Workaround for gcc array bound check issue

src/heap/slot-set.h

 // 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.
 
 #ifndef V8_SLOT_SET_H
 #define V8_SLOT_SET_H
 
 #include "src/allocation.h"
 #include "src/base/bits.h"
 #include "src/utils.h"
@@ skipping 176 matching lines @@
     }
     return result;
   }
 
   void ReleaseBucket(int bucket_index) {
     DeleteArray<uint32_t>(bucket[bucket_index]);
     bucket[bucket_index] = nullptr;
   }
 
   void MaskCell(int bucket_index, int cell_index, uint32_t mask) {
-    uint32_t* cells = bucket[bucket_index];
-    if (cells != nullptr && cells[cell_index] != 0) {
-      cells[cell_index] &= mask;
+    if (bucket_index < kBuckets) {
+      uint32_t* cells = bucket[bucket_index];
+      if (cells != nullptr && cells[cell_index] != 0) {
+        cells[cell_index] &= mask;
+      }
+    } else {
+      // GCC bug 59124: Emits wrong warnings
+      // "array subscript is above array bounds"
+      UNREACHABLE();
     }
   }
 
   // Converts the slot offset into bucket/cell/bit index.
   void SlotToIndices(int slot_offset, int* bucket_index, int* cell_index,
                      int* bit_index) {
     DCHECK_EQ(slot_offset % kPointerSize, 0);
     int slot = slot_offset >> kPointerSizeLog2;
     DCHECK(slot >= 0 && slot <= kMaxSlots);
     *bucket_index = slot >> kBitsPerBucketLog2;
@@ skipping 139 matching lines @@
   };
 
   Address page_start_;
   Chunk* chunk_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_SLOT_SET_H