Implement unaligned allocate and allocate heap numbers in runtime double unaligned.

src/heap/spaces-inl.h

Index: src/heap/spaces-inl.h
diff --git a/src/heap/spaces-inl.h b/src/heap/spaces-inl.h
index 78fda3c1e1562b99b99a9aa267b5b3ae79614868..ba1f15e96e40e612505fff92521fbae4de402c97 100644
--- a/src/heap/spaces-inl.h
+++ b/src/heap/spaces-inl.h
@@ -250,11 +250,17 @@ HeapObject* PagedSpace::AllocateLinearly(int size_in_bytes) {
 }
 
 
-HeapObject* PagedSpace::AllocateLinearlyDoubleAlign(int size_in_bytes) {
+HeapObject* PagedSpace::AllocateLinearlyAligned(int size_in_bytes,
+                                                AllocationAlignment alignment) {
   Address current_top = allocation_info_.top();
   int alignment_size = 0;
 
-  if ((OffsetFrom(current_top) & kDoubleAlignmentMask) != 0) {
+  if (alignment == kDoubleAligned &&
+      (OffsetFrom(current_top) & kDoubleAlignmentMask) != 0) {
+    alignment_size = kPointerSize;
+    size_in_bytes += alignment_size;
+  } else if (alignment == kDoubleUnaligned &&
+             (OffsetFrom(current_top) & kDoubleAlignmentMask) == 0) {
     alignment_size = kPointerSize;
     size_in_bytes += alignment_size;
   }
@@ -262,9 +268,10 @@ HeapObject* PagedSpace::AllocateLinearlyDoubleAlign(int size_in_bytes) {
   if (new_top > allocation_info_.limit()) return NULL;
 
   allocation_info_.set_top(new_top);
-  if (alignment_size > 0)
-    return heap()->EnsureDoubleAligned(HeapObject::FromAddress(current_top),
-                                       size_in_bytes);
+  if (alignment_size > 0) {
+    return heap()->EnsureAligned(HeapObject::FromAddress(current_top),
+                                 size_in_bytes, alignment);
+  }
   return HeapObject::FromAddress(current_top);
 }
 
@@ -293,9 +300,10 @@ AllocationResult PagedSpace::AllocateRaw(int size_in_bytes) {
 
 
 // Raw allocation.
-AllocationResult PagedSpace::AllocateRawDoubleAligned(int size_in_bytes) {
+AllocationResult PagedSpace::AllocateRawAligned(int size_in_bytes,
+                                                AllocationAlignment alignment) {
   DCHECK(identity() == OLD_SPACE);
-  HeapObject* object = AllocateLinearlyDoubleAlign(size_in_bytes);
+  HeapObject* object = AllocateLinearlyAligned(size_in_bytes, alignment);
   int aligned_size_in_bytes = size_in_bytes + kPointerSize;
 
   if (object == NULL) {
@@ -304,7 +312,7 @@ AllocationResult PagedSpace::AllocateRawDoubleAligned(int size_in_bytes) {
       object = SlowAllocateRaw(aligned_size_in_bytes);
     }
     if (object != NULL) {
-      object = heap()->EnsureDoubleAligned(object, aligned_size_in_bytes);
+      object = heap()->EnsureAligned(object, aligned_size_in_bytes, alignment);
     }
   }
 
@@ -321,20 +329,25 @@ AllocationResult PagedSpace::AllocateRawDoubleAligned(int size_in_bytes) {
 // NewSpace
 
 
-AllocationResult NewSpace::AllocateRawDoubleAligned(int size_in_bytes) {
+AllocationResult NewSpace::AllocateRawAligned(int size_in_bytes,
+                                              AllocationAlignment alignment) {
   Address old_top = allocation_info_.top();
   int alignment_size = 0;
   int aligned_size_in_bytes = 0;
 
   // If double alignment is required and top pointer is not aligned, we allocate
   // additional memory to take care of the alignment.
-  if ((OffsetFrom(old_top) & kDoubleAlignmentMask) != 0) {
+  if (alignment == kDoubleAligned &&
+      (OffsetFrom(old_top) & kDoubleAlignmentMask) != 0) {
+    alignment_size += kPointerSize;
+  } else if (alignment == kDoubleUnaligned &&
+             (OffsetFrom(old_top) & kDoubleAlignmentMask) == 0) {
     alignment_size += kPointerSize;
   }
   aligned_size_in_bytes = size_in_bytes + alignment_size;
 
   if (allocation_info_.limit() - old_top < aligned_size_in_bytes) {
-    return SlowAllocateRaw(size_in_bytes, true);
+    return SlowAllocateRaw(size_in_bytes, alignment);
   }
 
   HeapObject* obj = HeapObject::FromAddress(old_top);
@@ -342,12 +355,16 @@ AllocationResult NewSpace::AllocateRawDoubleAligned(int size_in_bytes) {
   DCHECK_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
 
   if (alignment_size > 0) {
-    obj = heap()->EnsureDoubleAligned(obj, aligned_size_in_bytes);
+    obj = heap()->PrecedeWithFiller(obj);
   }
 
   // The slow path above ultimately goes through AllocateRaw, so this suffices.
   MSAN_ALLOCATED_UNINITIALIZED_MEMORY(obj->address(), size_in_bytes);
 
+  DCHECK((kDoubleAligned && (OffsetFrom(obj) & kDoubleAlignmentMask) == 0) ||
+         (kDoubleUnaligned && (OffsetFrom(obj) & kDoubleAlignmentMask) != 0) ||
+         kWordAligned);

[Benedikt Meurer, 2015/05/12 09:08:39]

You really want to DCHECK kWordAligned here? Or is it a typo?

[Hannes Payer (out of office), 2015/05/12 11:14:54]

Leftover, removed.

+
   return obj;
 }
 
@@ -356,7 +373,7 @@ AllocationResult NewSpace::AllocateRaw(int size_in_bytes) {
   Address old_top = allocation_info_.top();
 
   if (allocation_info_.limit() - old_top < size_in_bytes) {
-    return SlowAllocateRaw(size_in_bytes, false);
+    return SlowAllocateRaw(size_in_bytes, kWordAligned);
   }
 
   HeapObject* obj = HeapObject::FromAddress(old_top);