diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index d11073fdc4..65177d876b 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -1519,7 +1519,7 @@ LInstruction* LChunkBuilder::DoHasInstanceType(HHasInstanceType* instr) {
 LInstruction* LChunkBuilder::DoGetCachedArrayIndex(
     HGetCachedArrayIndex* instr)  {
   ASSERT(instr->value()->representation().IsTagged());
-  LOperand* value = UseRegister(instr->value());
+  LOperand* value = UseRegisterAtStart(instr->value());
 
   return DefineAsRegister(new LGetCachedArrayIndex(value));
 }
diff --git a/src/arm/lithium-arm.h b/src/arm/lithium-arm.h
index 77d6b71a93..f036f76834 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -728,17 +728,6 @@ class LHasInstanceTypeAndBranch: public LControlInstruction<1, 0> {
 };
 
 
-class LHasCachedArrayIndex: public LTemplateInstruction<1, 1, 0> {
- public:
-  explicit LHasCachedArrayIndex(LOperand* value) {
-    inputs_[0] = value;
-  }
-
-  DECLARE_CONCRETE_INSTRUCTION(HasCachedArrayIndex, "has-cached-array-index")
-  DECLARE_HYDROGEN_ACCESSOR(HasCachedArrayIndex)
-};
-
-
 class LGetCachedArrayIndex: public LTemplateInstruction<1, 1, 0> {
  public:
   explicit LGetCachedArrayIndex(LOperand* value) {
@@ -750,6 +739,17 @@ class LGetCachedArrayIndex: public LTemplateInstruction<1, 1, 0> {
 };
 
 
+class LHasCachedArrayIndex: public LTemplateInstruction<1, 1, 0> {
+ public:
+  explicit LHasCachedArrayIndex(LOperand* value) {
+    inputs_[0] = value;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(HasCachedArrayIndex, "has-cached-array-index")
+  DECLARE_HYDROGEN_ACCESSOR(HasCachedArrayIndex)
+};
+
+
 class LHasCachedArrayIndexAndBranch: public LControlInstruction<1, 0> {
  public:
   explicit LHasCachedArrayIndexAndBranch(LOperand* value) {
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 6d4c7199df..9e046e74f7 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -1711,10 +1711,13 @@ void LCodeGen::DoHasInstanceTypeAndBranch(LHasInstanceTypeAndBranch* instr) {
 void LCodeGen::DoGetCachedArrayIndex(LGetCachedArrayIndex* instr) {
   Register input = ToRegister(instr->InputAt(0));
   Register result = ToRegister(instr->result());
-  Register scratch = scratch0();
 
-  __ ldr(scratch, FieldMemOperand(input, String::kHashFieldOffset));
-  __ IndexFromHash(scratch, result);
+  if (FLAG_debug_code) {
+    __ AbortIfNotString(input);
+  }
+
+  __ ldr(result, FieldMemOperand(input, String::kHashFieldOffset));
+  __ IndexFromHash(result, result);
 }
 
 
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 54b4801605..d84354f66c 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -1654,6 +1654,19 @@ void LCodeGen::DoHasInstanceTypeAndBranch(LHasInstanceTypeAndBranch* instr) {
 }
 
 
+void LCodeGen::DoGetCachedArrayIndex(LGetCachedArrayIndex* instr) {
+  Register input = ToRegister(instr->InputAt(0));
+  Register result = ToRegister(instr->result());
+
+  if (FLAG_debug_code) {
+    __ AbortIfNotString(input);
+  }
+
+  __ mov(result, FieldOperand(input, String::kHashFieldOffset));
+  __ IndexFromHash(result, result);
+}
+
+
 void LCodeGen::DoHasCachedArrayIndex(LHasCachedArrayIndex* instr) {
   Register input = ToRegister(instr->InputAt(0));
   Register result = ToRegister(instr->result());
@@ -1663,7 +1676,7 @@ void LCodeGen::DoHasCachedArrayIndex(LHasCachedArrayIndex* instr) {
   __ test(FieldOperand(input, String::kHashFieldOffset),
           Immediate(String::kContainsCachedArrayIndexMask));
   NearLabel done;
-  __ j(not_zero, &done);
+  __ j(zero, &done);
   __ mov(result, Factory::false_value());
   __ bind(&done);
 }
@@ -1678,7 +1691,7 @@ void LCodeGen::DoHasCachedArrayIndexAndBranch(
 
   __ test(FieldOperand(input, String::kHashFieldOffset),
           Immediate(String::kContainsCachedArrayIndexMask));
-  EmitBranch(true_block, false_block, not_equal);
+  EmitBranch(true_block, false_block, equal);
 }
 
 
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index e2fdf2c5ee..237ce55480 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1541,8 +1541,10 @@ LInstruction* LChunkBuilder::DoHasInstanceType(HHasInstanceType* instr) {
 
 LInstruction* LChunkBuilder::DoGetCachedArrayIndex(
     HGetCachedArrayIndex* instr)  {
-  Abort("Unimplemented: %s", "DoGetCachedArrayIndex");
-  return NULL;
+  ASSERT(instr->value()->representation().IsTagged());
+  LOperand* value = UseRegisterAtStart(instr->value());
+
+  return DefineAsRegister(new LGetCachedArrayIndex(value));
 }
 
 
diff --git a/src/ia32/lithium-ia32.h b/src/ia32/lithium-ia32.h
index ad0b0ca059..b8cba44e27 100644
--- a/src/ia32/lithium-ia32.h
+++ b/src/ia32/lithium-ia32.h
@@ -92,6 +92,7 @@ class LCodeGen;
   V(FixedArrayLength)                           \
   V(FunctionLiteral)                            \
   V(Gap)                                        \
+  V(GetCachedArrayIndex)                        \
   V(GlobalObject)                               \
   V(GlobalReceiver)                             \
   V(Goto)                                       \
@@ -743,6 +744,17 @@ class LHasInstanceTypeAndBranch: public LControlInstruction<1, 1> {
 };
 
 
+class LGetCachedArrayIndex: public LTemplateInstruction<1, 1, 0> {
+ public:
+  explicit LGetCachedArrayIndex(LOperand* value) {
+    inputs_[0] = value;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(GetCachedArrayIndex, "get-cached-array-index")
+  DECLARE_HYDROGEN_ACCESSOR(GetCachedArrayIndex)
+};
+
+
 class LHasCachedArrayIndex: public LTemplateInstruction<1, 1, 0> {
  public:
   explicit LHasCachedArrayIndex(LOperand* value) {
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 7e7ec987e6..2cbab4bf05 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1637,6 +1637,20 @@ void LCodeGen::DoHasInstanceTypeAndBranch(LHasInstanceTypeAndBranch* instr) {
 }
 
 
+void LCodeGen::DoGetCachedArrayIndex(LGetCachedArrayIndex* instr) {
+  Register input = ToRegister(instr->InputAt(0));
+  Register result = ToRegister(instr->result());
+
+  if (FLAG_debug_code) {
+    __ AbortIfNotString(input);
+  }
+
+  __ movl(result, FieldOperand(input, String::kHashFieldOffset));
+  ASSERT(String::kHashShift >= kSmiTagSize);
+  __ IndexFromHash(result, result);
+}
+
+
 void LCodeGen::DoHasCachedArrayIndex(LHasCachedArrayIndex* instr) {
   Register input = ToRegister(instr->InputAt(0));
   Register result = ToRegister(instr->result());
@@ -1646,7 +1660,7 @@ void LCodeGen::DoHasCachedArrayIndex(LHasCachedArrayIndex* instr) {
   __ testl(FieldOperand(input, String::kHashFieldOffset),
            Immediate(String::kContainsCachedArrayIndexMask));
   NearLabel done;
-  __ j(not_zero, &done);
+  __ j(zero, &done);
   __ LoadRoot(result, Heap::kFalseValueRootIndex);
   __ bind(&done);
 }
@@ -1661,7 +1675,7 @@ void LCodeGen::DoHasCachedArrayIndexAndBranch(
 
   __ testl(FieldOperand(input, String::kHashFieldOffset),
            Immediate(String::kContainsCachedArrayIndexMask));
-  EmitBranch(true_block, false_block, not_equal);
+  EmitBranch(true_block, false_block, equal);
 }
 
 
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index b73e7a995d..7c26468a38 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1522,8 +1522,10 @@ LInstruction* LChunkBuilder::DoHasInstanceType(HHasInstanceType* instr) {
 
 LInstruction* LChunkBuilder::DoGetCachedArrayIndex(
     HGetCachedArrayIndex* instr)  {
-  Abort("Unimplemented: %s", "DoGetCachedArrayIndex");
-  return NULL;
+  ASSERT(instr->value()->representation().IsTagged());
+  LOperand* value = UseRegisterAtStart(instr->value());
+
+  return DefineAsRegister(new LGetCachedArrayIndex(value));
 }
 
 
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index fed5b8cb88..bdc5b2b5cb 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -89,6 +89,7 @@ class LCodeGen;
   V(DoubleToI)                                  \
   V(FunctionLiteral)                            \
   V(Gap)                                        \
+  V(GetCachedArrayIndex)                        \
   V(GlobalObject)                               \
   V(GlobalReceiver)                             \
   V(Goto)                                       \
@@ -730,6 +731,17 @@ class LHasInstanceTypeAndBranch: public LControlInstruction<1, 0> {
 };
 
 
+class LGetCachedArrayIndex: public LTemplateInstruction<1, 1, 0> {
+ public:
+  explicit LGetCachedArrayIndex(LOperand* value) {
+    inputs_[0] = value;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(GetCachedArrayIndex, "get-cached-array-index")
+  DECLARE_HYDROGEN_ACCESSOR(GetCachedArrayIndex)
+};
+
+
 class LHasCachedArrayIndex: public LTemplateInstruction<1, 1, 0> {
  public:
   explicit LHasCachedArrayIndex(LOperand* value) {