[turbofan] Add comments to CodeAssembler

src/code-stub-assembler.cc

 // Copyright 2016 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.
 
 #include "src/code-stub-assembler.h"
 #include "src/code-factory.h"
 
 namespace v8 {
 namespace internal {
 
@@ skipping 754 matching lines @@
 }
 
 Node* CodeStubAssembler::AllocateJSArray(ElementsKind kind, Node* array_map,
                                          Node* capacity_node, Node* length_node,
                                          compiler::Node* allocation_site,
                                          ParameterMode mode) {
   bool is_double = IsFastDoubleElementsKind(kind);
   int base_size = JSArray::kSize + FixedArray::kHeaderSize;
   int elements_offset = JSArray::kSize;
 
+  Comment("begin allocation of JSArray");
+
   if (allocation_site != nullptr) {
     base_size += AllocationMemento::kSize;
     elements_offset += AllocationMemento::kSize;
   }
 
   int32_t capacity;
   bool constant_capacity = ToInt32Constant(capacity_node, capacity);
   Node* total_size =
       ElementOffsetFromIndex(capacity_node, kind, mode, base_size);
 
@@ skipping 1193 matching lines @@
   }
   return IntPtrAdd(
       IntPtrConstant(base_size),
       (element_size_shift >= 0)
           ? WordShl(index_node, IntPtrConstant(element_size_shift))
           : WordShr(index_node, IntPtrConstant(-element_size_shift)));
 }
 
 }  // namespace internal
 }  // namespace v8