| Index: src/x64/lithium-codegen-x64.cc
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| diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
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| index 8547b09be29686c301e6ad10f4d38b6c75175de8..fea0afa7842c2a784a97cb7b2f94ee5ff43a059d 100644
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| --- a/src/x64/lithium-codegen-x64.cc
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| +++ b/src/x64/lithium-codegen-x64.cc
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| @@ -1993,7 +1993,7 @@ void LCodeGen::DoGetCachedArrayIndex(LGetCachedArrayIndex* instr) {
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|    Register input = ToRegister(instr->value());
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|    Register result = ToRegister(instr->result());
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|  
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| -  __ AbortIfNotString(input);
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| +  __ AssertString(input);
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|  
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|    __ movl(result, FieldOperand(input, String::kHashFieldOffset));
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|    ASSERT(String::kHashShift >= kSmiTagSize);
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| @@ -3756,9 +3756,8 @@ void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
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|                           instr->index());
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|    if (instr->length()->IsRegister()) {
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|      Register reg = ToRegister(instr->length());
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| -    if (FLAG_debug_code &&
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| -        !instr->hydrogen()->length()->representation().IsTagged()) {
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| -      __ AbortIfNotZeroExtended(reg);
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| +    if (!instr->hydrogen()->length()->representation().IsTagged()) {
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| +      __ AssertZeroExtended(reg);
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|      }
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|      if (instr->index()->IsConstantOperand()) {
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|        int constant_index =
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| @@ -3770,9 +3769,8 @@ void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
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|        }
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|      } else {
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|        Register reg2 = ToRegister(instr->index());
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| -      if (FLAG_debug_code &&
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| -          !instr->hydrogen()->index()->representation().IsTagged()) {
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| -        __ AbortIfNotZeroExtended(reg2);
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| +      if (!instr->hydrogen()->index()->representation().IsTagged()) {
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| +        __ AssertZeroExtended(reg2);
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|        }
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|        __ cmpq(reg, reg2);
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|      }
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| @@ -3991,9 +3989,7 @@ void LCodeGen::DoDeferredStringCharCodeAt(LStringCharCodeAt* instr) {
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|      __ push(index);
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|    }
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|    CallRuntimeFromDeferred(Runtime::kStringCharCodeAt, 2, instr);
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| -  if (FLAG_debug_code) {
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| -    __ AbortIfNotSmi(rax);
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| -  }
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| +  __ AssertSmi(rax);
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|    __ SmiToInteger32(rax, rax);
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|    __ StoreToSafepointRegisterSlot(result, rax);
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|  }
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| @@ -4208,9 +4204,7 @@ void LCodeGen::DoSmiUntag(LSmiUntag* instr) {
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|      Condition is_smi = __ CheckSmi(input);
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|      DeoptimizeIf(NegateCondition(is_smi), instr->environment());
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|    } else {
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| -    if (FLAG_debug_code) {
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| -      __ AbortIfNotSmi(input);
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| -    }
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| +    __ AssertSmi(input);
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|    }
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|    __ SmiToInteger32(input, input);
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|  }
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| @@ -4620,7 +4614,7 @@ void LCodeGen::DoAllocateObject(LAllocateObject* instr) {
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|    __ movq(map, FieldOperand(scratch, JSFunction::kPrototypeOrInitialMapOffset));
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|  
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|    if (FLAG_debug_code) {
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| -    __ AbortIfSmi(map);
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| +    __ AssertNotSmi(map);
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|      __ cmpb(FieldOperand(map, Map::kInstanceSizeOffset),
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|              Immediate(instance_size >> kPointerSizeLog2));
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|      __ Assert(equal, "Unexpected instance size");
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| 
 |