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, 2 deletions

diff --git a/runtime/entrypoints/entrypoint_utils.cc b/runtime/entrypoints/entrypoint_utils.cc
index a78c2c005b..835d6e2b7e 100644
--- a/runtime/entrypoints/entrypoint_utils.cc
+++ b/runtime/entrypoints/entrypoint_utils.cc
@@ -90,7 +90,8 @@ mirror::Array* CheckAndAllocArrayFromCode(uint32_t type_idx, mirror::ArtMethod*
   gc::Heap* heap = Runtime::Current()->GetHeap();
   // Use the current allocator type in case CheckFilledNewArrayAlloc caused us to suspend and then
   // the heap switched the allocator type while we were suspended.
-  return mirror::Array::Alloc<false>(self, klass, component_count, klass->GetComponentSize(),
+  return mirror::Array::Alloc<false>(self, klass, component_count,
+                                     klass->GetComponentSizeShift(),
                                      heap->GetCurrentAllocator());
 }
 
@@ -109,7 +110,8 @@ mirror::Array* CheckAndAllocArrayFromCodeInstrumented(uint32_t type_idx,
   gc::Heap* heap = Runtime::Current()->GetHeap();
   // Use the current allocator type in case CheckFilledNewArrayAlloc caused us to suspend and then
   // the heap switched the allocator type while we were suspended.
-  return mirror::Array::Alloc<true>(self, klass, component_count, klass->GetComponentSize(),
+  return mirror::Array::Alloc<true>(self, klass, component_count,
+                                    klass->GetComponentSizeShift(),
                                     heap->GetCurrentAllocator());
 }