Some optimizations for the array alloc path.

- Force Array::Alloc() to be inlined.
- Simplify the array size overflow check.
- Turn fill_usable into a template parameter.
- Remove a branch in Array::DataOffset() and avoid
  Primitive::ComponentSize(), which has a switch, in the array alloc
  path.
- Strength reductions in the array size computation by using component
  size shifts instead of component sizes. Store component size shift
  in the upper 16 bits of primitive_type field.
- Speedup: ~4% (3435->3284) in MemAllocTest on N4.

Bug: 9986565

Change-Id: I4b142ffac4ab8b5b915836f1660a949d6442344c

1 files changed, 4 insertions, 3 deletions

diff --git a/runtime/native/java_lang_reflect_Array.cc b/runtime/native/java_lang_reflect_Array.cc
index 058458fa39..763a6645b9 100644
--- a/runtime/native/java_lang_reflect_Array.cc
+++ b/runtime/native/java_lang_reflect_Array.cc
@@ -59,9 +59,10 @@ static jobject Array_createObjectArray(JNIEnv* env, jclass, jclass javaElementCl
     return NULL;
   }
   DCHECK(array_class->IsObjectArrayClass());
-  mirror::Array* new_array = mirror::Array::Alloc<true>(soa.Self(), array_class, length,
-                                                        sizeof(mirror::HeapReference<mirror::Object>),
-                                                        runtime->GetHeap()->GetCurrentAllocator());
+  mirror::Array* new_array = mirror::Array::Alloc<true>(
+      soa.Self(), array_class, length,
+      ComponentSizeShiftWidth<sizeof(mirror::HeapReference<mirror::Object>)>(),
+      runtime->GetHeap()->GetCurrentAllocator());
   return soa.AddLocalReference<jobject>(new_array);
 }