9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_OOPS_ARRAYOOP_HPP
26 #define SHARE_OOPS_ARRAYOOP_HPP
27
28 #include "oops/oop.hpp"
29 #include "utilities/align.hpp"
30 #include "utilities/globalDefinitions.hpp"
31
32 // arrayOopDesc is the abstract baseclass for all arrays. It doesn't
33 // declare pure virtual to enforce this because that would allocate a vtbl
34 // in each instance, which we don't want.
35
36 // The layout of array Oops is:
37 //
38 // markWord
39 // Klass* // 32 bits if compressed but declared 64 in LP64.
40 // length // shares klass memory or allocated after declared fields.
41
42
43 class arrayOopDesc : public oopDesc {
44 friend class VMStructs;
45 friend class arrayOopDescTest;
46
47 // Interpreter/Compiler offsets
48
49 private:
50 // Returns the address of the length "field". See length_offset_in_bytes().
51 static int* length_addr_impl(void* obj_ptr) {
52 char* ptr = static_cast<char*>(obj_ptr);
53 return reinterpret_cast<int*>(ptr + length_offset_in_bytes());
54 }
55
56 // Given a type, return true if elements of that type must be aligned to 64-bit.
57 static bool element_type_should_be_aligned(BasicType type) {
58 #ifdef _LP64
59 if (type == T_OBJECT || type == T_ARRAY) {
60 return !UseCompressedOops;
61 }
62 #endif
63 return type == T_DOUBLE || type == T_LONG;
64 }
65
66 public:
67 // Header size computation.
68 // The header is considered the oop part of this type plus the length.
69 // This is not equivalent to sizeof(arrayOopDesc) which should not appear in the code.
70 static int header_size_in_bytes() {
71 int hs = length_offset_in_bytes() + (int)sizeof(int);
72 #ifdef ASSERT
73 // make sure it isn't called before UseCompressedOops is initialized.
74 static int arrayoopdesc_hs = 0;
75 if (arrayoopdesc_hs == 0) arrayoopdesc_hs = hs;
76 assert(arrayoopdesc_hs == hs, "header size can't change");
77 #endif // ASSERT
|
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_OOPS_ARRAYOOP_HPP
26 #define SHARE_OOPS_ARRAYOOP_HPP
27
28 #include "oops/oop.hpp"
29 #include "runtime/globals.hpp"
30 #include "utilities/align.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // arrayOopDesc is the abstract baseclass for all arrays. It doesn't
34 // declare pure virtual to enforce this because that would allocate a vtbl
35 // in each instance, which we don't want.
36
37 // The layout of array Oops is:
38 //
39 // markWord
40 // Klass* // 32 bits if compressed but declared 64 in LP64.
41 // length // shares klass memory or allocated after declared fields.
42
43
44 class arrayOopDesc : public oopDesc {
45 friend class VMStructs;
46 friend class arrayOopDescTest;
47
48 // Interpreter/Compiler offsets
49
50 private:
51 // Returns the address of the length "field". See length_offset_in_bytes().
52 static int* length_addr_impl(void* obj_ptr) {
53 char* ptr = static_cast<char*>(obj_ptr);
54 return reinterpret_cast<int*>(ptr + length_offset_in_bytes());
55 }
56
57 // Given a type, return true if elements of that type must be aligned to 64-bit.
58 static bool element_type_should_be_aligned(BasicType type) {
59 if (EnableValhalla && type == T_PRIMITIVE_OBJECT) {
60 return true; //CMH: tighten the alignment when removing T_PRIMITIVE_OBJECT
61 }
62 #ifdef _LP64
63 if (type == T_OBJECT || type == T_ARRAY) {
64 return !UseCompressedOops;
65 }
66 #endif
67 return type == T_DOUBLE || type == T_LONG;
68 }
69
70 public:
71 // Header size computation.
72 // The header is considered the oop part of this type plus the length.
73 // This is not equivalent to sizeof(arrayOopDesc) which should not appear in the code.
74 static int header_size_in_bytes() {
75 int hs = length_offset_in_bytes() + (int)sizeof(int);
76 #ifdef ASSERT
77 // make sure it isn't called before UseCompressedOops is initialized.
78 static int arrayoopdesc_hs = 0;
79 if (arrayoopdesc_hs == 0) arrayoopdesc_hs = hs;
80 assert(arrayoopdesc_hs == hs, "header size can't change");
81 #endif // ASSERT
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