Introduce a base pointer field in FixedTypedArrayBase and teach GC about it

src/heap/store-buffer.cc

 // Copyright 2011 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 <algorithm>
 
 #include "src/v8.h"
 
 #include "src/counters.h"
 #include "src/heap/store-buffer-inl.h"
@@ skipping 480 matching lines @@
                 case HeapObjectContents::kTaggedValues: {
                   Address start_address = obj_address + start_offset;
                   Address end_address = obj_address + end_offset;
                   // Object has only tagged fields.
                   FindPointersToNewSpaceInRegion(start_address, end_address,
                                                  slot_callback);
                   break;
                 }
 
                 case HeapObjectContents::kMixedValues: {
-                  if (FLAG_unbox_double_fields) {
+                  if (heap_object->IsFixedTypedArrayBase()) {
+                    FindPointersToNewSpaceInRegion(
+                        obj_address + FixedTypedArrayBase::kBasePointerOffset,
+                        obj_address + FixedTypedArrayBase::kHeaderSize,
+                        slot_callback);
+                  } else if (FLAG_unbox_double_fields) {
                     LayoutDescriptorHelper helper(heap_object->map());
                     DCHECK(!helper.all_fields_tagged());
                     for (int offset = start_offset; offset < end_offset;) {
                       int end_of_region_offset;
                       if (helper.IsTagged(offset, end_offset,
                                           &end_of_region_offset)) {
                         FindPointersToNewSpaceInRegion(
                             obj_address + offset,
                             obj_address + end_of_region_offset, slot_callback);
                       }
@@ skipping 68 matching lines @@
     }
     old_buffer_is_sorted_ = false;
     old_buffer_is_filtered_ = false;
     *old_top_++ = reinterpret_cast<Address>(int_addr << kPointerSizeLog2);
     DCHECK(old_top_ <= old_limit_);
   }
   heap_->isolate()->counters()->store_buffer_compactions()->Increment();
 }
 }  // namespace internal
 }  // namespace v8