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 3b291d2916cd8228d645f619f779adff0b5e9419..b7cc3299cfea764fb94748c7c8a5876ba71e9310 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -1986,31 +1986,54 @@ 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::GetMaximumFillToAlign(AllocationAlignment alignment) {
+  switch (alignment) {
+    case kWordAligned:
+      return 0;
+    case kDoubleAligned:
+    case kDoubleUnaligned:
+      return kDoubleSize - kPointerSize;
+    default:
+      UNREACHABLE();
   }
+  return 0;
+}
+
+
+int Heap::GetFillToAlign(Address address, AllocationAlignment alignment) {
+  intptr_t offset = OffsetFrom(address);
+  if (alignment == kDoubleAligned && (offset & kDoubleAlignmentMask) != 0)
+    return kPointerSize;
+  if (alignment == kDoubleUnaligned && (offset & kDoubleAlignmentMask) == 0)
+    return kDoubleSize - kPointerSize;  // No fill if double is always aligned.
+  return 0;
 }
 
 
-HeapObject* Heap::PrecedeWithFiller(HeapObject* object) {
-  CreateFillerObjectAt(object->address(), kPointerSize);
-  return HeapObject::FromAddress(object->address() + kPointerSize);
+HeapObject* Heap::PrecedeWithFiller(HeapObject* object, int filler_size) {
+  CreateFillerObjectAt(object->address(), filler_size);
+  return HeapObject::FromAddress(object->address() + filler_size);
+}
+
+
+HeapObject* Heap::AlignWithFiller(HeapObject* object, int object_size,
+                                  int allocation_size,
+                                  AllocationAlignment alignment) {
+  int filler_size = allocation_size - object_size;
+  DCHECK(filler_size > 0);
+  int pre_filler = GetFillToAlign(object->address(), alignment);
+  if (pre_filler) {
+    object = PrecedeWithFiller(object, pre_filler);
+    filler_size -= pre_filler;
+  }
+  if (filler_size)
+    CreateFillerObjectAt(object->address() + object_size, filler_size);
+  return object;
 }
 
 
 HeapObject* Heap::DoubleAlignForDeserialization(HeapObject* object, int size) {
-  return EnsureAligned(object, size, kDoubleAligned);
+  return AlignWithFiller(object, size - kPointerSize, size, kDoubleAligned);
 }