Misc

src/objects.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3709 matching lines @@
 template <typename Char>
 static inline bool CompareRawStringContents(Vector<Char> a, Vector<Char> b) {
   // Lint complains about taking sizeof a type rather than a variable.
   // That's just stupid in this case so I'm turning it off.
   const int kStepSize = sizeof(int) / sizeof(Char);  // NOLINT
   int length = a.length();
   ASSERT_EQ(length, b.length());
   int endpoint = length - kStepSize;
   const Char* pa = a.start();
   const Char* pb = b.start();
+#ifndef CAN_READ_UNALIGNED
+  // If this architecture isn't comfortable reading unaligned ints
+  // then we have to check that the strings are alingned and fall back
+  // to the standard comparison if they are not.
+  const int kAlignmentMask = sizeof(int) - 1;  // NOLINT

[Erik Corry, 2008/10/22 11:44:15]

Since you are accessing by uint32_t then that is what you should put in the
sizeof.

+  uint32_t pa_addr = reinterpret_cast<uint32_t>(pa);
+  uint32_t pb_addr = reinterpret_cast<uint32_t>(pb);
+  if ((pa_addr & kAlignmentMask) | (pb_addr & kAlignmentMask)) {

[Erik Corry, 2008/10/22 11:44:15]

!= 0

+    VectorIterator<Char> ia(a);
+    VectorIterator<Char> ib(b);
+    return CompareStringContents(&ia, &ib);
+  }
+#endif
   int i;
   // Compare blocks until we reach near the end of the string.
   for (i = 0; i <= endpoint; i += kStepSize) {
     uint32_t wa = *reinterpret_cast<const uint32_t*>(pa + i);
     uint32_t wb = *reinterpret_cast<const uint32_t*>(pb + i);
     if (wa != wb) {
       return false;
     }
   }
   // Compare the remaining characters that didn't fit into a block.
@@ skipping 2811 matching lines @@
   // No break point.
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 
 
 } }  // namespace v8::internal