HStoreKeyed for Smis optimized for x64 + related redundant moves of elements removed

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/108503004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18362 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.h

@@ -6684,6 +6684,8 @@ class HStoreKeyed V8_FINAL
  public:
   DECLARE_INSTRUCTION_FACTORY_P4(HStoreKeyed, HValue*, HValue*, HValue*,
                                  ElementsKind);
+  DECLARE_INSTRUCTION_FACTORY_P5(HStoreKeyed, HValue*, HValue*, HValue*,
+                                 ElementsKind, StoreFieldOrKeyedMode);
 
   virtual Representation RequiredInputRepresentation(int index) V8_OVERRIDE {
     // kind_fast:       tagged[int32] = tagged
@@ -6702,7 +6704,9 @@ class HStoreKeyed V8_FINAL
     if (IsDoubleOrFloatElementsKind(elements_kind())) {
       return Representation::Double();
     }
-
+    if (SmiValuesAre32Bits() && store_mode_ == STORE_TO_INITIALIZED_ENTRY) {
+      return Representation::Integer32();
+    }
     if (IsFastSmiElementsKind(elements_kind())) {
       return Representation::Smi();
     }
@@ -6720,12 +6724,15 @@ class HStoreKeyed V8_FINAL
     if (IsUninitialized()) {
       return Representation::None();
     }
-    if (IsFastSmiElementsKind(elements_kind())) {
-      return Representation::Smi();
-    }
     if (IsDoubleOrFloatElementsKind(elements_kind())) {
       return Representation::Double();
     }
+    if (SmiValuesAre32Bits() && store_mode_ == STORE_TO_INITIALIZED_ENTRY) {
+      return Representation::Integer32();
+    }
+    if (IsFastSmiElementsKind(elements_kind())) {
+      return Representation::Smi();
+    }
     if (is_external()) {
       return Representation::Integer32();
     }
@@ -6739,6 +6746,7 @@ class HStoreKeyed V8_FINAL
   bool value_is_smi() const {
     return IsFastSmiElementsKind(elements_kind_);
   }
+  StoreFieldOrKeyedMode store_mode() const { return store_mode_; }
   ElementsKind elements_kind() const { return elements_kind_; }
   uint32_t index_offset() { return index_offset_; }
   void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
@@ -6784,16 +6792,21 @@ class HStoreKeyed V8_FINAL
 
  private:
   HStoreKeyed(HValue* obj, HValue* key, HValue* val,
-              ElementsKind elements_kind)
+              ElementsKind elements_kind,
+              StoreFieldOrKeyedMode store_mode = INITIALIZING_STORE)
       : elements_kind_(elements_kind),
       index_offset_(0),
       is_dehoisted_(false),
       is_uninitialized_(false),
+      store_mode_(store_mode),
       new_space_dominator_(NULL) {
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
     SetOperandAt(2, val);
 
+    ASSERT(store_mode != STORE_TO_INITIALIZED_ENTRY ||
+           elements_kind == FAST_SMI_ELEMENTS);
+
     if (IsFastObjectElementsKind(elements_kind)) {
       SetFlag(kTrackSideEffectDominators);
       SetGVNFlag(kDependsOnNewSpacePromotion);
@@ -6820,6 +6833,7 @@ class HStoreKeyed V8_FINAL
   uint32_t index_offset_;
   bool is_dehoisted_ : 1;
   bool is_uninitialized_ : 1;
+  StoreFieldOrKeyedMode store_mode_: 1;
   HValue* new_space_dominator_;
 };
 

src/hydrogen.cc

@@ -1296,7 +1296,8 @@ HValue* HGraphBuilder::BuildCheckForCapacityGrow(HValue* object,
                                                  ElementsKind kind,
                                                  HValue* length,
                                                  HValue* key,
-                                                 bool is_js_array) {
+                                                 bool is_js_array,
+                                                 bool is_store) {
   IfBuilder length_checker(this);
 
   Token::Value token = IsHoleyElementsKind(kind) ? Token::GTE : Token::EQ;
@@ -1339,6 +1340,13 @@ HValue* HGraphBuilder::BuildCheckForCapacityGrow(HValue* object,
                           new_length);
   }
 
+  if (is_store && kind == FAST_SMI_ELEMENTS) {
+    HValue* checked_elements = environment()->Top();
+
+    // Write zero to ensure that the new element is initialized with some smi.
+    Add<HStoreKeyed>(checked_elements, key, graph()->GetConstant0(), kind);
+  }
+
   length_checker.Else();
   Add<HBoundsCheck>(key, length);
 
@@ -2102,7 +2110,7 @@ HInstruction* HGraphBuilder::BuildUncheckedMonomorphicElementAccess(
     NoObservableSideEffectsScope no_effects(this);
     elements = BuildCheckForCapacityGrow(checked_object, elements,
                                          elements_kind, length, key,
-                                         is_js_array);
+                                         is_js_array, is_store);
     checked_key = key;
   } else {
     checked_key = Add<HBoundsCheck>(key, length);
@@ -2266,7 +2274,10 @@ HInstruction* HGraphBuilder::AddElementAccess(
     if (elements_kind == EXTERNAL_PIXEL_ELEMENTS) {
       val = Add<HClampToUint8>(val);
     }
-    return Add<HStoreKeyed>(elements, checked_key, val, elements_kind);
+    return Add<HStoreKeyed>(elements, checked_key, val, elements_kind,
+                            elements_kind == FAST_SMI_ELEMENTS
+                              ? STORE_TO_INITIALIZED_ENTRY
+                              : INITIALIZING_STORE);
   }
 
   ASSERT(!is_store);

src/hydrogen.h

@@ -1272,7 +1272,8 @@ class HGraphBuilder {
                                     ElementsKind kind,
                                     HValue* length,
                                     HValue* key,
-                                    bool is_js_array);
+                                    bool is_js_array,
+                                    bool is_store);
 
   HValue* BuildCopyElementsOnWrite(HValue* object,
                                    HValue* elements,

src/x64/lithium-codegen-x64.cc

@@ -4241,7 +4241,7 @@ void LCodeGen::DoStoreKeyedFixedDoubleArray(LStoreKeyed* instr) {
 
 
 void LCodeGen::DoStoreKeyedFixedArray(LStoreKeyed* instr) {
-  Register elements = ToRegister(instr->elements());
+  HStoreKeyed* hinstr = instr->hydrogen();
   LOperand* key = instr->key();
   if (!key->IsConstantOperand()) {
     Register key_reg = ToRegister(key);
@@ -4250,38 +4250,56 @@ void LCodeGen::DoStoreKeyedFixedArray(LStoreKeyed* instr) {
     // input gets replaced during bound check elimination with the index
     // argument to the bounds check, which can be tagged, so that case
     // must be handled here, too.
-    if (instr->hydrogen()->IsDehoisted()) {
+    if (hinstr->IsDehoisted()) {
       // Sign extend key because it could be a 32 bit negative value
       // and the dehoisted address computation happens in 64 bits
       __ movsxlq(key_reg, key_reg);
     }
   }
 
+  int offset = FixedArray::kHeaderSize - kHeapObjectTag;
+  Representation representation = hinstr->value()->representation();
+
+  if (representation.IsInteger32()) {
+    ASSERT(hinstr->store_mode() == STORE_TO_INITIALIZED_ENTRY);
+    ASSERT(hinstr->elements_kind() == FAST_SMI_ELEMENTS);
+    // Store int value directly to upper half of the smi.
+    STATIC_ASSERT(kSmiTag == 0);
+    STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 32);
+    offset += kPointerSize / 2;
+  }
+
   Operand operand =
       BuildFastArrayOperand(instr->elements(),
                             key,
                             FAST_ELEMENTS,
-                            FixedArray::kHeaderSize - kHeapObjectTag,
+                            offset,
                             instr->additional_index());
+
   if (instr->value()->IsRegister()) {
-    __ movq(operand, ToRegister(instr->value()));
+    __ Store(operand, ToRegister(instr->value()), representation);
   } else {
     LConstantOperand* operand_value = LConstantOperand::cast(instr->value());
     if (IsInteger32Constant(operand_value)) {
-      Smi* smi_value = Smi::FromInt(ToInteger32(operand_value));
-      __ Move(operand, smi_value);
+      int32_t value = ToInteger32(operand_value);
+      if (representation.IsSmi()) {
+        __ Move(operand, Smi::FromInt(value));
+
+      } else {
+        __ movl(operand, Immediate(value));
+      }
     } else {
       Handle<Object> handle_value = ToHandle(operand_value);
       __ Move(operand, handle_value);
     }
   }
 
-  if (instr->hydrogen()->NeedsWriteBarrier()) {
+  if (hinstr->NeedsWriteBarrier()) {
+    Register elements = ToRegister(instr->elements());
     ASSERT(instr->value()->IsRegister());
     Register value = ToRegister(instr->value());
-    ASSERT(!instr->key()->IsConstantOperand());
-    SmiCheck check_needed =
-        instr->hydrogen()->value()->IsHeapObject()
+    ASSERT(!key->IsConstantOperand());
+    SmiCheck check_needed = hinstr->value()->IsHeapObject()
             ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     // Compute address of modified element and store it into key register.
     Register key_reg(ToRegister(key));

src/x64/lithium-x64.cc

@@ -508,6 +508,13 @@ LOperand* LChunkBuilder::UseTempRegister(HValue* value) {
 }
 
 
+LOperand* LChunkBuilder::UseTempRegisterOrConstant(HValue* value) {
+  return value->IsConstant()
+      ? chunk_->DefineConstantOperand(HConstant::cast(value))
+      : UseTempRegister(value);
+}
+
+
 LOperand* LChunkBuilder::Use(HValue* value) {
   return Use(value, new(zone()) LUnallocated(LUnallocated::NONE));
 }
@@ -2177,17 +2184,20 @@ LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
     LOperand* key = NULL;
     LOperand* val = NULL;
 
-    if (instr->value()->representation().IsDouble()) {
+    Representation value_representation = instr->value()->representation();
+    if (value_representation.IsDouble()) {
       object = UseRegisterAtStart(instr->elements());
       val = UseTempRegister(instr->value());
       key = UseRegisterOrConstantAtStart(instr->key());
     } else {
-      ASSERT(instr->value()->representation().IsSmiOrTagged());
-      object = UseTempRegister(instr->elements());
+      ASSERT(value_representation.IsSmiOrTagged() ||
+             value_representation.IsInteger32());
       if (needs_write_barrier) {
+        object = UseTempRegister(instr->elements());
         val = UseTempRegister(instr->value());
         key = UseTempRegister(instr->key());
       } else {
+        object = UseRegisterAtStart(instr->elements());
         val = UseRegisterOrConstantAtStart(instr->value());
         key = UseRegisterOrConstantAtStart(instr->key());
       }

src/x64/lithium-x64.h

@@ -2710,6 +2710,9 @@ class LChunkBuilder V8_FINAL BASE_EMBEDDED {
   // An input operand in a register that may be trashed.
   MUST_USE_RESULT LOperand* UseTempRegister(HValue* value);
 
+  // An input operand in a register that may be trashed or a constant operand.
+  MUST_USE_RESULT LOperand* UseTempRegisterOrConstant(HValue* value);
+
   // An input operand in a register or stack slot.
   MUST_USE_RESULT LOperand* Use(HValue* value);
   MUST_USE_RESULT LOperand* UseAtStart(HValue* value);