[Bug libgcj/26858] NullPointerException not generated for large classes...

mckinlay at redhat dot com gcc-bugzilla@gcc.gnu.org
Mon Mar 27 18:28:00 GMT 2006



------- Comment #3 from mckinlay at redhat dot com  2006-03-27 18:28 -------
GCJ could be made to generate explicit null checks when large offsets are used.
It is probably relatively rare to have a normal object that is larger than a
page, so performance for most apps shouldn't be effected.

Note that array accesses should not need this as the "length" field will be
dereferenced first, triggering NullPointerException, assuming bounds checks are
used. I would also expect Strings should not have a problem.

Do we know who's heap exactly is mapped at such a low address? If its mapped by
Java/Boehm GC, then we can probably just fix the GC to not map things at such
low addresses (or to insert guard pages there instead).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26858



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