Clean up aligned allocation code in preparation for SIMD alignments.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index b5850271170967281dceddf308021fc936ec7598..b45033a629907085d1c8720dcb5369939a76b29d 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -1972,31 +1972,32 @@ STATIC_ASSERT((HeapNumber::kValueOffset & kDoubleAlignmentMask) !=
 #endif
 
 
-HeapObject* Heap::EnsureAligned(HeapObject* object, int size,
-                                AllocationAlignment alignment) {
-  if (alignment == kDoubleAligned &&
-      (OffsetFrom(object->address()) & kDoubleAlignmentMask) != 0) {
-    CreateFillerObjectAt(object->address(), kPointerSize);
-    return HeapObject::FromAddress(object->address() + kPointerSize);
-  } else if (alignment == kDoubleUnaligned &&
-             (OffsetFrom(object->address()) & kDoubleAlignmentMask) == 0) {
-    CreateFillerObjectAt(object->address(), kPointerSize);
-    return HeapObject::FromAddress(object->address() + kPointerSize);
-  } else {
-    CreateFillerObjectAt(object->address() + size - kPointerSize, kPointerSize);
-    return object;
-  }
+int Heap::GetAlignmentSize(Address address, AllocationAlignment alignment) {
+  intptr_t offset = OffsetFrom(address);
+  if (alignment == kDoubleAligned && (offset & kDoubleAlignmentMask) != 0)
+    return kPointerSize;
+  if (alignment == kDoubleValueAligned && (offset & kDoubleAlignmentMask) == 0)
+    return kPointerSize;
+  return 0;
 }
 
 
-HeapObject* Heap::PrecedeWithFiller(HeapObject* object) {
-  CreateFillerObjectAt(object->address(), kPointerSize);
-  return HeapObject::FromAddress(object->address() + kPointerSize);
+HeapObject* Heap::PrecedeWithFiller(HeapObject* object, int fill_size) {
+  CreateFillerObjectAt(object->address(), fill_size);
+  return HeapObject::FromAddress(object->address() + fill_size);
 }
 
 
 HeapObject* Heap::DoubleAlignForDeserialization(HeapObject* object, int size) {
-  return EnsureAligned(object, size, kDoubleAligned);
+  Address address = object->address();
+  int fill_size = GetAlignmentSize(address, kDoubleAligned);
+  // If object is not aligned, add fill to align it.
+  if (fill_size) return PrecedeWithFiller(object, kPointerSize);
+
+  // object is aligned. Add fill in the extra space at the end.
+  // TODO(bbudge) Calculate alignment fill earlier to avoid this.
+  CreateFillerObjectAt(address + size - kPointerSize, kPointerSize);
+  return object;
 }
 
 
@@ -2847,7 +2848,7 @@ AllocationResult Heap::AllocateHeapNumber(double value, MutableMode mode,
   HeapObject* result;
   {
     AllocationResult allocation =
-        AllocateRaw(size, space, OLD_SPACE, kDoubleUnaligned);
+        AllocateRaw(size, space, OLD_SPACE, kDoubleValueAligned);
     if (!allocation.To(&result)) return allocation;
   }