Reviewers: Erik Corry,

Description:
Fix bug in Page::GetRegionMaskForSpan.

When checking for a wrap take into account offset of the start address in the
region.

BUG=http://crbug.com/94425
TEST=test/mjsunit/regress/regress-94425.js

Please review this at http://codereview.chromium.org/7779037/

SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/

Affected files:
  M     src/spaces-inl.h
  A     test/mjsunit/regress/regress-94425.js


Index: src/spaces-inl.h
===================================================================
--- src/spaces-inl.h    (revision 9090)
+++ src/spaces-inl.h    (working copy)
@@ -155,7 +155,8 @@

 uint32_t Page::GetRegionMaskForSpan(Address start, int length_in_bytes) {
   uint32_t result = 0;
-  if (length_in_bytes >= kPageSize) {
+  static const intptr_t kRegionMask = (1 << kRegionSizeLog2) - 1;
+  if (length_in_bytes + (OffsetFrom(start) & kRegionMask) >= kPageSize) {
     result = kAllRegionsDirtyMarks;
   } else if (length_in_bytes > 0) {
     int start_region = GetRegionNumberForAddress(start);
Index: test/mjsunit/regress/regress-94425.js
===================================================================
--- test/mjsunit/regress/regress-94425.js       (revision 0)
+++ test/mjsunit/regress/regress-94425.js       (revision 0)
@@ -0,0 +1,46 @@
+// Copyright 2010 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-gc
+
+var N = 2040 - 2 + 10;
+var arr = new Array(N);
+
+gc();
+gc();
+gc();
+
+// arr is in the large object space now.
+// Write new space object into it.
+arr[arr.length - 2] = new Object;
+
+// Shift array multiple times to ensure that young
+// object crosses region boundary.
+for (var i = 0; i < 9; i++) arr.shift();
+
+// Do a GC to verify region dirty marks.
+gc();


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