Apply change 4431 to trunk
Review URL: http://codereview.chromium.org/1523026
git-svn-id: http://v8.googlecode.com/svn/trunk@4432 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 3529336..c465c4d 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -143,7 +143,17 @@
InNewSpace(object, value, equal, &done);
- if ((offset > 0) && (offset < Page::kMaxHeapObjectSize)) {
+ // The offset is relative to a tagged or untagged HeapObject pointer,
+ // so either offset or offset + kHeapObjectTag must be a
+ // multiple of kPointerSize.
+ ASSERT(IsAligned(offset, kPointerSize) ||
+ IsAligned(offset + kHeapObjectTag, kPointerSize));
+
+ // We use optimized write barrier code if the word being written to is not in
+ // a large object chunk or is in the first page of a large object chunk.
+ // We make sure that an offset is inside the right limits whether it is
+ // tagged or untagged.
+ if ((offset > 0) && (offset < Page::kMaxHeapObjectSize - kHeapObjectTag)) {
// Compute the bit offset in the remembered set, leave it in 'value'.
lea(value, Operand(object, offset));
and_(value, Page::kPageAlignmentMask);