Generated code for substring slices in ia32.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 6c8888bf1447c2f6d3340793838c694840350ee4..53ba981c85b2f794dae8c0187be0a8aae3270964 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -496,6 +496,11 @@ STATIC_ASSERT(
 STATIC_ASSERT(
     (kSlicedStringTag & kIsIndirectStringMask) == kIsIndirectStringTag);
 
+// Use this mask to distinguish between cons and slice only after making
+// sure that the string is one of the two (an indirect string).
+const uint32_t kSlicedNotConsMask = kSlicedStringTag & ~kConsStringTag;
+STATIC_ASSERT(IS_POWER_OF_TWO(kSlicedNotConsMask) && kSlicedNotConsMask != 0);
+
 // If bit 7 is clear, then bit 3 indicates whether this two-byte
 // string actually contains ascii data.
 const uint32_t kAsciiDataHintMask = 0x08;