7110152: assert(size_in_words <= (julong)max_jint) failed: no overflow
Summary: Reduce what arrayOopDesc::max_array_length() returns to avoid int overflow
Reviewed-by: kvn, dholmes, tonyp
--- a/hotspot/src/share/vm/oops/arrayOop.hpp Wed Nov 09 23:21:00 2011 +0100
+++ b/hotspot/src/share/vm/oops/arrayOop.hpp Tue Nov 15 20:17:33 2011 +0100
@@ -110,10 +110,16 @@
assert(type >= 0 && type < T_CONFLICT, "wrong type");
assert(type2aelembytes(type) != 0, "wrong type");
- const size_t max_element_words_per_size_t = align_size_down((SIZE_MAX/HeapWordSize - header_size(type)), MinObjAlignment);
- const size_t max_elements_per_size_t = HeapWordSize * max_element_words_per_size_t / type2aelembytes(type);
+ const size_t max_element_words_per_size_t =
+ align_size_down((SIZE_MAX/HeapWordSize - header_size(type)), MinObjAlignment);
+ const size_t max_elements_per_size_t =
+ HeapWordSize * max_element_words_per_size_t / type2aelembytes(type);
if ((size_t)max_jint < max_elements_per_size_t) {
- return max_jint;
+ // It should be ok to return max_jint here, but parts of the code
+ // (CollectedHeap, Klass::oop_oop_iterate(), and more) uses an int for
+ // passing around the size (in words) of an object. So, we need to avoid
+ // overflowing an int when we add the header. See CRs 4718400 and 7110613.
+ return align_size_down(max_jint - header_size(type), MinObjAlignment);
}
return (int32_t)max_elements_per_size_t;
}