Support string add in crankshaft:

o The type recording binary stub got a new type for string + string.

o Added HStringAdd and LStringAdd based on the new type info.

o Started using HValue types to avoid unneccesary checks.

Review URL: http://codereview.chromium.org/6852015

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7622 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/code-stubs-arm.cc

@@ -1817,6 +1817,9 @@ void TypeRecordingBinaryOpStub::Generate(MacroAssembler* masm) {
     case TRBinaryOpIC::ODDBALL:
       GenerateOddballStub(masm);
       break;
+    case TRBinaryOpIC::BOTH_STRING:
+      GenerateBothStringStub(masm);
+      break;
     case TRBinaryOpIC::STRING:
       GenerateStringStub(masm);
       break;
@@ -2257,6 +2260,36 @@ void TypeRecordingBinaryOpStub::GenerateStringStub(MacroAssembler* masm) {
 }
 
 
+void TypeRecordingBinaryOpStub::GenerateBothStringStub(MacroAssembler* masm) {
+  Label call_runtime;
+  ASSERT(operands_type_ == TRBinaryOpIC::BOTH_STRING);
+  ASSERT(op_ == Token::ADD);
+  // If both arguments are strings, call the string add stub.
+  // Otherwise, do a transition.
+
+  // Registers containing left and right operands respectively.
+  Register left = r1;
+  Register right = r0;
+
+  // Test if left operand is a string.
+  __ JumpIfSmi(left, &call_runtime);
+  __ CompareObjectType(left, r2, r2, FIRST_NONSTRING_TYPE);
+  __ b(ge, &call_runtime);
+
+  // Test if right operand is a string.
+  __ JumpIfSmi(right, &call_runtime);
+  __ CompareObjectType(right, r2, r2, FIRST_NONSTRING_TYPE);
+  __ b(ge, &call_runtime);
+
+  StringAddStub string_add_stub(NO_STRING_CHECK_IN_STUB);
+  GenerateRegisterArgsPush(masm);
+  __ TailCallStub(&string_add_stub);
+
+  __ bind(&call_runtime);
+  GenerateTypeTransition(masm);
+}
+
+
 void TypeRecordingBinaryOpStub::GenerateInt32Stub(MacroAssembler* masm) {
   ASSERT(operands_type_ == TRBinaryOpIC::INT32);
 

src/arm/code-stubs-arm.h

@@ -158,6 +158,7 @@ class TypeRecordingBinaryOpStub: public CodeStub {
   void GenerateHeapNumberStub(MacroAssembler* masm);
   void GenerateOddballStub(MacroAssembler* masm);
   void GenerateStringStub(MacroAssembler* masm);
+  void GenerateBothStringStub(MacroAssembler* masm);
   void GenerateGenericStub(MacroAssembler* masm);
   void GenerateAddStrings(MacroAssembler* masm);
   void GenerateCallRuntime(MacroAssembler* masm);

src/arm/lithium-arm.cc

@@ -1945,6 +1945,13 @@ LInstruction* LChunkBuilder::DoStoreNamedGeneric(HStoreNamedGeneric* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoStringAdd(HStringAdd* instr) {
+  LOperand* left = UseRegisterAtStart(instr->left());
+  LOperand* right = UseRegisterAtStart(instr->right());
+  return MarkAsCall(DefineFixed(new LStringAdd(left, right), r0), instr);
+}
+
+
 LInstruction* LChunkBuilder::DoStringCharCodeAt(HStringCharCodeAt* instr) {
   LOperand* string = UseRegister(instr->string());
   LOperand* index = UseRegisterOrConstant(instr->index());

src/arm/lithium-arm.h

@@ -152,6 +152,7 @@ class LCodeGen;
   V(StoreKeyedSpecializedArrayElement)          \
   V(StoreNamedField)                            \
   V(StoreNamedGeneric)                          \
+  V(StringAdd)                                  \
   V(StringCharCodeAt)                           \
   V(StringCharFromCode)                         \
   V(StringLength)                               \
@@ -1706,6 +1707,22 @@ class LStoreKeyedSpecializedArrayElement: public LTemplateInstruction<0, 3, 0> {
 };
 
 
+class LStringAdd: public LTemplateInstruction<1, 2, 0> {
+ public:
+  LStringAdd(LOperand* left, LOperand* right) {
+    inputs_[0] = left;
+    inputs_[1] = right;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(StringAdd, "string-add")
+  DECLARE_HYDROGEN_ACCESSOR(StringAdd)
+
+  LOperand* left() { return inputs_[0]; }
+  LOperand* right() { return inputs_[1]; }
+};
+
+
+
 class LStringCharCodeAt: public LTemplateInstruction<1, 2, 0> {
  public:
   LStringCharCodeAt(LOperand* string, LOperand* index) {

src/arm/lithium-codegen-arm.cc

@@ -3223,6 +3223,14 @@ void LCodeGen::DoStoreKeyedGeneric(LStoreKeyedGeneric* instr) {
 }
 
 
+void LCodeGen::DoStringAdd(LStringAdd* instr) {
+  __ push(ToRegister(instr->left()));
+  __ push(ToRegister(instr->right()));
+  StringAddStub stub(NO_STRING_CHECK_IN_STUB);
+  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+}
+
+
 void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
   class DeferredStringCharCodeAt: public LDeferredCode {
    public:

src/hydrogen-instructions.h

@@ -155,6 +155,7 @@ class LChunkBuilder;
   V(StoreKeyedGeneric)                         \
   V(StoreNamedField)                           \
   V(StoreNamedGeneric)                         \
+  V(StringAdd)                                 \
   V(StringCharCodeAt)                          \
   V(StringCharFromCode)                        \
   V(StringLength)                              \
@@ -1707,6 +1708,16 @@ class HCheckInstanceType: public HUnaryOperation {
   virtual void Verify();
 #endif
 
+  virtual HValue* Canonicalize() {
+    if (!value()->type().IsUninitialized() &&
+        value()->type().IsString() &&
+        first() == FIRST_STRING_TYPE &&
+        last() == LAST_STRING_TYPE) {
+      return NULL;
+    }
+    return this;
+  }
+
   static HCheckInstanceType* NewIsJSObjectOrJSFunction(HValue* value);
 
   InstanceType first() const { return first_; }
@@ -1748,6 +1759,18 @@ class HCheckNonSmi: public HUnaryOperation {
   virtual void Verify();
 #endif
 
+  virtual HValue* Canonicalize() {
+    HType value_type = value()->type();
+    if (!value_type.IsUninitialized() &&
+        (value_type.IsHeapNumber() ||
+         value_type.IsString() ||
+         value_type.IsBoolean() ||
+         value_type.IsNonPrimitive())) {
+      return NULL;
+    }
+    return this;
+  }
+
   DECLARE_CONCRETE_INSTRUCTION(CheckNonSmi, "check_non_smi")
 
  protected:
@@ -3407,6 +3430,29 @@ class HStoreKeyedGeneric: public HTemplateInstruction<4> {
 };
 
 
+class HStringAdd: public HBinaryOperation {
+ public:
+  HStringAdd(HValue* left, HValue* right) : HBinaryOperation(left, right) {
+    set_representation(Representation::Tagged());
+    SetFlag(kUseGVN);
+    SetFlag(kDependsOnMaps);
+  }
+
+  virtual Representation RequiredInputRepresentation(int index) const {
+    return Representation::Tagged();
+  }
+
+  virtual HType CalculateInferredType() {
+    return HType::String();
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(StringAdd, "string_add")
+
+ protected:
+  virtual bool DataEquals(HValue* other) { return true; }
+};
+
+
 class HStringCharCodeAt: public HBinaryOperation {
  public:
   HStringCharCodeAt(HValue* string, HValue* index)

src/hydrogen.cc

@@ -4888,10 +4888,21 @@ HStringCharCodeAt* HGraphBuilder::BuildStringCharCodeAt(HValue* string,
 HInstruction* HGraphBuilder::BuildBinaryOperation(BinaryOperation* expr,
                                                   HValue* left,
                                                   HValue* right) {
+  TypeInfo info = oracle()->BinaryType(expr);
   HInstruction* instr = NULL;
   switch (expr->op()) {
     case Token::ADD:
-      instr = new(zone()) HAdd(left, right);
+      if (info.IsString()) {
+        AddInstruction(new(zone()) HCheckNonSmi(left));
+        AddInstruction(new(zone()) HCheckInstanceType(
+            left, FIRST_STRING_TYPE, LAST_STRING_TYPE));
+        AddInstruction(new(zone()) HCheckNonSmi(right));
+        AddInstruction(new(zone()) HCheckInstanceType(
+            right, FIRST_STRING_TYPE, LAST_STRING_TYPE));
+        instr = new(zone()) HStringAdd(left, right);
+      } else {
+        instr = new(zone()) HAdd(left, right);
+      }
       break;
     case Token::SUB:
       instr = new(zone()) HSub(left, right);
@@ -4926,7 +4937,6 @@ HInstruction* HGraphBuilder::BuildBinaryOperation(BinaryOperation* expr,
     default:
       UNREACHABLE();
   }
-  TypeInfo info = oracle()->BinaryType(expr);
   // If we hit an uninitialized binary op stub we will get type info
   // for a smi operation. If one of the operands is a constant string
   // do not generate code assuming it is a smi operation.

src/ia32/code-stubs-ia32.cc

@@ -446,6 +446,9 @@ void TypeRecordingBinaryOpStub::Generate(MacroAssembler* masm) {
     case TRBinaryOpIC::ODDBALL:
       GenerateOddballStub(masm);
       break;
+    case TRBinaryOpIC::BOTH_STRING:
+      GenerateBothStringStub(masm);
+      break;
     case TRBinaryOpIC::STRING:
       GenerateStringStub(masm);
       break;
@@ -909,6 +912,38 @@ void TypeRecordingBinaryOpStub::GenerateStringStub(MacroAssembler* masm) {
 }
 
 
+void TypeRecordingBinaryOpStub::GenerateBothStringStub(MacroAssembler* masm) {
+  Label call_runtime;
+  ASSERT(operands_type_ == TRBinaryOpIC::BOTH_STRING);
+  ASSERT(op_ == Token::ADD);
+  // If both arguments are strings, call the string add stub.
+  // Otherwise, do a transition.
+
+  // Registers containing left and right operands respectively.
+  Register left = edx;
+  Register right = eax;
+
+  // Test if left operand is a string.
+  __ test(left, Immediate(kSmiTagMask));
+  __ j(zero, &call_runtime);
+  __ CmpObjectType(left, FIRST_NONSTRING_TYPE, ecx);
+  __ j(above_equal, &call_runtime);
+
+  // Test if right operand is a string.
+  __ test(right, Immediate(kSmiTagMask));
+  __ j(zero, &call_runtime);
+  __ CmpObjectType(right, FIRST_NONSTRING_TYPE, ecx);
+  __ j(above_equal, &call_runtime);
+
+  StringAddStub string_add_stub(NO_STRING_CHECK_IN_STUB);
+  GenerateRegisterArgsPush(masm);
+  __ TailCallStub(&string_add_stub);
+
+  __ bind(&call_runtime);
+  GenerateTypeTransition(masm);
+}
+
+
 void TypeRecordingBinaryOpStub::GenerateInt32Stub(MacroAssembler* masm) {
   Label call_runtime;
   ASSERT(operands_type_ == TRBinaryOpIC::INT32);

src/ia32/code-stubs-ia32.h

@@ -153,6 +153,7 @@ class TypeRecordingBinaryOpStub: public CodeStub {
   void GenerateHeapNumberStub(MacroAssembler* masm);
   void GenerateOddballStub(MacroAssembler* masm);
   void GenerateStringStub(MacroAssembler* masm);
+  void GenerateBothStringStub(MacroAssembler* masm);
   void GenerateGenericStub(MacroAssembler* masm);
   void GenerateAddStrings(MacroAssembler* masm);
 

src/ia32/lithium-codegen-ia32.cc

@@ -3308,6 +3308,22 @@ void LCodeGen::DoStringLength(LStringLength* instr) {
 }
 
 
+void LCodeGen::DoStringAdd(LStringAdd* instr) {
+  if (instr->left()->IsConstantOperand()) {
+    __ push(ToImmediate(instr->left()));
+  } else {
+    __ push(ToOperand(instr->left()));
+  }
+  if (instr->right()->IsConstantOperand()) {
+    __ push(ToImmediate(instr->right()));
+  } else {
+    __ push(ToOperand(instr->right()));
+  }
+  StringAddStub stub(NO_STRING_CHECK_IN_STUB);
+  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr, RESTORE_CONTEXT);
+}
+
+
 void LCodeGen::DoInteger32ToDouble(LInteger32ToDouble* instr) {
   LOperand* input = instr->InputAt(0);
   ASSERT(input->IsRegister() || input->IsStackSlot());

src/ia32/lithium-ia32.cc

@@ -2001,6 +2001,13 @@ LInstruction* LChunkBuilder::DoStoreNamedGeneric(HStoreNamedGeneric* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoStringAdd(HStringAdd* instr) {
+  LOperand* left = UseOrConstantAtStart(instr->left());
+  LOperand* right = UseOrConstantAtStart(instr->right());
+  return MarkAsCall(DefineFixed(new LStringAdd(left, right), eax), instr);
+}
+
+
 LInstruction* LChunkBuilder::DoStringCharCodeAt(HStringCharCodeAt* instr) {
   LOperand* string = UseRegister(instr->string());
   LOperand* index = UseRegisterOrConstant(instr->index());

src/ia32/lithium-ia32.h

@@ -39,6 +39,7 @@ namespace internal {
 // Forward declarations.
 class LCodeGen;
 
+
 #define LITHIUM_ALL_INSTRUCTION_LIST(V)         \
   V(ControlInstruction)                         \
   V(Call)                                       \
@@ -154,6 +155,7 @@ class LCodeGen;
   V(StoreKeyedSpecializedArrayElement)          \
   V(StoreNamedField)                            \
   V(StoreNamedGeneric)                          \
+  V(StringAdd)                                  \
   V(StringCharCodeAt)                           \
   V(StringCharFromCode)                         \
   V(StringLength)                               \
@@ -1769,6 +1771,21 @@ class LStoreKeyedGeneric: public LTemplateInstruction<0, 4, 0> {
 };
 
 
+class LStringAdd: public LTemplateInstruction<1, 2, 0> {
+ public:
+  LStringAdd(LOperand* left, LOperand* right) {
+    inputs_[0] = left;
+    inputs_[1] = right;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(StringAdd, "string-add")
+  DECLARE_HYDROGEN_ACCESSOR(StringAdd)
+
+  LOperand* left() { return inputs_[0]; }
+  LOperand* right() { return inputs_[1]; }
+};
+
+
 class LStringCharCodeAt: public LTemplateInstruction<1, 2, 0> {
  public:
   LStringCharCodeAt(LOperand* string, LOperand* index) {

src/ic.cc

@@ -1990,6 +1990,7 @@ const char* TRBinaryOpIC::GetName(TypeInfo type_info) {
     case INT32: return "Int32s";
     case HEAP_NUMBER: return "HeapNumbers";
     case ODDBALL: return "Oddball";
+    case BOTH_STRING: return "BothStrings";
     case STRING: return "Strings";
     case GENERIC: return "Generic";
     default: return "Invalid";
@@ -2005,6 +2006,7 @@ TRBinaryOpIC::State TRBinaryOpIC::ToState(TypeInfo type_info) {
     case INT32:
     case HEAP_NUMBER:
     case ODDBALL:
+    case BOTH_STRING:
     case STRING:
       return MONOMORPHIC;
     case GENERIC:
@@ -2019,12 +2021,17 @@ TRBinaryOpIC::TypeInfo TRBinaryOpIC::JoinTypes(TRBinaryOpIC::TypeInfo x,
                                                TRBinaryOpIC::TypeInfo y) {
   if (x == UNINITIALIZED) return y;
   if (y == UNINITIALIZED) return x;
-  if (x == STRING && y == STRING) return STRING;
-  if (x == STRING || y == STRING) return GENERIC;
-  if (x >= y) return x;
+  if (x == y) return x;
+  if (x == BOTH_STRING && y == STRING) return STRING;
+  if (x == STRING && y == BOTH_STRING) return STRING;
+  if (x == STRING || x == BOTH_STRING || y == STRING || y == BOTH_STRING) {
+    return GENERIC;
+  }
+  if (x > y) return x;
   return y;
 }
 
+
 TRBinaryOpIC::TypeInfo TRBinaryOpIC::GetTypeInfo(Handle<Object> left,
                                                  Handle<Object> right) {
   ::v8::internal::TypeInfo left_type =
@@ -2046,9 +2053,11 @@ TRBinaryOpIC::TypeInfo TRBinaryOpIC::GetTypeInfo(Handle<Object> left,
     return HEAP_NUMBER;
   }
 
-  if (left_type.IsString() || right_type.IsString()) {
-    // Patching for fast string ADD makes sense even if only one of the
-    // arguments is a string.
+  // Patching for fast string ADD makes sense even if only one of the
+  // arguments is a string.
+  if (left_type.IsString())  {
+    return right_type.IsString() ? BOTH_STRING : STRING;
+  } else if (right_type.IsString()) {
     return STRING;
   }
 
@@ -2081,11 +2090,11 @@ RUNTIME_FUNCTION(MaybeObject*, TypeRecordingBinaryOp_Patch) {
   TRBinaryOpIC::TypeInfo type = TRBinaryOpIC::GetTypeInfo(left, right);
   type = TRBinaryOpIC::JoinTypes(type, previous_type);
   TRBinaryOpIC::TypeInfo result_type = TRBinaryOpIC::UNINITIALIZED;
-  if (type == TRBinaryOpIC::STRING && op != Token::ADD) {
+  if ((type == TRBinaryOpIC::STRING || type == TRBinaryOpIC::BOTH_STRING) &&
+      op != Token::ADD) {
     type = TRBinaryOpIC::GENERIC;
   }
-  if (type == TRBinaryOpIC::SMI &&
-      previous_type == TRBinaryOpIC::SMI) {
+  if (type == TRBinaryOpIC::SMI && previous_type == TRBinaryOpIC::SMI) {
     if (op == Token::DIV || op == Token::MUL || kSmiValueSize == 32) {
       // Arithmetic on two Smi inputs has yielded a heap number.
       // That is the only way to get here from the Smi stub.
@@ -2097,8 +2106,7 @@ RUNTIME_FUNCTION(MaybeObject*, TypeRecordingBinaryOp_Patch) {
       result_type = TRBinaryOpIC::INT32;
     }
   }
-  if (type == TRBinaryOpIC::INT32 &&
-      previous_type == TRBinaryOpIC::INT32) {
+  if (type == TRBinaryOpIC::INT32 && previous_type == TRBinaryOpIC::INT32) {
     // We must be here because an operation on two INT32 types overflowed.
     result_type = TRBinaryOpIC::HEAP_NUMBER;
   }

src/ic.h

@@ -586,6 +586,7 @@ class TRBinaryOpIC: public IC {
     INT32,
     HEAP_NUMBER,
     ODDBALL,
+    BOTH_STRING,  // Only used for addition operation.
     STRING,  // Only used for addition operation.  At least one string operand.
     GENERIC
   };

src/type-info.cc

@@ -275,6 +275,8 @@ TypeInfo TypeFeedbackOracle::BinaryType(BinaryOperation* expr) {
         return TypeInfo::Integer32();
       case TRBinaryOpIC::HEAP_NUMBER:
         return TypeInfo::Double();
+      case TRBinaryOpIC::BOTH_STRING:
+        return TypeInfo::String();
       case TRBinaryOpIC::STRING:
       case TRBinaryOpIC::GENERIC:
         return unknown;

src/x64/code-stubs-x64.cc

@@ -372,6 +372,9 @@ void TypeRecordingBinaryOpStub::Generate(MacroAssembler* masm) {
     case TRBinaryOpIC::ODDBALL:
       GenerateOddballStub(masm);
       break;
+    case TRBinaryOpIC::BOTH_STRING:
+      GenerateBothStringStub(masm);
+      break;
     case TRBinaryOpIC::STRING:
       GenerateStringStub(masm);
       break;
@@ -771,6 +774,36 @@ void TypeRecordingBinaryOpStub::GenerateStringStub(MacroAssembler* masm) {
 }
 
 
+void TypeRecordingBinaryOpStub::GenerateBothStringStub(MacroAssembler* masm) {
+  Label call_runtime;
+  ASSERT(operands_type_ == TRBinaryOpIC::BOTH_STRING);
+  ASSERT(op_ == Token::ADD);
+  // If both arguments are strings, call the string add stub.
+  // Otherwise, do a transition.
+
+  // Registers containing left and right operands respectively.
+  Register left = rdx;
+  Register right = rax;
+
+  // Test if left operand is a string.
+  __ JumpIfSmi(left, &call_runtime);
+  __ CmpObjectType(left, FIRST_NONSTRING_TYPE, rcx);
+  __ j(above_equal, &call_runtime);
+
+  // Test if right operand is a string.
+  __ JumpIfSmi(right, &call_runtime);
+  __ CmpObjectType(right, FIRST_NONSTRING_TYPE, rcx);
+  __ j(above_equal, &call_runtime);
+
+  StringAddStub string_add_stub(NO_STRING_CHECK_IN_STUB);
+  GenerateRegisterArgsPush(masm);
+  __ TailCallStub(&string_add_stub);
+
+  __ bind(&call_runtime);
+  GenerateTypeTransition(masm);
+}
+
+
 void TypeRecordingBinaryOpStub::GenerateOddballStub(MacroAssembler* masm) {
   Label call_runtime;
 

src/x64/code-stubs-x64.h

@@ -152,6 +152,7 @@ class TypeRecordingBinaryOpStub: public CodeStub {
   void GenerateHeapNumberStub(MacroAssembler* masm);
   void GenerateOddballStub(MacroAssembler* masm);
   void GenerateStringStub(MacroAssembler* masm);
+  void GenerateBothStringStub(MacroAssembler* masm);
   void GenerateGenericStub(MacroAssembler* masm);
 
   void GenerateHeapResultAllocation(MacroAssembler* masm, Label* alloc_failure);

src/x64/lithium-codegen-x64.cc

@@ -2512,14 +2512,7 @@ void LCodeGen::DoApplyArguments(LApplyArguments* instr) {
 
 void LCodeGen::DoPushArgument(LPushArgument* instr) {
   LOperand* argument = instr->InputAt(0);
-  if (argument->IsConstantOperand()) {
-    EmitPushConstantOperand(argument);
-  } else if (argument->IsRegister()) {
-    __ push(ToRegister(argument));
-  } else {
-    ASSERT(!argument->IsDoubleRegister());
-    __ push(ToOperand(argument));
-  }
+  EmitPushTaggedOperand(argument);
 }
 
 
@@ -3113,6 +3106,14 @@ void LCodeGen::DoStoreKeyedGeneric(LStoreKeyedGeneric* instr) {
 }
 
 
+void LCodeGen::DoStringAdd(LStringAdd* instr) {
+  EmitPushTaggedOperand(instr->left());
+  EmitPushTaggedOperand(instr->right());
+  StringAddStub stub(NO_STRING_CHECK_IN_STUB);
+  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+}
+
+
 void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
   class DeferredStringCharCodeAt: public LDeferredCode {
    public:
@@ -3772,14 +3773,7 @@ void LCodeGen::DoFunctionLiteral(LFunctionLiteral* instr) {
 
 void LCodeGen::DoTypeof(LTypeof* instr) {
   LOperand* input = instr->InputAt(0);
-  if (input->IsConstantOperand()) {
-    __ Push(ToHandle(LConstantOperand::cast(input)));
-  } else if (input->IsRegister()) {
-    __ push(ToRegister(input));
-  } else {
-    ASSERT(input->IsStackSlot());
-    __ push(ToOperand(input));
-  }
+  EmitPushTaggedOperand(input);
   CallRuntime(Runtime::kTypeof, 1, instr);
 }
 
@@ -3807,19 +3801,14 @@ void LCodeGen::DoTypeofIs(LTypeofIs* instr) {
 }
 
 
-void LCodeGen::EmitPushConstantOperand(LOperand* operand) {
-  ASSERT(operand->IsConstantOperand());
-  LConstantOperand* const_op = LConstantOperand::cast(operand);
-  Handle<Object> literal = chunk_->LookupLiteral(const_op);
-  Representation r = chunk_->LookupLiteralRepresentation(const_op);
-  if (r.IsInteger32()) {
-    ASSERT(literal->IsNumber());
-    __ push(Immediate(static_cast<int32_t>(literal->Number())));
-  } else if (r.IsDouble()) {
-    Abort("unsupported double immediate");
+void LCodeGen::EmitPushTaggedOperand(LOperand* operand) {
+  ASSERT(!operand->IsDoubleRegister());
+  if (operand->IsConstantOperand()) {
+    __ Push(ToHandle(LConstantOperand::cast(operand)));
+  } else if (operand->IsRegister()) {
+    __ push(ToRegister(operand));
   } else {
-    ASSERT(r.IsTagged());
-    __ Push(literal);
+    __ push(ToOperand(operand));
   }
 }
 
@@ -3965,20 +3954,8 @@ void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
 void LCodeGen::DoDeleteProperty(LDeleteProperty* instr) {
   LOperand* obj = instr->object();
   LOperand* key = instr->key();
-  // Push object.
-  if (obj->IsRegister()) {
-    __ push(ToRegister(obj));
-  } else {
-    __ push(ToOperand(obj));
-  }
-  // Push key.
-  if (key->IsConstantOperand()) {
-    EmitPushConstantOperand(key);
-  } else if (key->IsRegister()) {
-    __ push(ToRegister(key));
-  } else {
-    __ push(ToOperand(key));
-  }
+  EmitPushTaggedOperand(obj);
+  EmitPushTaggedOperand(key);
   ASSERT(instr->HasPointerMap() && instr->HasDeoptimizationEnvironment());
   LPointerMap* pointers = instr->pointer_map();
   LEnvironment* env = instr->deoptimization_environment();

src/x64/lithium-codegen-x64.h

@@ -268,8 +268,9 @@ class LCodeGen BASE_EMBEDDED {
                      Handle<Map> type,
                      Handle<String> name);
 
-  // Emits code for pushing a constant operand.
-  void EmitPushConstantOperand(LOperand* operand);
+  // Emits code for pushing either a tagged constant, a (non-double)
+  // register, or a stack slot operand.
+  void EmitPushTaggedOperand(LOperand* operand);
 
   struct JumpTableEntry {
     explicit inline JumpTableEntry(Address entry)

src/x64/lithium-x64.cc

@@ -1940,6 +1940,13 @@ LInstruction* LChunkBuilder::DoStoreNamedGeneric(HStoreNamedGeneric* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoStringAdd(HStringAdd* instr) {
+  LOperand* left = UseOrConstantAtStart(instr->left());
+  LOperand* right = UseOrConstantAtStart(instr->right());
+  return MarkAsCall(DefineFixed(new LStringAdd(left, right), rax), instr);
+}
+
+
 LInstruction* LChunkBuilder::DoStringCharCodeAt(HStringCharCodeAt* instr) {
   LOperand* string = UseRegister(instr->string());
   LOperand* index = UseRegisterOrConstant(instr->index());

src/x64/lithium-x64.h

@@ -152,6 +152,7 @@ class LCodeGen;
   V(StoreKeyedSpecializedArrayElement)          \
   V(StoreNamedField)                            \
   V(StoreNamedGeneric)                          \
+  V(StringAdd)                                  \
   V(StringCharCodeAt)                           \
   V(StringCharFromCode)                         \
   V(StringLength)                               \
@@ -1684,6 +1685,21 @@ class LStoreKeyedGeneric: public LTemplateInstruction<0, 3, 0> {
 };
 
 
+class LStringAdd: public LTemplateInstruction<1, 2, 0> {
+ public:
+  LStringAdd(LOperand* left, LOperand* right) {
+    inputs_[0] = left;
+    inputs_[1] = right;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(StringAdd, "string-add")
+  DECLARE_HYDROGEN_ACCESSOR(StringAdd)
+
+  LOperand* left() { return inputs_[0]; }
+  LOperand* right() { return inputs_[1]; }
+};
+
+
 class LStringCharCodeAt: public LTemplateInstruction<1, 2, 0> {
  public:
   LStringCharCodeAt(LOperand* string, LOperand* index) {