heap number/undefined/true/false");
     __ mov(input_reg, Operand::Zero());
   } else {
     DeoptimizeIf(ne, instr, "not a heap number");
 
     __ sub(ip, scratch2, Operand(kHeapObjectTag));
     __ vldr(double_scratch2, ip, HeapNumber::kValueOffset);
     __ TryDoubleToInt32Exact(input_reg, double_scratch2, double_scratch);
     DeoptimizeIf(ne, instr, "lost precision or NaN");
 
     if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
@@ skipping 64 matching lines @@
   Register result_reg = ToRegister(instr->result());
   Register scratch1 = scratch0();
   DwVfpRegister double_input = ToDoubleRegister(instr->value());
   LowDwVfpRegister double_scratch = double_scratch0();
 
   if (instr->truncating()) {
     __ TruncateDoubleToI(result_reg, double_input);
   } else {
     __ TryDoubleToInt32Exact(result_reg, double_input, double_scratch);
     // Deoptimize if the input wasn't a int32 (inside a double).
-    DeoptimizeIf(ne, instr);
+    DeoptimizeIf(ne, instr, "lost precision or NaN");
     if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
       Label done;
       __ cmp(result_reg, Operand::Zero());
       __ b(ne, &done);
       __ VmovHigh(scratch1, double_input);
       __ tst(scratch1, Operand(HeapNumber::kSignMask));
-      DeoptimizeIf(ne, instr);
+      DeoptimizeIf(ne, instr, "minus zero");
       __ bind(&done);
     }
   }
 }
 
 
 void LCodeGen::DoDoubleToSmi(LDoubleToSmi* instr) {
   Register result_reg = ToRegister(instr->result());
   Register scratch1 = scratch0();
   DwVfpRegister double_input = ToDoubleRegister(instr->value());
   LowDwVfpRegister double_scratch = double_scratch0();
 
   if (instr->truncating()) {
     __ TruncateDoubleToI(result_reg, double_input);
   } else {
     __ TryDoubleToInt32Exact(result_reg, double_input, double_scratch);
     // Deoptimize if the input wasn't a int32 (inside a double).
-    DeoptimizeIf(ne, instr);
+    DeoptimizeIf(ne, instr, "lost precision or NaN");
     if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
       Label done;
       __ cmp(result_reg, Operand::Zero());
       __ b(ne, &done);
       __ VmovHigh(scratch1, double_input);
       __ tst(scratch1, Operand(HeapNumber::kSignMask));
-      DeoptimizeIf(ne, instr);
+      DeoptimizeIf(ne, instr, "minus zero");
       __ bind(&done);
     }
   }
   __ SmiTag(result_reg, SetCC);
-  DeoptimizeIf(vs, instr);
+  DeoptimizeIf(vs, instr, "overflow");
 }
 
 
 void LCodeGen::DoCheckSmi(LCheckSmi* instr) {
   LOperand* input = instr->value();
   __ SmiTst(ToRegister(input));
-  DeoptimizeIf(ne, instr);
+  DeoptimizeIf(ne, instr, "not a Smi");
 }
 
 
 void LCodeGen::DoCheckNonSmi(LCheckNonSmi* instr) {
   if (!instr->hydrogen()->value()->type().IsHeapObject()) {
     LOperand* input = instr->value();
     __ SmiTst(ToRegister(input));
-    DeoptimizeIf(eq, instr);
+    DeoptimizeIf(eq, instr, "Smi");
   }
 }
 
 
 void LCodeGen::DoCheckInstanceType(LCheckInstanceType* instr) {
   Register input = ToRegister(instr->value());
   Register scratch = scratch0();
 
   __ ldr(scratch, FieldMemOperand(input, HeapObject::kMapOffset));
   __ ldrb(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
 
   if (instr->hydrogen()->is_interval_check()) {
     InstanceType first;
     InstanceType last;
     instr->hydrogen()->GetCheckInterval(&first, &last);
 
     __ cmp(scratch, Operand(first));
 
     // If there is only one type in the interval check for equality.
     if (first == last) {
-      DeoptimizeIf(ne, instr);
+      DeoptimizeIf(ne, instr, "wrong instance type");
     } else {
-      DeoptimizeIf(lo, instr);
+      DeoptimizeIf(lo, instr, "wrong instance type");
       // Omit check for the last type.
       if (last != LAST_TYPE) {
         __ cmp(scratch, Operand(last));
-        DeoptimizeIf(hi, instr);
+        DeoptimizeIf(hi, 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));
       __ tst(scratch, Operand(mask));
-      DeoptimizeIf(tag == 0 ? ne : eq, instr);
+      DeoptimizeIf(tag == 0 ? ne : eq, instr, "wrong instance type");
     } else {
       __ and_(scratch, scratch, Operand(mask));
       __ cmp(scratch, Operand(tag));
-      DeoptimizeIf(ne, instr);
+      DeoptimizeIf(ne, instr, "wrong instance type");
     }
   }
 }
 
 
 void LCodeGen::DoCheckValue(LCheckValue* instr) {
   Register reg = ToRegister(instr->value());
   Handle<HeapObject> object = instr->hydrogen()->object().handle();
   AllowDeferredHandleDereference smi_check;
   if (isolate()->heap()->InNewSpace(*object)) {
     Register reg = ToRegister(instr->value());
     Handle<Cell> cell = isolate()->factory()->NewCell(object);
     __ mov(ip, Operand(Handle<Object>(cell)));
     __ ldr(ip, FieldMemOperand(ip, Cell::kValueOffset));
     __ cmp(reg, ip);
   } else {
     __ cmp(reg, Operand(object));
   }
-  DeoptimizeIf(ne, instr);
+  DeoptimizeIf(ne, instr, "value mismatch");
 }
 
 
 void LCodeGen::DoDeferredInstanceMigration(LCheckMaps* instr, Register object) {
   {
     PushSafepointRegistersScope scope(this);
     __ push(object);
     __ mov(cp, Operand::Zero());
     __ CallRuntimeSaveDoubles(Runtime::kTryMigrateInstance);
     RecordSafepointWithRegisters(
         instr->pointer_map(), 1, Safepoint::kNoLazyDeopt);
     __ StoreToSafepointRegisterSlot(r0, scratch0());
   }
   __ tst(scratch0(), Operand(kSmiTagMask));
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, "instance migration failed");
 }
 
 
 void LCodeGen::DoCheckMaps(LCheckMaps* instr) {
   class DeferredCheckMaps FINAL : public LDeferredCode {
    public:
     DeferredCheckMaps(LCodeGen* codegen, LCheckMaps* instr, Register object)
         : LDeferredCode(codegen), instr_(instr), object_(object) {
       SetExit(check_maps());
     }
@@ skipping 36 matching lines @@
     Handle<Map> map = maps->at(i).handle();
     __ CompareMap(map_reg, map, &success);
     __ b(eq, &success);
   }
 
   Handle<Map> map = maps->at(maps->size() - 1).handle();
   __ CompareMap(map_reg, map, &success);
   if (instr->hydrogen()->HasMigrationTarget()) {
     __ b(ne, deferred->entry());
   } else {
-    DeoptimizeIf(ne, instr);
+    DeoptimizeIf(ne, instr, "wrong map");
   }
 
   __ bind(&success);
 }
 
 
 void LCodeGen::DoClampDToUint8(LClampDToUint8* instr) {
   DwVfpRegister value_reg = ToDoubleRegister(instr->unclamped());
   Register result_reg = ToRegister(instr->result());
   __ ClampDoubleToUint8(result_reg, value_reg, double_scratch0());
@@ skipping 18 matching lines @@
   __ UntagAndJumpIfSmi(result_reg, input_reg, &is_smi);
 
   // Check for heap number
   __ ldr(scratch, FieldMemOperand(input_reg, HeapObject::kMapOffset));
   __ cmp(scratch, Operand(factory()->heap_number_map()));
   __ b(eq, &heap_number);
 
   // Check for undefined. Undefined is converted to zero for clamping
   // conversions.
   __ cmp(input_reg, Operand(factory()->undefined_value()));
-  DeoptimizeIf(ne, instr);
+  DeoptimizeIf(ne, instr, "not a heap number/undefined");
   __ mov(result_reg, Operand::Zero());
   __ jmp(&done);
 
   // Heap number
   __ bind(&heap_number);
   __ vldr(temp_reg, FieldMemOperand(input_reg, HeapNumber::kValueOffset));
   __ ClampDoubleToUint8(result_reg, temp_reg, double_scratch0());
   __ jmp(&done);
 
   // smi
@@ skipping 449 matching lines @@
   DCHECK(!environment->HasBeenRegistered());
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
 
   GenerateOsrPrologue();
 }
 
 
 void LCodeGen::DoForInPrepareMap(LForInPrepareMap* instr) {
   __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
   __ cmp(r0, ip);
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, "undefined");
 
   Register null_value = r5;
   __ LoadRoot(null_value, Heap::kNullValueRootIndex);
   __ cmp(r0, null_value);
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, "null");
 
   __ SmiTst(r0);
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, "Smi");
 
   STATIC_ASSERT(FIRST_JS_PROXY_TYPE == FIRST_SPEC_OBJECT_TYPE);
   __ CompareObjectType(r0, r1, r1, LAST_JS_PROXY_TYPE);
-  DeoptimizeIf(le, instr);
+  DeoptimizeIf(le, instr, "wrong instance type");
 
   Label use_cache, call_runtime;
   __ CheckEnumCache(null_value, &call_runtime);
 
   __ ldr(r0, FieldMemOperand(r0, HeapObject::kMapOffset));
   __ b(&use_cache);
 
   // Get the set of properties to enumerate.
   __ bind(&call_runtime);
   __ push(r0);
   CallRuntime(Runtime::kGetPropertyNamesFast, 1, instr);
 
   __ ldr(r1, FieldMemOperand(r0, HeapObject::kMapOffset));
   __ LoadRoot(ip, Heap::kMetaMapRootIndex);
   __ cmp(r1, ip);
-  DeoptimizeIf(ne, instr);
+  DeoptimizeIf(ne, 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, Operand(Smi::FromInt(0)));
   __ b(ne, &load_cache);
   __ mov(result, Operand(isolate()->factory()->empty_fixed_array()));
   __ jmp(&done);
 
   __ bind(&load_cache);
   __ LoadInstanceDescriptors(map, result);
   __ ldr(result,
          FieldMemOperand(result, DescriptorArray::kEnumCacheOffset));
   __ ldr(result,
          FieldMemOperand(result, FixedArray::SizeFor(instr->idx())));
   __ cmp(result, Operand::Zero());
-  DeoptimizeIf(eq, instr);
+  DeoptimizeIf(eq, instr, "no cache");
 
   __ bind(&done);
 }
 
 
 void LCodeGen::DoCheckMapValue(LCheckMapValue* instr) {
   Register object = ToRegister(instr->value());
   Register map = ToRegister(instr->map());
   __ ldr(scratch0(), FieldMemOperand(object, HeapObject::kMapOffset));
   __ cmp(map, scratch0());
-  DeoptimizeIf(ne, instr);
+  DeoptimizeIf(ne, instr, "wrong map");
 }
 
 
 void LCodeGen::DoDeferredLoadMutableDouble(LLoadFieldByIndex* instr,
                                            Register result,
                                            Register object,
                                            Register index) {
   PushSafepointRegistersScope scope(this);
   __ Push(object);
   __ Push(index);
@@ skipping 76 matching lines @@
   __ Push(scope_info);
   __ push(ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal