src/share/vm/oops/arrayOop.cpp

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rev 2779 : 7102044: G1: VM crashes with assert(old_end != new_end) failed: don't call this otherwise
Summary: arrayOopDesc::max_array_length() should return a value that does not overflow a size_t if it is converted to bytes.
Reviewed-by: duke

@@ -22,10 +22,67 @@
  *
  */
 
 #include "precompiled.hpp"
 #include "oops/arrayOop.hpp"
-#include "oops/objArrayOop.hpp"
-#include "oops/oop.inline.hpp"
-#include "oops/symbol.hpp"
 
-// <<this page is intentionally left blank>>
+#ifndef PRODUCT
+
+#include "utilities/globalDefinitions.hpp"
+// Unit tests
+
+bool arrayOopDesc::check_overflow(BasicType type) {
+  int32_t length = max_array_length(type);
+  size_t bytes_per_element = type2aelembytes(type);
+  size_t bytes = (size_t)length * bytes_per_element + header_size_in_bytes();
+  return (bytes - header_size_in_bytes()) / bytes_per_element == (size_t)length;
+}
+
+// The old implementation of max_array_length. For 64-bit platforms the old
+// and new implementations should return the same value.
+int32_t arrayOopDesc::old_max_array_length(BasicType type) {
+   const int bytes_per_element = type2aelembytes(type);
+    if (bytes_per_element < HeapWordSize) {
+      return max_jint;
+    }
+    const int32_t max_words = align_size_down(max_jint, MinObjAlignment);
+    const int32_t max_element_words = max_words - header_size(type);
+    const int32_t words_per_element = bytes_per_element >> LogHeapWordSize;
+    return max_element_words / words_per_element;
+}
+
+bool arrayOopDesc::test_max_array_length() {
+  tty->print_cr("test_max_array_length");
+  
+  assert(check_overflow(T_BOOLEAN), "size_t overflow for boolean array");
+  assert(check_overflow(T_CHAR), "size_t overflow for char array");
+  assert(check_overflow(T_FLOAT), "size_t overflow for float array");
+  assert(check_overflow(T_DOUBLE), "size_t overflow for double array");
+  assert(check_overflow(T_BYTE), "size_t overflow for byte array");
+  assert(check_overflow(T_SHORT), "size_t overflow for short array");
+  assert(check_overflow(T_INT), "size_t overflow for int array");
+  assert(check_overflow(T_LONG), "size_t overflow for long array");
+  assert(check_overflow(T_OBJECT), "size_t overflow for object array");
+  assert(check_overflow(T_ARRAY), "size_t overflow for array array");
+  assert(check_overflow(T_NARROWOOP), "size_t overflow for narrowOop array");
+
+  // T_VOID and T_ADDRESS are not supported by max_array_length()
+
+#ifdef _LP64
+  assert(max_array_length(T_BOOLEAN) == old_max_array_length(T_BOOLEAN), "calculation changed for boolean");
+  assert(max_array_length(T_CHAR) == old_max_array_length(T_CHAR), "calculation changed for char");
+  assert(max_array_length(T_FLOAT) == old_max_array_length(T_FLOAT), "calculation changed for float");
+  assert(max_array_length(T_DOUBLE) == old_max_array_length(T_DOUBLE), "calculation changed for double");
+  assert(max_array_length(T_BYTE) == old_max_array_length(T_BYTE), "calculation changed for byte");
+  assert(max_array_length(T_SHORT) == old_max_array_length(T_SHORT), "calculation changed for short");
+  assert(max_array_length(T_INT) == old_max_array_length(T_INT), "calculation changed for int");
+  assert(max_array_length(T_LONG) == old_max_array_length(T_LONG), "calculation changed for long");
+  assert(max_array_length(T_OBJECT) == old_max_array_length(T_OBJECT), "calculation changed for object");
+  assert(max_array_length(T_ARRAY) == old_max_array_length(T_ARRAY), "calculation changed for array");
+  assert(max_array_length(T_NARROWOOP) == old_max_array_length(T_NARROWOOP), "calculation changed for narrowOop");
+#endif
+
+  return true;
+}
+
+
+#endif //PRODUCT