[𝘀𝗽𝗿] initial version

Created using spr 1.3.4

Author: fmayer

compiler-rt/lib/sanitizer_common/sanitizer_allocator_local_cache.h

@@ -166,7 +166,10 @@ struct SizeClassAllocator32LocalCache {
       DCHECK_GT(c->count, 0);
     }
     void *res = c->batch[--c->count];
-    PREFETCH(c->batch[c->count - 1]);
+    // By not doing pointer arithmetic, we avoid the OOB if c->count = 0.
+    // We just prefetch the previous member of the PerClass struct, which
+    // doesn't do harm.
+    PREFETCH(reinterpret_cast<uptr>(c->batch) + sizeof(c->batch[0])* (c->count - 1));
     stats_.Add(AllocatorStatAllocated, c->class_size);
     return res;
   }