Clean up aligned allocation code in preparation for SIMD alignments.

src/heap/heap.h

 // Copyright 2012 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.
 
 #ifndef V8_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 698 matching lines @@
   bool CanExpandOldGeneration(int size) {
     return (CommittedOldGenerationMemory() + size) < MaxOldGenerationSize();
   }
 
   // Returns a deep copy of the JavaScript object.
   // Properties and elements are copied too.
   // Optionally takes an AllocationSite to be appended in an AllocationMemento.
   MUST_USE_RESULT AllocationResult
       CopyJSObject(JSObject* source, AllocationSite* site = NULL);
 
-  // This method assumes overallocation of one word. It will store a filler
-  // before the object if the given object is not double aligned, otherwise
-  // it will place the filler after the object.
-  MUST_USE_RESULT HeapObject* EnsureAligned(HeapObject* object, int size,
-                                            AllocationAlignment alignment);
+  // Calculates the maximum amount of filler that could be required by the
+  // given alignment.
+  static int GetMaximumFillToAlign(AllocationAlignment alignment);
+  // Calculates the actual amount of filler required for a given address at the
+  // given alignment.
+  static int GetFillToAlign(Address address, AllocationAlignment alignment);
 
-  MUST_USE_RESULT HeapObject* PrecedeWithFiller(HeapObject* object);
+  // Creates a filler object and returns a heap object immediately after it.
+  MUST_USE_RESULT HeapObject* PrecedeWithFiller(HeapObject* object,
+                                                int filler_size);
+  // Creates a filler object if needed for alignment and returns a heap object
+  // immediately after it. If any space is left after the returned object,
+  // another filler object is created so the over allocated memory is iterable.
+  MUST_USE_RESULT HeapObject* AlignWithFiller(HeapObject* object,
+                                              int object_size,
+                                              int allocation_size,
+                                              AllocationAlignment alignment);
 
   // Clear the Instanceof cache (used when a prototype changes).
   inline void ClearInstanceofCache();
 
   // Iterates the whole code space to clear all ICs of the given kind.
   void ClearAllICsByKind(Code::Kind kind);
 
   // FreeSpace objects have a null map after deserialization. Update the map.
   void RepairFreeListsAfterDeserialization();
 
@@ skipping 1987 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_