Make sure fixed typed array is always double aligned for doubles

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/hydrogen.h"
 
 #include <sstream>
 
 #include "src/v8.h"
 
@@ skipping 9871 matching lines @@
     ExternalArrayType array_type,
     bool is_zero_byte_offset,
     HValue* buffer, HValue* byte_offset, HValue* length) {
   Handle<Map> external_array_map(
       isolate()->heap()->MapForExternalArrayType(array_type));
 
   // The HForceRepresentation is to prevent possible deopt on int-smi
   // 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,
       HObjectAccess::ForFixedArrayLength(), length);
 
   HValue* backing_store = Add<HLoadNamedField>(
       buffer, nullptr, HObjectAccess::ForJSArrayBufferBackingStore());
 
   HValue* typed_array_start;
   if (is_zero_byte_offset) {
@@ skipping 32 matching lines @@
     total_size = AddUncasted<HAdd>(byte_length,
         Add<HConstant>(FixedTypedArrayBase::kHeaderSize));
     total_size->ClearFlag(HValue::kCanOverflow);
   }
 
   // The HForceRepresentation is to prevent possible deopt on int-smi
   // conversion after allocation but before the new object fields are set.
   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,
       HObjectAccess::ForFixedArrayLength(),
       length);
 
   HValue* filler = Add<HConstant>(static_cast<int32_t>(0));
 
   {
     LoopBuilder builder(this, context(), LoopBuilder::kPostIncrement);
@@ skipping 3212 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal