Make sure fixed typed array is always double aligned for doubles

Allows for getting rid of the special casing for float64 and is probably
faster.

BUG=v8:3996
R=verwaest@chromium.org,dslomov@chromium.org,plind44@gmail.com
LOG=n

Review URL: https://codereview.chromium.org/1128433006

Cr-Commit-Position: refs/heads/master@{#28281}

src/globals.h

@@ -640,6 +640,10 @@ struct AccessorDescriptor {
 #define CODE_POINTER_ALIGN(value)                               \
   (((value) + kCodeAlignmentMask) & ~kCodeAlignmentMask)
 
+// DOUBLE_POINTER_ALIGN returns the value algined for double pointers.
+#define DOUBLE_POINTER_ALIGN(value) \
+  (((value) + kDoubleAlignmentMask) & ~kDoubleAlignmentMask)
+
 // Support for tracking C++ memory allocation.  Insert TRACK_MEMORY("Fisk")
 // inside a C++ class and new and delete will be overloaded so logging is
 // performed.

src/heap/heap.cc

@@ -2714,8 +2714,8 @@ bool Heap::CreateInitialMaps() {
     ALLOCATE_VARSIZE_MAP(BYTE_ARRAY_TYPE, byte_array)
     ALLOCATE_VARSIZE_MAP(FREE_SPACE_TYPE, free_space)
 
-#define ALLOCATE_EXTERNAL_ARRAY_MAP(Type, type, TYPE, ctype, size)        \
-  ALLOCATE_MAP(EXTERNAL_##TYPE##_ARRAY_TYPE, ExternalArray::kAlignedSize, \
+#define ALLOCATE_EXTERNAL_ARRAY_MAP(Type, type, TYPE, ctype, size) \
+  ALLOCATE_MAP(EXTERNAL_##TYPE##_ARRAY_TYPE, ExternalArray::kSize, \
                external_##type##_array)
 
     TYPED_ARRAYS(ALLOCATE_EXTERNAL_ARRAY_MAP)
@@ -3619,7 +3619,7 @@ AllocationResult Heap::AllocateExternalArray(int length,
                                              ExternalArrayType array_type,
                                              void* external_pointer,
                                              PretenureFlag pretenure) {
-  int size = ExternalArray::kAlignedSize;
+  int size = ExternalArray::kSize;
   AllocationSpace space = SelectSpace(size, pretenure);
   HeapObject* result;
   {

src/hydrogen.cc

@@ -9835,11 +9835,8 @@ HValue* HOptimizedGraphBuilder::BuildAllocateExternalElements(
   // conversion after allocation but before the new object fields are set.
   length = AddUncasted<HForceRepresentation>(length, Representation::Smi());
   HValue* elements =
-      Add<HAllocate>(
-          Add<HConstant>(ExternalArray::kAlignedSize),
-          HType::HeapObject(),
-          NOT_TENURED,
-          external_array_map->instance_type());
+      Add<HAllocate>(Add<HConstant>(ExternalArray::kSize), HType::HeapObject(),
+                     NOT_TENURED, external_array_map->instance_type());
 
   AddStoreMapConstant(elements, external_array_map);
   Add<HStoreNamedField>(elements,
@@ -9892,9 +9889,16 @@ HValue* HOptimizedGraphBuilder::BuildAllocateFixedTypedArray(
   length = AddUncasted<HForceRepresentation>(length, Representation::Smi());
   Handle<Map> fixed_typed_array_map(
       isolate()->heap()->MapForFixedTypedArray(array_type));
-  HValue* elements =
-      Add<HAllocate>(total_size, HType::HeapObject(),
-                     NOT_TENURED, fixed_typed_array_map->instance_type());
+  HAllocate* elements =
+      Add<HAllocate>(total_size, HType::HeapObject(), NOT_TENURED,
+                     fixed_typed_array_map->instance_type());
+
+#ifndef V8_HOST_ARCH_64_BIT
+  if (array_type == kExternalFloat64Array) {
+    elements->MakeDoubleAligned();
+  }
+#endif
+
   AddStoreMapConstant(elements, fixed_typed_array_map);
 
   Add<HStoreNamedField>(elements,

src/objects-inl.h

@@ -4312,14 +4312,6 @@ typename Traits::ElementType FixedTypedArray<Traits>::get_scalar(int index) {
 }
 
 
-template<> inline
-FixedTypedArray<Float64ArrayTraits>::ElementType
-    FixedTypedArray<Float64ArrayTraits>::get_scalar(int index) {
-  DCHECK((index >= 0) && (index < this->length()));
-  return READ_DOUBLE_FIELD(this, ElementOffset(index));
-}
-
-
 template <class Traits>
 void FixedTypedArray<Traits>::set(int index, ElementType value) {
   DCHECK((index >= 0) && (index < this->length()));
@@ -4329,14 +4321,6 @@ void FixedTypedArray<Traits>::set(int index, ElementType value) {
 }
 
 
-template<> inline
-void FixedTypedArray<Float64ArrayTraits>::set(
-    int index, Float64ArrayTraits::ElementType value) {
-  DCHECK((index >= 0) && (index < this->length()));
-  WRITE_DOUBLE_FIELD(this, ElementOffset(index), value);
-}
-
-
 template <class Traits>
 typename Traits::ElementType FixedTypedArray<Traits>::from_int(int value) {
   return static_cast<ElementType>(value);

src/objects.h

@@ -4645,8 +4645,7 @@ class ExternalArray: public FixedArrayBase {
   // ExternalArray headers are not quadword aligned.
   static const int kExternalPointerOffset =
       POINTER_SIZE_ALIGN(FixedArrayBase::kLengthOffset + kPointerSize);
-  static const int kHeaderSize = kExternalPointerOffset + kPointerSize;
-  static const int kAlignedSize = OBJECT_POINTER_ALIGN(kHeaderSize);
+  static const int kSize = kExternalPointerOffset + kPointerSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalArray);
@@ -4888,7 +4887,7 @@ class FixedTypedArrayBase: public FixedArrayBase {
  public:
   DECLARE_CAST(FixedTypedArrayBase)
 
-  static const int kDataOffset = kHeaderSize;
+  static const int kDataOffset = DOUBLE_POINTER_ALIGN(kHeaderSize);
 
   inline int size();
 
@@ -4917,14 +4916,6 @@ class FixedTypedArray: public FixedTypedArrayBase {
 
   DECLARE_CAST(FixedTypedArray<Traits>)
 
-  static inline int ElementOffset(int index) {
-    return kDataOffset + index * sizeof(ElementType);
-  }
-
-  static inline int SizeFor(int length) {
-    return ElementOffset(length);
-  }
-
   inline ElementType get_scalar(int index);
   static inline Handle<Object> get(Handle<FixedTypedArray> array, int index);
   inline void set(int index, ElementType value);