Guard calls to ByteAddr when a ByteArray copy length is 0.

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
@@ skipping 7810 matching lines @@
 }
 
 
 void ByteArray::Copy(uint8_t* dst,
                      const ByteArray& src,
                      intptr_t src_offset,
                      intptr_t length) {
   ASSERT(Utils::RangeCheck(src_offset, length, src.Length()));
   {
     NoGCScope no_gc;
-    memmove(dst, src.ByteAddr(src_offset), length);
+    if (length > 0) {
+      memmove(dst, src.ByteAddr(src_offset), length);
+    }
   }
 }
 
 
 void ByteArray::Copy(const ByteArray& dst,
                      intptr_t dst_offset,
                      const uint8_t* src,
                      intptr_t length) {
   ASSERT(Utils::RangeCheck(dst_offset, length, dst.Length()));
   {
     NoGCScope no_gc;
-    memmove(dst.ByteAddr(dst_offset), src, length);
+    if (length > 0) {
+      memmove(dst.ByteAddr(dst_offset), src, length);
+    }
   }
 }
 
 
 void ByteArray::Copy(const ByteArray& dst,
                      intptr_t dst_offset,
                      const ByteArray& src,
                      intptr_t src_offset,
                      intptr_t length) {
   ASSERT(Utils::RangeCheck(src_offset, length, src.Length()));
   ASSERT(Utils::RangeCheck(dst_offset, length, dst.Length()));
   {
     NoGCScope no_gc;
-    memmove(dst.ByteAddr(dst_offset), src.ByteAddr(src_offset), length);
+    if (length > 0) {
+      memmove(dst.ByteAddr(dst_offset), src.ByteAddr(src_offset), length);
+    }
   }
 }
 
 
 uint8_t* ByteArray::ByteAddr(intptr_t byte_offset) const {
   // ByteArray is an abstract class.
   UNREACHABLE();
   return NULL;
 }
 
@@ skipping 498 matching lines @@
   result.set_num_args_tested(num_args_tested);
   // Number of array elements in one test entry (num_args_tested + 1)
   intptr_t len = num_args_tested + 1;
   // IC data array must be null terminated (sentinel entry).
   Array& ic_data = Array::Handle(Array::New(len, Heap::kOld));
   result.set_ic_data(ic_data);
   return result.raw();
 }
 
 }  // namespace dart